Chemical engineering education

http://cee.che.ufl.edu/ ( Journal Site )
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Title:
Chemical engineering education
Alternate Title:
CEE
Abbreviated Title:
Chem. eng. educ.
Physical Description:
v. : ill. ; 22-28 cm.
Language:
English
Creator:
American Society for Engineering Education -- Chemical Engineering Division
Publisher:
Chemical Engineering Division, American Society for Engineering Education
Publication Date:
Frequency:
quarterly[1962-]
annual[ former 1960-1961]
quarterly
regular

Subjects

Subjects / Keywords:
Chemical engineering -- Study and teaching -- Periodicals   ( lcsh )
Genre:
serial   ( sobekcm )
periodical   ( marcgt )

Notes

Citation/Reference:
Chemical abstracts
Additional Physical Form:
Also issued online.
Dates or Sequential Designation:
1960-June 1964 ; v. 1, no. 1 (Oct. 1965)-
Numbering Peculiarities:
Publication suspended briefly: issue designated v. 1, no. 4 (June 1966) published Nov. 1967.
General Note:
Title from cover.
General Note:
Place of publication varies: Rochester, N.Y., 1965-1967; Gainesville, Fla., 1968-

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Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
oclc - 01151209
lccn - 70013732
issn - 0009-2479
sobekcm - AA00000383_00162
Classification:
lcc - TP165 .C18
ddc - 660/.2/071
System ID:
AA00000383:00162


This item is only available as the following downloads:

Rowan University, C. Stewert Slater, Robert P. Hesketh, James A. Newell, Stephanie Farrell, Zenaida Otero Gephardt, Mariano J. Savelski, Kevin D. Dahm, Brian G. Lefebvre ( PDF )

Alice Gast of the Massachussetts Institute of Technology, Channing R. Robertson, Kenneth A. Smith ( PDF )

Speaking of Everything-II, Richard M. Felder ( PDF )

Micromixing Experiments in the Introductory Chemical Reaction Engineering Course, Kevin D. Dahm, Robert P. Hesketh, Mariano J. Savelski ( PDF )

Decision Analysis for Equipment Selection, J.J. Cilliers ( PDF )

An Automated Distillation Column for the Unit Operations Laboratory, Douglas M. Perkins, David A. Bruce, Charles H. Gooding, Justin T. Butler ( PDF )

Using Mathematica to Teach Process Units: A Distillation Case Study, Maria G. Rasteiro, Fenando P. Bernardo, Pedro M. Saraiva ( PDF )

Incorporating Molecular and Cellular Biology into a ChE Degree Program, Kim C. O'Connor ( PDF )

Cooperative Work that Gets Sophomores on Board, Charles H. Gooding ( PDF )

Building Molecular Biology Laboratory Skills in ChE Students, Melanie McNeil, Ludmila Stoynova, Sabine Rech ( PDF )

A Simple Classroom Demonstration of Natural Convection, Dean R. Wheeler ( PDF )

Computer Science or Spreadsheet Engineering? An Excel/VBA- Based Programming and Problem Solving Course, Daniel G. Coronell ( PDF )

The Paradox of Papermaking, Martin A. Hubbe, Orlando J. Rojas ( PDF )

The Potato Cannon: Determination of Combustion Principles for Engineering Freshmen, Hazel M. Pierson, Douglas M. Pice ( PDF )

Community-Based Presentations in the Unit Ops Laboratory, Brian S. Mitchell, Victor J. Law ( PDF )

Making Room for Group Work: Teaching Engineering in a Modern Classroom Setting, Robert J. Wilkens, Amy R. Ciric ( PDF )

( PDF )


Full Text








EDITORIAL AND BUSINESS ADDRESS:
Chemical Engineering Education
Department of Chemical Engineering
University of Florida Gainesville, FL 32611
PHONE and FAX: 352-392-0861
e-mail: cee@che.ufl.edu

EDITOR
Tim Anderson

ASSOCIATE EDITOR
Phillip C. Wankat

MANAGING EDITOR
Carole Yocum

PROBLEM EDITOR
James O. Wilkes, U. M1/. 1/, I" ,

LEARNING IN INDUSTRY EDITOR
William J. Koros, G ... -.,, Institute of Technology


-PUBLICATIONS BOARD

CHAIRMAN
E. Dendy Sloan, Jr.
Colorado School of Mines

MEMBERS
Pablo Debenedetti
Princeton University
Dianne Dorland
Rowan University
Thomas F. Edgar
University of Texas at Austin
Richard M. Felder
North Carolina State University
Bruce A. Finlayson
University of Washington
H. Scott Fogler
University of Michigan
Carol K. Hall
North Carolina State University
William J. Koros
Georgia Institute of Technology
John P. O'Connell
University of Virginia
David F. Ollis
North Carolina State University
Ronald W. Rousseau
Georgia Institute of Technology
Stanley L Sandler
University of Delaware
Richard C. Seagrave
Iowa State University
C. Stewart Slater
Rowan University
Donald R. Woods
McMaster University


Chemical Engineering Education

Volume 39 Number 2 Spring 2005


D DEPARTMENT
82 Rowan University,
C. Stewert Slater Robert P Hesketh, James A. Newell, Stephanie
Farrell, Zenaida Otero Gephardt, Mariano J. Savelski, Kevin D.
Dahm, Brian G. Lefebvre

> EDUCATOR
88 Alice Gast of the Massachusetts Institute of Technology,
( is. ....... R. Robertson, Kenneth A. Smith

> RANDOM THOUGHTS
93 Speaking of Everything-II, Richard M. Felder
> CLASSROOM
94 Micromixing Experiments in the Introductory Chemical Reaction
Engineering Course,
Kevin D. Dahm, Robert P Hesketh, Mariano J. Savelski
100 Decision Analysis for Equipment Selection, J.J. Cilliers
116 Using Mathematica to Teach Process Units: A Distillation Case Study,
Maria G. Rasteiro, Fernando P Bernardo, Pedro M. Saraiva
134 Building Molecular Biology Laboratory Skills in ChE Students,
Melanie McNeil, Ludmila Stoynova, Sabine Rech
138 A Simple Classroom Demonstration of Natural Convection,
Dean R. Wheeler
156 The Potato Cannon: Determination of Combustion Principles for
Engineering Freshmen, Hazel M. Pierson, Douglas M. Price
160 Community-Based Presentations in the Unit Ops Laboratory,
Brian S. Mitchell, Victor J. Law
164 Making Room for Group Work: Teaching Engineering in a Modem
Classroom c II hi. R.obert J. Wilkens, Amy R. Ciric

> LABORATORY
104 An Automated Distillation Column for the Unit Operations Laboratory,
Douglas M. Perkins, DavidA. Bruce, Charles H. Gooding, Justin T
Butler

> CURRICULUM
110 Drawing the Connections Between Engineering Science and Engineering
Practice, Faith A. Morrison
124 Incorporating Molecular and Cellular Biology into a ChE Degree
Program, Kim C. O'Connor
142 Computer Science or Spreadsheet Engineering? An Excel/VBA-Based
Programming and Problem Solving Course, Daniel G. Coronell
146 The Paradox of Papermaking, Martin A. Hubbe, Orlando J. Rojas

> CLASS AND HOME PROBLEMS
128 Cooperative Work that Gets Sophomores on Board, Charles H. Gooding


122 Call for Papers


CHEMICAL ENGINEERING EDUCATION (ISSN 0009-2479) is published quarterly by the Chemical Engineering
Division, American Society for Engineering Education, and is edited at the University of Florida. Correspondence
regarding editorial matter, circulation, and changes of address should be sent to CEE, Chemical Engineering Department,
University of Florida, Gainesville, FL 32611-6005. Copyright 2005 by the Chemical Engineering Division, American
Society for Engineering Education. The statements and opinions expressed in this periodical are those of the writers and not
necessarily those of the ChE Division, ASEE, which body assumes no responsibility for them. Defective copies replaced if
notified within 120 days of publication. Write for information on subscription costs and for back copy costs and availability.
POSTMASTER: Send address changes to Chemical Engineering Education, ChemicalEngineeringDepartment., University
of Florida, Gainesville, FL 32611-6005. Periodicals Postage Paid at Gainesville, Florida and additional post offices.


Spring 2005










]f department


Rowan


University


C. STEWART SLATER, ROBERT P. HESKETH, JAMES A. NEWELL, STEPHANIE FARRELL,
ZENAIDA OTERO GEPHARDT, MARIANO J. SAVELSKI, KEVIN D. DAHM, AND BRIAN G. LEFEBVRE
Rowan University Glassboro, New Jersey 08028


n recruiting Rowan's faculty and the first class of stu-
dents, the Founding Dean, James H. Tracey, said, "Build
it and they will come. "-it was built, and they came!
Doors were opened to engineering students in 1996, and the
first class graduated in 2000. Today, Rowan University's un-
dergraduate chemical engineering program is ranked third in
the nation by U.S. News and World Report's "2005 America's
Best Colleges." This success can be attributed to the dedica-
tion and talent of the faculty, the high quality of its students,
and its state-of-the-art facilities. The faculty have pioneered
an innovative curriculum for students at Rowan that spans
the engineering disciplines and is characterized by a "hands-
on, minds-on" approach to engineering education.

THE ROWAN GIFT
Rowan University's origins are as a teacher's college, and
today it is still a leader in producing education majors for the
state of New Jersey. Since its founding in 1923 as Glassboro


Normal School, Rowan has had two major events of interna-
tional significance. The first was in June of 1967 when Presi-
dent Lyndon Johnson and Soviet Primer Aleksei Kosygin held
the first summit between the U.S. and the Soviet Union-a
meeting that led to a thaw in the cold war. The second event
occurred in June of 1992 when Henry and Betty Rowan gave
$100 million to Glassboro State College-the largest contri-
bution to a public university at that time. He gave this gift for
the purpose of starting an "outstanding" engineering school
to better serve the students of the southern New Jersey re-
gion. The institution was subsequently renamed in honor of
the Rowans, and it achieved university status in 1997.
Planning for the new and innovative engineering program
began in 1993 with the formation of a National Advisory
Council, a group of prominent engineers from around the
country. Then in 1994, the founding Dean, James Tracey, was
hired and joined Zenaida Otero Gephardt, who served as As-
sistant Dean to this fledgling enterprise. In 1995, C. Stewart


Chemical Engineering Education










Slater became the founding chair of chemical engineering,
and new faculty was hired every succeeding year until it
reached a complement of eight full-time faculty in 2000. Rob-
ert Hesketh, who joined the faculty in the fall of 1996, be-
came chair in 2004. The first class graduated in May of
2000 and the department received accreditation by ABET
the following year (retroactive to the first class). Dianne


Dorland became Dean of the College of En-
gineering in 2000.
Stewart Slater was an enthusiastic and ener-
getic chair, traits that were essential in creating
a new chemical engineering program. He be-
lieved engineering education should be trans-
formed and he knew that if given a chance, he
could lead Rowan's chemical engineering de-
partment into anew and exciting future. The syn-
ergy among the Rowan faculty, as a result, is
cohesive and has produced one of the best un-
dergraduate programs in the country.
Today, Rowan University has more than 9,500
students in 36 undergraduate majors, 26 master's
degree programs, and a doctoral program in edu-
cational leadership. The College of Engineer-
ing offers bachelor and master of science de-
grees from the departments of chemical, civil
and environmental, electrical and computer, and
mechanical engineering. There are currently 112
chemical engineering undergraduate majors and
12 graduate students.
Rowan is a selective, medium-sized state uni-
versity located in southern New Jersey between
Philadelphia and Atlantic City. The region is an


the teamwork approach to problem solving, emphasis on com-
munication skills, hands-on laboratories and modem com-
puter tools, safety and environmental issues, economics and
entrepreneurship, and industrial partnerships.

ENGINEERING CLINICS
The most innovative and unique feature of the engineering


Doors were
opened to
engineering
students
in 1996,
and the
first class
graduated
in 2000. Today,
Rowan
University's
undergraduate
chemical
engineering
program is
ranked third
in the
nation...


eclectic mix of suburban and rural areas, and the home county
of Gloucester is one of the fastest growing counties in the
state. The average class size in chemical engineering is 14
and the student/faculty ratio is 10 to 1. All classes are taught
by professors, which provides for an excellent student-cen-
tered learning environment.

ACTIVE LEARNING
AND A PROJECT-BASED CURRICULUM
"Tell me and If' ... i. show me and I may remember, but
involve me andI understand," a quote attributed to the states-
man-inventor Benjamin Franklin, is a fundamental philoso-
phy of the department. Students are involved in the learning
process from the first day of the program. They participate
through in-class cooperative problem solving, experiments
and demonstrations, computer exercises, and small-scale and
semester-long projects. This is accomplished through a cur-
riculum that blends the fundamental chemical engineering
knowledge with applications, design, and research in many
of the emerging fields of tkceli.i .-1.. The hallmarks of the
College of Engineering include a project-based curriculum,


curriculum is the engineering clinic sequence.
Loosely modeled after the medical school ap-
proach to teaching (first used in engineering by
Harvey Mudd College), the eight-semester se-
quence gives students a real engineering expe-
rience on the very first day of their freshman
year and culminates in a major project experi-
ence in their junior and senior years. Each sec-
tion of the engineering clinic sequence involves
students from all four of the engineering disci-
plines, and many of the clinic projects are funded
by industry and faculty research grants.
The Rowan program was one of the first in
the country to focus on providing a one-year
freshman experience with engineering experi-
mentation, multidisciplinary teamwork, and
communication skills. In the fall semester, stu-
dents conduct experiments from each of the four
engineering disciplines to learn about engineer-
ing measurements and to become familiar with
engineering in general. Many innovative experi-
ments have been developed in chemical engi-
neering. For example, a fluidized bed polymer
coating experiment introduces basic chemical
engineering concepts by using a fluidized bed


to demonstrate polymer coating and heat transfer, and a drug
delivery experiment shows students some basic principles,
such as rate control in the delivery of modem medicines. Stu-
dents have even visited the campus cogeneration plant to ex-
amine the measurement techniques used in the production of
steam and electricity for the campus. In the spring semester,
students reverse-engineer a process or product-examples in-
clude an automatic drip coffee maker, a beer-brewing pro-
cess, and the human body. The beer production project has
been one the most popular projects; students start the semes-
ter investigating the brewing process and finish by designing
a new brewing process.
The Sophomore Clinic is a unique integrated course where
professors in college writing and public speaking teach com-
munication concepts through the use of an engineering project.
These multidisciplinary design projects have focused on the
design, optimization, and economic analysis of a baseball sta-
dium, a NASA Mars mission, recycling, a stair climber for
the disabled, a bridge design, and microbial fuel cells.
The Junior and Senior Clinics are the most ambitious part
of the program. There, multidisciplinary teams (3-4 students


Spring 2005










on a team) work on real-world, Student at i io
open-ended projects in various bimproce.-ing andn
areas that are linked to industry bit, areaI re'earc
or to a grant from a state or fed- R
eral agency. The majority of
()ne ral the nlrst popula
these projects run for an entire e r*ppui
the load product ldeeln
year (two semesters) and involve lab i, here student cran
applied research, development, and te-t their product'..
or design that solves some par-
ticular engineering problem. Li
These projects emanate from a
particular discipline, are led by
that department's faculty, and
typically involve an industrial
mentor. The teams are matched
by faculty project managers to
achieve the best results in indi-
vidual projects. Teams may com-
bine various fields of expertise
within a classical discipline (such
as biochemical and polymer in
chemical .1 hillul ill. or com-
bine other disciplines (such as
science, business, and other en-
.ii1lin-i as may be appropri-
ate to the project goals. Students
are required to meet weekly with a faculty advisor and/or
an industrial mentor for project updates, they must write
a final report or a paper/journal publication, and they must
present an oral report at the end of each semester.
A recent Junior/Senior Clinic project involved evaluation
of novel separation processes for recovery of precious met-
als from process streams, sponsored by Johnson Matthey, Inc.
The student team was composed of chemical engineering and
chemistry students. The project outcomes included a litera-
ture review, critical analysis of equipment potential, ex-
perimental testing, modeling and verification, and eco-
nomic process analysis. The results of the project were
incorporated in the processing plant. Such association of
students and industrial partners has often led to full-time
jobs as well as internships.
Another interesting Clinic partnership came as a result of
the department's interaction with the Pillsbury division of
General Mills. Pillsbury sponsored several Clinic projects for
improvement and optimization of its dough line processes.
One project focused on the analysis of raw materials, the sec-
ond project optimized a process line, and the third investi-
gated wastewater minimization.
These projects also provide student teams with an oppor-
tunity to perform research that is more typically associated
with graduate students and encourages them to pursue ad-
vanced degrees. Work on high-performance polymers and
composites, done in the Clinics under the supervision of James


rk in the
Related
h lab at
ran (in. >
r lab( i'
ppment
create


I


A i- Ilazea oea( er polymer coraing
experiment in the Jreshnlan clinic.


Newell, has resulted in four papers being published in peer-
reviewed technical literature, and five of his undergraduate
students have gone on to graduate study.

ChE-FOCUSED COURSES
The chemical engineering curriculum consists of the four-
year engineering clinic sequence summarized above, coupled
with a unique combination of chemical engineering subjects.
Examination of the course names will reveal many of the
core subjects, such as material and i iL balances, fluid,
heat, mass transfer, and thermodynamics, but these courses
are not typical chemical engineering courses. Imagine trying
to remove 14 credit hours from 131 credit hours, or more
importantly 36 contact hours from the curriculum, to make
room for a multidisciplinary project-based engineering clinic
sequence! At Rowan, however, it has been proven that it is
possible to make major changes in the chemical engineering
curriculum. The process of transforming traditional chemi-
cal engineering courses began with the founding chair, Stewart
Slater, and the curriculum continued to be evaluated and trans-
formed as each new faculty member was hired. This process
continues today through biannual evaluation meetings and
involves in-depth participation of each of the eight faculty
members. The faculty members evaluate the content of each
course at meetings that last one to two days, and as a result,
new and innovative topics have been integrated throughout
the curriculum. Subjects and courses have been removed as


Chemical Engineering Education










Grant' from the \SF ha e funded lab experiment' in nne el
areas 1uch a( thi< re erne on',ir' membrane i

The high bal labipratipr\. I tI industrial proce"e' 'ruch a. a 2.--lt dlitillation column l
and a specialty chemical pilet plant. V

^j I'1*B iS^"H


well as added, constantly improving the curriculum. The pro-
cess that is now in place allows the department to continually
transform the curriculum to better prepare engineers for the
future. The ability to constructively evaluate and make these
changes is directly attributed to the good working relation-
ship between all chemical engineering faculty members.
Departmental faculty have also been successful in work-
ing with other colleges to reshape and improve traditional
math, science, and general education courses, e.g., the ex-
ample of the sophomore clinics given above in which stu-
dents are instructed by both communications faculty and en-
gineering faculty on how to effectively communicate their
results. In working with the biological science faculty, a new
required course, "Biological Systems and Applications," has
been created that integrates microbiology and other life sci-
ence topics into the sophomore year. There has also been co-
operation with the chemistry and math departments in creat-
ing unique courses for engineering students.

ROWAN'S IMPACT ON ChE EDUCATION
The Rowan department is influencing chemical engineer-
ing education by sharing its innovations with other educators
through publication, presentations, and workshops. It has re-
ceived numerous grants from the National Science Founda-
tion, the U.S. Environmental Protection Agency, and the State
of New Jersey to innovate the curriculum and to discover
how engineering students really learn.
For example, one of the NSF grants funded membrane ex-
periments for the unit operations course as well as smaller-


* *)

1 ~


1 '.1 Il i Illh l \ l l hI I I-Ifflleach
liil llC .\110IIIhI N -I m IIIII.ld mi-








ilig iliLU ilhC clituillul d lu disslenllt ate
been strong advocates of a interactive classroom with coop-
IIL .'ihlllln t.h illl Il.I ,iiiiulwl. .& %.0 w ith
NN ,II N ii 1.1 .\ IIIIiP lA n ndi 1.- hi, hl l. din-
t,,t.p lk l I .111%] Nhil .Iil.b L Lnll-,llleer-
ill1 ilnto lit cUl'licululll anld tu di ,lllimate
this to many other schools. The faculty have
been strong advocates of an interactive classroom with coop-
erative learning, experiments and demos, and unique learn-
ing methods. James Newell has developed a game-show class-
participatory project using Hollywood Squares and Survivor
to help students learn about material science and chemical
principles, and the plant-design course has used a "business
meeting" concept involving College of Business faculty and
engineers from industry to review student design presenta-
tions. Kevin Dahm has taught process economic analysis with
interactive economic simulation as a semester-long project.
Zenaida Gephardt is leading the incorporation of experimen-
tal design in the curriculum.
The department has been a leader in developing assess-
ment tools designed to address ABET criteria. This work has
expanded through NSF funding to use profiles of student-
learning preferences to develop metacognition in engineer-
ing students and to improve their performance in teams.
Bio and pharmaceutical engineering focused innovations
have occurred at many levels in Rowan's chemical engineer-
ing labs and courses. Stephanie Farrell has been a pioneer in
invigorating the Freshman Engineering Clinic with bioengi-
neering experiments-rug delivery system testing, "Hands
on the Human Body" biomedical experiments, and brewing-
process investigations, etc. Food product and process engi-
neering has been a recent theme of the department. As a first
step in response to the regional emphasis on food processing,
Mariano Savelski developed a course that integrates applied
food engineering coursework and food chemistry experi-
ments. This course provides students with skills directly rel-


Spring 2005






























IM
The Rowan Chemical Engineering team: left to right, Susan Patterson,
Zenaida Otero Gephardt, Brian G. Lefebvre, Kevin D. Dahm, Robert
P. Hesketh, C. Stewart Slater, Mariano J. Savelski, Marvin Harris, James
A. Newell, and Stephanie Farrell.

evant to the evolving needs of the food processing industry.
Rowan faculty have not only taught students in an innovative way, but have
also helped improve the process of how chemical engineering is taught. In 1998,
Stewart Slater and Robert Hesketh received funding from the NSF to conduct
two workshops for other chemical engineering faculty on novel process science
and engineering principles. The ASEE Summer School for Chemical Engineer-
ing Faculty and AIChE meetings have had Rowan leadership in workshops
focusing on communication skills, assessment, experiential and inductive learn-
ing, and green engineering. Through these workshops, faculty at other schools
have been impacted, and the Rowan innovations are now being used in educat-
ing chemical engineering students across the country. The faculty have also
ventured into other parts of the world to spread the "Rowan way," as invited
speakers at conferences and universities in Argentina, Australia, Brazil, Canada,
Chile, China, Czech Republic, Mexico, Norway, Spain, and the United Kingdom.

STATE-OF-THE-ART FACILITIES
Henry M. Rowan Hall is the home of Rowan's Engineering College. This
$29 million engineering building, completed in 1998, is equipped with the lat-
est chemical engineering equipment and instrumentation. The 95,000 ft2 build-
ing is designed to facilitate problem-based leaning with classrooms integrated
with fully equipped modem laboratories. The high-bay facility and food prod-
uct development lab (as well as the instructional and research laboratories) have
pilot-scale equipment such as: an advanced distillation system designed for
education with a 25-ft high column with full computer control; a specialty chemi-
cal pilot plant for the manufacture of flavors, fragrances, and other unique prod-
ucts; a reverse-osmosis system for water reuse and recovery in chemical pro-
cessing; a climbing film evaporator that was used in pharmaceutical produc-
tion; a supercritical fluid extraction system for the recovery of nutraceutical
products; and clinical-grade cardiorespiratory, pulmonary function, and meta-
bolic testing equipment. In addition to many other chemical engineering appara-
tus, these laboratories are supported by state-of-the-art analytical instrumentation.

FACULTY LEADERSHIP
Faculty members are leaders in chemical engineering education. Because of


TABLE 1
Rowan's Chemical Engineering Team
U Robert P Hesketh, Professor and Chair
BS, University of Illinois; PhD, University of Delaware
Reaction engineering Novel separation processes
U Dianne Dorland, Professor and Dean
BS, MS, South Dakota School of Mines; PhD,
University of West Virginia
Green engineering Management
] James A. Newell, Profesor
BS, Carnegie-Mellon University; MS, Pennsylvaia State
University; PhD, Clemson University
Polymer science and engineering
U C. Stewart Slater, Professor
BS, MS, Rutgers University; PhD, Rutgers University
Membrane separations
U Kevin D. Dahm, Associate Professor
BS, Worcester Polytechnic Institute; PhD, Massachusetts
Institute of Technology
Reaction kinetics Process modeling
U Stephanie Farrell, Associate Professor
BS, University of Pennsylvania; MS, Stevens Institute;
PhD, New Jersey Institute of Technology
Controlled release I .
technology
U Zenaida Otero Gephardt, Associate Professor
BS, Northwestern University; MS, University of
Delaware; PhD, University of Delaware
Experimental design Particle technology
U Mariano J. Savelski, Associate Professor
BS, University of Buenos Aires; ME, University of
Tulsa; PhD, University of Oklahoma
Design for pollution prevention Foodprocess
technology Supercritical fluids
] Brian G. Lefebvre, Assistant Professor
BE, U. of Minnesota; PhD, University of Delaware
Biomolecular and protein engineering *
Bioseparations
" Marvin Harris, Process Technician
] Susan Patterson, Secretary


Chemical Engineering Education










their varied backgrounds and prior experience, the Rowan
team is well-respected by its peers in both scholarly and tech-
nical pursuits. Many of the faculty have received national
awards and recognition. Four (Stephanie Farrell, Robert
Hesketh, James Newell, and Stewart Slater) have received
the Dow Outstanding New Faculty Award, and four (Kevin
D. Dahm, Stephanie Farrell, Robert Hesketh, and James
Newell) have been recognized with the Ray W. Fahien Award
of ASEE. ASEE's Joseph J. Martin Award has been given to
Rowan faculty four times, and James Newell and Kevin Dahm
have won a PIC-III best paper award. In 2004, Stephanie
Farrell was selected to receive ASEE's National Outstanding
Teaching Medal, while Robert Hesketh was recently given
ASEE's Robert G. Quinn award, recognizing his distinguished
accomplishments in experiential education. Stewart Slater has
received such honors as ASEE Fellow Member status, and
the George Westinghouse, John Fluke, and Chester Carlson
awards for innovation in engineering education.
Faculty have also assumed leadership roles in professional
societies, most notably the Dean of the College of Engineer-
ing, Dianne Dorland, was President of AIChE. Robert Hesketh
and Stephanie Farrell have chaired the Undergraduate Edu-
cation group of AIChE, and Robert helped create the AIChE
National Chem-E-Car competition and has been its emcee.
Stewart Slater has chaired the Chemical Engineering and
Experimentation and Laboratory-Oriented Studies Divi-
sions of ASEE. Mariano Savelski has also chaired the
Division for Experimentation and Laboratory-Oriented
Studies, and Stephanie Farrell is Chair of the Mid-Atlan-
tic Section of ASEE.

AWARD-WINNING STUDENTS
In the Department's short history, it students have distin-
guished themselves in many ways. When they start their ca-
reer at Rowan, they have already passed through selective
admissions requirements resulting in average SAT scores of
1240 and high school class ranking in the top 86 percentile.
Every Rowan student works on multidisciplinary teams of
students that are closely supervised by faculty, and many of
these students have presented their work and won awards at
regional and national meetings.
Students have obtained internships and full-time employ-
ment in a wide variety of companies in the pharmaceutical,
food, chemical, petrochemical, and materials t liin, b, h',- ar-
eas. They have been accepted into leading graduate programs
at a variety of universities such as Delaware, Princeton,
Clemson, Virginia Tech, Lehigh, Massachusetts, and Colo-
rado State. In addition to pursuing advanced study in chemi-
cal engineering, students have gone on to graduate business
schools and several have entered medical school.

INDUSTRIAL PARTNERSHIPS
Another unique characteristic of the Rowan chemical en-

Spring 2005


gineering program is its strong partnership with industry. Ever
since it was founded, there was the belief that a program with
active involvement in industry would be a win-win situa-
tion for industry, faculty, and students alike. Its location
in the New Jersey, Pennsylvania, and Delaware tri-state
region has been an asset since many of the well known
(and less well known) names in the field are located within
a couple hours drive.
Partnerships with the department have developed in many
ways. Involvement in the clinic program provides the most
intimate interaction and has led to numerous successful
projects. According to our industrial advisors, students who
engage in an industrial clinic project and participate in an
industrial summer internship program compare favorably to
graduates with full-timejob experience. For example, Johnson
Matthey, Inc., the world's leader in precious metals process-
ing, initially sponsored scholarships for the first engineering
class in 1996. It has gone on to hire students for both part-
time and full-time jobs and has provided continuous spon-
sorship of clinic projects since 1998.
Industry has also helped shape the curriculum. The de-
partment has sought industry input for the program's ob-
jectives, curriculum, and assessment efforts though its
Chemical Engineering Industrial Advisory Board. It also
routinely looks to industry for guest lecturers and adjunct
faculty.

FUTURE DIRECTIONS
The College of Engineering continues to develop its pro-
grams in undergraduate education, particularly through the
engineering clinics, and innovation in educational delivery.
The delivery of experiential education will benefit from a
new Tcli .iil .'. Park that will house significant clinic ac-
tivities in conjunction with developing tllin cl 1-, ventures.
Tenants of the Park will have access to the research, develop-
ment, and commercialization expertise of the Rowan Uni-
versity engineering and business faculty.
External research and development funding from federal,
state, and private sources to the College and Department has
increased, fueled primarily by engineering's strength in its
outreach to industry. The chemical engineering faculty ob-
tained over a half million dollars in external funding last year.
Many of these grants are in multidisciplinary areas of bio-
thl llih.y, 1.nlichllil -hvy, advanced materials,
sustainability, and engineering p] d.-., -.'.
Chemical engineering has always been a dynamic field and
while universities must adapt to the shifting marketplace, the
department will not waver from its focus on producing skilled
problem solvers who are capable of functioning in teams on
diverse projects that expand beyond a single discipline, and
who can effectively communicate their findings to many dif-
ferent audiences. Our commitment to developing these new
engineers remains steadfast! -









educator
--- ----e________________________________-


Alice

of the
Massachusetts Institute of Technology


CHANNING R. ROBERTSON
Sit, i 1i University Sif, i-. 1. CA 94305-5025
KENNETH A. SMITH
Massachusetts Inst. of Tech. Cambridge, MA 02139


A lice P. Gast wanted to be a scientist ever since she
was a little girl visiting her father's biochemistry
laboratory. She almost diverged to become an ar-
cheologist at one point, and at another time an aptitude
test told her to become an auto mechanic, but she went on
to find the right home for her talents in chemical engineer-
ing. A ChemE since her freshman year in college, Alice
says she loves the field and the collegiality of the commu-
nity. What she didn't foresee, however, was that she would
eventually become an academic administrator-a job she
now finds even more challenging and rewarding.
As Associate Provost and Vice President for Research
at MIT, Alice holds one of the more interesting, impor-
tant, and complex positions in American academic admin-
istration. The position reports to MIT's Provost, Robert A.
Brown, and to President Susan Hockfield. It is Alice's re-
sponsibility to advise them on matters of research policy.
Diverse policy issues in areas such as research integrity,
intellectual property, international student visas, and the
terms of research agreements are continuously evolving
and require Alice's attention and influence. She also views
her job as being a "champion of interdisciplinary research,"
and she can think of no better place to promote it than in
the vibrant research environment of MIT. Reflecting on
how she got this "dream job" she says that one thing sim-
ply led to another.

PERSONAL BACKGROUND
The seeds of scientific curiosity were planted early in
Alice's life when she would go to her dad's lab and look at
pictures from his electron microscope. Later, she found


Gast


that being in junior high school was made tolerable by a circle
of studious and like-minded friends ... as well as by joining a
track team. She says that growing up in California made "beach
runs" de ; i;. ,1 and that it was easier to be a serious student
when one was a jock and a nerd at the same time. She remem-
bers one time that she was embarrassed by her high school his-
tory teacher when a picture showing her executing a long-jump
appeared in the local paper. He said "I could tell it was Alice
because she is sitting down and her eyes are closed!" (Alice
says she was simply honing that important academic talent of
sleeping through lectures!)


Copyright ChE Division ofASEE 2005


Chemical Engineering Education






































E --T:-- ,

Top: Family visit to Paris for Stanford
chemical engineering colleague Michel
Boudart's 80th birthday.

Above: Alice and fellow chemical
engineer Chip Zukoski are longtime
friends and Gordon Conference tennis
partners.

Alice and cold-weather friend, a new
challenge for a California girl.

Beloved bi-coastal family pet, Stumpy.

Below: Alice's Stanford research group
and kids gather at her Massachusetts
home during a trip to set up Alice's MIT
lab in February of 2003.


Spring 2005


Later, at USC, Alice enjoyed the flexibility of the pro-
gram they offered, the excellent teachers there, and under-
graduate research opportunities that abounded. She took
.. courses in chemical engineering, chemistry, music, and
history-and met Brad Askins, the boy next door. Brad was a
history major at the time (another good influence) but later
became a computer scientist. Alice says he has always been a
source of inspiration for her. Another bonus is that she has
her own technical support person in Brad and is thus able to
gain insight into complex computer issues that are outside of
her area of expertise.
Alice and Brad moved to
Princeton for grad school, experienced
living with snow for the first time,
adopted their cat, Stumpy, and found
close friends to share their lives and
ambitions with, friends like Chip
Zukoski and Barbara Morgan. During
this period, Alice also tremendously en-
joyed conducting research with her men-
Stors Bill Russel and Carol Hall.
Later, a year in Paris as a postdoc
turned into a great adventure and made
serious Francophiles out of both Alice
and Brad. She has since returned to
France several times for sabbatical stays
and more recently has spent time in Ger-
many as a Humboldt Fellow. She relishes
Sthe opportunity to return to Europe from
time to time to conduct research or to
transact Institute business and to sharpen
her language skills.
Alice claims that her most effective
training for university administration
was in negotiating with her kids, Rebecca and David,
when they were about four and two, respectively. At
those ages, neither of them wanted to stay at a
daycare facility in the morning and took a bit of on-
site coaxing to accept the situation each day-but
Alice was always quite anxious to leave before any
of the other kids took the opportunity to decorate
her attire with paint or sticky food. She found that the best
approach was to "redirect" the kids attention so that they found
something really interesting in the room, and thinking it was
their own discovery, became engaged and forgot all about
not wanting to stay. Alice says the same approach is true when
you can get your colleagues to adopt a new and challenging
idea and make it their own, truly engaging them-then you
have done something worthwhile.
,/ Now that their kids are eight and ten, Alice and Brad find
themselves enjoying recitals, soccer games, cross-country ski-
ing, and biking adventures. The whole family is fortunate
that Brad has a flexible work schedule and can shuttle the
89










Below: Press conference announcing the establishment of the Institute for
Soldier Nanotechnologies (ISN) at MIT, Also pictured from the left are
Provost Robert Brown, Dean of Engineering Thomas Magnanti, ISNDirector
Edwin Thomas, and Chemical Engineering Professor Paula Hammond.

Left: At work and at play-Alice is shown lecturing at a conference in
Les Houches, France, and in a more relaxed setting
exploring the tidepools in Baja, California.


kids to the various activities they take part in. Family hikes and camping trips
are the highlights of the year and take a high priority in the scheme of things.

THE STANFORD DAYS
Alice arrived in the chemical engineering department at Stanford to begin her
academic career in late 1985 after returning from France, where she spent a year
as a NSF NATO Postdoctoral Fellow at the Ecole Superieure de Physique et de
Chimie Industrielles in Paris. She had been vigorously recruited by several uni-
versities and her champions at Stanford felt fortunate to have won the battle.
During her sixteen years at Stanford, Alice established a world-wide reputa-
tion in the area of polymer solutions, colloidal dispersions, and interfacial be-
havior of proteins. She displayed an uncanny knack for developing and apply-
ing sophisticated tools to probe the intricacies of these complex systems, and
often used statistical mechanics to interpret her experimental results. She was
able to reveal the connections between molecular behavior and macroscopic
manifestation in polymeric micelles, colloidal and protein crystallization pro-
cesses, and polymer and protein adsorption phenomena in ways that were both
foundational and revolutionary.
To accomplish all of this, Alice had a certain magnetism that allowed her to
attract the best available PhD students into her group. Her ability to mentor and
guide students through the highs and lows of doing research is legendary. It has
been claimed that students were also attracted to her group meetings, which
featured fine French cheeses, water crackers, home
made bread, and even, on occasion, some fine wine. And one cannot forget the
many parties that she and Brad hosted at their home. Indeed, everyone looked
forward to a celebration at the Gast household following another successful PhD
defense by one of her students (she has had thirty PhD students in all). She was
sometimes assisted by her colleague, Channing Robertson, who would enter-
tain the kids with his reenactment of "the claw"-something he pulled from
a grade-B horror movie. It is fair to say that Alice's research group was a
"family" of sorts, and created an atmosphere in which the very best was
coaxed from the minds of many talented students.


Alice was among the most popular teach-
ers in the Stanford department. Her style was
engaging and she set a high bar for the stu-
dents. She loved to involve them in projects.
Her "animal guts" project made the reactor
design course much more interesting and
entertaining for the students and offered nu-
merous open-ended design problems for
them to tackle. She would have the students
demonstrate the fruits of their labor at a pre-
sentation for the entire department. Some-
times they cooked "gumbo" for their post-
final party (following Alice's family recipe,
not the one in the excellent text by Scott
Fogler). To recognize her efforts, Alice re-


Chemical Engineering Education












As Associate Provost and Vice President for Research at MIT,
Alice holds one of the more interesting, important, and complex positions
in American academic administration.


ceived a Camille and Henry
Dreyfus Teacher Scholar
Award and was honored as Pro-
fessor of the Year by Stanford's
Society of Women Engineers.
Alice's research accomplish-
ments did not go unnoticed for
long. In 1992 she received two
prestigious awards-the Allan
P. Colburn Award from the
AIChE and the NationalAcad-
emy of Science Award for In-
novative Research. As could be
expected, Alice found herself
in great demand to give plenary
talks, to organize conferences, Alice in the role
and to serve on government New York's Cent
panels. She did all these things
with enthusiasm, but was al-
ways able to strike a balance
between her family and her passion for research and teach-
ing. Her fellow teachers viewed her as an extraordinary and
remarkable faculty colleague in every sense of the word.

As Stanford began to embark on a bold new interdiscipli-
nary research enterprise, dubbed Bio-X, she was pegged by
her colleague, Channing Robertson, to play a key role in the
design process for the James H. Clark Center, the focal point
for the effort. In so doing she worked with Sir Norman Fos-
ter, the primary architect, as well as a multitude of faculty
and administrators, to bring about Stanford's showcase cross-
disciplinary enterprise. It was a daunting task, given the num-
ber of stakeholders involved, and a divergence of opinion
soon arose as to how the project should go forward. Alice
deserves much credit for her ingenuity and the leadership she
provided during those exhilarating, yet trying, times. As a
result of the project, Stanford is positioned to play a leader-
ship role in redefining the way in which multidisciplinary
research is conducted in the future. Alice's legacy in this re-
gard will never fade, and the Stanford community is forever
indebted to her.

As if her plate were not full enough, Alice somehow found
time to work with the late Arthur Adamson (in the chemistry
department at her alma mater, USC) in helping to revise the
latest edition of the famous textbook, Physical Chemistry of
Surfaces. It was a common sight at Stanford to see Alice re-
turn to campus after her kids were tucked away at home, burn-


ral
ral P


ing the midnight candle well
into the next day as she toiled
on revision after revision of
the book. It was none other
than a monumental labor of
love for her. Because of her
effort, generations of students
will now have the benefit of
her wisdom and her keen
ability to communicate diffi-
cult topics in an understand-
able and palatable fashion.
Alice's days at Stanford
were full of joy, discovery,
some failures, and many suc-
ourist, posing with cesses. All of her colleagues
ark as a backdrop. there remember them well.
Alice is missed in ways that
her colleagues find difficult
to express and feel that MIT is incredibly fortunate to have
such a treasure in its midst.

THE MOVE TO MIT
Alice was difficult to uproot from Stanford, her California
home. One day, in early 2001 her fellow chemical engineer,
Bob Brown, the MIT Provost, called her to discuss the possi-
bility of potential new challenge for her-that of Associate
Provost and Vice President for Research at MIT. After re-
flecting seriously and at length about her love of graduate
education and research, she decided to take the plunge into
academic administration and accepted the challenge. Alice
says that "It has been a wonderful ride and I am very grateful
that such an opportunity arose."
Alice found that some of the interesting issues that have
always motivated her emerge in a totally unpredictable fash-
ion and intersect with the government and industrial commu-
nities. She found she had to actively work with government
and academic groups to improve the visa processes for inter-
national students and scholars. She has also been engaged in
defending the ability of universities to freely publish their
fundamental research results and to openly collaborate with
students and colleagues from abroad. Because Washington is
the source of both opportunities and problems for university
research, and because all universities are subject to a similar
set of opportunities and obstacles, Alice is frequently a par-
ticipant in Washington activities of various sorts.


Spring 2005










In addition to policy issues, Alice enjoys being respon-
sible for and promoting interdisciplinary research at MIT. The
intellectual span of these interdisciplinary activities is con-
siderable, ranging from the Plasma Science and Fusion Cen-
ter to the Computational and Systems Biology Initiative, to
the Institute for Soldier Nanotechnologies.
In her oversight of important labs and centers, Alice brings
the same talent as a supportive mentor that has always been
evident in her interactions with students. She enjoys having
the opportunity to work with laboratory directors in making
their programs even more vibrant and exciting. Alice also
enjoys meeting the critics and sponsors of the labs, centers,
and programs she oversees, and communicating the Institute's
support and appreciation for them. She is always willing to
provide liaison with sponsors or to help a lab develop an ex-
citing new program.
Alice says the best part of her job is the opportunity to
encourage new initiatives and to nurture new efforts. Although
every situation is different, they often require that she as-
semble just the right combination of people with just the right
intellectual skills to address the opportunity at hand, making
sure they have the interpersonal skills that will lead to rapid
development of a cohesive team. She is comfortable remain-
ing in the background and allowing the team to determine its
own destiny, providing enthusiastic support when it is needed.
A good example of this process is the Institute for Soldier
Nanotechnologies at MIT. This was MIT's response to a RFP
from the Army, which promised a five-year grant at the level
of $10M/year. As one might expect, competition was intense
and many good proposals were submitted. One requirement
of the proposal was creation of a new facility-and Alice and
a team of faculty and project managers designed and con-
structed one in record time. She was at ease functioning as
the project manager, balancing the budget while at the same
time ensuring that the research needs of the program, faculty,
and students were not compromised. Alice's support and col-
legiality during this process led to a great sense of accom-
plishment and satisfaction among her team members, who
expressed their appreciation and their willingness to join her
in any future endeavors.
Another of Alice's areas that draws on her breadth of ex-
perience is the Office of Tcihliii ,h1' Licensing. Alice has
worked hard to balance the interests of faculty, who receive
compensation for the intellectual property that they generate,
and the needs of the university, which provided the support-
ive environment and which actually owns and licenses the
IP. She remarks that a few years ago, she "learned a lot about
intellectual property from some very smart lawyers during
an interesting consulting experience."
One of Alice's challenges is working to keep the university
and the funding communities focused on the proper role of
university research as a vehicle for the education of young


people. In addition, there is a fine line between research and
development. In times of tight budgets or international eco-
nomic tension, there is often the tendency to push university
researchers toward technology development problems, just
to "help out." But, as Alice points out, "All you end up doing
is diminishing basic research at a time when industry and the
country need it most."
All of this may seem to be a major departure from her
former activities as a teacher and scholar, but Alice views her
research interests as interdisciplinary and she credits her
mentors Bill Russel and Carol Hall with teaching her to ap-
ply concepts from one field to other areas. Her work at
Stanford in helping to design the Clark Center and working
with the Materials Center and the Synchrotron Laboratory
were experiences that she has been able to draw on many
times since arriving at MIT. Alice comments that she is al-
ways surprised to find how important past experiences and
things learned along the way can be, and usually in unex-
pected ways. Her experience as an investigator at Stanford's
Synchrotron Radiation Laboratory has come in handy more
than once in working with some of MIT's laboratories, espe-
cially when some of the lab's investigators are not aware of
her background.
Alice's diverse experiences have also served her well in
her work on behalf of international students and scholars.
She gained valuable experience from her postdoctoral year
in Paris working on fluid mechanics or something like it, as
well as from the better part of a year (split over several trips)
spent working on biophysical issues in Munich, as an
Alexandar Von Humboldt Awardee. Not only did these expe-
riences give her a first-hand understanding of what it is like
to be a researcher in a foreign country dealing with different
cultures and government systems, but she also made a num-
ber of close contacts who can now share insights on what it is
like to deal with the U.S. Government when they come over
here on international collaborations.
Among her varied activities, Alice values most the days
she spends with her research group in the Landau building at
MIT. There she can work with talented undergraduate, gradu-
ate, and postdoctoral students and think about science and
development of their research projects. She has always viewed
her students as her best research "products" and has been
fortunate to work with the best.
All in all, Alice says she loves MIT and cannot think of a
better place to be working as an advocate for research and
interdisciplinary collaborations. "MIT is just this most amaz-
ing place," Alice is fond of saying, usually after discovering
another area of fascinating research. Alice goes on, "MIT is
probably one of the few places on the planet where my fam-
ily would rather come in and meet me on a Friday night, to
see something like a student robot competition, than have me
come home to them." 7


Chemical Engineering Education











Random Thoughts...





SPEAKING OF EVERYTHING II



RICHARD M. FIELDER
North Carolina State University Raleigh, NC 27695


> There is always an easy solution to every human prob-
lem-neat, plausible, and wrong. H.L. Mencken
D The problem is not that there are problems. The problem
is expecting otherwise and thinking that having problems
is a problem. Theodore Rubin
- If you had to identify, in one word, the reason why the
human race has not achieved, and never will achieve,
its full potential, that word would be "meetings."
Dave Barry
P I went to a restaurant that serves "breakfast at any time."
So I ordered French Toast during the Renaissance.
Steven Wright
- Do unto yourself as your neighbors do unto themselves,
and look pleasant. G. -.-. Ade
- I went to a bookstore and asked the saleswoman, "Where's
the self-help section?" She said if she told me, it would
defeat the purpose. G.. -. Carlin
- Every prayer reduces itself to this: Great God, grant that
two plus two not equal four. Ivan Tin, .. ,. i
- The intellect of man is forced to choose
Perfection of the life, or of the work WB. Yeats
- Students achieving oneness will move ahead to twoness.
Woody Allen
- Middle age is having a choice between two temptations
and choosing the one that'll get you home earlier. *
Dan Bennett
- 42.7 percent of all statistics are made up on the spot. *
Steven Wright
- The causes we know everything about depend on causes
we know very little about, which depend on causes we
know absolutely nothing about. Tom Stoppard
- Buying the right computer and getting it to work prop-
erly is no more complicated than building a nuclear reac-
tor from wristwatch parts in a darkened room using only
your teeth. Dave Barry


> Hemingway said a long time ago-and I subscribe to it-
that a smart writer quits for the day when he's really steam-
ing, when he knows it's good and knows where it's go-
ing. If you can do that, you've fought half the next day's
battle. James Michener
D How can I know what I think until I see what I say?
WH. Auden
- From the moment I picked your book up until I put it
down I was convulsed with laughter. Some day I intend
reading it. Groucho Marx
- If a politician tells you he's going to make a "realistic
decision," you immediately understand that he's resolved
to do something bad. Mary McCarthy
- The whole aim of practical politics is to keep the popu-
lace in a continual state of alarm (and hence clamorous to
be led to safety) by menacing them with an endless series
of hobgoblins, all of them imaginary. H.L. Mencken
- A fanatic is a man who does what he thinks the Lord would
do if he knew the facts of the case. Finley Peter Dunne
- I have had a perfectly wonderful evening, but this wasn't
it. Groucho Marx
- Having a dog teaches a boy fidelity, perseverance, and
to turn around three times before lying down.
Robert Benchley
- My esteem in this country has gone up substantially. It is
very nice now that when people wave at me they use all
their fingers Jimmy Carter
- I intend to live forever. So far, so good. Steven Wright

Richard M. Felder is Hoechst Celanese Pro-
fessor Emeritus of Chemical Engineering at
North Carolina State University. He received his
t BChE from City College of CUNY and his PhD
9 from Princeton. He is coauthor of the text El-
S ementary Principles of Chemical Processes
(Wiley 2000) and codirector of the ASEE Na-
tional Effective Teaching Institute.


Copyright ChE Division ofASEE 2005


Spring 2005












classroom


MICROMIXING EXPERIMENTS

In the Introductory Chemical Reaction Engineering Course




KEVIN D. DAHM, ROBERT P. HESKETH, MARIANO J. SAVELSKI
Rowan University Glassboro, NJ 08028-1701


n practice, the issue of mixing and chemical reactions is
very important in the economic aspects of chemical re-
action engineering. A major priority in industrial reac-
torsE1" is to optimize the yield of desired products. This opti-
mization is a function of reactor geometry, the chemical and
physical characteristics of the reacting system, the degree of
mixing, and the mode of supplying the reactor with reagents.
Bourne and GablingerE21 have shown how process chemistry
developed in the laboratory can go awry when scaled to in-
dustrial reactors. An excellent example of the classic series-
parallel reaction using an azo dye chemistry is presented by
Bourne and Gholap.E31 A chemist working on a bench scale
will optimize this reaction to obtain very high reaction rates
for the desired reaction. In the industrial scale reactor, micro-
mixing becomes a limiting factor, negatively impacting the
process chemistry.[4]

As EtchellsE51 noted, however, a typical undergraduate re-
actor design course focuses on ideal reactors. In the chapter
on multiple reactions in the standard chemical reaction engi-
neering text by Fogler,E61 it is assumed that the reactions are
slow compared to the mixing of species. The classic examples
for parallel reactions and series reactions are given, but these
examples do not cover the basic concept of micromixing with
respect to the reactants. It is only in the final chapter of this
text that the concept of micromixing is introduced, and the
presented mathematical theory is relatively complex for un-
dergraduates.

Idealized reactor models provide an excellent framework
for a conceptual introduction to reaction engineering and re-
actor design, but they can be easily misused. In attempting to
use ideal reactor models for the azo dye system, for example,
one would overlook the impact of mixing on the reaction ki-
netics and on the formation of trace byproducts. A thorough
treatment of the modeling of micromixing is beyond the scope


of the introductory undergraduate chemical reaction engineer-
ing course, but the experiments described in this paper pro-
vide a qualitative and quantitative demonstration of the sig-
nificance of the mixing effect and the limitations of the ide-
alized reactor models, with minimal time investment.

Baldyga and BourneE71 summarize a number of experimen-
tal examples of product distributions sensitive to mixing. Ex-
amples of parallel or competitive reactions include Diazo


Kevin D. Dahm is Associate Professor of
Chemical Engineering at Rowan University He
received his PhD in 1998 from Massachusetts
Institute of Technology and his BS in 1992 from
Worcester Polytechnic Institute. Prior to join-
ing the faculty of Rowan University, he served
as anAdjunct Professor of Chemical Engineer-
ing at North Carolina A& T State University and
a postdoctoral researcher at the University of
California at Berkeley.


Robert P Hesketh is Professor of Chemical
Engineering at Rowan University. He received
his BS in 1982 from the University of Illinois
and his PhD from the University of Delaware
in 1987. After his PhD, he conducted research
at the University of Cambridge, England.
Robert's teaching and research interests are
in reaction engineering, green engineering,
and separations.

Mariano J. Savelski is Associate Professor of
Chemical Engineering at Rowan University He
received his BS in 1991 from the University of
Buenos Aires, his ME in 1994 from the Univer-
sity of Tulsa, and his PhD in 1999 from the
Universityof Oklahoma. His technical research
is in the area of process design and optimiza-
tion. His prior academic experience includes
two years as Assistant Professor in the Math-
ematics Department at the Universityof Buenos
Aires, Argentina.


@ Copyright ChE Division ofASEE 2005


Chemical Engineering Education











coupling with simultaneous reagent decompositionE81 and lo-
date/iodine reaction with neutralization.E1l Examples of par-
allel-series reactions or competitive-consecutive reactions
include Diamines with isocyantes or other acylating agents,
nitrations of dibenzyl, durene, and alkyl benzenes and diazo
couplings. The experiments described in this paper involve
this pair of parallel competitive reactions, carried out in an
aqueous solution:

H2BO +H+ H3BO3 (1)

51- +03 +6H- 3I2 +3H20 (2)

The first reaction is essentially instantaneous, and can be
modeled as an equilibrium reaction with K = 1.38 x 106 at
ambient conditions.E10'11 The second reaction is essentially
irreversible, with a rate that is first order in concentration of
10, second order in I- and second order in H+. The rate con-
stant has been modeled as a function of the ionic strength of
the solution9,10]1 and at the conditions of this reaction, k2 ~ 3.6








LItd-


Figure 1.

2-L reactor
with
Lightnin
mixer.


x 10 M-4sec-'. Thus the second reaction is fast, but orders of
magnitude slower than the first reaction. So when H+ is added
as the limiting reagent, a perfectly mixed system would pro-
duce essentially no 1,. Production of a significant quantity of
12 is attributed to a local excess of H+; a condition in which all
H2BO, in a region is consumed and H+ remains to react with
I- and IO1-.
Any 2I formed in solution will react further with I-

12 +1I- I (3)
The concentration of the 13I ion can be measured accurately
with spectrophotometry and Beer's law. Thus, the yield of
reaction 2 is readily determined. Consequently, this reaction
was deemed suitable for an undergraduate experiment be-
cause it meets several important criteria:

E The reagents are readily available, cheap, and
reasonably safe, with water acting as the solvent.
E Quantitative results can be obtained with a fairly
simple analytical method.
E The kinetics of both reactions have been studied.l9 I
E Imperfect mixing has an c:ttr, t on product distribution
that is ,i,. ;. l, f. ..... I to quantify and explain.
E Finally, the iodine formed in solution has a ,i l / ..
yellow color. This is a perk compared to a solution
that remains transparent l,,.... /,. .,it the reaction
because the solution appears to be homogeneous.
The yellow color grows darker as the reaction
progresses but appears uniform at any given time.
The fact that ...... it,;,,. can be well mixed macro-
scopically but poorly mixed on a molecular level is
an important take-home message of this experiment.

The experiment was integrated into a junior course on
chemical reaction engineering in the Spring 2003 semester.
The remainder of this paper describes the experimental ap-
paratus itself, provides sample results, discusses the integra-
tion of the experiment into the course, and gives the results
of a short quiz that was administered to assess the impact of
the experiment.

APPARATUS
A team of Rowan undergraduate students designed and as-
sembled the apparatus and developed an experimental pro-
cedure as an Engineering ClinicE121 project. There are two dis-
tinct experimental setups: one uses a 2-L reactor with baffles
and a Lightnin Mixer (shown in Figure 1) and the other uses
an ordinary 600-mL beaker with a magnetic stirring bar. In
the first setup, a syringe pump is used to add the limiting
reagent, sulfuric acid, at a controlled, known rate. In the sec-
ond setup an Eppendorf pipet is used to add the acid all at
once. Both experiments require stock solutions as summa-
rized in Table 1. The purpose of the sodium hydroxide is to
neutralize a portion of the boric acid, so that the H2BO, ion


Spring 2005


TABLE 1
Reagent Stock Solutions

Reagent Concentration (mol/I) MW (g/mol)
HBO3 0.606 61.83
NaOH 1.0 40.0
KIO3 0.0233 214
KI 1.167 166
H2SO4 0.50 98.04











will be present with a concentration of 0.02 mol/L when
the addition of sulfuric acid begins.

EXPERIMENTAL PROCEDURE
The impeller speed of the mixer is the parameter that
was varied, spanning the range outlined in Figure 3. The
experimental procedure developed for the Lightnin
Mixer is as follows:

1) Fill reactor with the 1080ml of DI water.
2) Add 225ml of the HBO3 solution.
3) Add 30ml of the NaOH solution.
4) Add 150ml of the KIO3 solution.
5) Start mixer at 500 rpm (regardless of
desired experimental speed) and allow
solution to mix thoroughly.
6) Add 15ml of the KI solution. Let solution
mix for several minutes to insure homoge-
neity.
7) Reset mixer to experimental speed.
8) Inject 10 ml of the sulfuric acid solution
with the syringe pump, at a rate of 50 mL/
hr.
9) After injection is complete, wait approxi-
mately 2 minutes (to insure homogeneity of
the solution) then turn off mixer.
10) Take samples from various points in the
reactor.


Because the first reaction is essentially instantaneous
and the second essentially irreversible,(9,101 the compo-
sition does not change in the two minutes after the addi-
tion of acid is completed, but the mixing in step 9 en-
sures that the samples taken will be representative of
the solution as a whole.
The procedure for the beaker-stirring bar system is
analogous. The total solution volume 300 mL rather than
1.5 L as in the Lightnin Mixer but the proportions of the
reagents used are the same. The analysis of samples was
completed using a Spec220, with the following proce-
dure:


1) Set the wavelength to 353nm, the sensitivity
to high, and the mode to Absorbance.
2) Fill one quartz cuvet with DI water and set the
absorbance of this control sample to zero.
3) Take 1 mL of sample using Eppendorf pipet
and inject into 10-mL volumetric flask. Fill
the remainder of the 10-mL volume with DI


water (mix well).
4) Pour the diluted sample into a quartz cuvet. Take to
Spec220 and read the absorbance (reading should be
between 0 and 1.999; if not, change the dilution as
needed.)

DATA ANALYSIS
A calibration curve relating 13- concentration to absorbance is shown
in Figure 2. The 13- concentration is quantified by applying Beer's
law

A
C =A (4)
13 Et

The 2I and I- concentrations can then be deduced from the follow-
ing known equilibrium relationship for reaction (3): 13]

Log(Ke) = 555 /T(K) + 7.355- 2.575 Log[T(K)] (5)

Thus, one can deduce the extent of reaction 2, and by applying stan-
dard chemical reaction engineering principles of species balances and


1.E-04
,-J
8.E-05
E
6.E-05
o
.2
S4.E-05

c 2.E-05
.E+
O.E+00


Absorbance


Figure 2. Calibration curve for I; ion concentration.


2
*5 30

S20

10

0


0 200 400 600 800 1000 1200
Impeller Speed (RPM)

Figure 3. Effect of increased mixing on selectivity of
reaction 1 to reaction 2.


Chemical Engineering Education


U U
A
A
A


* A Lightnin Mixer A Beaker/Stir Bar










equilibrium relationships, one can compute the amounts of
the added H+ that were consumed by reactions 1 and 2, re-
spectively. These fractions are a function of the rate of mi-
cro-mixing.
The product distribution can be quantified using the same
method as Guichardon and Falk,E101 in which
two limiting conditions are identified:
Perfect Mixing in which the system
acts like the perfectly mixed CSTR
familiar to the students from early in the exp
reaction engineering course. In this de
system, the yield of reaction 2 is
insignificant under perfect mixing. in th
Total S. ... v, i. i, describes a system in pr
which micro mixing is infinitely slow, qualil
so both reaction rates are essentially qua
instantaneous by comparison. In this
situation the rates of reaction 1 and 2 demo
will be in proportion with the local o
concentrations of H2BO3 and I-, and signij
independent of the kinetic rate constants
of the reactions.
effect
Guichardon and Falk characterize the sys- e
tem by dividing the total volume of the reac- limit
tor into a "perfectly mixed volume" VM and the i
a "totally segregated volume" VTS. The react(
"micromixedness ratio," a, is defined as VM/ with
VTS. Details of calculating a for this system
are given in their paper.E101 The calculation of time il
a, however, was deemed beyond the scope
of the one-period introduction to
micromixing presented in this paper. Instead,
the more familiar selectivity was used to quantify the results,
and the total segregation and perfect mixing models were
presented qualitatively as an explanation for the disparity
between observed and predicted selectivity.
Selectivity throughout this paper is defined as:

moles H+consumed by reaction 1 (6)
moles H+ consumed by reaction 2
Figure 3 shows the selectivity vs. impeller speed for both
experimental setups. Note that in both cases an increase in
impeller speed leads to an increase in selectivity. This obser-
vation helps demonstrate to the students that poor mixing is
indeed the reason for the discrepancy between prediction and
observation.
The two experiments were carried out with different vol-
umes to demonstrate the relationship between scale and mix-
ing, which was cited in the introduction to this paper as a
major motivation for teaching micromixing. The larger-scale
experiment used a better impeller, a vessel with baffled walls,
and a slow, controlled rate of addition of the limiting reagent,
Spring 2005


all factors that are known to produce better mixing. Quanti-
tative modeling of the effects of these differences is possible
with, for example, the E model of inhomogeneous turbu-
lence.E6] While such a theoretical treatment is again beyond
the scope of this module, students readily agree that qualita-
tively, the larger reactor is better designed to achieve good
mixing. The data show, however, that the
selectivity curves are in fact very similar
he for the two experimental setups, because
the increase in scale offsets the benefits
nents gained from using better equipment.
bed
aper CLASSROOM USE OF
le a MICROMIXING EXPERIMENT
ve and The Spring 2002 offering of chemical
active reaction engineering included one 75-
minute class period devoted to
ration micromixing. The topics discussed in this
e period were:
Since Of E[ Why mixing rates and reaction rates can
xing be interrelated
nd the l Qualitative coverage of the concepts of
perfect mixing and total segregation
ons of E The "perfectly mixed" and "totally
lized .. i. .. reactor models.
models, At the conclusion of this period, the in-
nimal structor explained that real reactors could
Stent. be modeled as a combination of a "perfectly
mixed" volume and a "totally segregated"
volume. The purpose of this class period
was to illustrate the shortcomings of the


idealized reactor models that had been used throughout the
semester. The presentation was in a lecture format and used
sample data produced with POLYMATH, 141 but had no ex-
perimental component.
During the Spring 2003 semester, the course included a
100-minute period devoted to micromixing. The topical cov-
erage was the same as in the 2002 session, but this time, the
experiment was integrated. Students were first shown the pair
of competitive reactions and the initial composition of the
reactor (excluding the H,2SO). The rate expression for reac-
tion 2, as discussed in the introduction section, is

r2 =k2[H+]2[I-]2[IO3] (7)
The rate expression for reaction 1 was presented as

r = k([H+][H2BO ]-[H3B03]/K) (8)

with K, = 1.38 x 106 and k = 101. (The value of k, is not
important so long as it is set sufficiently high that the reac-
tion is in effect modeled as an instantaneous equilibrium re-
action.)


. tf
erin
scri
is '
)vi
Wati
ntit
nst
f tl
ica
mi
t a
ati
dec
or n
mi
nve










A common teaching technique used throughout this course
was for the instructor to pose a problem and then challenge
the students to derive model equations describing the sys-
tem. Once this was completed, the instructor would distribute
handouts showing a POLYMATH solution of the equations.
In this case, the applicable design equation from Folger's
textE6] is the semibatch equation

dCB vO(BO -CB) (
dt rB + (9)
dt V
in which the addition term is 0 for all species except the acid,
which is added gradually as the limiting reagent. When si-
multaneous species balances for the reaction system described
here were solved, the selectivity was 3800.
The students next proceeded to the laboratory, where the
setup (steps 1-7) for an experiment with the Lightnin mixer
had already been completed. Students recognized this as a
semibatch reactor-a mixed vessel with all reactants initially
present except for one that was slowly added. When the ad-
dition of acid was started, the solution immediately turned
yellow-ualitative evidence that iodine was present in sig-
nificant quantities. The experiment and sample analysis was
completed as a demonstration. The demonstration ended with
the calculation of the overall selectivity, which was on the
order of 101.
The instructor then presented the data shown in Figure 3,
saying "the experiment we just did would be one point on
this graph." The data show that the baffled reactor with the
Lightnin mixer provides a slightly higher selectivity (despite
the larger scale) than an unbaffled beaker with a stir bar, and
in both setups the selectivity of reaction 1 increases as the
impeller speed increases. Both observations are evidence that
mixing influences the reaction kinetics.
The instructor then continued with a discussion of
micromixing and the "perfectly mixed" and "totally segre-
gated" models that had also been presented in the Spring of
2002. This model allows quantitative prediction of selectivi-
ties,E1 but the calculations were beyond the intended scope of
this one-period introduction. Consequently, the ideas of per-
fect mixing and total segregation were presented as qualita-
tive explanations of why mixing influences the kinetics of
fast reactions.
It is important to note that in both 2002 and 2003, the topi-
cal coverage of the introduction to micromixing was the same,
and in both years students were responsible for the material
and there was a 10-point question on micromixing on the
final exam. The only difference in the presentations was the
use of an experimental demonstration in the second year. The
rest of the course was also substantially the same in both years
and used the same syllabus and Fogler's book as the text.
In the spring of 2004, micromixing was not covered at all
in the chemical reaction engineering course. In this offering
of the course (and in the previous two years), students were


responsible for the derivation of the CSTR design equation
on the first exam, so students were exposed to the
assumptions, including perfect mixing, behind the equation.
In order to provide a contrast with previous years, however,
micromixing was not covered through lecture or lab.

ASSESSMENT OF EXPERIMENT
The anecdotal feedback on the micromixing experiment
was favorable. Students appreciated seeing the real equip-
ment and expressed surprise that a system that qualitatively
looked well-mixed behaved so differently from an ideal re-
actor. The primary goal, however, was to prevent future mis-
use of the idealized reactor models by illustrating their short-
comings. In an attempt to assess the effectiveness of this, in
September of 2002, 2003, and 2004, the following question
was included in a non-graded "assessment quiz" that was ad-
ministered to the senior classes.
Our specialty chemical pilot plant includes a reactor that
is a -20-L kettle with a steam-heating jacket and an
agitator You are asked to model the reactor and a
classmate has suggested using the CSTR design equation
that you learned in chemical reaction engineering last
spring. Is this appropriate? If your answer is "yes or
"no," explain why, and if it is "maybe," explain what
factors it depends upon.
There were three other questions on the quiz, covering
Bernoulli's equation, vapor pressures and dew points. The
students were told that the quiz was intended to assess reten-
tion of concepts from the junior year, but were not told there
was a specific agenda of assessing the micromixing experi-
ment. For each class this quiz was unannounced, was closed-
book with no preparation of any kind, and was administered
five months after the conclusion of the chemical reaction
engineering course.


TABLE 2
Student Responses to Whether or Not It is Appropriate to
Use CSTR Design Equation for 20-L Agitated Reactor

Date "Yes" "No" Il ,.. "
September 2002 4 0 17
September 2003 1 0 14
September 2004 4 1 11



TABLE 3
Factors Cited by Students Who Responded "Maybe"

Date Steady-State or Not Mixing
September 2002 13 4
September 2003 12 5
September 2004 7 0


Chemical Engineering Education












While a thorough coverage of mixing and chemical kinetics is beyond the scope of most
introductory chemical reaction engineering courses, this experiment introduces
students to the field and illustrates the limitations of the
idealized reactor models.


The student responses to this question are summarized in
Tables 2 and 3. All three years, most students said "maybe,"
with some mention of whether the process was "continuous"
or "steady-state," (as opposed to "batch or semi-batch") be-
ing most commonly cited as the determining criteria. The
fraction of students, however, who specifically mentioned
"perfect mixing" in their response increased from 19% (4 of
21) to 33% (5 of 15) in the second year, and was zero for the
2004 control group, who were not exposed to micromixing.
The students who answered "yes," in all cases used the ratio-
nale that because the reactor has an agitator, it must be a
CSTR-exactly the sort of error that this introduction to
micromixing was intended to prevent. The number of stu-
dents who responded this way dropped from 19% (4 of 21)
to 7% (1 of 15) the second year, and was 23% (4 of 17) in the
control group.
A Chi-squared analysis of the differences between the three
classes cited in the last paragraph was performed. This
showed:
E The second class (lecture and lab) performed better
on the quiz than the first (lecture only) class but the
improvement was not statistically *.;.-,;f. ,,t at 95%
i.., t,. 1, ,. (p~0.3).
E The first class (lecture only) performed better than
the control .,i. *,,ii This ,ili. ,. was also not
statistically ...,i,;;,. ,1,i at 95% confidence (p~0.1).
E The ,in,,. .. between the second class (lecture
and lab) and the control ..,' was statistically
..r.-,,i, ,,, i to (p~0.02).
Thus, the quiz indicates that an introduction to micromixing
achieved the goals of improving retention and illustrating the
limitations of the idealized reactor models, but no statistical
conclusion can be drawn regarding whether the improvement
was primarily attributable to the lecture, the lab, or both.


SUMMARY AND CONCLUSIONS

The traditional chemical reaction engineering course is
taught using idealized reactor models, such as the CSTR and
the PFR models, with little discussion of mixing. This paper
presents a micromixing experiment and its use in an intro-
ductory chemical reaction engineering course. While a thor-
ough coverage of mixing and chemical kinetics is beyond
the scope of most introductory chemical reaction engineer-
ing courses, this experiment introduces students to the field
and illustrates the limitations of the idealized reactor models.
A quiz was administered to the students five months after

Spring 2005


the course was completed. The results suggested that an in-
troduction to micromixing using this experiment is helpful
for illustration and retention of the concepts.

ACKNOWLEDGEMENTS
Support for the laboratory development activity described
in this paper was provided for by a grant (DUE- 0088501)
from the National Science Foundation through the Division
for Undergraduate Education. The authors gratefully acknowl-
edge the following undergraduate students who contributed
to this project: Robert McKeown, Andrew Dunay, David
Urban, Danielle Baldwin, William Engisch, and Shaun
Rendall.

REFERENCES
1. Belkhiria, S., T.Meyer, A.Renken, "Study of Micromixing in Poly-
merization Reactions and Its Application in Experimental Copolymer-
ization," in Industrial Mixing Technology: Chemical and 1.' I
Applications, E.L.Gaden, Jr., G.B.Tatterson, R.V.Calabrese,
W.R.Penney, eds., AIChE Symp. Ser., Vol. 90, No. 299 (1994)
2. Bourne, J.R., H. Gablinger, "Local pH Gradients and the Selectivity
of Fast Reactions. II. Comparisons Between Model and Experiments,"
Chem. Eng. Sci., 44(6), 1347 (1989)
3. Bourne, J.R., R.V. Gholap, "Approximate Method for Predicting the
Product Distribution of Fast Reactions in Stirred-Tank Reactors,"
Chem. Eng. J. and Biochem. Eng. J., 59(3), 293 (1995)
4. Baldyga, J., J.R. Bourne, S.J. Hearn, "Interaction Between Chemical
Reactions and Mixing on Various Scales," ( .. i. Sci., 52(4), 457
(1997)
5. Etchells, A., "Notes on Mixing in the Process Industries: Lecture and
Short Course Material," DuPont USA, Wilmington, DE (1998)
6. Fogler, H. Scott, Elements f 1 '... ,- i, .. i ... ... 3rd ed.,
Prentice Hall PTR, New Jersey (1999)
7. Baldyga, J., and J.R. Bourne, Turbulent Mixing and Chemical Reac-
tions, John Wiley & Sons, Chichester (1999)
8. Nienow A.W., S.M. Drain, A.P. Boyes, R. Mann, A.M. E1-Hamouz,
and K.J. Carpenter, "A New Pair of Reactions to Characterise Imper-
fect Macromixing and Partial Segregation in a Stirred Semi-Batch
Reactor," Chem. Eng. Sci., 47, 2825 (1992)
9. Fournier, M.C., L. Falk, and J. Villermaux, "A New Parallel Compet-
ing Reaction System for Assessing Micromixing Efficiency: Experi-
mental Approach," Chem. Eng. Sci., 51, 5053 (1996)
10. Guichardon, P., and L. Falk, "Characterization of Micromixing Effi-
ciency by the Iodide-Iodate Reaction System. Part I: Experimental
Procedure," Chem. Eng. Sci., 55, 4233 (2000)
11. Guichardon, P., L. Falk, and J. Villermaux, "Characterization of
Micromixing Efficiency by the Iodide-Iodate Reaction System. Part
II: Kinetic Study," Chem. Eng. Sci., 55, 4245 (2000)
12. Schmalzel, J., A. Marchese, and R. Hesketh, "What's Brewing in the
Engineering Clinic?" Hewlett Packard Engineering Educator. 2(1), 6
(1998)
13. Palmer, D.A., R.W. Ramette, and R.E. Mesmer, "Triodide Ion Forma-
tion Equilibrium and Activity Coefficients in Aqueous Solution," J.
Solution Chem., 13, 9, (1984)
14. Shacham, M., N. Brauner, and M.B. Cutlip, "Efficiently Solve Com-
plex Calculations," Chem. Eng. Prog., 99, 10 (2003) 1











classroom


DECISION ANALYSIS

FOR EQUIPMENT SELECTION


J.J. CILLIERS
The University of Manchester Manchester M60 1QD,
Process design is the synthesis of a complete chemical
operation as an assembly of unit operations. A key part
of the design process is the selection, specification,
and design of each unit operation so that the equipment will
perform the specific function required.
The equipment used in a chemical plant can be divided
into two classes: proprietary and nonproprietary. Proprietary
equipment is designed and manufactured by specialist com-
panies, and its detailed design is not normally the responsi-
bility of the chemical engineer. The chemical engineer is, how-
ever, required to select and size the equipment required for a
specific duty, to consult with vendors to ensure suitability,
and to carry out any customization that may be required.'1
This paper will focus on equipment selection to meet the de-
sign requirements.
Process design and equipment selection by its very nature
requires engineering judgment and subjective analysis, and
is therefore a typical "semi-structured" taskE21 in which nei-
ther judgment alone nor a rigorous procedure by itself is ad-
equate. Equipment selection falls between structured (pro-
grammed) and unstructured (non-programmed) decision-
making,E31 the complexity being principally a result of the large
number of interacting criteria that have to be considered. In
multiple-criteria decision-making problems, the engineer must
combine conflicting measures to assess the desirability of
different decision alternatives-in this case equipment types.
Often, much of the knowledge and design experience in an
engineering organization is not in a tractable form, but is
based on the experience of individuals. This requires
knowledge managementE41 to develop some form of "in-
stitutional memory."
Selection of proprietary equipment therefore involves three
aspects: first, a thorough knowledge of the types of available
equipment and their characteristics; second, a methodology
to balance multiple criteria, which may include a combina-


United Kingdom


In this paper, a novel pedagogic approach...
is offered in which students are taught how
to develop a multi-criteria selection
procedure and then how to
implement such a system in practice.

tion of technical, legal, economic, and social aspects for
selecting the most appropriate among the available
choices; and finally, a sensitivity analysis to ensure that
the choice is robust.
When educating students on solving a specific aspect of
chemical engineering that involves design and, more specifi-
cally, the selection of proprietary equipment, the pedagogic
focus is often on introducing and explaining the types of
equipment available and their operating characteristics. This
descriptive focus is further evident in numerous design and
process engineering textbooks that describe in detail the equip-
ment and its sizing, but only give fleeting reference to mak-
ing a selection from different types that may all be suitable.
Selection is often based on flowcharts that eliminate alterna-
tives, or on tables of properties. In general, any analysis of
the sensitivity of the selection to changing conditions or re-
quirements is neglected.
From the point of view of both student and lecturer, the

Jan Cilliers is Professorof Chemical Engineer-
ing the Universityof Manchester. Originally from
SouthAfrica, where he completed his BSc, MSc
and PhD studies, he joined the University 10
years ago. In 2001 he graduated with an MBA
from the Manchester Business School. It was
during those studies that he developed an in-
terest in decision-making methods and its ap-
plication to teaching. His academic research
focuses on froth and foam physics, in particular
for application to mineral separations.


Copyright ChE Division ofASEE 2005


Chemical Engineering Education











description of equipment application and sizing, while often
interesting, is of less long-term and general value than either
a robust methodology for making a selection between alter-
natives or for evaluating the robustness of that selection. The
question is, however, how to teach the methodologies of
equipment selection and analysis without neglecting the es-
sential descriptive aspects.
In this paper, a novel pedagogic approach to this dilemma
is offered in which students are first taught how to develop a
multi-criteria selection procedure and then how to implement
such a system in practice. Multiple criteria decision analysis
(MCDA) is a methodology for making decisions, such as
equipment selection, in a rigorous andjustifiable way. A par-
ticularly straightforward MCDA technique for equipment se-
lection is "value tree analysis," which treats decision-mak-
ing as a weighting problem in which the criteria are struc-
tured hierarchically and weighted by their importance. The
value of the various equipment choices is then calculated from
the weighted sum of the criteria. A particular benefit is that
sensitivity analyses can be performed to ensure decision ro-
bustness. Value tree analysis as applied to equipment selec-
tion will be discussed in greater detail later in the paper.
It is suggested here that by framing the equipment descrip-
tions within a decision-making and analysis framework, a
deeper understanding of the difficulties involved in making
multi-criteria decisions will be imparted to the students,
while the specific knowledge required to make sensible
choices is emphasized.
The example used in this paper deals with the selection of
appropriate equipment for pollution abatement by removal
of particulates from gases. The use of computer-aided learn-
ing for design was tested previously"51 when a knowledge-
based system was used to evaluate student designs after the


event. The approach used in this study is significantly differ-
ent, however-the student's task is to develop a decision sys-
tem for a specific application, and learning occurs through
collation and transformation of equipment information into a
useable and relevant form.
The use of MCDA-and in particular quantitative value
tree analysis-for making design decisions is, of course, not
new. Ulrich,[61 for example, gives a very clear description of
its use in selecting chemical engineering process alternatives.
It is of interest that he considers the method useful for indi-
cating the superiority of one alternative over another, but does
not consider the sensitivity of the choice to changes in prior-
ity. Sensitivity analysis is strongly emphasized in the teach-
ing example given here.

EQUIPMENT SELECTION USING
CONVENTIONAL AND MULTICRITERIA
DECISION ANALYSIS

Conventional Selection Procedures
Conventionally, the selection of gas-cleaning equipment
for pollution abatement is largely qualitative and highly sub-
jective. As an example, Table 1, abridged from Muir,E71 shows
the problem attributes to consider and the qualitative mea-
sures within each attribute. Although not shown here in full,
two tables of attributes to consider are given, with 11 pri-
mary and 14 secondary attributes.
When using a table-based approach to make equipment
selection, the less-suitable equipment is progressively elimi-
nated until a final choice is made from the remaining selec-
tions. It is evident that it will be difficult to make and justify
a choice between types of equipment based solely on such
tables. In part, this is due to the highly qualitative measures


TABLE 1
Qualitative Equipment Selection Criteria
(A limited selection taken from Ref 7)


Smallest particle size
to be collected


Gas temperature
inlet to collector


User preferences
(if practical)


Attributes 1-10 Sub >400C Near Dry Low Initial
micron micron Dewpoint Product Cost

Alternatives
Cyclones Care Beware Care

Wet Electrostatic Precipitator Beware Beware Unlikely
Aggregate Filter Care Care]

Key
] Can generally cope with the process requirements if well designed
Care Special attention required in plant design and operation to prevent problems
Beware Could lead to severe operational difficulties; alternatives that avoid the problem are normally sought
Unlikely On purely economic grounds, alternatives are generally favored if suitable


Spring 2005











used in each aLttibute considered and the fact that they can-
not readily be weighted by their importance to the particular
design problem. Further, and of increasing importance, is
the need for decisions to be justifiable. Qualitative selec-
tion procedures make objective justification of choices at
a later date difficult.

Multi-Criteria Decision Analysis (MCDA)

In multi-criteria decision analysis using a value tree, the
objective is the final choice-in this case the most suitable
type of equipment for the specific situation. Each type of
equipment is an alternative and is described by a number of
attributes, as shown in Table 1. Each attribute has a real value,
for example its capital cost.
Attribute values are scaled using a value function to bring
them to a common relative value range, usually between 0
and 1. The value functions can be linear or nonlinear and can
be positively or negatively correlated with the attribute val-
ues. For example, a high real-capital cost can be scaled lin-
early to have a low relative attribute value, while a high real-
operating cost may be scaled nonlinearly. In the simplest form,
the decision problem is defined by weighing the importance
of each attribute to the specific situation. For example, both
capital cost and technical complexity may be rated very low
when retrofitting gas-cleaning equipment to an old plant. The
objective is achieved by considering the weighted sum of
attributes for each alternative.
A critical and largely neglected aspect of equipment selec-
tion and design is the sensitivity of the decision to changing
circumstances and process conditions. For example, when
selecting equipment for pollution mitigation where public
health may be at risk, choosing equipment that fulfills only
current legal requirements is highly risky. Changes in legis-
lation, economics, and process conditions may lead to sig-
nificant changes in specifications that must be met; choosing
equipment with excess capability in the short-term may be a
better long-term economic and political decision. Sensitivity
analysis is not readily performed when confronted with highly
qualitative selection criteria, such as shown in Table 1. When
using MCDA, sensitivity analyses can be performed by con-
sidering the effect of changing each weight in turn on the
decision made.
The use of a robust decision-making procedure makes the
potential for improving selection greater and the use of MCDA
more attractive, not only for the design process itself but also
for teaching and demonstrating the importance of sensitivity
analysis during the design process. For teaching purposes,
the procedure for developing an MCDA system was formal-
ized into a highly structured, procedural approach, summa-
rized as "The 5 Stages to Multi-Criteria Decision Analysis":
1. For each alternative (equipment), allocate a numerical
value to each of the ,,11 t i-n. (e.g., capital cost)


2. Scale the i,, di,t. values to a common range by
,'I,'l\t iI- an appropriate scaling function
3. In the context of the problem under consideration,
allocate importance -:. ;1-lti;, .: to each of the at-
tributes
4. Calculate the total-i. ;i-.-l. 1 attribute scores for each
alternative. The i;:-l. .i % .... in alternatives) form the
basis of the initial selection
5. Perform a sensitivity analysis to assess the robustness
of the decision
The 5-stage procedure and its application to pollution-abate-
ment equipment selection will be described in greater detail
in the following sections.

STRUCTURE OF THE TEACHING EXERCISE

The teaching module consists of two three-hour sessions.
Previously, these were divided as follows:

Session 1
Introduction to gas pollution problems, processes, and
equipment
Performance description: quantitative measures
Other selection criteria: qualitative measures
Session 2
Detailed equipment descriptions
Equipment selection by elimination
Selection of equipment: industrial examples

It was decided that all the above material should be re-
tained under the MCDA-based format. Since, in addition,
decision making and MCDA had to be introduced, the fol-
lowing structure was implemented:

Session 1
Introduction to gas pollution problems
Detailed introduction to processes and equipment
Performance description: quantitative measures
Self-study: Detailed equipment descriptions
Session 2
Other selection criteria: qualitative measures
5 Steps to an MCDA system
Decision support systems: example (restaurants)
On-line MCDA demonstrations:
-Restaurant selection
-Gas-cleaning equipment selection
Student MCDA development exercise

It can be seen that in the MCDA framework the basic de-
scriptive element has been retained, but the detailed descrip-
tions are relegated to self-study. Note further that a simple
example is used to introduce the MCDA concepts and that
this is augmented with an on-line demonstration. A further
demonstration shows an MCDA for equipment selection.
The module concludes with a computer exercise in which


Chemical Engineering Education










the students have to develop an MCDA of their own, on a
topic of their own choosing. Examples of systems that have
been implemented, in addition to equipment selection, are
the selection of computers, cars, and jobs.

THE TEACHING AND LEARNING
EXPERIENCE

This section describes in more detail the teaching of the
MCDA approach following the 5-stage format and its appli-
cation to the pollution abatement problem. Some of the inter-
esting problems and findings that were encountered are de-
tailed, and the difference in the learning experience it brings
to the students is illustrated. A class example of selecting a
restaurant to suit a particular occasion is also detailed.

The 5 Stages to MCDA
The first two steps of the procedure are:

> Stage 1
Score each alternative (equipment), ,;,ni.t each of
the lowest-level attributes.
> Stage 2
B, i,.. the score of each alternative to a comparable
scale by ,/,/\;1 iin. an appropriate .. .ili;i.- function.

The first two stages lead to development of an equipment
database where the various pieces of information about the
same attributes for all the available types of equipment are
collated and brought to a common scale. During a teaching
course, this defines the scope of the lectures and ensures that
all the appropriate information is available for all the equip-
ment to be discussed. Since the more tedious, descriptive
material could be relegated to self-study in this way, the class
time could be devoted to more interactive and exciting dem-
onstrations, which is more satisfying for both students and
lecturer.
The MCDA approach also gives a clear structure in which
the need for (and importance of) quantitative performance
measures can be explained. Particular emphasis is needed on
converting qualitative data to quantitative values and on the
transformations required to bring all the data to a common
scale. Referring again to Table 1, the qualitative measures
associated with the efficiency of removing specific particle
sizes can be quantified by introducing the partition curve, its
calculation and interpretation. Similarly, the equipment capi-
tal and operating costs become true financial costs but must
be scaled to a common throughput rate.
Transforming the other qualitative measures in Table 1 (e.g.,
gas inlet temperature, dry product) is more difficult and in-
volves some subjectivity, but it can be seen that, in general,
the qualitative criteria can be transformed to 0% or 100%,
i.e., the equipment is either unsuitable or suitable based on
that attribute alone.


Emphasis is given at this stage of the lectures to the con-
cept of the "institutional memory" and knowledge manage-
ment.41 Using MCDA, an internally consistent database of
equipment and their attributes is generated as a result of the
above two stages, which captures this expertise in a form
that is consistent and directly useable by the whole organiza-
tion.
It is of interest that, for the students, the least difficulty was
with the mathematical transformations used for scaling, while
the greatest was with allocating quantitative values to quali-
tative information as shown in Table 1.

> Stage 3
Allocate importance : ;:.-lit;, .- to each of the
,t1ni -ii. This is done in the context of the process
under consideration.

Stage 3 is the first point at which the process design re-
quirements are considered. Here an "importance weighting"
is allocated to the scaled score, which quantifies its impor-
tance to each possible equipment choice. By explicitly mak-
ing the distinction between the scaling (Stage 2) and weight-
ing (Stage 3), the scoring of an attribute and its significance
is decoupled, separating the process selection from the equip-
ment that can be used.
In the pollution abatement example, two highly disparate
process examples were used for illustration: sawdust from a
sawmill and catalyst dust in the offgas from a refinery. The
students generally have either visited such plants or are able
to visualize the problems. The sawmill produces a relatively
coarse dust and requires a low-cost/low-maintenance solu-
tion in which the dust has to be kept dry. In contrast, the dust
in the refinery may be extremely hazardous and therefore re-
quires equipment with a high efficiency, and neither cost nor
moisture is important.
These two process examples clearly illustrate the impor-
tance weightings, as (for most attributes) the needs are very
different. For example, in Table 1, the importance ranking for
the attributes of "submicron" and "dry product" will be at op-
posite ends of the scale for the sawmill and the refinery.

> Stage 4
The :. ;i-lii.. I.n, riod. scores are added to .-1I. an
overall score for each alternative. The hid-i. i.
., ;,, in alternative(s)form the basis of the initial
selection.

At this stage the attribute values of all the equipment choices
are weighted by the importance to the sawmill and refinery.
Considering the alternatives given in Table 1, the appropriate
equipment choice for each application is very clear.
The mathematical function used for making the selection
was also found to be of great interest. Conventionally, a simple
Continued on page 109.


Spring 2005











MR n= laboratory


AN AUTOMATED


DISTILLATION COLUMN

For the Unit Operations Laboratory




DOUGLAS M. PERKINS, DAVID A. BRUCE, CHARLES H. GOODING, JUSTIN T. BUTLER
Clemson University Clemson SC 29634


Distillation is one of the most common separation pro-
cesses; hence, it is important for undergraduates to
have some hands-on exposure to this unit operation
during the course of their studies. Additionally, working with
batch distillation towers provides students with an opportu-
nity to experience and learn about a dynamic process that is
widely used in the pharmaceutical and specialty chemical in-
dustries. It is equally important for undergraduate students to
work with automated processes, since similar control features
are commonly implemented in industry to reduce labor costs,
provide greater processing flexibility, and improve process
safety and product purity.
For these reasons, an automated batch distillation column
was designed and constructed on-site for the Clemson Unit
Operations Laboratory (UO Lab). The pilot-scale tower uses
sieve plates to separate a mixture of 2-propanol (IPA) and 1-
propanol (NPA). Some background information about the
Clemson curriculum should be mentioned before going into
more depth about this particular experiment. First, the se-
nior-level UO Lab course consists of groups of students (typi-
cally three to four students per group) conducting four ex-
periments during the course of the semester. Lab groups de-
velop their own experimental procedures to accomplish the
assigned objectives. They are given three three-hour lab pe-
riods to conduct each experiment, and the results of these
experiments are presented either in writing or orally in front
of a panel of their peers and professors.
Having three lab periods to perform each experiment pro-
vides students with the ability to explore different aspects of
a particular process and to collect enough data to explore sta-
tistical variations. Additionally, the process control course,
while providing students with both the practical aspects and
fundamental mathematical principles of control, has no lab
associated with it. Therefore, students can only simulate how
a change in a manipulated variable affects a process control


variable using software such as Control Station.'1 Thus, the
senior-level UO Lab course incorporates process control con-
cepts into several of the classical unit operations so that stu-
dents gain hands-on experience working with and tuning con-
trollers in automated chemical processes. Ultimately, this
better prepares them for work with complex, real-world pro-
cesses than would conducting experiments with idealized pro-
cesses, such as simple tanks in series.

EQUIPMENT
Though the basic design for the batch distillation appara-
tus was developed by Clemson faculty, the detailed design
and most of the construction was accomplished by under-
graduates involved in the project.J21 This afforded the stu-
dents an opportunity to gain hands-on knowledge about metal
machining and process engineering. The apparatus required
approximately six months and $25,000 to build. The key com-
ponents of the apparatus (shown in Figure 1) include
A 180-liter jacketed vessel (Owens Mechanical & Fabrica-

Douglas M. Perkins is a recent chemical engineering graduate from
Clemson University During his undergraduate careerhe worked closely
with Dr. Bruce on designing and building multiple experiments for the
Unit Operations Laboratory as well as being the lead student designer/
builder of the batch distillation column.
DavidA. Bruce isAssociate Professor in the Department of Chemical
Engineering at Clemson University He earned his BS degrees in Chem-
istry and Chemical Engineering and his PhD in Inorganic Chemistry
from Georgia Institute of Technology His research interests include
heterogeneous catalysts with controlled pore geometries, advanced
oxidation processes, and quantum and molecular mechanics model-
ing.
Charles H. Gooding is Professor of Chemical Engineering at Clemson
University He earned his BS and MS degrees at Clemson and his PhD
at North Carolina State University, all in chemical engineering. His teach-
ing and research interests are in chemical process design, analysis,
and control.
Justin T. Butler is a recent chemical engineering graduate from
Clemson University. He aided in building/designing the batch column.

Copyright ChE Division ofASEE 2005


Chemical Engineering Education











tion), which serves as the reboiler
A 4-in. diameter glass distillation tower (Labglass) with six aluminum sieve
plates vertically spaced 6 in. apart
A single-pass shell-and-tube heat exchanger using water coolant in the tube
side
Coriolisflow meters (Micromotion CMF025) andpneumatic control valves
(Fisher Rosemount 5100 valves with 3661 positioners) on both the reflux
and distillate lines
Data acquisition and control hardware and software (National Instru-
ments).
All vapor lines are 2-in NPT pipe and all liquid lines are 1/2-in NPT steel
pipe. Additional information, such as vendor addresses, a wiring diagram,
and a more detailed equipment list, are available upon request from Profes-
sor Bruce.

DESIGN METHODOLOGY
The chemical system as well as several key components of the batch col-
umn were chosen to be similar to those previously used in another pilot-
scale distillation apparatus in the UO Lab. This was done because the previ-
ously built column had proven to be very safe to operate and there were
well-established performance characteristics, such as optimal flow rates, heat
duty for the condenser, and stage efficiencies. Specifically, the IPA/NPA bi-
nary system was chosen because: 1) the chemicals are relatively inexpen-
sive; 2) they have low toxicity; 3) they have high short-term exposure limits
(> 250 ppm); 4) fires can be extinguished by water, dry chemical powder, or
CO,; 5) they have moderate vapor pressures (< 45 torr) at STP conditions;
and 6) mixture compositions are easily analyzed by gas chromatography.


Figure 1. Schematic for batch distillation apparatus.


The IPA/NPA system also exhibits relatively
ideal behavior as indicated by the vapor-liquid
equilibrium (VLE) data shown in Figure 2. This
figure includes both experimentally measured
dataE3 and compositions predicted by a Margules
activity coefficient model. 4E Binary parameters
calculated by GInI liiilly' for other activity co-
efficient models are shown in Table 1 along with
the mean deviations associated with each
model. As can be seen in the table, all of the
activity coefficient models do an excellent job
at describing the VLE data for this non-azeo-
tropic system.
Another key design feature was the choice to
use gravity, rather than a pump, to return reflux
flow to the column. This necessitated that the
pressure drop across all flow measuring/control
devices be kept to a minimum. For this reason,
Coriolis flow meters were chosen both for their
accuracy and their low-pressure drop charac-
ter istics. An added bonus in using the Co-


09

I07
06
S05
04
03
02
011

0 01 02 03 04 05 06 07 08 09 1
weight fraction 2-propanol in liquid, xI

Figure 2. Vapor-liquid equilibrium data for
mixtures of 2-propanol and 1-propanol at 1
atm. Curve corresponds to compositions pre-
dicted using the Margules parameters listed in
Table 1 and (*) represent experimental data
collected by Ballard and Van Winkle, 1952.


TABLE 1
VLE Binary Parameters for Activity
Coefficient Models of the
2-propanol/1-propanol System[4]

Mean
Activity Binary Parameters Deviation from
Cof('ii n AIPANPA ANAIPA Experimental
Model Vapor Fractions

Margules 0.1321 -0.0621 0.0046
Van Laar 0.0100 25765.3800 0.0090
Wilson 818.3291 -481.0590 0.0048
UNIQUAC -399.2278 575.0956 0.0050


Spring 2005










riolis flow meters is that they can not only measure mass
flow rate, but also volumetric flow rate, density, and tem-
perature of the fluid in the pipes.
The reflux and distillate control valves were selected for
their ability to control low flows with a very small pressure
drop across the valve. At first, an actuated ball valve was
considered to allow for the low-pressure drop requirements,
but after talking with several vendors it became apparent that
a ball valve would not be a viable option, due to sizing diffi-
culties. The selected needle valves were chosen based on
their ability to meet the above criteria, specifically, a low-
pressure drop across the valve and integral positioners for
adjusting the needle.
The Labview data acquisition and control software (Na-
tional Instruments) was chosen because it has several key
features that make it attractive for use in the UO Lab. These
include low cost, widespread use across campus, user-friendly
graphical programming language, and most importantly,
preprogrammed algorithms for PID control of specified
measurables. Labview can also log data that is acquired dur-
ing an experiment (e.g., temperatures, flow rates, and pres-
sures) and store them in an Excel spreadsheet. This not only
allows students to have more time during the lab period to
observe column dynamics, but it also allows for post-lab
analysis to be conducted virtually instantaneously.
Another important aspect of Labview is the graphical user
interface, which allows students to look at pictorial represen-
tations of numbers (e.g., a virtual thermometer) instead of
simply looking at the raw data/numbers. This interface also
allows for plots of time variations in process variables to be
continuously displayed so that students can easily observe
when the process or a measured variable reaches steady state.
Finally, safety limits can be programmed into the software,
meaning that a student would not be capable of running the
column under dangerous conditions, such as an over-pres-
surized reboiler. If a student did try to run the column at an
unsafe condition, Labview would override the student's at-
tempt and bring the column back within safe operating lim-
its. A copy of the distillation control program used in Labview
can be obtained from Professor Bruce.

MODES OF OPERATION

There are four basic modes of operation and control for the
column: total reflux, constant distillate flow rate, constant
distillate composition, and fixed reflux ratio. For all modes
of operation, the liquid level in the sight glass is maintained
at a setpoint using either the distillate or the reflux valve.
Additionally, the column is currently operated so as to main-
tain a constant reboiler steam pressure (4-6 psi) for all modes
of operation. Future experiments may examine the possi-
bility of manipulating the steam pressure to control the
reflux or distillate rate.


Initially, the column is started in total reflux. This is the
simplest mode of column operation and involves control of
only the reboiler steam pressure and liquid level in the sight
glass. This mode allows the rising vapor and falling liquid to
heat the tower. Once the column has reached steady state, the
overall tray efficiency can be determined from composition
analysis of samples collected from the top and bottom of the
column. By varying the setpoint of the reboiler steam pres-
sure, it is possible to determine how tray efficiency varies
with vapor flow rate.
The column can be operated in three other modes. Con-
stant reflux ratio is used least often because it requires that
the distillate and reflux valves be adjusted to maintain a con-
stant fluid level in the sight glass as well as a fixed reflux
ratio. Noise and interaction make this mode difficult to tune
and operate in a satisfactory manner.
Rather than filter the signals from the two Coriolis flow
meters to improve control, a simpler yet related mode of op-
eration has been used more commonly by the students. This
mode of operation maintains a constant distillate flow rate,
which is essentially the same as maintaining a fixed reflux
ratio if the steam pressure remains constant and the composi-
tion of the pot does not vary significantly over the course of
the lab period. The control scheme for constant distillate flow
is very straightforward; the reflux valve maintains a constant
fluid level in the sight glass, while the distillate valve con-
trols the distillate flow rate. Common operating conditions
maintain a distillate flow of 5 kg/hr and a reflux ratio of ap-
proximately 3. Running the column at a constant distillate
flow rate allows the students to see how column tempera-
tures and both the distillate and reboiler composition
change over time.
The final mode of operation is constant distillate composi-
tion. This is accomplished by adjusting the distillate flow rate
to keep the temperature at the top of the column constant,
while using the reflux valve to control the fluid level in the
sight glass. The purity of the distillate product is checked
periodically by GC to adjust the temperature setpoint or en-
sure that the composition is not varying.


ASSIGNMENTS

As described earlier, each student group has three lab peri-
ods to work with the distillation column. Essentially, this al-
lows for three different experiments to be run by each group.
During the first day, students typically run the column in to-
tal reflux with preset controller tuning parameters and note
changes in column operation and the visual appearance of
liquid hold-up on the trays at different reboiler duties (i.e.,
different reboiler steam pressures). Three or four conditions
can be tested after the initial 30- to 45-minute start-up time
for the column to reach pseudo steady state. Temperatures
are monitored and samples of liquid and vapor are collected


Chemical Engineering Education










for GC analysis from the sample ports indicated in Figure 1.
On the second day the students start the column at total
reflux and then shift to either a constant distillate flow or
constant distillate composition mode to accomplish a particu-
lar assigned objective. The third day is typically devoted to
basic closed-loop tuning exercises on the control loops
(reboiler steam pressure, sight glass fluid level, distillate flow,
or distillate composition). The controller tuning assignment
can be made somewhat more challenging by making it the
first-day task with little or no guidance on where to start.

RESULTS/DISCUSSION

Experience during the first two semesters of operation has
confirmed some of the design objectives, while at the same
time revealing a few surprises. Overall the column has per-
formed very well. The six trays yield approximately 4 equi-
librium stages with the pot functioning as a 5th. The 60 to
70% range of tray efficiencies is consistent with predictions
of various correlations for overall plate efficiency. E5 The con-
stant distillate rate scheme can provide a distillate composi-
tion ranging from 60 to 80% IPA with an initial pot com-
position of approximately 25% IPA. The constant com-
position scheme can provide a small amount of product
up to 70% IPA with the expected tradeoff between prod-
uct quantity and purity.
During initial column operation, the severity of reset
windupE[6 in the control loops was not anticipated. The basic
controller logic provided by Labview did not include anti-
windup, and the column was started with each loop config-
ured for PI control. As a result, both the steam pressure and
sight glass level control loops substantially overshot their set-
points, and the students were puzzled as to why the control
loops "didn't work." It is relatively easy to program anti-
windup measures into Labview, but the faculty decided not
to do this. Having the students experience setpoint offset and
reset windup first-hand rather than just hearing the principles
behind them in class is thought to be highly beneficial.
The students are initially told to turn off integral action
before starting the program, and leave it off until each con-
trol variable nears its setpoint. This allows them to observe
the offset, which disappears when integral action is added.
Later they are told to make substantial changes in setpoint,
which allows them to observe reset windup when the con-
troller fails to reverse the control action until the controlled
variable is well past the setpoint.
Another anomaly in the column is a tendency to drift and
exhibit hysteresis during total reflux operation. This means
that the "steady state" conditions seemingly change during
the course of a lab. In essence, students believe that they have
reached a steady-state condition as evidenced by constant fluid
level in the sight glass and apparently constant temperatures
and flow rates, but closer observation shows that the tem-


peratures and flow rates tend to drift slowly. Also the appar-
ent steady-state temperatures and flow rates one achieves at
a particular reboiler duty/steam pressure may actually depend
on the history of the steam pressures used since startup. The
main reason for this anomalous behavior is thought to be heat
loss from the uninsulated column. Essentially, each glass sec-
tion has to heat up to the temperature of the vapor and liquid
inside the column before it can correctly be considered to be
at steady state. To minimize this drift and cut down on startup
time, students are initially told to start the reboiler with a
high steam pressure of 10 psig until condensate begins to
leave the condenser, and then return the steam pressure to the
desired operating condition.
Once the column has reached steady state, the response
time for the controlled process variables is rather fast. The
reboiler steam pressure, distillate flow rate, and sight glass
fluid level respond fully to a change in setpoint in less than a
minute. When the steam pressure is changed, however, it takes
approximately 5 to 30 minutes for the column to reach a new
steady state, depending on the magnitude of the change. When
controlling the exiting vapor temperature distillatee com-
position) at the top of the column, the response time is
approximately one to two minutes depending on the size
of the change in setpoint.
An example of batch column performance when operated
in constant distillate flow rate mode is shown in Figure 3.
The column was initially allowed to reach steady state con-
ditions at total reflux before data collection began. Specifi-
cally, Figure 3 shows how changes in distillate flow rate and
sight glass level setpoints affect the sight glass level, reflux
mass flow rate, temperature on the top tray of the tower, and
distillate mass flow rate. The following changes in setpoint
were used for this study: 1) at 48 seconds, the distillate flow
rate setting was increased from 0 to 5 kg/h; 2) at 86 seconds,
the distillate flow rate was increased further to 10 kg/h; 3) at
402 seconds, the sight glass level setpoint was changed from
28 to 27 inches; 4) at 546 and 599 seconds, the sight glass
level setting was increased by 1 inch; and 5) at 734 seconds
the distillate flow rate was changed from 10 to 7 kg/h. As
mentioned earlier, the column rapidly adjusts to changes in
both distillate flow rate and sight glass level; however, the
temperature within the column and purity of the distillate
stream are much slower to respond, as evidenced by the slow
rise in temperature of the top tray of the tower. This increase
in temperature is the result of less separation in the tower,
which is caused by the reduction in reflux ratio. Addition-
ally, it can be observed that the sight glass level controller is
tuned much more tightly than one would normally operate in
industry. Most industrial operators would prefer to let the level
adjust slowly and not subject the column to dramatic changes
in reflux flow rate that could affect product purity.
The undergraduate students who built this batch column
certainly gained from the experience by designing and build-


Spring 2005











ing a real process. The students were involved in, and
for the most part headed up, the design of the column
45
from the beginning. They learned how to communi-
cate with equipment vendors, how to recognize the 40
need for and implement design changes during con-
struction, and how to make other daily engineering 35
decisions based on their classroom experience. Finally,
these students learned that start-up of a new process 30
is as much about troubleshooting as it is about testing
the capabilities of the equipment. In essence, the stu- 25
dent builders were able to see what they would likely
do as an entry-level process engineer, while at the same 20
time solidifying the application of classroom theories
in all aspects of the design.
UO Lab students who operate the automated batch 10
distillation apparatus benefit in several ways. All of
our lab experiments require the students to investi- 5
gate background information and prepare a brief lit-
erature review on the subject, to design an experiment 0
(logically, if not statistically), to write an operating
procedure, to evaluate their procedure for safe opera-
tion, to present their plans for approval before run-
ning the experiment, to operate the equipment, to
collect data, to analyze their data, and to prepare a
final report. And, of course, all of these experiences
involve teamwork.
This particular experiment involves one of the most com-
mon unit operations used by chemically related industries.
The experiment is driven primarily from a computer inter-
face, much like the control room environment students will
encounter in industry; unlike industry, however, the actual
apparatus is only five feet away. The glass column allows the
students to observe tray phenomena, such as weeping and
entrainment flooding. Specific assignments can be varied so
that the students learn how to achieve an operating or pro-
duction objective, such as a specified distillate purity. The
control environment provides hands-on experience with nu-
merous concepts that might remain abstract if taught only in
the classroom or even if supplemented with computer simu-
lations. Some of the concepts we have explored already in-
clude offset, reset windup, control valve saturation, loop in-
teraction, and nature and magnitude of disturbances. There
are surely others that experience and ingenuity will reveal.

CONCLUSIONS

The batch column performs in a manner similar to that of
a typical industrial column with an overall tray efficiency
ranging from 60 to 70%, a distillate composition ranging from
60 to 80% IPA for the constant distillate mode when there is
25% IPA initially in the still pot, and up to 70% IPA for the
constant composition mode. The inherent characteristics (i. e.,
graphically based interface) of the Labview software make
operating the column easy. Once the students gain a little

108


-A: Sight Glass Level, inches
-B: Reflux Flow, kg/h
-C: Top Temperature, C/10
-D: Distillate Flow, kg/h
A


----- --WV-- I

S4--1-- -----






-


0 100 200 300 400 500 600 700 800
Time (sec)

Figure 3. Non-steady-state operational data from the batch
distillation tower.


experience with the controllers, they are able to manipulate
and optimize the process in a control room environment, while
at the same time observing common tray phenomena and the
effects of different operating conditions on column perfor-
mance. Finally, the students are able to gain insights into as-
pects of process control that might otherwise elude them in
class work or simulation assignments alone.

ACKNOWLEDGMENTS
The authors would like to thank lab technologist Bill
Colburn for the many hours he spent helping program the
software and piping water and steam to the column. Addi-
tionally, they would like to thank the National Science Foun-
dation (CAREER-9985022) and Dow Chemical Company for
financial support.

REFERENCES
1. Cooper, D., Control Station (Computer software), Control Station Tech
(2001)
2. Bruce, D.A., R.W. Rice, and C.H. Gooding, "Educational Outcomes
from Having Undergraduates Design and Build Unit Operations Lab
Equipment", to be submitted to Chem. Eng. Ed. (2005)
3. Ballard, L.H., and M. Van Winkle, "Vapor-Liquid Equilibria at 760
mm. Pressure," Ind. Eng. Chem., 44, 2450 (1952)
4. Gmehling, J., and V. Onken, Vapor-Liquid Equilibrium Data Collec-
tion, Dechema, New York (1977)
5. Seader, J.D., and E.J. Henley, Separation Process Principles, John
Wiley & Sons, New York (1998)
6. Riggs, J.B., Chemical Process Control, 2nd ed., Ferret Publishing, Lub-
bock, TX, (2001) 1


Chemical Engineering Education











Decision Analysis for Equipment Selection
Continued from v. 103.

weighted sum is used. In cases where any choice is com-
pletely inappropriate, however, the form does not reflect this.
Therefore, it must be emphasized that, since the MCDA meth-
odology evaluates all the equipment available, completely
unsuitable equipment may still appear as a possibility based
on other attributes, and the answers must be interpreted intel-
ligently. UlrichE[6 describes an elegant approach to interpret-
ing the results in which the attributes are divided into "wants"
and "musts." Equipment that does not satisfy the "musts" is
eliminated before considering the remaining alternatives.
Again, this modification was not difficult to explain and was
readily understood.

> Stage 5
A sensitivity analysis is performed.

Sensitivity analysis was found to be difficult to convey
adequately without the benefit of a demonstration. An on-
line demonstration during the lecture is highly effective for
illustrating the importance and benefit of sensitivity analy-
sis. The further benefit of performing this on-line is that the
number of equipment alternatives is far greater, and the best
choice is less obvious.

The importance and utility of sensitivity analysis can be
shown using the refinery case study. For example, either fil-
ters or electrostatic precipitators (Table 1) may be a suitable
solution for the problem. The optimal choice, however, can
be changed by changing the importance weighting given to
submicron particles. This may be the result of future changes
in legislation or adverse publicity-both graphic illustrations.

Additional Teaching Example: Choosing a Restaurant
If required, the 5-step procedure can be illustrated quickly
and simply using the example of selecting a restaurant. This
is a particularly good class example, as it allows vivid sce-
narios to be painted, e.g., dinner with a partner or the boss, a
quick meal before theater, etc. Further, the institutional
memory concept became very clear, and the students sug-
gested that it could be used as the basis for an Internet restau-
rant selection facility. With relatively few :il i ilhi i (e.g., cost,
quality, and service) and a small number of restaurant types
(e.g., fast food, steakhouse, and expensive), a simple sensi-
tivity analysis can be performed during the lecture.

A number of complex issues are also highlighted using the
restaurant example-in particular the importance of clarity
in attribute specification. For example, the attribute "Dura-
tion of meal" could refer to either long or short, and is better
stated as "Meal takes long," which may be weighted high or
low. This example attribute can also be confused with "Ser-
vice quality," which is best incorporated as a further attribute.

Spring 2005


On-line demonstrations and exercise
An excellent set of on-line decision support tools has been
developed by the Helsinki University of T.clin .l l- and is
available at no cost on the Internet.181 From this toolbox, WEB-
HIPRE was used for on-line demonstrations. The output from
WEB-HIPRE is highly visual, particularly in regard to the
sensitivity analysis, which aids understanding. Further, the
system is intuitive to use, and the students can readily de-
velop their own systems during the exercise.

Course assessment
Examining the course has been made more flexible with
the MCDA approach. Instead of relatively predictable descrip-
tive examination questions, MCDA can be used either as a
project assessment, or more flexibly in a conventional ex-
amination. Student feedback to date has been very positive,
and the course rating has improved markedly. It is clear that
the students find the approach novel and useful, and the teach-
ing enjoyable.


CONCLUSIONS

The use of MCDA as a framework for teaching the selec-
tion of equipment for gas pollution abatement was very suc-
cessful. In particular, two aspects were highlighted that oth-
erwise would not have been-the development of an "insti-
tutional memory" and the importance and utility of sensitiv-
ity analysis. The students enjoyed the class, and the use of
interactive computer techniques was found to be exciting.
It has been statedE91 that a hard problem addressed with sup-
port for successfully solving and i ll l.lii on the problem
will lead to deep, transferable knowledge and skills. It is be-
lieved that the MCDA approach gives the support required,
and that this approach is particularly appropriate for the teach-
ing of "hard problem" design-type courses.

REFERENCES
1. Sinnott, R.K., Coulson & Richardson's Chemical Engineering, Vol-
ume 6, Pergamon Press, Oxford, UK (1993)
2. Keen, P.G.W., and M.S. Scott Morton, Decision Support Systems: An
Organizational Perspective, Addison-Wesley, MA (1978)
3. Simon, H.A., The New Science of Management Decision, Harper and
Row, New York, NY (1960)
4. Macintosh, A., I. Filby, and J. Kingston, "Knowledge Management
Techniques: Teaching and Dissemination Concepts, Intl. J. Human
Computer Studies, 51, 3, 549 (1999)
5. Toll, D.G., and R.J. Barr, "A Computer-Aided Learning System for
the Design of Foundations," Advances in Eng. Software, 29, 7, 637
(1998)
6. Ulrich, G.D., A Guide to Chemical Engineering Process Design and
Economics, John Wiley & Sons, New York, NY (1984)
7. Muir, D.M., Dust and Fume Control A User Guide, IChemE, Rugby,
UK (1992)
8.
9. Guzdial, M., etal., "Computer Support for Learning Through Complex
Problem Solving," Communications ofthe ACM, 39, 4, 43 (1996) 1











curriculum
----- -- s________________________________-0_


Drawing the Connections Between

ENGINEERING SCIENCE AND


ENGINEERING PRACTICE




FAITH A. MORRISON
Michigan Technological University Houghton, MI 49931-1295


Change is a fact of life, and engineers make their ca-
reers out of bringing about changes in their surround-
ings. In today's chemical engineering departments
we hear of the need for changes in our institutions and meth-
ods. Alumni, employers, and researchers in the field bring
back news of the need for new priorities for the curriculum-
the need for students to have more teamwork experience, to
develop better communication skills and critical thinking
skills,11 and to acquire specialized knowledge in emerging
areas such as bio- and n.iiin ., in l 'li- ',.. In addition, there is
continuing pressure for better preparation of graduates in each
of the established, and diverse, fields in which chemical en-
gineers find employment.
The passive approach to these demands would be to pack
more and more into the chemical engineering curriculum,
extending the undergraduate years and demanding more of
the students. This runs counter to other institutional and
national priorities, however, that demand high four-year
graduation rates and low overall costs for undergraduate
education.
Finding a solution to a problem amid seemingly contradic-
tory requirements is the exact task that the practicing engi-
neer faces on a daily basis. We can find a solution to the peda-
gogical dilemma posed above by following the same engi-
neering problem-solving processes we seek to develop in our
students. We should begin by defining the problem as we
perceive it and exploring the context in which the problem
presents itself. We then can bring our own expertise and ex-
perience and the expertise and experience of others to bear
on the problem, seeking clarification and (hopefully) a solu-
tion. Finally, we test the proposed solution and evaluate its
effects, feeding back our observations into a refined solution
as we iterate and hopefully converge to the best solution.


What is the best way now and in the future to educate a
chemical engineer? To address this question we need to re-
flect a bit on what a chemical engineer is-what abilities and
expertise is a chemical engineer expected to have? How are
these abilities different from those of other engineers and sci-
entists? How has the field of chemical engineering survived
throughout a century of tremendous change? What are the
strengths and weaknesses of the chemical engineering edu-
cation we currently deliver?
Before there were chemical engineers, there were mechani-
cal engineers who worked in the chemical process industry
along with industrial chemists who had become experts in
large-scale production. The industrial need for individuals
with chemical and engineering expertise suggested (to some)
the establishment of a new discipline. Chemical engineering
thus had very practical and industrial roots and an instant
identity crisis-are the practitioners chemists or are they en-
gineers? And, if they are something altogether new, how are
they different from the chemists and engineers who have been
doing the job up until now?
The answer for the early founders of our discipline was
that chemical engineers were specialists in the chemical pro-
cess industries-in particular, experts on unit operations. The


Copyright ChE Division ofASEE 2005


Chemical Engineering Education


Faith Morrison is Associate Professor of
Chemical Engineering at Michigan Tech, where
she has taught for 15 years. She is also the
author of Understanding Rheology (Oxford,
2001), an undergraduate textbook on non-
Newtonian flows, andis the undergraduate ad-
visor for chemical engineering at Michigan
Tech. Her research is in polymer rheology and
viscoelastic phenomena. This paper is dedi-
cated to Professor Philip W Morrison of Case
Western Reserve University, who passed away
in 2002.


Ott












The key to the survival of the discipline [is] the ability to adapt to changing economies
and technologies while retaining a fundamental, and valued, expertise .... Today's
chemical engineering degree represents something of value to employers, but
changing technologies and changing conditions in the workplace put
new demands on the education of a chemical engineer.


organization of chemical pro-
cesses around a finite set of unit
Fundamentals
operations established both an Fundamentals
identity and a pedagogy that could Physics, chemistry, m
carry the new field forward. Mass/energy balances
The unit-operations paradigm Thermodynamics
served the field well through Transport phenomena
World War II, but the maturing of Chemical reaction kin
the commodity chemical indus-
tries through the 1950s led to some Practice
new challenges for the discipline. Process Control
Faced with a dwindling need for Staged operations
chemical engineers to do classi- Unit operations
cal chemical-plant engineering,
the field adapted to new technolo- Process design
gies (polymers, electronics, Electives
nuclear power) and claimed them Technical (chemistry,
as fields addressed by chemical
engineering. This was possible be- Figure 1. Outline of the
cause a new paradigm was ing curriculum, organize
adopted in engineering educa- tice, and electives.
tion-the engineering-science
paradigm. By moving down in length-scale from the process-
unit scale (unit operations) to the molecular scale (transport
phenomena, chemical kinetics, thermodynamics), chemical
engineers could broaden the number of fields to which they
could apply their analytical skills and methods.
In the last 100 years, therefore, chemical engineers have
established themselves as problem solvers in the field of
chemical processes, including both large-scale chemical
manufacturing processes and molecular chemical processes.
The key to the survival of the discipline was the ability to
adapt to changing economies and technologies while retain-
ing a fundamental, and valued, expertise.
How do we currently educate a chemical engineer? While
the chemical engineering curriculum varies from place to
place, there is a general structure, shown in Figure 1. Indus-
try-specific content is addressed in the practice courses (unit
operations, design, controls) and is also addressed in the cur-
riculum by including elective courses that allow students to
follow their interests. These elective courses (e.g., polymer
engineering, environmental engineering, business, biochem-
istry, bioprocess engineering, etc.) are sometimes offered from
within the chemical engineering department, but are often


current chemical engineer-
ed into fundamentals, prac-


courses taught outside of chemi-
cal engineering. Within one of the
fundamental courses there may
also be some exposure to indus-
try-specific content, depending on
how the particular instructor
implements his or her course.
Many of the more recently pub-
lished textbooks also go to some
lengths to include individual prob-
lems or case studies that draw
from a wide range of industries.
Due to the emphasis of most text-
books, however, it is also possible
(even probable) to complete an
entire undergraduate chemical en-
gineering degree without consid-
ering any chemical processes out-
side of the commodity-chemical
or petroleum industries.


What are the challenges and
changes that must be addressed?
If tkciiin lh ,-'. and society remained stagnant, no changes in
an effective curriculum would be needed. Two questions
should be asked, therefore:

Is our curriculum n. i as is?
What changes in technology and in society have
taken place, or are anticipated to take place, that
might ,,n. t the chemical ,..-i. ,, i .,- curriculum?

To address the effectiveness of our curriculum, we need to
assess the experiences of our students, our alumni, and their
employers. The good news is that chemical engineers are still
in demand in industry, the current employment downturn not
withstanding. Salaries for chemical engineers still top the list
of engineering salaries, and employers have often shown a
preference for classically trained chemical engineers over
more specialized engineers (e.g., environmental, biomedical,
materials) because of the versatility of the chemical engineers.
There is room for improvement, however, as reflected in
alumni surveys and in discussions with industrial advisors.
At Michigan Technological University we have surveyed our
alumni and industrial partners and some of the common con-
cerns are given in Figure 2. High on the list of comments is


Spring 2005


ath, liberal arts, general education




etics/reactor design


One particular kind of
practice (petroleum or
...... . chemical
processing)


biology), engineering











that alumni and industrial partners would like to see an in-
crease in teamwork experience and an improvement in com-
munication skills, critical-thinking skills, and learning skills
in chemical engineering graduates. Richard Felder has re-
ported similar responses from NC State alumni.[21

Changes in tk elliiiln '1 and in society challenge the cur-
riculum as well. New technologies, including bi, IkC li%.1 ,1 n-,
and nanoscale engineering, are a vibrant part of chemical
engineering research and a potential source for growth in
chemical engineering employment. Fundamental changes
have also taken place at colleges and universities in the last
twenty years. Research is now a central activity at most uni-
versities, and for public universities the proportion of sup-
port coming from state governments has fallen to an average
of only 32% of total expenditures.[3] The university degree
has never been more popular, however-a fact that itself
brings its own challenges since there are increasing numbers
of underprepared students in need of remedial work and spe-
cial attention. These changes at universities have been ac-
companied by double-digit tuition inflation, reflecting the
broadened mission of the university and the decrease in state
support for the universities' missions. Paradoxically, decreas-
ing public funding for universities has been accompanied by
calls for tuition controls, for sanctions for universities with
poor four-year graduation rates, and for reduction or elimi-
nation of remedial programs. [4,5

Thus, we face a dilemma. Today's chemical engineering
degree represents something of value to employers, but chang-
ing technologies and changing conditions in the workplace
put new demands on the education of a chemical engineer. In
addition, our universities themselves have gone through a
fundamental change, increasing their research emphasis,
broadening their missions to include less-well-prepared stu-
dents, all the while facing financial challenges. How can we
preserve what is right about chemical engineering education
while adjusting to these new realities?


CONTENT VERSUS PROCESS
At the end of the day, the chemical engineering curriculum
is a list of courses (experiences) that are required by an aca-
demic department. These courses have content-subjects that
are presented, explained, practiced, and mastered. Part of the
educational process requires that the student master the con-
tent of the courses. Often this is the part on which we con-
centrate. The debates over chemical engineering curricula are
usually discussions of content.
Another part of a student's education is the experience of
confronting the material and structure of a course-the pro-
cess of mastering the content. The educational process in-
cludes interactions with faculty and peers, managing time,
working in groups, and developing and implementing a learn-
ing strategy for a course. We do not test on the mastery of
process. Or perhaps we do, indirectly, since students who suc-
ceed in mastering content usually do so because they have
mastered process-they are able to determine the goals of
the course, and they plan their conduct to allow them to suc-
ceed. As the education scholar Jerome BrunerE61 notes, "To
instruct someone... is not a matter of getting him to commit
results to mind. Rather, it is to teach him to participate in the
process that makes possible the establishment of knowledge."
As we assess and redesign the chemical engineering cur-
riculum, we may ask ourselves, "Do we need to revamp the
content? Or should we concentrate only on process and pre-
sume that whatever technical content is covered or omitted
will be addressed in the graduate's subsequent career?" A
graduate who has mastered the education process, in fact,
sounds very much like the ideal engineer: a person who is
able to learn new topics, work in teams, communicate effec-
tively, focus on goals, and develop strategies to solve prob-
lems. To a certain extent, we have always relied on content
not mattering too much, since it has always been important
for engineers to be able to adapt to new technologies (life-
long k.iliiii.-


Common Curricular Feedback
Don't know bioengineering and other cutting-edge fields
Don't use math after graduation
Too much petroleum processing in curriculum
Electives are taken for convenience instead of as part of a deliberate educational plan
No time for undergraduate research
STeamwork
Communication skills
Need more emphasis on Critical thinking
Learning versus teaching
Lifelong learning

Figure 2. Summary of some curricular feedback received from alumni
and industrial partners.


Chemical Engineering Education










Shall we conclude then, that, within reasonable bounds,
content does not matter? We can examine two case studies to
explore these questions.

Case I
Is Content IqmoirtanLt' D. 1. *.;1,v'. TWi;l ,i: Skills
in F ,r.'i,. I i :-.
I had been frustrated by the quality of unit operations labo-
ratory reports, and I volunteered to teach the technical com-
munications course to see what could be done to improve it.
The previous instructors had shown the students how to write
a proposal and then asked them to write a proposal of their
own. The topic of the proposal could be anything they
wished-it did not need to be technical. I wanted to see if
this could be improved upon.
I formulated the hypothesis that the students needed more
technical content in their writing exercises in order to gain
proposal-writing skills. In my section of the course, I asked
the students to write an essay on why fluid mechanics is im-
portant to chemical engineers. The results of this assignment
were uniformly terrible. The students were unable to "find"
the answer to the question, so they simply wrote appropriate-
length texts consisting of paraphrases from various textbooks
and submitted them as their essays. They appeared to not know
how to write even cogent sentences.
Frustrated with this outcome, I gave them a focused lec-
ture on a new subject and asked them to write an essay ex-
plaining back to me the content that I provided. Specifically,
I gave a lecture on how to produce good technical writing
and asked the students to write an essay explaining the im-
portant features of good technical writing. The results of the
second assignment were uniformly excellent. Each essay be-
gan with the appropriate introduction and statement of the
problem. The three key content components on which I had
lectured were listed. A final paragraph was constructed that
summarized the essay.
What was the difference in the two assignments? In the
first assignment, I gave them an open-ended problem-they
had to first find the content that they needed to report on in
the assigned essay. The students did not know why fluid me-
chanics is important to chemical engineers, however, and they
did not know how to find out. In the second assignment, I
spoon-fed them the content ahead of time, and they repeated
it back to me using writing skills that they possessed. For the
first assignment, critical thinking and problem-solving skills
were essential and apparently lacking in the class. What had
looked like a writing-skill deficit had turned out to be a defi-
cit in critical-thinking/problem-solving skills.
Conclusion: Content-in this case the decision to con-
front the students Ni ili .1 . ti, question that required
analysis, reflection, and discovery rather than simple
disgorgement of presented material-can be critical.

Spring 2005


We may be guilty of content errors in our chemical engi-
neering curriculum. For example, we show students how to
make tray-by-tray calculations on a distillation column. We
then ask them to make such calculations. They succeed. When
they arrive at their senior year in unit operations laboratory
however, they may fail to recognize that the open-ended or
ill-defined problem they have been asked to solve requires
a tray-by-tray calculation on a distillation column. We may
not have taught them how to determine what calculations
are necessary.


Case II
Is Content Important? The Process of Problem S.- i ;i,:
There was once a television commercial that touted the
Internet as the place to find the answers to any questions one
might have. In the advertisement they listed a question of
fact that was quite obscure, and, using an Internet browser,
they found the answer in seconds. The implication was that
any question you might formulate could be answered easily
if you have an Internet connection.
We all have enough Internet experience to know that this is
not true. Going to an obscure site and formulating a question
that is answered by that site is a far cry from having a spe-
cific need and actually finding a reliable answer to the ques-
tion. In order to do the latter effectively, you need problem-
solving skills and experience.
To find information effectively, one must learn the process
of finding information. The process is something like the fol-
lowing:
A processfor fi,,. 1;,: information or .. '1\ ;,,- a problem:
1. Know where to start
2. Slog through unfamiliar nomenclature
3. Struggle with missing background (on your part) in the
subject
4. Return to fundamentals for a refresher
5. Seek out experts presuming you can determine what kind
of expert you need
6. Postulate a solution (a location for your information)
7. Evaluate the accuracy of the solution, appropriateness of
assumptions
8. Return to the appropriate step and repeat, depending on
what you find and decide

In the case of the Internet search engine advertisement, they
made finding something on the Web look incredibly easy be-
cause they skipped every one of these steps. They knew the
answer they wanted ahead of time and went right to it. This is
analogous to assigning homework or exam problems that are
just like the examples in the book-students become accus-
tomed to this practice and come to believe that the practice of
engineering will be an exercise of finding a previously solved
problem that is similar to the problem presented to them.
Conclusion: Skipping process prevents learning.










Returning to our topic, is content important? The answer
we arrive at is yes. And no. Content is important (Case Study
I) in that it must be real, open-ended, specific, and, although
we did not discuss it, it must integrate physical and chemical
principles that are fundamental to the types of problems that
are faced by chemical engineers. Content is not important in
the specifics, however (Case Study II), since problem-solv-
ing process is generic and common to all types of engineer-
ing (and i niit -i -- i i i problems.
We cannot teach chemical engineering without specifics,
i.e., without choosing content. But an engineering graduate
who studies petroleum processes should be able to design a
lysine fermentation process with recourse to additional ma-
terials and by consulting knowledgeable experts-if that
graduate has mastered critical thinking and problem solving.
And likewise, an engineering graduate who studied fer-
mentation reactors should be able, with some backfilling
of missing or forgotten techniques, to confront distilla-
tion-column design.

A PROPOSAL:
RENEWED EMPHASIS ON INTEGRATION

There has been much discussion on improvements to engi-
neering education in the last decade, including calls for more
integration of engineering practice,E71 adoption of coopera-
tive learning methods,E[8 expansion of the engineering degree
to a five-year degree,[9] changes in faculty reward structures,E10
and insertion into the curriculum of international experience
and the studies of ethics,E111 government regulation,[12] and
many other subjects.[13-15] These ideas have merit, but
wholesale change is expensive, time consuming, and of-
ten unrewarded.
We have discussed the question, what is the best way now
and in the future to educate a chemical engineer? In address-
ing this question we have found good things about the cur-
rent method. We have also identified some challenges to main-
taining the quality of the chemical engineering curriculum.
Finally, we have discussed the curriculum as being composed
of two components-content and process. Content and pro-
cess are delivered together, and it is in the specifics of how
this is done that we see an opportunity to address some of the
challenges identified above.
The typical chemical engineering curriculum in 2005 re-
quires roughly two years of science and mathematics study
followed by a year of discipline-specific engineering science
followed by a capstone senior experience. Engineering prac-
tice, therefore, is left until senior year (or late in the junior
year), in large measure because of the need to build on the
prerequisite material. To improve this curriculum we need to
strengthen the exposure to engineering practice, make room
for new subjects, and bolster teamwork and communication
skills. These challenges can mostly be addressed by attend-


ing to the integration of chemical engineering practice into
the delivery of the existing subjects.
All courses can .ri. i,.-i,. students' mastery of chemical
,..;ii. ;,. practice ;1 iii. ,.i;, attention toproblem-solv-
., .-process. While it is true that sophomores and juniors are
not ready to tackle full-fledged engineering design, the prob-
lem-solving process used in chemical engineering senior de-
sign is the generic problem-solving process we discussed
above. This process can be integrated into the first-year,
sophomore, and junior courses by using open-ended prob-
lems and by assigning homework that stretches students
beyond the "pattern recognition" response. Such problem-
based learning methodsE16,171 have been advocated by many
on a wide scale, but it is also possible to implement it
piecemeal to good effect.
Elective courses in, ..;,.. ;in- can broaden students'ex-
posure to newfields /i i,. also i.~. i,-.i,. i,;,.- their problem-
,... 7 ;1, i ii, d i i;,; iii.- skills. To do this, engineering/tech-
nical electives need to be designed to emphasize the prob-
lem-solving process. Engineering/technical electives need to
make explicit the connections between engineering-science
background material (math, sciences, introductory engi-
neering subjects) and the types of problems that are tack-
led in the elective.
New textbooks that emphasize integrated ri., 1.1. 'I.. in ,
process can be written and adopted. An instructor's greatest
ally when designing a course is a well-written textbook. The
textbook is not just a compilation of notes on a subject, how-
ever. An instructor dedicated to integrating problem-solving
process into a course may do so with almost any text, but the
whole process is made much easier if the textbook is designed
with the problem-solving process in mind.
Iiii. .-i, n exercises can be added to all courses. Integra-
tion exercisesE181 are activities or classroom exercises that serve
to bring together subjects that have been studied indepen-
dently. Classroom exercises could integrate mass and. i --,.
balance concepts, staged-operations concepts, and various
mathematical and chemical concepts into one whole. The
result will be a greater understanding of chemical processes
and a greater appreciation of how all the pieces of a chemical
engineering education fit together.
Co-ops and .,,.. ,...i,,.. research can be emphasized.
Co-ops and undergraduate research are two classic ways in
which students have gained exposure to engineering practice
and problem solving. These are excellent sources of integra-
tion between engineering science and engineering practice
and should be encouraged.
Academic, ,. I ;.;,1. can be ,.. ....n,;. .1, an importantpiece
also.11 i ti. .,#i.i ., ,.i. in.. science on,. / *i. i;ii.,prac-
tice. Beyond helping students to plan their schedules, aca-
demic advisors can discuss with students the trade-offs of
various choices for engineering/technical electives as well as


Chemical Engineering Education











the potential benefits to taking a minor or masters in a par-
ticular subfield. The discussion with the advisor is an inte-
gration exercise in itself. It can challenge the student as to
what are his/her goals in making these choices, and it can
challenge the student to articulate those goals effectively.

Finally, the senior ,. ;..-,, class, both traditional and non-
traditional, can be retained and refined as the mainstay of
.',ii. .1,, 'it of 1 .*; ,. ; science and, .-ii;, .. ; ,.- practice
in the chemical, ,.-'i;,.. i;.- curriculum. Traditional senior
design has students pulling together all their background stud-
ies to design chemical plants, typically in the commodity
chemicals industry. More nontraditional approaches could
range from choosing less classical design problems all the
way to alternate design experiences such as working on in-
terdisciplinary design teams with other majors, such as in the
Engineering Enterprise Program we have at Michigan Tech.E191

SUMMARY AND CONCLUSIONS

An engineering problem-solving approach has been applied
to the problem of evaluating and seeking to improve the
chemical engineering curriculum. Various demands on the
curriculum may be seen as different views of the same de-
sire: the desire for a chemical engineering graduate to be well-
versed in the processes of problem solving that can be ap-
plied to any of the diverse fields employing chemical engi-
neers. To educate engineers in these processes, we must use
specific, real systems for study and calculation, and the need
to specialize in this way may seem to narrow the education
of the engineer. This need not be the case, however, if proper
notice is taken of the processes used to solve the problem,
and if the proper connections are drawn between the engi-
neering science background common to all chemical engi-
neering problems and the specific chemical engineering
practice confronted in the classroom. As BrunerE[6 notes,
"To instruct someone. .. is not a matter of getting him to
commit results to mind. Rather, it is to teach him to par-
ticipate in the process that makes possible the establish-
ment of knowledge."
Engineering graduates from Michigan Technological Uni-
versity have long been valued by employers for their ability
to "hit the ground running." In the current decade, however,
the number of fields in which a chemical engineering gradu-
ate can find employment is impossibly broad-our gradu-
ates cannot possibly "hit the ground running" in every field.
We need to change our approach so that our graduates "hit
the ground jogging"-no matter the field in which they land,
they should land in motion, and they should be able to rap-
idly ramp up as they acquire the specific knowledge they need
to succeed in their chosen field. The key to "IIIIIIi ; the ground
jogging" is an education that emphasizes learning the pro-
cess of engineering problem solving through a deliberate and
widespread integration of fundamental knowledge (engineer-
ing science) with practical application (engineering practice).


ACKNOWLEDGEMENTS
Many thanks to the colleagues who read and gave feed-
back on previous drafts of this paper.

REFERENCES
1. Hannon, Kerry, "Educators are Struggling to Prepare Well-Rounded
Engineers for Today's Workplace," Prism, 12(9), May-June 2003:

2. Felder, Richard, "Random Thoughts: The Alumni Speak," (. .
Ed., 34(3), 238 (2000)
3. Selingo, Jeffrey, "The Disappearing State in Public Higher Education,"
Chron. Higher Ed., 49(25) A22, February 28 (2003)
4. Burd, Stephen, "Colleges Catch a Glimpse of Bush Policy on Higher
Education, and Aren't Pleased," Chron. Higher Ed., A25 March 8,
(2002)
5. Burd, Stephen, "Education Department Wants to Create Grant Pro-
gram Linked to Graduation Rates," Chron. Higher Ed., 49(17), A31
January 3 (2003)
6. Bruner, Jerome S., The Process ofEducation, Harvard University Press
(1966)
7. Cussler, E., "What Happens to Chemical Engineering Education,"
ConocoPhillips Lecture Series in Chemical Engineering given at Okla-
homa State University, Stillwater, OK, March 1, (2002):

8. Johnson, Roger T., and David W. Johnson, "The Cooperative Learn-
ing Center at the University of Minnesota,"
9. The push for a 5-year degree was felt at Michigan Tech from both
industrial advisory board members and from faculty members con-
cerned that room needed to be found for new topics and also in recog-
nition of the reality that many students were taking 5 years to obtain
their BS degree.
10. Felder, Richard, "The Myth of the Superhuman Professor," Conoco-
Phillips Lecture Series in Chemical Engineering given at Oklahoma
State University, Stillwater, OK, May 1, (1992)

11. Grose, Thomas K., "Opening a New Book," ASEE Prism, 13(6), 21
February (2004)
12. Creighton, Linda, "School for Wonks," ASEE Prism, 13(6), 37, Feb-
ruary (2004)
13. Meyers, Carolyn, and Edward W. Ernst, "NSF 95-65 Restructuring
Engineering Education: AFocus on Change," Report of an NSF Work-
shop on Engineering Education, August 16, (1995)
14. Augustine, Norman R., Rebuilding Engineering Education," Chron.
Higher Ed., May 24 (1996)
15. Subrata, Sengupta, "The Center For Engineering Education and Prac-
tice: Rethinking Engineering Education"

accessed February 16, 2004; the Center is associated with the College
of Engineering and Computer Science at University of Michigan
Dearborn.
16. University of Delaware, Web site on Problem Based Learning,
and references cited therein.
17. Felder, Richard M., "Changing Times and Paradigms," Chem. Eng.
Ed., 38(1), 32 (2004)
18. Wenger, Win, "The Other End of Bruner's Spiral: A Proposed Educa-
tive Procedure for Easy Integration of Knowledge. A Learning Model
for Summer School in College or High School," Project Renaissance,
(301) 948 (1987)

accessed September 25, 2003.
19. Michigan Tech's Enterprise Program gives teams of students the op-
portunity to participate in real-world settings to solve engineering prob-
lems supplied by industry partners. The program prepares students for
the challenges that await them after their education, and gives new
perspectives to sponsors, businesses, and organizations who partici-
pate. On the Web at 1


Spring 2005











classroom


USING MATHEMATICS


TO TEACH PROCESS UNITS

A Distillation Case Study




MARIA G. RASTEIRO, FERNANDO P. BERNARDO, PEDRO M. SARAIVA
University of Coimbra 3030-290 Coimbra, Portugal


Today it is well accepted that courses on process units
should incorporate some kind of computational
and/or simulation tools in order to perform the inten-
sive calculations often required in the analysis and design of
process equipment. A common approach in the past, also fol-
lowed at the University of Coimbra, was to propose a design
project where the students had to construct their own pro-
grams in a structured language such as Fortran. Nowadays,
process simulators, such as Aspen Plus or HYSYS,1"- 4 or gen-
eral-purpose computational platforms, such as Mathematica,
MATLAB, or spreadsheet programs,E5-8] are widely accepted
tools throughout the chemical engineering curriculum, par-
ticularly in the teaching of process units. When compared
with Fortran programming, these higher-level computational
tools have the obvious advantage of allowing complex cal-
culations with less programming effort. In addition, their
graphical interface can be used as a tk.i lnl;l k.iiunil plat-
form, allowing exploratory simulations and quick visualiza-
tion of the corresponding results.
Process simulators, however, have a potential pedagogical
drawback-students may eventually use them as black boxes,
without really understanding the physico-chemical model
embedded in the simulator. Wankat and Dahm recognize this
limitation and propose a cautious use of process simulators,
leading students to physically interpret simulation results.3 41
On the other hand, if a general-purpose platform is used, stu-
dents have to write down the process model equations and
program their basic solution strategy. Therefore, it is the opin-
ion of the authors that this kind of tool is more adequate to
support a basic process units course. Process simulators can
also be used, but mainly for inductive presentation of con-
ceptsE2,41 and to compare solutions and methods.[8] A more
intensive use of simulators should be left for later instruc-


tion in a senior design course.
In the case study presented in this paper, we have chosen
Mathematica, a very powerful general-purpose platform, to
support the teaching of distillation in a process units course.
Similar experiences have been reported using spreadsheet pro-
grams,E7,81 which have the advantage of being easier to learn.
Mathematica is much more powerful, however, and has a
comprehensible working environment that makes it possible
to introduce its key capabilities using engineering problems
as a starting point, as will be explained later. In a previous
evaluation, made from the viewpoint of an undergraduate stu-
dent seeking to solve four simple chemical engineering prob-
lems, Mathematica received the highest rating, ahead of
MATLAB, Maple, and Excel.E61
Mathematica has been used in our process units course for
the last two academic years (2001/2002 and 2002/2003), and
in particular, it was used to teach distillation operations. Two
initial computer classes introduce students to some key
Mathematica capabilities, using vapor-liquid equilibrium cal-

Maria G. Rasteiro is Associate Professor in the Chemical Engineering
Departmentat Coimbra University. She received a PhD in Chemical Engi-
neering/Unit Operations in 1988. Her research interests are in the fields of
process units, particle technology, and multiphase processes as well as in
improving teaching and learning in engineering education. She is a mem-
ber ofASEE and of the Working Party on Particle Characterization from
EFCE.
Fernando P Bernardo is a TeachingAssistant at the University of Coimbra
and is currently preparing his PhD in the area of Chemical Product and
Process Design. He has collaborated in courses on applied computation
andnumerical methods as well as transferphenomena andprocess units.
Pedro M. Saraiva is Associate Professor in the Department of Chemical
Engineering, University of Coimbra. He received his PhD in 1993 from
Massachusetts Institute of Technology His research interests are in the
areas of process systems engineering, applied statistics, and quality man-
agement.


Copyright ChE Division ofASEE 2005


Chemical Engineering Education







culations as a starting problem. Later, the interactive user in-
terface of Mathematica (known as notebook) is used to illus-
trate several design methods and modes of operation, mak-
ing it possible for students to perform complex calculations
followed by more perceptible graphical representations. Ad-
ditionally, a simulation project is given
to student teams, with two computer
classes supporting it. At the end of this
distillation course, students should be When co
able to use Mathematica as a tool in de- Fortran P
signing other process units in addition these h
to distillation. coput
compute
In order to evaluate this methodology,
t1 Ahavet
a class survey was conducted to judge
both the benefits and the difficulties ex- advantage
perienced by students, with a resulting complex
general appraisal that was quite positive. with less
In comparison with our previous ap- effort.
proach, students now achieve a wider
understanding of distillation processes their grapi
and simultaneously learn a powerful can be
computational tool that they will actu- teachii
ally use later in other courses, namely platform
in the senior design course.
exploratoj
The remaining parts of this paper are and q
organized as follows: First, we give a and quick
brief introduction to the computational of the co
tool we selected (Mathematica) and out-
line its capabilities; then, the teaching
strategy we adopted will be explained


in the context of our distillation case study and will be illus-
trated by two examples (design of a binary continuous distil-
lation column and simulation of a batch distillation opera-
tion); finally, the results of the class survey will be discussed
and some final conclusions will be drawn.

THE COMPUTATIONAL PLATFORM -
MATHEMATICA
Mathematica is a general-purpose computational platform
that performs numerical and symbolic mathematical calcula-
tions. It can be used as a simple calculator, as a high-level
programming language, or as a software platform to run pre-
viously built packages for specific purposes. An extensive
list of internal functions is available that covers a wide vari-
ety of mathematical fields, such as numerical solution of al-
gebraic and differential equations, linear algebra, and statis-
tics. All tasks can be performed through an interactive docu-
ment, known as the notebook, in which the user can mix
simple calculations or complex function calls with text and
graphics, creating an autonomous technical document that
can be visualized in class and used as a tool for study. A very
good manual is availablet19 that describes the Mathematica


mp
rog
ighi
atiol
he o
,e oJ
cal
pro
In a
hica
us
ig/h
mn, a
ry s
vis
Prres
?sul


Spring 2005


platform and covers a wide range of mathematical topics:
the whole book with extra documentation is also available in
the on-line program help, where it is possible to look quickly
for information and find clear examples.
In our case study, focused on the distillation process. we
have used the standard Mathematica
system (Version 4. 1999), applying its
hired with capabilities at the levels of numerical
solution of algebraic equations, numeri-
ramming, cal integration, linear algebra and graph-
er-level ics.
nal tools
.b s TEACHING STRATEGY:
obviouss
lowi DISTILLATION CASE STUDY
allowing
a n The Process Units II course in the
cuations chemical engineering curriculum at the
ramming lUn~' ers, of Coimbra is dedicated to
addition, equilibrium-staged separation opera-
l interface tions. based on a mass transfer mecha-
nism-namely distillation and liquid-liq-
as a uid extraction.1"f"'u The organization of
airing the distillation lectures, taking a total of
'lowing 18 hours, is described below.
imulations Before enrolling in this course. stu-
ualization dents have already had a course on ther-
modynamics, so we begin by revisiting
po g the fundamentals of vapor/liquid equi-
ts. librium, and we introduce Mathematica
in computer classes at this early stage.
We then move to the design and analysis
of distillation processes, based mainly on both mass and en-
ergy balances to each equilibrium stage or to the distillation
system as a whole.
The balances can be either in a differential or algebraic
form, depending on whether we are dealing with batch or
continuous processes. Equations are often organized in an
algorithmic form. and we stress the analysis of their degrees
of freedomi10 in order to guide their subsequent computa-
tional solution using Mathematica. In parallel to this analyti-
cal approach, we present graphical methods-namely the
McCabe-Thiele method for binary distillation. Ahli h'ulih rig-
orous analytical solutions are preferred, we emphasize that
graphical methods are important tools for quickly visualiz-
ing interactions between process variables, which are not so
perceptible when looking only at model -eq,1iotimli. ",
As far as the continuous processes are concerned, we first
give students binary problems iteed, with just two compo-
nents) and then move to multicomponent problems, which
are usually solved by putting the balance equations in a ma-
trix form." Simpler problems, with just one feed and two
product streams, as well as more complex problems involv-
ing multiple feeds and products are approached. Regarding








batch operation, we only consider binary feeds and simple
models, neglecting column holdup. The differential balances
are integrated considering both constant and variable reflux
ratios.
The primary goal of the proposed design exercises is to
compute the number of ideal stages required for a specified
degree of separation. Additionally, we must obtain informa-
tion on the variation of temperature, composition, and flow
rates (vapor and liquid phases) along the column, on the heat
needed in the reboiler, and also on the heat withdrawn in the
condenser. In the case of a continuous column, we also con-
sider the problem of optimum stages for feeds and purges.
In addition to the aforementioned theory lectures, the prac-
tical application of distillation fundamentals is set for stu-
dents over three different projects:
(P1) A case study illustrating different distillation
operations and calculations involved in their design,
using Mathematica notebooks
(P2) A list of proposed simple problems, most of them
solvable by hand calculations and/or graphical
methods
(P3) A simulation project where students are asked to
design a multicomponent continuous distillation
column
Students are guided through the above projects with three
types of practical classes:
(A) Full classes (3 x 2 hours, with 30-40 students)
introducing a case study (P1), with the main goal of
teaching applied distillation using Mathematica
(B) Tutorial classes (4 x 2 hours, maximum of 25


students), mainly supporting project (P2), where
autonomy in problem solving and critical thinking are
encouraged
S(C) Computer classes (4 x 2 hours, maximum of 15
students, with 2-3 students per computer) with the
main goal of leading students to learn the basics of
Mathematica and providing support to project (P3)
Table 1 shows the complete program of practical classes
for the school year 2002/2003. Comparing it to the 2001/
2002 schedule shows that we introduced some minor changes
based on the results of the class survey as well as on our own
experiences.

Introductory Computer Classes
Students have not previously gone through any formal
classes introducing them to Mathematica, although they have
had introductory courses on Fortran programming and nu-
merical methods. Therefore, our teaching strategy includes
two initial computer classes programmed to informally in-
troduce them to Mathematica fundamentals, motivated by the
difficulties that arise even in one-stage distillation calcula-
tions.
Our first class, for instance, starts with the question
As you know, distillation design calculations are usually
based on the concept of equilibrium stage. So, the prediction
of vapor/liquid equilibrium conditions in multicomponent
systems is an essential tool in the design of distillation
equipment. Let us then consider a liquid quaternary mixture
of i-butane, n-butane, n-pentane and n-hexane, with molar
fractions of 0.10, 0.35, 0.45 and 0.10, respectively. How can
we predict the boiling temperature of such a liquid for a
pressure of 3 bar (bubble-T calculation)?


Chemical Engineering Education


TABLE 1
Program of Distillation Practical Classes (2002/2003)

Class Summary
Cl (2 hrs) Introduction to Mathematica using vapor-liquid equilibrium (VLE) calculations as a starting point.
Al (2 hrs) Drawing VLE diagrams in Mathematica. Effect of pressure on relative volatility. One-stage batch distillation; integration of mass balances.
C2 (2 hrs) Flash calculations using Mathematica. Partial condensation of vapor coming from the top of a distillation column.
B 1, B2, B3 Design of a continuous binary distillation column: VLE model based on constant volatility; number of ideal stages computed by Lewis-
(3 x 2 hrs) Sorel method; minimum number of ideal stages; minimum reflux ratio; approximate column sizing; qualitative discussion of the effect of
pressure and reflux ratio on column dimensions.
A2 (2 hrs) Design of a continuous binary distillation column using Mathematica; effect of feed location, pressure, and reflux ratio on design results.
Simulation of a batch binary distillation column; constant and variable reflux ratio.
B4 (2 hrs) Shortcut design method of Fenske-Underwood-Gilliland for continuous multicomponent distillation. Selection of operating pressure and
estimation of the number of stages required.
A3 (2 hrs) Design of a continuous multicomponent distillation column. Shortcut methods and rigorous stage-by-stage calculations by Lewis-Matheson
method. Synthesis of distillation column sequences; heuristics to select the most promising alternatives.
C3. C4 Programming Wang-Henke rigorous design method in Mathematica. Simulation of a continuous distillation column with multiple feeds and
(2 x 2 hrs) product streams; graphical representation of compositions, temperature, and flow rates along the column.







The problem formulation, assuming ideal vapor behavior,
UNIFAC model to quantify interactions in liquid phase,[121
and the Antoine equation to predict pure components vapor
pressures, results in a single nonlinear algebraic equation to
be solved for temperature.
Starting from a Mathematica notebook, with the Antoine
equation and UNIFAC method already programmed, students
are asked to: 1) construct the nonlinear equation in tempera-
ture and solve it using the internal function FindRoot (Fig-
ure 1 shows the notebook for this case, considering the liquid
phase ideal), and 2) explicitly program in Mathematica lan-
guage a numerical method to solve this equation.
While performing these tasks, students learn some funda-
mentals of Mathematica, such as lists (vectors and matrixes),
functions, For cycles and modules (subroutines), and how
to seek information from the online help. At the end of this
class, students are told how to use the modules in the note-
book vle.nb, which has been pre-programmed by us so as to


(, Antoine equation: T in K, ps in bar .)
ps[T_, Ant] := ExprAnt[[1]] -Alnt[[2]]/ (T Ant[[3]])]:
(. Inverted Antoine equation *)
Teb[ps_, Ant_] := Ant.[[21(Anl]] / [[]]- Log[ps]) Ant[[3]]1

nc = 4 (. HNmier ot components .)
(. Antoine constants, 3 for each component w)
Ant = 119.5905, 2371.9, -13.665), (9.6286, 2447.6, -18.128),
(9.3734, 2561.6, -35.5401, (9.3006, 2741.7, -46.698});
x= (0.1, 0.35, 0.45, 0.1): (. Liquid molar fractions .)
p= 3: (, Pressure n)

(. Non-linear equation in T, resulting from Raoult' s law =)
Clear T];
equation= Sunm[x[i]] rpsl[, Ant[[i]]]/p, {i, 1, nc)] -1 :0



l. E 0 *= i


(, Initial estimate *)
TO Sun[Teb[p, Bnt[[i]]] .x[[i]], (i, 1, nc)]


(s Solution *)
sol = EindRoot[equation, (T, (TO, TO 1))]


I T 11 I


Figure 1. Boiling temperature of a liquid mixture, assuming
Raoult's law is valid.


Spring 2005


easily perform the bubble-T calculation they have just pro-
grammed as well as other bubble and dew point calculations.
Illustrative Type-A Classes
The case study (P1) consists of the separation by distilla-
tion of a hydrocarbon mixture into two or more streams with
specified compositions. A set of problems is formulated and
solved in Mathematica notebooks, covering most of the fun-
damental topics in distillation, from vapor/liquid equilibrium
calculations to equipment sizing, including binary and mul-
ticomponent feeds and continuous and batch operation. Type-
A classes are dedicated to this collection of problems, with
Mathematica notebooks being visualized and evaluated
throughout the classes. In this way, it is possible to quickly
illustrate the influence of several parameters on the perfor-
mance of distillation processes (reflux ratio, operating pres-
sure, feed location) and also different design methods (short-
cut or rigorous stage-by-stage calculations) and their results.
Students are provided with Mathematica notebooks so they


can explore other situations not covered dur-
ing class and, at the same time, become more
familiar with Mathematica capabilities. Two
examples will be described in more detail be-
low.
- Design of a Continuous Distillation Col-
umn
The design of a n-butane/n-pentane continu-
ous distillation column (Figure 2) is set for stu-
dents using the Lewis-Sorel method (constant
liquid and vapor molar flows in each column
section). The desired degree of separation is
98% recovery of butane in the distillate and
95% recovery of pentane in the bottom prod-
uct. We begin by computing the number of
ideal stages required assuming certain condi-
tions (approximately constant pressure of 5 bar,


Figure 2. Continuous distillation column.

119


1[,3 bubble-pint-calculatonlnb MR Es


i.








saturated liquid feed, total condenser and saturated reflux, reflux
ratio of 2), with some of them being discussed further later on. The
approximated column dimensioning is left to a subsequent class.

After formulating the solution to the problem on the blackboard,
we begin to use the Mathematica platform as a simple calculator,
alternating between linear mass balances and dew point calcula-
tions (note that at this point students are already familiar with VLE
calculations using Mathematica). Then, we show how the Lewis-



co tin o ist iat io .


p = 5 (* pressure in bar x);
PR]= 2, (* reflux ratio *)
Reai. 0. 98; (N butane recovery'*)
Rea2 0.95; (* pentane recovery *)
LaewsSozrel[p,. R, Relr Rea2]


I r, It 1 7 -i1 :- It r r c i, -


hi :1 .

4 ,
'4 *:- :.


I


.4






1


I :.


: 1

S 6
. .i "


.4. 1


:. I4.,.
,. 9.,
It' .


S I
* :





S141

1.
4.* 4:*
14.r
.>91~


e 4. 4


'". " i
S .

. .-14. 1

0 i-d,,.
, J .., =

, A., 4- .


Nnaj ,.t t r* *C !'ii Ei r.3. N i i



i A; C C i : ** -*- i :. H I t. 1

H:.-- I'tr..lc.-', ,r. r.-. : '.rr, '-.- : -." 4 hi1

F : I I 4 1- -,A r : .,. A I H ,

i


I O . 4 t i

I.... .....loo x A jj


AA


Sorel procedure can be easily programmed within a mod-
ule (named as LewisSorel), with adequate criteria for
optimal feed location being adopted; the module output
includes stage-by-stage temperature and composition in-
formation and also the respective McCabe-Thiele diagram


0.2 0.4 0.6 0.8 1


Figure 4. Effect of a non-optimal feed location (7th
instead of 4th stage): number of stages required
increases from 11 to 12.


T (K)
365 -

360 .
355 --- .. NF=7

350 / -.

345
340

335

Stage
2 4 6 8 10 12



Figure 5. Temperature profiles for optimal (NF=4)
and non-optimal feed locations (NF= 7).


Figure 6. Effect of decreasing the reflux ratio from
2 to 1.1: number of stages required increases from
11 to 17 (minimum reflux ratio = 0.97),


Chemical Engineering Education


Figure 3. Results from Lewis-Sorel design method (continuous
distillation column for butane/pentane separation, with optimal
feed location; Tis temperature, xand y are molar fractions of
butane in liquid and vapor phases, respectively).


0.2 0.4 0.6 0.8 1


T i i -T r aI' rl rj i : : r p 7 1 i : r. T r '. r i I t 7







(Figure 3). This module can now be used to illustrate a non-optimal feed
location (Figures 4 and 5) or the effect of decreasing the reflux ratio and,
consequently, the concept of minimum reflux ratio (Figure 6), among
other relevant points of discussion (effects of operating pressure, opti-
mal reflux ratio, etc.).
- Operation of a Batch Distillation Column
Having applied the Lewis-Sorel method to design a continuous distil-
lation column, students are then confronted with the problem of simulat-


Figure 7. Batch distillation column.
. .. - -- - - . . --.

O B 5000(s feed in nol );
xBO =0.44; (, initial butane mole fraction a)
P = 3; (w nlmier of ideal stages) )
p = 5 ( pressure in bar *);
xB =0.15;. ( final butane mole traction i)
Vapor= 1.29(a vapor boilup rate'in mol/s r)'
BR ,t:,(freflux ratio.") .) -. .
Bf =BO.OExp['I .:..*
S te'.. atbel/ [(xDkrect[lPBR, xBi -B),
xH.4.i. . ..... ..
a aH. t. k-, .' ..&. o-& .. t. .. * ', . ,

P(




TI- -.7 W .


: ; i :. . 'r r LE : .- : :' J.-
:r~:~~i [.,, ; ~D :l. : ., : ': 3''1i :: "
.. ''.',,.& 'g:':,,' .9 :" .,: .:'' d :,,, _: ,,;,.,,j .
.pi .["D I~~ .D =''t I0Dti".m&;:l -!, ...
:i ]: ,* <':,.<: >': :; ,' ;: ", . : ,


C,,. '.


Spring 2005


-- Distillate (D)











er
-Heating


ing a batch distillation operation conducted in a
boiler + rectifying column (Figure 7). The goal is
to separate the same binary mixture of n-butane/n-
pentane as before, studying both constant and vari-
able reflux ratio operations. The main simplifying
assumptions considered here are constant vapor
boilup rate, negligible column holdup, and con-
stant liquid and vapor molar flows along the col-
umn.
For a bottom liquid composition xB (molar frac-
tion of butane), a Mathematica module (named
xDrect) is constructed to predict the distillate
composition obtained in the top of a column with
NP ideal stages and operating with reflux ratio RR.
For a constant reflux ratio, this module is used in
conjunction with Rayleigh equation (differential
mass balances) to compute the final bottom prod-
uct quantity (Bf) with a specified composition
(xBf). After this, the accumulated distillate quan-
tity (Df), its average composition (xDf) and the
distillation time (tf) are easily computed through
simple mass balances (Figure 8). For a variable
reflux ratio operation, the reflux ratio profile (Fig-
ure 9) required to obtain a distillate with a con-
stant composition of 90% in butane, using the same
column, is computed integrating the mass balances
together with the non-linear equation
xDrect[NP,RR,xB] = 0.9, solved for RR (a
4th order Runge-Kutta method is selected and pro-
grammed in Mathematica).
Simulation Project (P3)
The aim of project (P3) is to confront students
with an open engineering problem: design a mul-
ticomponent continuous distillation column, with
a given feed and certain restrictions on operating
conditions, that provides a specified degree of sepa-
ration. Similar problems are set for teams of 3 ele-
ments each, with the final evaluation being based
on a technical report (about 20 pages), which is

Reflux Ratio
4
3.5
3
2.5
2
1.5
15 t (min)
10 20 30 40 50

Figure 9. Results for a batch distillation simula-
tion with constant distillate composition and
variable reflux ratio.

121


Figure 8. Results for a batch distillation simulation with constant
reflux ratio.


iijcilijri: iC :i~~:. iu:l ;ie







orally discussed. There is also an individual task for each
team member.
In order to guide students faced with such an open prob-
lem, project (P3) is scheduled in 6 steps: (1) VLE prediction;
(2) calculation of stream enthalpies; (3) flash calculations (in-
dividual task); (4) preliminary evaluation of operating con-
ditions; (5) shortcut method for column design; (6) rigorous
stage-by-stage column design by the Wang-Henke
method.'13'"41 Teams are advised to use case study (P1) as a
starting point to proceed along the various steps and their
work is closely followed with short oral discussions. Step (6)
is the one requiring most programming skills, and thus two
computer classes (C3 and C4) are dedicated to mentor stu-
dents through it, introducing them, simultaneously, to ma-
trix manipulation and efficient linear algebra calculations
with Mathematica. Having completed a base case simula-
tion, students are then encouraged to study and discuss
the influence of several operating conditions on column
performance and design.

ASSESSMENT OF
STUDENTS' PERCEPTIONS
Students' perceptions of the advantages and disadvantages
of the teaching strategy adopted were evaluated through both
an oral discussion and a written survey.
In the oral discussion, students were asked to outline some
conclusions based on the set of problems studied during type-
A classes, and at two different levels: (i) the particular pro-
cess unit studied (distillation); (ii) process engineering de-
sign problems in general. Table 2 presents the most relevant
collected opinions.


TABLE 2
Students' Conclusions Regarding Project (P1)

Distillation Level
Flash distillation promotes a coarse separation appropriate to
pretreatment of mixtures with highly volatile components.
In a continuous column, an increase in the operating reflux ratio
implies an increment in energetic costs.
Decreasing column operating pressure facilitates separation since
relative volatility increases.
Process Engineering Design Problems
Design calculation results should be criticized in terms of their
practical execution.
There are available shortcuts and more rigorous design methods,
the former being good starting points for the latter.
The degrees of freedom analysis is an important tool for problem
formulation and subsequent solution.
Mathematica is an accessible calculation tool that allows one to
perform parametric studies, but is not very efficient in terms of
computational time.


The written survey aimed at evaluating the impact of our
teaching strategy under four domains-the main results are
given in Table 3.
The overall evaluation is positive, with a relevant improve-
ment in the second school year. The strongest point mentioned
by students was related to the advantages of learning distilla-
tion with the assistance of Mathematica, especially concern-
ing the software's graphics facilities. Though students men-
tion having experienced some difficulties in getting started
with Mathematica through the case studies proposed (state-
ment 2), that is somehow contradicted by the conclusion
reached under statement 3. In fact, after this experience, they
consider themselves reasonably well prepared to tackle other
design problems assisted by Mathematica. This point has been
confirmed in other courses, with students .choosing
Mathematica to support their projects, namely in the simula-
tion of chemical reactors and milling operations and also, in
some cases, in their final year process/product design projects.
The students' difficulties revealed by statement 2 have led
us to include two introductory computer classes (Cl and C2)
in 2002/2003, instead of just one. We have, however, main-
tained the perspective of learning the fundamentals of
Mathematica through its application in solving distilla-
tion problems.

CONCLUSIONS
The strategy presented in this paper combines both the
teaching of process units design and the use of a general-
purpose computational platform. We believe there are mu-
tual benefits in combining these two subjects. Students ac-
quire a good understanding of the process units, formulating


TABLE 3
Main Results from Written Survey

Classification (scale 0-20)
Domains Evaluated 2001/02 2002/03
1. Learning Distillation Using Mathematica
Mathematica code visualized in type A classes
did not perturb the perception of fundamental
concepts. 13 14
Type A classes illustrated a wide range of
situations, giving a broad view of distillation
processes. 13 14
The graphical capabilities of Mathematica
allowed for quick visualization and several
operating aspects. 17 16
2. Learning Mathematica through the design
of distillation processes 10 12
3. Using Mathematica to study other process
units besides distillation 12 13
4. Benefit/ effort balance 11 12
Sample (number of students / students
developing project (P3)) 23/45 30/49


Chemical Engineering Education





































and solving integrated problems and remaining always close
to the underlying physical/chemical phenomena. Simulta-
neously, they learn how to use a computational platform in a
perceptive way, motivated by the problems that arise while
studying a given process unit. Altogether, this methodology
represents an improvement on the more traditional strategy
of teaching process units and computational tools separately.
In fact, there is a clear reduction in the total number of
hours required for teaching and it is possible to benefit
from the graphical facilities of the computational tool to
lead students to the understanding of the processes stud-
ied, namely the design features.
The computational tool selected (Mathematica) supports
our simultaneous teaching strategy in several ways: the in-
teractive document known as notebook can be visualized
in class and used by students as a tool of study, the sym-
bolic calculation capabilities help students to formulate
problems and check results, and the online help greatly
supports the program.
Regarding our distillation case study, Mathematica has of-
fered an adequate environment to illustrate a wide range of
situations, including those with a heavy mathematical con-
tent, such as batch distillation. Moreover, the notebook fea-
ture allows for an easy graphical representation of the re-
sults, which then become more comprehensible to students.
In addition, students have successfully used Mathematica
while developing a proposed simulation project. After this
distillation experience, we can confirm that students are
reasonably well prepared to tackle other process-design


problems using Mathematica.

REFERENCES
1. Seider, W.D., J.D. Seader, and D.R. Lewin, Process Design Principles,
John Wiley & Sons, New York, NY (1999)
2. Dahm, K.D., R.P. Hesketh, and M.J. Savelski, "Is Process Simulation
Used Effectively in ChE Courses?" Chem. Eng. Ed., 36(3), 192 (2002)
3. Wankat, P.C., "Integrating the Use of Commercial Simulators into Lec-
ture Courses," J. Eng. Ed., 91(1), 19 (2002)
4. Dahm, K.D., "Process Simulation and McCabe-Thiele Modeling,"
Chem. Eng. Ed., 37(2), 132 (2003)
5. Dorgan, J.R., and J.T. McKinnon, "Mathematica in the ChE Curricu-
lum," Chem. Eng. Ed., 30(2), 136 (1996)
6. Mackenzie, J.G., and M. Allen, "Mathematica Power Tools," Chem.
Eng. Ed., 32(2), 156 (1998)
7. Bums, M.A., and J.C. Sung, "Design of Separation Units Using Spread-
sheets," Chem. Eng. Ed., 30(1), 62 (1996)
8. Hinestroza, J.P., and K. Papadopoulos, "Using Spreadsheets and Vi-
sual Basic Applications as Teaching Aids for a Unit Operations Course,"
Chem. Eng. Ed., 37(4), 316 (2003)
9. Wolfram, S., The Mathematica Book, 3rd ed., Wolfram Media/Cam-
bridge University Press (1996)
10. Henley, E.J., and J.D. Seader, Equilibrium-Stage Separation Opera-
tions in Chemical Engineering, John Wiley & Sons, New York, NY
(1981)
11. Wankat, P.C., Equilibrium Staged Separations, Prentice-Hall, Upper
Saddle River, NJ (1988)
12. Reid, R.C., J.M. Prausnitz, and B.E. Pauling, The Properties of Gases
and Liquids, 4th ed., McGraw-Hill, New York, NY (1987)
13. Wang, J.C., and G.E. Henke, "Tridiagonal Matrix for Distillation,"
Hydrocarbon Proc., 45(8), 155 (1966)
14. Monroy-Loperena, R., "Simulations of Multicomponent Multistage
Vapour-Liquid Separations: An Improved Algorithm Using the Wang-
Henke Tridiagonal Matrix Method," Ind. Eng. Chem. Res., 42(1), 175
(2003) 0


Spring 2005


CALL FOR PAPERS


Fall 2005 Graduate Education Issue of

Chemical Engineering Education

We invite articles on graduate education and research for our Fall 2005 issue. If you are interested in contributing,
please send us your name, the subject of the contribution, and the tentative date of submission.


Deadline is June 1, 2005

Respond to

Chemical Engineering Education c/o Chemical Engineering Department
University of Florida Gainesville, FL 32611-6005

Phone and Fax: 352-392-0861 e-mail: cee@che.ufl.edu











curriculum


INCORPORATING

MOLECULAR AND CELLULAR BIOLOGY

INTO A ChE DEGREE PROGRAM


KIM C. O'CONNOR
Tulane University New Orleans, LA 70118


Chemical engineers have the unique opportunity and
challenge to translate recent advances in the biologi-
cal sciences into useful products. There has been tre-
mendous growth in the understanding of living systems at
the molecular and cellular level, typified by insight into the
human genome,E1 tissue repair with stem cells,E21 and the mo-
lecular basis for many diseases.J31 Educational programs that
provide chemical engineers with a strong foundation in mo-
lecular and cellular biology (MCB) can produce a workforce
capable of both biological discovery and product develop-
ment. This training can ultimately foster interdisciplinary
collaboration and accelerate productivity.
The chemical engineering curriculum provides an excel-
lent platform on which to develop an interdisciplinary edu-
cational program that exposes engineers to MCB. With its
historical roots in chemistry, chemical engineering has re-
tained its ties to the molecular sciences, and as a result, ki-
netics, transport phenomena, and other core concepts in the
chemical engineering curriculum can be readily adapted to
the molecular-based advances that are prevalent in the bio-
logical sciences today, such as cell iIi.iIIIg'yI and drug re-
sistance in tumors."' Moreover, the quantitative-systems view
to problem solving that is a hallmark of an engineering educa-
tion is particularly relevant to emerging biological disciplines
that require analysis of large data sets or complex reaction path-
ways, with metabolic. IIll It. 111%;' I as a prominent example.
If past performance is an indicator of future achievements,
chemical engineers will make great strides in the develop-
ment of bik ci. el. 1 -.1.. From the manufacturing of penicillin
during World War II and the first artificial kidney in the 1960s,
to current production of pharmaceuticals and fabrication of
living tissue equivalents,E'-9 chemical engineers have been
instrumental in the development of biological products that
have touched lives on a global scale and revolutionized the
health-care industry. Consequently, the initial industrial em-
ployment of chemical engineers in the biotechnology and
pharmaceutical sector has risen over the past five years for


graduates at the bachelor's, master's, and doctoral levels (see
Figure 1). The current figures of 12.5% (BS), 16.3% (MS),
and 18.3% (PhD) of industrial employment most likely rep-
resent lower limits since the chemical, food, and environ-
mental sectors require bioengineers as well.101
Anticipating the direction of growth in the biological sci-
ences and the resulting hiring trend, the National Research
Council recommended development of innovative interdis-
ciplinary programs in a "Frontiers in Chemical Engineering"
report published in 1988.71 This call for change has been ech-
oed over the years by numerous sources.[9111 In response,
chemical engineering departments are developing new
bioengineering courses, incorporating biology into existing
engineering courses, exposing students to bioengineering re-
search and laboratory experiments, and/or changing the name
of their departments.11 12]
For the past decade, Tulane University has offered a com-
bined degree program that integrates chemical engineering
and MCB. The program was initiated at the graduate level
and then extended to undergraduates in response to student
demand. At the cornerstone of this program is a strong foun-
dation in both chemical engineering and the biological sci-
ences that is research intensive at both the graduate and un-
dergraduate levels. In celebration of its tenth anniversary, the
program is described herein as one department's response to
the growing need for interdisciplinary curricula and as a ref-
erence for other departments to address this issue.

Kim O'Connor is a Professor of Chemical
and Biomolecular Engineering at Tulane
University and is a graduate of Rice Univer-
sity (BS '82) and the California Institute of
Technology (PhD '87). Herpostdoctoral train-
ing is in molecular and cellular biology, and
her research interests are cellular and tis-
sue engineering. She founded and directs
the Graduate Combined Degree Program,
and was Co-Director and Interim Director of
the Interdisciplinary MCB Program.

Copyright ChE Division ofASEE 2005
Chemical Engineering Education











PROGRAM ORGANIZATION
Tulane University is composed of three campuses: the Uni-
versity, Health Sciences Center, and Primate Center. While
graduate programs are offered on all Tulane campuses, only
the University provides undergraduate education. The Com-
bined Degree Program is offered by the Department of Chemi-
cal and Biomolecular Engineering (CBE) on the University
campus in conjunction with the Interdisciplinary MCB Pro-
gram that spans the three Tulane campuses (Figure 2). Ad-
ministration of the Combined Degree Program is under the
direction of a CBE faculty member who is also a member of
the Interdisciplinary MCB Program. The CBE Department
has ten faculty members, five of whom are engaged in bioengi-
neering research.
As shown in the organizational chart in Figure 2, the Inter-
disciplinary MCB Program encompasses four different
schools. There are over 100 MCB faculty with a broad range
of expertise and with primary appointments in one of twenty
departments and four
20 centers. The CBE De-
16 apartment is one of the
1 participating depart-
g 12t
12 ments on the Tulane
S8 University campus.
4 Membership criteria for
o the faculty include pro-
98 99-00 00-'01 01-'02 02-03 ductivity and funding
Year level in MCB research.
Figure 1. Employment trends in This large program is
the biotechnology and pharma- governed by a steering
ceutical sectorfor BS (0), MS (*), committee of appointed
and PhD (A) chemical engineers faculty representatives
upon graduation. Data is pre- from each of the partici-
sented as a percentage of initial pa g
placement in all industrial sec- p depar
tors. Source: AIChE Career Ser- units, and is under the
vices.o01 leadership of two Co-
Directors and a Director


Director

Co-Directors

Steering Committee


Microbiology/Immunology
Pathology
Pharmacology
Physiology
Structural & Cellular Biology


selected by MCB faculty in a general election.

GRADUATE EDUCATION
The Combined Degree Program was approved by Tulane
in Fall, 1993, and offered first at the graduate level in Spring,
1994. Applicants must satisfy the admission requirements of
both the CBE Department and Interdisciplinary MCB Pro-
gram to be admitted to the Combined Degree Program. Gradu-
ate students achieve a critical understanding of biology and
engineering principles underlying their field of research
through CBE and MCB coursework, lab rotations and inde-
pendent research. Upon completing the program requirements,
students earn a Master of Science degree with thesis through
the Interdisciplinary MCB Program and a Doctor of Philoso-
phy degree through the CBE Department. This typically re-
quires five years of study.

- Curriculum
Doctoral students in the CBE Department are required to
complete a series of core courses and electives for 48 credit
hours. In the Combined Degree Program, some of the elec-
tives are replaced with graduate-level bioengineering and
MCB courses (see Table 1). The bioengineering component
includes capstone courses in biomolecular engineering that
integrate molecular-based biology and chemical engineering.
Lecture topics include kinetics of the apoptotic pathway, com-
putational approaches to tissue engineering, and delivery of
gene therapies, as well as more established topics such as
enzyme kinetics, bioreactor design, and transport of metabo-
lites. New bioengineering courses are under development,
and existing courses are updated regularly.
In addition to MCB courses in biochemistry, cell biology,
and genetics, the core curriculum includes a two-part course
titled "Research Methods" that consists of faculty research
seminars and a lab rotation (Table 1). During the Fall semes-
ter, the 100+ MCB faculty make a series of short presenta-
tions to introduce Combined Degree and MCB graduate stu-


OB/GYN
Ophthalmology
Otolaryngology
Pediatrics
Urology


Figure 2. Organizational chart of the Interdisciplinary MCB Program for faculty and students in the biological sciences at
Tulane University, Health Sciences Center, and Primate Center.


Spring 2005











dents to the biological sciences and to specific research oppor-
tunities within the Interdisciplinary MCB Program. In the fol-
lowing semester, Combined Degree students complete a rota-
tion in the laboratory of a MCB faculty member other than
their dissertation advisor. Students earn a letter grade for their
productivity on a well-defined research project. A graduate-
level MCB laboratory course can be substituted for the rota-
tion. Traditional chemical engineering graduate students directly
enter their research advisor's laboratory. Rotations provide an
opportunity for Combined Degree students to broaden their
knowledge of the biological sciences and learn specific experi-
mental techniques required for their own dissertation research.
In consultation with their dissertation advisor, Combined
Degree students choose electives related to their field of inter-
est from courses offered by CBE Department, Interdisciplinary
MCB Program, and other graduate programs at Tulane. Topics
include numerical methods, molecular basis of disease, and
biostatistics. Also, students can earn a limited number of
elective credits for independent study in the laboratory on
their dissertation topic.
When graduate students enter the Combined Degree Program
with a bachelor's degree in an area other than chemical engi-
neering, they are required to become proficient with the funda-
mental principles required of chemical engineers by complet-
ing undergraduate courses on unit operations and either reactor
design, process control, or process design. These requirements
can be modified based on each student's specific background.
Undergraduate courses do not count toward the credit require-
ment for advanced degrees. Graduate students with a bachelor's
degree in engineering can opt to take undergraduate biology
courses to overcome deficiencies.
- Research
The Combined Degree Program requires that graduate stu-
dents 1) demonstrate the ability to conduct independent research
that results in a novel contribution to their field of study or an
original interpretation of existing knowledge, 2) document their
findings in a master's thesis and doctoral dissertation, and 3)
defend this scholarly work in an oral exam administered by
MCB faculty for the master's degree and CBE faculty for the
doctorate. Of the two documents, the former focuses on the
fundamental biology of the research project, whereas the doc-
toral dissertation addresses the engineering applications. Stu-
dents are encouraged to defend their thesis by the third year of
graduate study and their dissertation by the fifth year.
Both the thesis and dissertation can be under the direction of
a single research advisor if the professor is a member of the
CBE Department and Interdisciplinary MCB Program. Alter-
natively, MCB faculty can direct the master's thesis as long as
a CBE faculty member directs the doctoral dissertation. The
latter can arise from a research collaboration between two fac-
ulty. Consider, for example, a research project to improve sur-
vival of mammalian cells under harsh culturing conditions in a
bioreactor. A MCB faculty member can direct a fundamental


study of protein expression and cell signaling along critical path-
ways under different reactor conditions, and a CBE faculty can
direct kinetic modeling of the pathways and develop corrective
strategies based on the simulations.

UNDERGRADUATE EDUCATION
In 1997, the Combined Degree Program was extended to
the undergraduate level at the request of undergraduates who
worked with Combined Degree graduate students in the labo-
ratory and wanted a similar education. From their freshman
year until graduation, the undergraduates are engaged in a
comprehensive learning experience in the classroom and
through co-curricular activities. The curriculum provides
knowledge of the principles and applications of chemical
engineering and the biological sciences. Co-curricular activi-
ties are designed to reinforce and supplement classroom in-
struction. Upon completing the four-year program, students
can earn a Bachelor of Science degree in chemical engineer-
ing with a second major or minor in the biological sciences
from the Department of Cell and Molecular Biology within
the Interdisciplinary MCB Program (see Figure 2).
- Curriculum
At Tulane, bioengineering training in the CBE Department
currently has four components at the undergraduate level: a
sophomore-level bioengineering course, Practice School,
concentration of technical electives, and double major/minor
in the biological sciences. All undergraduates entering the
CBE Department are required to complete an introductory
bioengineering course that teaches biology fundamentals, en-
gineering applications, and problem-solving skills (Table 2).
In addition, all CBE seniors are required to participate in a
one-semester internship, called Practice School. Students have
the option to fulfill internship requirements with bioengineer-
ing pi kicl ..11 i i, Tulane Health Sciences Center that involve


TABLE 1
Curriculum Requirements for
MS in Molecular & Cellular Biology and
PhD in Chemical Engineering

Field Course
Chemical Engineering Advanced Reactor Design
Transport Phenomena I or II
Thermodynamics or Applied Statistical Mechanics
Biomolecular Engineering Two of the
Biochemical Engineering
Gene Therapy
Advances in Biotechnology
Biology Biochemistry
Advanced Cell Biology
Research Methods
Molecular Genetics or Biochemical Genetics
Technical Electives Electives in Engineering, Science, and/or Medicine


Chemical Engineering Education











independent research and/or computer programming
under CBE and MCB faculty supervision.
The curriculum has been designed to allow CBE
students to focus their technical electives in a spe-
cialized area. The biomolecular engineering concen-
tration includes graduate bioengineering courses that
are co-listed at the undergraduate level and MCB
courses. This concentration has the flexibility to
enable CBE students to obtain a second major or
minor in the biological sciences. The core courses
for a biology major are general biology, genetics,
cell biology, molecular biology, biochemistry, cell
or molecular biology laboratory, and neuroscience
or developmental biology. Biochemistry is one of
the courses that fulfills the advanced chemistry re-
quirement in the chemical engineering curriculum
(Table 2). In addition, three electives are required
for the biology major: two laboratories and either a


TABLE 2
Curriculum Requirements for BS in Chemical
Engineering with Second Major (*) or Minor (t)
in Cell and Molecular Biology


Field
Chemical Engineering










Other Engineering




Chemistry & Physics




Math


Technical Electives
Four courses required
for chemical
engineering
curriculum







Liberal Arts: 6 courses


Course
Material and Energy Balances
Thermodynamics I and II
Transport Phenomena I and II
Numerical Methods for ChEs
Unit Operations Lab I and II
Separation Processes
Kinetics and Reactor Design
Process Design
Process Control
Practice SchoolI and II


Intro. Eng. and Computer Science
Software Design and Programming
Intro. Chemical Engineering
Intro. Biomolecular Engineering

General Chemistry + Lab I and II
General Physics + Lab I and II
Organic Chemistry + Lab I and II
Advanced Chemistry (Biochemistry *t)

Calculus I, II, and III
Applied Math

Bioengineering elective
General Biology *t
Genetics*t
Cell Biology*t
Molecular Biology*t
Cell Biology Lab* or
Molecular Biology Lab*
Neuroscience* or Dev. Biology*
Two* (onet) of the following:
Biology Elective 1 and 2 (Lab)
Biology Elective 3 (Lecture or Lab)

Humanities/Social Science Distribution


lecture or another laboratory. Independent research gained in a co-cur-
ricular activity counts as an elective. To avoid overloading their course
schedules, students either enter the program with advanced place-
ment credit or are encouraged to fulfill requirements for introduc-
tory courses over the summer.
For a minor in the biological sciences, the MCB core and elective
component are reduced to general biology, genetics, cell biology and
molecular biology, and two biology electives. The technical electives
and advanced chemistry course in the chemical engineering curriculum
fulfill the majority of these requirements. Undergraduates are encour-
aged to satisfy at least one biology elective with a laboratory to be ex-
posed to MCB experimental techniques.
> Co-Curricular Activities
Undergraduates are encouraged to participate in co-curricular activi-
ties that reinforce and supplement classroom instruction. A popular choice
is independent research in the laboratory of a faculty member in the
CBE Department or another department participating in the Interdisci-
plinary MCB Program (Figure 2). Research supplements the traditional
academic curriculum by exposing students to the practice of science and
engineering. In so doing, it helps students think creatively, develop
problem-solving and time-management skills, work in groups, and
learn the importance of patience and perseverance when solving dif-
ficult research problems.
There are several co-curricular activities for students preparing for
medical school. Clinical faculty allow chemical engineering students to
participate in rounds to their patients and volunteer in the surgical suites
at the Tulane Health Sciences Center. On the University campus, un-
dergraduates volunteer in public health projects and in an emergency
medical program to administer prehospital care and ambulance ser-
vice to students.
Summer provides an opportunity for students to continue their learn-
ing experiences without time constraints imposed by coursework. Ac-
tivities include research at a university, employment in industry or a
national laboratory, and training programs at medical schools.

STUDENTS
The Combined Degree Program has produced a diverse cadre of tal-
ented students. At the doctoral level, 66% of the graduates have been US
citizens; 34% female. Unfortunately, none of the graduates to date have
been minorities. They enter the Combined Degree Program with a 3.5
undergraduate GPA, 590 verbal GRE score, and 740 quantitative GRE,
on average. Comparable statistics for enrolled graduate students in the
School of Engineering at Tulane reveal that 51% were US citizens, 27%
were women and 6% were minorities in 2004. Graduate students enter-
ing the School of Engineering in 2004 had an average score of 3.4 for
undergraduate GPA, 570 verbal GRE, and 740 quantitative GRE. At the
undergraduate level, 83% of the Combined Degree students have come
from high schools outside of Louisiana, 33% have been female, and
51% have been minorities. The students are frequently in the top decile
of their senior class and have had an average SAT score of 1380. In
comparison, approximately 70% of Tulane Engineering freshman are
out-of-state, and 65% were in the top decile of their senior class in 2004.
Continued on page 133.


Spring 2005











MWn class and home problems


COOPERATIVE WORK

THAT GETS SOPHOMORES ON BOARD


CHARLES H. GOODING
Clemson University Clemson, SC 29634-0909


he chemical engineering curriculum at most univer-
sities begins with a mass and i i-, balance course.
In some cases this is preceded by a general engineer-
ing course that covers concepts such as unit conversions,
graphical data representation, and basic statistics. One of the
challenges in these lower-level courses is to help students
grasp big-picture issues that faculty often take for granted.
Some examples are
E The importance of error, uncertainty, significance,
cause and effect, and/or quantitative relationships
among real process data.
"What do you mean 'error'? I ii. .,:.-i they did
the experiment carefully."
"Why should I use a linearfit if the polynomial
.-I. ,. a higher R2?"
El Understanding, at least in a rudimentary way, how
process equipment works.
S"In problem 4.11, what do they mean by..."
"How do I know if it's adiabatic or not?"
El Understanding something about the diversity,
breadth, and connections among companies that
employ chemical engineers.
"Why would I want to spend the rest of my life
i ii, vi i.- tetrahydrofuran?"
"Advil comes from oil? No : , '


Simple cooperative assignments can be
particularly useful in the first two
courses .... Three examples are
presented in this paper.


Cooperative learning is a proven technique for helping stu-
dents learn through discovery and discussion.l" Simple co-
operative assignments can be particularly useful in the first
two courses to deal with the issues cited above. Three ex-
amples are presented in this paper. The problem statements
and basic rationale are explained, and typical solutions are
shown in part.
These assignments not only help students understand im-
portant basic concepts, but also help them begin to think like


Copyright ChE Division ofASEE 2005


Chemical Engineering Education


The object of this column is to enhance our readers' collections of interesting and novel prob-
lems in chemical engineering. Problems of the type that can be used to motivate the student by
presenting a particular principle in class, or in a new light, or that can be assigned as a novel
home problem, are requested, as well as those that are more traditional in nature and that eluci-
date difficult concepts. Manuscripts should not exceed fourteen double-spaced pages and should
be accompanied by the originals of any figures or photographs. Please submit them to Professor
James O. Wilkes (e-mail: wilkes@umich.edu), Chemical Engineering Department, University
of Michigan, Ann Arbor, MI 48109-2136.


Charles H. Gooding is Professor of Chemical
Engineering at Clemson University He received
BS and MS degrees from Clemson and a PhD
from North Carolina State University He teaches
the introductory course in material and energy
balances, unit operations laboratory, process
control, and process design.











chemical engineers. Moreover, these examples work best as
team exercises with written and oral reporting requirements,
which can contribute to the development of productive rela-
tionships among the students and to developing or refining
their communication and presentation skills.



EXAMPLE 1



ACCESSING AND USING DATA FROM
A REAL PROCESS
Clemson University is fortunate to have an Energy Sys-
tems Laboratory (ESL), which was developed to provide real-
time energy usage and equipment performance data for simu-
lation, modeling, and analysis by students and faculty. The
ESL is located adjacent to the Central Energy Plant. It pro-
vides physical and virtual access to operating data from
three gas turbines and extensive data on other utility sys-
tems and equipment that are under the purview of Uni-
versity Facilities.
The capstone microturbine virtual interface is the most con-


venient ESL tool for students and faculty to use. The physi-
cal facility consists of a 30-kW gas-fired turbine and an inte-
grated heat exchanger, which recovers part of the sensible
heat from the turbine exhaust gases and transfers it into the
campus steam system. Data from this facility can be accessed
and used as a virtual lab by anyone who has a web connec-
tion. The user first encounters a photograph of the facility
and then the schematic of the gas turbine and heat exchanger,
shown in Figure 1.
Real-time operating data can be accessed by clicking the
"Refresh" button and waiting a few moments. As shown in
the figure, data are available on the feed gas, exhaust gas,
water, and power generation to support several types of engi-
neering analysis. Historical data can also be obtained on any
of the process variables shown.
We usually start this assignment by giving freshman or
sophomore students a tutorial that sends them individually to
the microturbine web site to view and print a copy of Figure
1 with typical operating data shown in the blocks. They bring
this to the next class meeting, which is held at the ESL. There
they see a full-scale cutaway mock-up of a gas turbine and
hear a brief lecture on turbine operations and energy conver-
sion. This is followed immediately by a short walk to see the


figure i. capstone microturnoe scnematnc wit typical aara.


Spring 2005











actual microturbine and heat exchanger facility for further
observation, explanation, and questions and answers.
The goals of this ESL assignment at the freshman level are
to introduce students to ,i ii -. conversion, to have them ex-
plore and gain a rudimentary understanding of the equipment
operation, and to have them conduct basic exercises in data
presentation and analysis. The first homework requires them
to write a short narrative description of the integrated, i l I --
conversion facility after visiting it and to answer questions
such as

What kind of gas enters the turbine and where does it
come from?
What does SCFH mean?
Where does the air for combustion enter the turbine?
Is the airflow rate metered?
What type of energy is measured by the "energy
meter"?
What do the bowties on the thin lines in the sche-
m atic ;.1,. .. it '


assumptions and approximations. In this case the students
must assume something about the composition of the fuel
gas, e.g., that it is 100% methane or that it has some average
natural gas composition.
When they have completed the material balances, students
can ,', iidl.i i-. I y balances on the facility. Again using data
from Figure 1, they can determine the fraction of the chemi-
cal .I i y from the fuel that is converted into electricity in
the microturbine, the fraction that is transferred to the water
in the heat exchanger, the fraction lost up the stack, and the
fraction lost elsewhere.
This assignment is an excellent springboard for introduc-
ing concepts of alternative Ii i conversion, conservation
strategies, thermodynamic limitations, environmental conse-
quences, and economics. Complete discussion of these top-
ics may have to wait until the students encounter other courses,
but the seeds of interest can certainly be planted at the sopho-
more, or even the freshman, level.


In the second ESL assignment the freshman stu-
dents are given access to an Excel spreadsheet that
contains data from the microturbine and heat ex-
changer tabulated at regular intervals over several
hours. They are instructed to plot a specified pro-
cess variable versus time (see Figure 2) and to plot
against one another two variables that should be
correlated (see Figure 3). For the single-process
variable plotted on the ordinate against time they
calculate statistics such as mean, range, and stan-
dard deviation, and then brainstorm and explain
several physical reasons why the standard devia-
tion is not equal to zero, i.e., what are the influ-
ences on this process variable, how is it measured,
and why does the measured value change with
time? For the correlated-process variables they
fit a simple linear model and discuss the physical
interpretation of the slope and intercept and the
goodness of fit.

The objectives of these exercises are to develop
the students' basic skills in data representation and
their understanding of statistical and modeling con-
cepts such as measurement error, random varia-
tion, and cause and effect.

After students study mass balances, data from
this facility can be used further for a real-world
comprehensive assignment. They are told to start
from the data set such as the one shown in Figure
1 and determine the composition of the exhaust
gas and the amount of excess air used in the tur-
bine. They soon learn that another engineering skill
is needed to accomplish this-making reasonable


192


190
1-
0
g 188

E


mean = 186.2 OF
_ std dev = 1.5F F
range = 184.0 to 190.5 F



*
--T


186 *
*~i *


e.


184 *-


182
0 50 100 150 200 250
Sample time, minutes


i


300 350 400


Figure 2. Heat exchanger outlet water temperature vs. time.


27 .0 I t I I I I I 1 I I






2 -







21 2 ,
23*


370


395


Fuel flow, SCFM
Figure 3. Microturbine power generated vs. fuel flow rate.


Chemical Engineering Education


375 380 385 390


E
$
s













EXAMPLE 2



WHAT IS IT AND HOW DOES IT WORK?
This simple assignment is designed to help students in the
mass and i i. balance course understand common chemi-
cal engineering processes that are used frequently in home-
work problems and quizzes. Early in the semester, teams of
two or three students are assigned an unnamed apparatus in
the Unit Operations Laboratory and told to complete the fol-
lowing tasks:
1. Prepare a simple ,li in;- of the apparatus. The
drawing doesn't have to show nonfunctional details or
be artistic, but it should be wit., 1. a1 to help you
explain how the device works. Make a .i, sketch
when you are in the lab, and then use that to make a


Steam


Room Air wet solids
Condensate
Fan Heat Exchanger Dryer

The apparatus shown above is used to remove moisture
from solids. Wet material is placed on a rack inside the
dryer. Room air is pushed by an electric fan through a heat
exchanger and then through the dryer. The heat exchanger
consists of small tubes inside a larger cylinder. The air
passes through the tubes, and steam is fed into the outer
cylinder. In the dryer, moisture evaporates into the hot air,
leaving a dry solid after a period of time.
Material balance
Air enters the fan andpasses l ..... 1h the heat
exchanger and dryer then back into the room.
Steam condenses in the heat exchanger and leaves
as water.
Moisture is evaporated from the solids and leaves
as water vapor with the air.
The solids put into the dryer are taken out later
(minus the moisture).
Energy balance
Steam put into the heat exchanger loses thermal
energy to the air
Electrical energy put into the fan, raises the
pressure of the air
The air cools when it heats the solids and
evaporates the moisture.

Figure 4.


neater 1, .,n ;i,.- later for inclusion in your written
submission and to use in your oral presentation.
2. Figure how the device works and write a brief narra-
tive description to accompany your, ., n i ;.- Explain
the material and energy balance aspects of the process
as well as you understand them at this point in your
studies. D. ... i.. what goes in where and what comes
out wheredi, n1;.- typical operation. Explain how
energy gets into the system and where and how it is
converted to another form or where it comes out.
3. Prepare and present a three-minute oral summary on
your results.
Students are encouraged to ask upper-class chemical engi-
neering students in the Unit Ops Lab to help them under-
stand how an apparatus works. They are also referred to the
ChE library to consult Perry's Chemical FE-ii,.. 's Hand-
book, the Kirk-Othmer Encyclopedia of Chemical Technol-
ogy, and the assortment of textbooks and periodicals stored
there. They discover not only that descriptive help is avail-
able, but also that there are cutaway pictures and diagrams in
these references that will help them understand the equip-
ment.
The sketch and narrative summary in the example shown
in Figure 4 are typical of those handed in for this assignment.
Although the description doesn't include sufficient detail to
ensure that correct mass and ,I i i balances would follow,
it reflects a reasonable understanding of the process.
After examining process equipment and discussing how it
works, sophomores are much better equipped to decipher
written and verbal process descriptions in their classes and to
correctly lay out process flow diagrams.



EXAMPLE 3


CHEMICAL GENEALOGY
In this assignment each team investigates the "-e l .llal -y"
of a family of related chemicals. They are assigned a chemi-
cal intermediate (e.g., acrylonitrile, ethylene oxide, styrene),
which is defined for them as a compound that is made (per-
haps in multiple steps) from naturally occurring materials and
is then used to make other compounds, until ultimately the
products become part of consumer goods. Each team must
conduct a literature research and complete the following tasks:
1. Identify the p1,,. I,- and one set of "~ ,i,./1,"i. i .
of the ,, ,. .;,. .1 intermediate. In other words, .'.. nif,
an industrially relevant reaction route that produces
the intermediate, and then pick one of the reactants of
that reaction and determine how it is made.
2. Investigate one "child" and one "grandchild" of the


Spring 2005










intermediate; i.e., identify one product that is made
from the intermediate and one product that is made
from that product.
3. .1/. i,/;' one member of the chemicalfamily that can be
identified as a ',..r.-i/. product and ., i.;, it to class
(safely!). The "grandchild" might be the most likely
candidate, but the product can contain any member of
the J.,,il,. This product must be ,..., 'Iti,;. that is
commonly used or can be purchased for less than $5.
4. For each of the four steps in the genealogy ( i, Irii,,"
to take the analogy a bit farther), teams do the
f -111, 111 ..
a. Write the primary reaction involved. Make sure it is
balanced.
b. D. ... /. the industrial-scale reaction conditions
(e.g., physical layout of reactor equipment; tem-
perature and pressure of operation)
c. D .. ... i/ the separations that follow the reaction to
ir, 1i; the product.
d. Determine the annual production rate in the U.S.
(or globally) of the primary product. Name at least
one company that produces a substantial amount of
it.
e. Determine the unit value of the primary product
(, I.. 1.
5. For each of the four steps in the genealogy, :..,i, i and
I .".,,/i;:. the information so that it fits on a 1.;.-1.
overhead or PowerPoint slide, -,.;in no fonts smaller
than 16 points. A i.- to class the four slides and a
hard-copy report that consists of the four slides plus a
list of references, .'. 1i. t ;ir-, what was obtained from
each. Each team must present a five-minute oral
summary of its work in class.
The :w .ll, l-. assignment gives students a glimpse of the
structure, breadth, and connections in industries that employ
chemical engineers. It reinforces their study of organic chem-
istry and introduces them to future chemical engineering top-
ics such as reaction and separation equipment and economics.
To afford some flexibility, teams are allowed to shift the
position of their starting compound to the second or fourth
position in the lineage if they wish. Other options include
restricting the in-class "show-and-tell" product to a certain
category such as personal care products or pharmaceuticals.
A typical assignment is shown in Figure 5. Chemical and
Fi..-i;,. .i ;,.- News is a good source of ideas and variations
on this assignment.

SUMMARY
Most students entering chemical engineering curricula to-
day have had no hands-on experience other than a high school
chemistry lab, have had no exposure to process equipment,


Given chloroform as the initial assignment, one team
identified methyl chloride as a parent,
chlorodifluoromethane as a child, tetrafluoro-ethylene
as a grandchild, and poly-tetrafluoroethylene as a
great-grandchild. They brought a PTFE coated pan to
class and presented the following information on step
one of the ,~cl. .

Reaction
CH C1 + 2C12 = CHCI3 + 2HC1

Reactor configuration and conditions
Chloroform is produced in the gas phase reaction of
methyl chloride and chlorine, with hydrogen chloride
as a by-product. Methylene chloride and carbon
tetrachloride are also produced in the successive
substitution reaction. Usually the reactants are
preheated and fed into a cylindrical metal tank with
methyl chloride in excess. The exothermic reaction is
very fast (residence time of about 10 seconds), and
the products leave at about 470 C and 1500 kPa.

Separations
The chemicals leaving the reactor are separated in a
series of distillation columns. Unreacted methyl
chloride and methylene chloride are recycled to the
reactor. HC1 and CCl4 are sold as by-products or used
elsewhere in the plant.


The annual production rate of chloroform in the U.S. is
about 300 million kg. The market value is about $1/kg.
Dow Chemical Company is a major producer.


Figure 5.

and have only a vague idea of what constitutes the chemical
industry and what chemical engineers actually do. These as-
signments introduce students to real issues and concepts that
chemical engineers confront every day. They complement en-
gineering fundamentals that are taught early in the curricu-
lum, making these courses less abstract and more interest-
ing-which rewards both the students and the professor. The
assignments also foster teamwork and contribute to the de-
velopment of communication skills.

REFERENCES
1. Felder, R.M., and R. Brent, Cooperative Learning in Technical
Courses: Procedures, Pitfalls, and I ,. ERIC Document Repro-
duction Service, ED 377038 (1994). (This reference and numerous
others on cooperative learning are available at effective_teaching/>.) 1

Chemical Engineering Education











Molecular and Cellular Biology
Continued from P, .. 127.
Their SAT scores ranged from 1070 (25th percentile) to 1490
(75th percentile). Twenty-five percent of the bachelor's de-
grees awarded by the School of Engineering were to women
in 2004, and 24% were to minorities. Enrollment in the CBE
Department at Tulane ranges from 7 to 11 new graduate stu-
dents per year and 17 to 25 undergraduates per class. Com-
bined Degree students represent 15% of the entering gradu-
ate class in 2004, and 10 to 20% of the sophomores. Since
the Department changed its name in 2003 to reflect the
bioengineering in its curriculum, our enrollment has increased.
Upon graduation, Combined Degree students have earned
on average a 3.7 GPA over 5.5 years in the graduate program
and 3.9 GPA over 4 years in the undergraduate program. For
the School of Engineering as a whole, the comparable time
to fulfill degree requirements is 5 years for the doctorate and
4 years for a bachelor's degree. During their graduate stud-
ies, Combined Degree students produced 4 peer-reviewed
publications on average. Sixty percent of these graduate stu-
dents entered industry upon graduation; 40% remained in aca-
demia. They have obtained positions at leading institutions
such as Johns Hopkins, Johnson & Johnson, Memorial-Sloan
Kettering Cancer Institute, and Merck. Their contributions
to the field of bioengineering to date include development
and delivery of anti-cancer therapeutics, drug formulation,
and tissue engineering. Upon earning a bachelor's degree from
Tulane, 83% of Combined Degree students enrolled in medical
school at, for example, Columbia, Johns Hopkins, and Yale.

IMPACT ON BIOLOGISTS
While chemical engineers are the focus of this article, biol-
ogy faculty and students also benefit from an interdiscipli-
nary learning experience. There are numerous opportunities
for dialog between the two groups in the classroom and labo-
ratory, as well as through co-curricular activities, research
collaborations that result in or are the product of student train-
ing, and leadership activities in the Interdisciplinary MCB
Program. For example, a faculty member of the CBE De-
partment has served as Director of the Interdisciplinary MCB
Program and, in this capacity, was responsible for graduate
MCB training across the three Tulane campuses. Collabora-
tions have formed between faculty in the CBE Department
and Departments of Biochemistry, Medicine, Pathology,
Ophthalmology and Surgery, to name a few. In addition, bi-
ologists work side by side with engineers in the laboratory
on research projects and for lab rotations. These forms of
exchange expose biologists to an engineer's perspective on
problem solving. Not only is the approach inherently more
quantitative, but also an engineer is trained to consider a sys-
tem as a whole and the interactions between its components.
This quantitative systems view is relevant in an age of bioin-
formatics and molecular-based biology.


COMPARISON WITH OTHER PROGRAMS
A survey of the twenty leading chemical engineering de-
partments in the United States as ranked by U. S. News and
World Report reveals that 40% of the departments have in-
terdisciplinary programs in bioengineering at the graduate
level. Seventy-five percent of the departments provide a
bioengineering curriculum for undergraduates. These pro-
grams were developed recently, two of which will be intro-
duced in 2005. In 30% of the departments, graduate students
have the opportunity to participate in interdepartmental pro-
grams in the biological sciences, bi, i'l, ihin .li-, or bioengi-
neering. The amount of biology and bioengineering in the
undergraduate curriculum varies widely among the chemical
engineering departments. The bioengineering curriculum at
the undergraduate level is in the form of a course, concentra-
tion, certificate program, minor or double major. A biology
requirement is being introduced to the chemical engineering
curriculum in a limited number of departments. Features of
the Tulane Combined Degree Program are the continuity of
interdisciplinary training at the undergraduate and graduate
levels, depth of training in chemical engineering and the bio-
logical sciences, scope of the Interdisciplinary MCB Program,
and longevity of the program.

ACKNOWLEDGMENTS
The academic experiences of the following students have
been instrumental in the evolution of the Combined Degree
Program: Nancy Cowger, Richard Enmon, Carrie Giordano,
Shamik Jain, Jim Muhitch, Hong Song, Sandeep Sule, Julie
Talavera, Murthy Tata and Nina Watson.

REFERENCES
1. Baltimore, D., "Our Genome Unveiled," Nature, 409, 814 (2001)
2. Prockop, D.J., C.A. Gregory, and J.L. Spees, "One Strategy for Cell
and Gene Therapy: Harnessing the Power of Adult Stem Cells to Re-
pair Tissue," Proc. Natl. Acad. Sci. USA, 100, 11917 (2003)
3. Parekh, R., "Proteomics and Molecular Medicine," Nat. Biotechnol.,
17, 19 (1999)
4. Asthagiri, A.R., and D.A. Lauffenburger, "Bioengineering Models of
Cell Signaling," Ann. Rev. Biomed. Eng., 2, 31 (2000)
5. Jain, R.K., "Delivery of Molecular and Cellular Medicine to Solid
Tumors," J. Control. Release, 53, 49 (1998)
6. Stephanopoulos, G., and J. Kelleher, "How to Make a Superior Cell,"
Science, 292, 2024 (2001)
7. Frontiers in Chemical Engineering: Research Needs and Opportuni-
ties, National Academy Press, Washington, DC (1988)
8. Putting 1. .. to Work: Bioprocess Engineering, National
Academy Press, Washington, DC (1992)
9. Rudolph, F.B., and L.V. McIntire, 1.. .. Science, Engineer-
ing and Ethical ( !. .. Twenty-First Century, Joseph Henry
Press, Washington, DC (1996)
10. "Initial Placement of Chemical Engineering Graduates," and www.aiche.org/careerservices/trends/placement.htm>, AIChE Career
Services (2003)
11. Varma, A., "Future Directions in ChE Education: ANew Path to Glory,"
Chem. Eng. Ed., 37, 284 (2003)
12. Westmoreland, PH., "Chemistry and Life Sciences in a New Vision of
Chemical Engineering," Chem. Eng. Ed., 35, 248 (2001) 1


Spring 2005











classroom


BUILDING MOLECULAR BIOLOGY


LABORATORY SKILLS IN


ChE STUDENTS


MELANIE MCNEIL, LUDMILA STOYNOVA, SABINE RECH
San Jose State University San Jose CA 95192


Historically, chemical engineering graduates have been
hired predominantly by the chemical process indus-
try and petrochemical industry, a fact indicated by
the focus of applications in the chemical engineering cur-
riculum.'1 Nowadays, however, chemical engineering gradu-
ates are also heavily recruited for jobs in the pharmaceutical,
semiconductor, and environmental industries.E21 This diver-
sity of job opportunities is expected to increase as new tech-
nologies, such as I.sii~ 'illhiiil- ., smart drug design, and
bioinformatics, continue to evolve.
Since the 1980s, chemical engineering educators have been
encouraged to modify the curriculum to include new tech-
nologies, such as bi, ,iieliii l -.b .' and semiconductor process-
ing.E3-4] In particular, the bi> ,illin li -.' area has been receiv-
ing increased attention since many of the high-tech applica-
tions of bi, .incli lh %I..- (such as drug engineering, drug dis-
covery and pharmaceutical production based on recombinant
DNA processes) have become established in the marketplace.
As these processes have been scaled up for production, the
participation of chemical engineers has become a necessity.
Many underlying chemical engineering principles, such as
reactor design and mass transfer, can be transferred to the
biiniiir i 1~- industry, but educators have begun to realize
that biology itself must be incorporated into the chemical en-
gineering curriculum in order for chemical engineering gradu-
ates to be competitive in industry.[2,5,61 This situation is simi-
lar to a prior shift to focus on chemistry in the curriculum
when chemical engineering graduates were predominantly
hired in the chemical process and petrochemical industries.
In fact, a number of chemical engineering departments have
changed their names to the "Chemical and Biology Engineer-
ing Department"'-111 or similar designations, in recognition
of the increased importance of biology in many of the jobs
their graduates will one day be hired for. However, constraints
such as ABET requirements, significant General Education
requirements (along with a push to keep the units required
for the degree as low as possible), and even the current appli-


cations focused on in many popular chemical engineering
textbooks, have posed challenges to increasing the biology
content to acceptable levels.E121
Although some chemical engineering departments have in-
troduced basic biology into the curriculum, it has become
increasingly important for chemical engineers hired by bio-
tielliii11. .\, companies to have some understanding of mo-
lecular biology, an advanced topic. One of the best ways to
help students achieve this understanding is by successfully
completing molecular biology experiments. Not only do stu-
dents gain the hands-on skills required for successful mo-
lecular biology protocols, but they also must explain what
they did and what their results mean in laboratory reports.
Chemical engineering students at San Jose State Univer-
sity are exposed to these experiments in a biochemical engi-
neering laboratory course developed by Drs. Komives (ChE),
McNeil (ChE), and Rech (Biological Sciences). The course
is a senior-level course open to chemical engineering stu-
dents, biochemistry students, and biology students. Chemi-
cal engineering students are required to have a biochemistry
course and biochemical engineering lecture course prior to

Melanie A. McNeil is Professor of Chemical Engineering at San Jose
State University. She teaches courses in chemical engineering kinetics
and reactor design, biochemical engineering, heat transfer, fluids, safety
and ethics, and statistics. Her research experience includes nanowire
synthesis, RNA/peptide binding interactions, development of sequence
search algorithms, and enzyme kinetics.
Sabine Rech is Assistant Professor in the Department of Biological Sci-
ences at San Jose State University. She obtained a BS in Biology from
Santa Clara University, an MA in Microbiology from San Jose State Uni-
versity, and a PhD in microbiology from UCDavis. She is teaching courses
in general microbiology microbial physiology and microbial diversity. Her
research interests include the isolation of natural products, gene expres-
sion in environmentally important bacteria, and the study of microbial di-
versity in the soils of salt marshes in the process of restoration.
Ludmila Stoynova is a research technician and a part-time lecturer in
the Department of Chemistry at San Jose State University. She has a BS
degree in Chemistry from Sofia University, Bulgaria, and an MS degree in
Chemistry from San Jose State University. She teaches an introductory
biochemistry laboratory class. Her research is concentrated on the nuclear
vitamin D3 receptor, a ligand-dependent transcription factor.


@ Copyright ChE Division ofASEE 2005


Chemical Engineering Education











enrolling in the laboratory. The first half of this laboratory course
is focused on molecular biology experiments such as polymerase
chain reaction, ligation, and bacterial transformation, while the
latter half is focused on enzyme kinetics, fermentation, and pro-
tein purification.
The nature of molecular biology is that small volumes (microliter
levels) are used and the results of a given experiment are often not
known until two or three experiments later, corresponding to two or
three weeks later in a laboratory course. Thus, it is imperative to
quickly and effectively train chemical engineers in basic biological
techniques such as micropipetting, sterile techniques, streaking and
spreading samples on agar plates, and loading DNA-containing
samples on an agarose gel.
In addition, our laboratory course attracts a multidisciplinary popu-
lation of students from biology, biochemistry, and chemical engi-
neering. A number of the science students have some or most of the
required laboratory skills. In order to avoid redundancy for the ex-
perienced science students, and because the laboratory curriculum
does not allow multiple days to train chemical engineering students,
we have developed a one-day Biology Laboratory Skills-Building
session for students. On the first day of class, students answer a ques-
tionnaire regarding their prior laboratory experience and are given
protocols for each procedure they will complete during the skills-
building session that is held during the first day of the laboratory.
They are arranged into two- or three-member teams and are instructed
to meet with their team prior to the first laboratory session so they
will arrive prepared to complete the activities. Every attempt is made
to include at least one student experienced in the necessary labora-
tory techniques on each team.

BIOLOGY LABORATORY
SKILLS-BUILDING SESSION
The course is set up as two lecture hours directly followed by a
three-hour laboratory session. Due to the nature of some of the ex-
periments,E131 however, the laboratory portion often takes the entire
five hours. This is the case for the Biology Laboratory Skills-Build-
ing Session. Table 1 lists the skills- building stations that students
complete during the first official laboratory session of the semester.
It is not enough for the students to blindly perform each activity.
Instead, they are allowed to make mistakes at the various stations so
they can figure out what the most common mistakes might be and

TABLE 1
Biology Laboratory Skills-Building Stations

1. Micropipetting All groups at once
2. Autoclaving Two groups at a time, one at each autoclave
3. Gel loading Two groups at a time, one at each gel
4. Material data safety sheets (MSDSs) One group at each computer
5. Agarose gel preparation Two groups at a time
6. Sterile techniques and agar plate streaking Each group separately
7. Station clean up Each group separately


how to identify them. The students must also answer a
set of questions associated with each station-questions
that have been written to help the students identify com-
mon errors or common pitfalls associated with a given
protocol. The activities and questions associated with each
station are described in Table 1. The answers to most of
the protocol questions can be answered by the students
with reference to the protocol sheet they were given on
the first day of class.

STATION ACTIVITIES
The instructions for activities and questions associated
with each station are as follows:
1. Micropipetting
Each group should check each other out to confirm that each
member understands the use of micropipettes. Be able to dem-
onstrate the answer to the following questions and record your
answers in your laboratory notebook:
a. How do you set the volume required?
b. Which tips go on which pipettes for which range of
volumes?
c. How do you pipette a certain aliquot of solution? Note
how you might get aerosols, suction against the tube
bottom, or air bubbles-none of which you want.
d. How do you release the aliquot?
e. How should the micropipettes be stored?
f. In which direction should you NOT hold loaded
micropipettes (our students have often been observed
holding the micropipette in directions such that the
chamber can become contaminated)?
g. What aspects of sterile technique should you keep in
mind while micropipetting?
2. Autoclaving
Each group should autoclave 500 ml of DI water, in a labeled
capped bottle (label should include contents, composition, date,
one team member's initials, and course number).
a. Which settings should you use?
b. How do you program the autoclave?
c. How do you add the water used for steam?
d. How long should you autoclave?
e. How should your container of water be autoclaved e.g.
with a lid?
f. How do you remove items after autoclaving?
g. How do you know if the autoclave has reached
sterilization temperature?
h. How do you know if the contents are sterile?
i. What aspects of sterile technique should you keep in
mind while autoclaving?
3. Gel Loading
Each gel contains two sets of 16-well lanes. Each group can use
ONE set of 16, although you don't have to use them all if all
group members are confident on their loading technique sooner.
Pipette 150 RL of sterilized water into an Eppendorf tube
using a STERILE pipette tip.
Add 10 RL of loading dye.


Spring 2005











Fingertip flick to mix.
Load 10 tL at a time into each gel.
Make sure your tip is in the well.
The dye is heavy so it will sink.
If you haven't loaded before, hit the bottom of one of the lanes
just to see what it feels like.
a. What is best technique for you to steady your hand
when you load?
b. Are you satisfied with the way your sample loaded in
the well?
c. Where are the tips disposed?
d. What aspects of sterile technique should you keep in
mind while loading the gel?
4. Material Data Safety Sheets (MSDSs)
Each group will download two MSDSs from the Internet and will
give a brief report on any safety hazards associated with that chemi-
cal at the end of the lab period.
Group 1 Ethidium bromide, Tris
Group 2 EDTA, agarose
Group 3 Glacial acetic acid, LB medium
Group 4 DMSO, glucose
5. Agarose Gel Preparation
The instructor will demonstrate preparation of the agarose gel. Note:
Some glassware is reserved for making the gel since residual amounts
of ethidium bromide may contaminate the glassware.
a. How do you tell when the gel solution has been
microwaved long enough.?
b. How do you tell when to pour the gel?
c. How do you tape the gel plate?
d. When is the ethidium bromide added and in what amount?
e. Where are the ethidium bromide-contaminated tips etc.
collected?
6. Sterile technique and agar plate streaking
Each group will get four LB agar Petri dishes.
Label the dishes so they can be identified (content, date, one
members initials, and course number)
Where should you label, top, bottom, and/or side? TELL THE
INSTRUCTOR YOUR ANSWER BEFORE LABELING.
Each member should practice streaking using the technique
shown on the handout given in the first class.
One member should streak with unsterilized tap water, one
with unsterilized DI water and one with the water you just
sterilized in this lab. REMEMBER to use sterile techniques
when pouring your sterilized water. Review your sterile
techniques protocol. Put your dishes upside down in a 37 C
incubator, after they have been streaked. Use the Internet to
find out the difference between streaking and spreading
techniques.
The fourth dish is to show you why you need to use sterile
techniques.
Group 1 open up the dish and talk over it, then close it up
and incubate it.
Group 2 swab the doorknob with a cotton tip, then lightly
streak your dish, and then incubate it.


Group 3 have each member swab their hand, each with
their own cotton swab, then lightly streak each swab on
your dish, and then incubate the dish.
Group 4 swab the computer keyboard, then lightly streak
your dish, and then incubate it.
These dishes should incubate for 24-36 hours. If someone in
your group cannot come in to put the dishes in the refrigerator,
e-mail the instructor and she will take care of that step.
All groups should review all 4 of these plates after incubation.
Label them well.

7. Station Clean-up
When you are done, clean up your station. Review the clean-
up protocol you were given on the first day.
a. What clean-up protocol do you need to follow?
b. Where do the waste chemicals go?
c. Where do the waste plastic supplies go?


DISCUSSION AND CONCLUSIONS

The activities included in the Biology Laboratory Skills-
Building session were designed to serve several purposes.
We recognized that each subsequent molecular biology-
related laboratory would occupy essentially all of the student's
concentration due to the detailed nature of the protocols and
the number of samples, controls, and calibration standards
that would be tested. It has been our experience that students
can concentrate on one new activity at a time. All of the
molecular biology experiments were new, and thus areas
such as safety or sterile techniques tend to be ignored if
they were first introduced at the same time as the new
molecular biology protocol.
The Biology Laboratory Skills-Building session was de-
signed to introduce students to safety, sterile techniques, and
basic protocols (pil p.iiiil-- an agar gel, Iliici.'ipipe i ill-. auto-
,1.'\ iil-.i before their concentration was focused on the new
molecular biology protocols (ligation, digestion, transforma-
tion, etc.). For instance, the MSDSs that they had to down-
load were selected for chemicals that had the most safety
hazards to consider and for chemicals that were used most
often. The questions assigned to each activity were designed
to have the students address important issues-for instance,
how to dispose of ethidium bromide-contaminated items or
what not to do with a loaded micropipette.
The inclusion of this skills-building session has not elimi-
nated all problems associated with the lack of molecular bi-
ology skills common to chemical engineering students with-
out prior experience. For instance, during the transformation
experiment later in the semester, some students gouged their
agar as they roughly spread their transformed bacteria. This
resulted in zero colony growth. Also, sterile techniques were
often treated with less diligence than was optimal. Students
were very appreciative of the initial training session, how-
ever. All students were visibly impressed with the colonies


Chemical Engineering Education











that grew on their agar after the first laboratory session. The
colonies obtained off swabs from their skin, the doorknob,
and the computer keyboard were multicolored and profuse,
making a vivid impression on the students. During the se-
mester, anytime they relaxed their attention, one refer-
ence back to these colonies inspired them to renew their
sterile techniques.
It should be noted that it takes a fairly long period of time
for many students to gain an appreciation and mastery of bi-
ology laboratory skills such as sterile techniques,
micropipetting, and culturing. When SJSU science and engi-
neering faculty compared the skill levels of students in their
laboratory courses, the general consensus was that microbi-
ology students have higher skills than biochemistry students,
who have higher skills than biochemical engineering students.
Not surprisingly, the higher skill level corresponds to the
greater amount of time these topics are focused on in the typi-
cal curriculum (lecture and laboratory) in microbiology, bio-
chemistry, and chemical engineering. Other universities may
be able to offer one, two, or three biology-related courses in
their chemical engineering curriculum, but even that number
will not be sufficient to build up skills to the level required in
industry. It is an acceptable start, however-especially given
the constraints (ABET, unit load, textbook examples, etc.)
chemical engineering departments face as they try to incor-
porate additional biology into the curriculum.[6,7,121
We have found that the experienced science students were
invaluable during the skills-building session. It would be hard
to imagine one instructor and one graduate student assistant
being able to work with every group at every station in enough
depth to make sure the students were being properly trained.
With at least one experienced student on every team, there
was enough experience and attention to make sure the less-
experienced students were adequately trained. If experienced
students are not available at other universities (for instance if
such a class was open only to chemical engineering students),
it might be more productive to take two sessions to make
sure all the students had enough time to gain adequate com-
petency in these critical basic skills. Molecular biology-re-
lated experiments, such as ligation and transformation, are
complex and time intensive. Lack of the basic biology labo-
ratory skills can be a major reason for the failure in obtaining
desired results (e.g., failed transformation) in molecular bi-
ology-related experiments. Students tend to be very disap-
pointed if they spend a few weeks on a experiment only to
find out it has failed. Thus, it is worthwhile to spend time at
the beginning to build the basic biology laboratory skills
so students can focus on the multitude of steps needed to
successfully complete their subsequent molecular biology-
related experiments.

Since it can be difficult for a chemical engineering depart-
ment to have all the equipment and supplies necessary to run
in-depth molecular biology experiments, we thought it might


be useful to mention that the Bay Area B i, iin % li. 1 l '.' Edu-
cation Consortium (BABEC) has developed some kit experi-
ments that are sold through Bio-Rad. The experiments are
described on the BABEC website at curricula.htm>. Incorporating the Biology Laboratory Skills-
Building session along with one or more of these kit experi-
ments (several of which are designed to be done in sequence,
if desired) would be a low-cost means of giving chemical
engineering students hands-on exposure to important molecu-
lar biology skills.
In conclusion, incorporating a Biology Laboratory Skills-
Building session prior to the start of molecular biology ex-
periments has resulted in student teams, predominantly popu-
lated with students having low biology laboratory skills, suc-
cessfully completing complex molecular biology experiments.
Issues such as safety, sterile techniques, and basic biology
laboratory skills (making an agarose gel, micropipetting, au-
tl, l.i ill-i were emphasized, allowing these skills to be de-
veloped early so the students could then concentrate on the
new concepts introduced by each molecular biology pro-
tocol introduced in subsequent experiments (ligation,
transformation, etc.).
We would like to thank NSF, California State University
Program for Education and Research in Biiclhllil'h-',
(CSUPERB), and the Department of Chemical and Materi-
als Engineering for providing support for the development of
the ChE 194 laboratory course.

REFERENCES
1. "75 Years of Progress-AHistory of AIChE 1908-1983," AIChE (1983)
2. Committee on Challenges for the Chemical Sciences in the 21st Cen-
tury, National Research Council, "Beyond the Molecular Frontier: Chal-
lenges for Chemistry and Chemical Engineering," www.oit.doe.gov/chemicals/pdfs/beyond_molecular_frontier.pdf>
April 23, 2003, accessed on December 20, 2004
3. Frontiers in Chemical Engineering: Research Needs and Opportuni-
ties (Amundson Report), National Academy Press, Washington, D.C.
(1988)
4. Veggeberg, S., "The Interface Of Biology And Chemical Engineer-
ing," The Scientist, 7(3), 15, February 8 (1995)
5. Georgakis, C., "Revolutions: All Sorts...But Mostly Scientific," CAST
Comm., Summer 2002, pdf> accessed January 5, 2005
6. "Integration of Chemical and Biological Engineering in the Under-
graduate Curriculum: A Seamless Approach," July 2003, ase.tufts.edu/chemical/news/excerptsNSFgrant.pdf> accessed January
5, 2005
7.
8.
9.
10.
11.
12. Ydstie, B. Erik, "New Frontiers in Chemical Engineering: Impact on
Undergraduate Curriculum Workshop," WPI May 7, 2004 www.wpi.edu/News/Conf/CHEFrontiers/Presentations/ydstie.pdf> ac-
cessed January 5, 2005
13. Komives, C., S. Rech, and M. McNeil, Chem. Eng. Ed., 38(3), 212,
(2004) 1


Spring 2005











classroom


A Simple Classroom Demonstration of

NATURAL CONVECTION




DEAN R. WHEELER
Brigham Young University Provo, UT84602


Natural or free convection results when there is a fluid
density gradient in a system with a density-based
body force such as the gravitational force. In an oth-
erwise quiescent fluid, a density gradient can be caused by
temperature gradients and/or species concentration gradients.
Natural-convection currents enhance heat and mass transfer
relative to conduction and diffusion in a quiescent fluid."1
This is an important process for engineers to understand. For
instance, natural convection is a key process in the passive
cooling of people, machinery, and computer chips, and in the
volatilization of exposed liquids in an indoor or windless en-
vironment.
The topic of natural convection is typically covered during
two or three classroom hours in a junior-level heat and mass
transport course. One of the difficulties in such math-inten-
sive courses is helping students get a qualitative and physical
understanding of the phenomena. It is easy for students to
get lost in dimensionless numbers and correlations when they
don't have basic engineering sense. One way to remedy this
is for students to observe the relevant phenomena and to dis-
cuss their observations and how they relate to the equations.
This article explains a simple way to demonstrate natural
convection in the classroom using an overhead projector. The
demonstration is based on the principle of schlieren imaging,
commonly used to visualize variations in density of gas flows.


Copyright ChE Division ofASEE 2005


The demonstration requires a few hours of preparation time
but very little in materials cost, assuming an overhead pro-
jector is already available. It could be prepared by the in-
structor or by students as part of a class-related project. In
the discussion below, I assume the reader is more familiar
with the principles of natural convection than with schlieren


imaging. Therefore, I focus
schlieren technique, the
preparation required for the
demonstration, and the re-
sults that one can expect.

SCHLIEREN
IMAGING
Schlieren images, along
with shadowgraphs and inter-
ferometry, are a means of vi-
sualizing density variations
in transparent media.[2] These
techniques work on the prin-
ciple that the index of refrac-
tion of a fluid depends on its
density. The path and phase
of a light wave passing
through the fluid therefore
depends on its density and its
spatial derivatives. Schlieren
optics as such was invented
in 1864 by August Toepler, a
German chemist and physi-
cist (schlieren means
"streaks" in German).[3] The
technique has been exten-
sively used to visualize shock
waves in supersonic flight.
The wavy appearance of the


on the principle behind the


image I --


filter




object


filter -1 1- 1-

Figure 1. The principle of
schlieren imaging. Rays of
light, moving from bottom
to top, encounter a filter, a
refractive object, a second
filter, and then the image
plane. Density gradients in
the refractive object bend
light rays such that some
are screened out by the
second filter, resulting in
intensity variations on the
imaging surface.

Chemical Engineering Education


Dean R. Wheeler completed a BS at Brigham
Young University (1996) and a PhD at the Uni-
versity of California, Berkeley (2002), both in
chemical engineering. Returning to his Utah
roots, he began teaching as an assistant pro-
fessor at Brigham Young University in 2003.
His research area is electrochemical engineer-
ing, with ongoing projects to optimize pro-
cesses in lithium batteries and in metal elec-
trodeposition.



















L-


Figure 2. View of the optical setup from above. Point L indicates the overhead-projector carriage lens.
Points S and S'indicate the small and large stripe filters, respectively. Points 0 and indicate
the free-convection object and its projected schlieren image, respectively.


horizon above a hot road is a simple example of schlieren
imaging of natural convection.
Figure 1 illustrates the principle of schlieren imaging. A
series of two filters with periodically alternating transparent
and opaque stripes is used in combination with a light source.
The fluid to be imaged has a gradient in its index of refrac-
tion, which causes spatial variations in the amount of light
that passes through both filters. This produces an image in
which light and dark areas correspond to variations in the


.- 30 cm .-


fluid density gradient. Conversely, if the fluid object has a
uniform density gradient, the image will be uniformly gray.

DEMONSTRATION SETUP
How can one adapt the schlieren technique for classroom
use? Figure 2 shows how the optics that are part of an over-
head projector can be used to project a schlieren image of an
object onto a screen. The schematic is a view from above,
which means that the overhead projector is turned on its side.
This is necessary so that vertically traveling fluid currents
around the free-convection object are largely orthogonal to
the light path. The optical principles of this setup, including
the use of striped filters, is the same as in Figure 1, except
that a focusing lens increases the brightness of the projected
image by collecting and distributing the light from the pro-
jector lamp. The smaller filter (point S) is attached to the
surface of the overhead projector, and both filters have their
stripes in a vertical orientation.
In order for the setup in Figure 2 to work, the optical planes
associated with points O and 0' must be "in focus" with each
other, as must the planes associated with points S and S'.
Assuming the lens is ideal, this means that
1 1 1 1 1
--+ -= -+-= (1)
do do, ds ds, f

where dx indicates optical distance between the lens and point
X, and f is the focal length of the lens. Because the projector
lens is mounted on a movable carriage, we have a great deal
of freedom in positioning the various optical elements.
Figure 3 shows the two striped filters used in my optical
setup. They were made by creating the black-and-white striped
patterns in a computer graphics program, laser printing onto
transparent sheets, and attaching the sheets onto frames con-


Spring 2005


Figure 3. Schematic of the small and large stripe filters.
The dotted lines indicate boundaries of single-page trans-
parencies that are taped onto frames made of foam-core
board.











structed from foam-core board purchased from the art sup-
plies section of the campus bookstore. The smaller filter has
a size comparable to the free-convection object to be imaged
and has black stripes of thickness 0.5 mm and periodicity of
1 mm. (Because of the vagaries of my laser printer, it was
necessary to make the black stripes 0.67 mm thick in the
graphics program to affect a printed thickness close to 0.5
mm.) The larger filter is basically an enlarged image of the
smaller filter-in this case enlarged by a factor of 3.7.
The enlargement factor is equal to the ratio of optical dis-
tances ds,/ds.
It is advantageous to make the large filter as small as the
optics allow and customize it for the overhead projector to be
used. To determine the optimal large filter
* Make the smallfilter, place it on the overhead projec-
tor surface, and project its image onto a wall.
Move the lens,,,, I,i i .. to its uppermost (furthest)
position relative to the surface. This maximizes
distance ds and hence minimizes ds,, .... *1;.,i- to Eq.
(1).
Move the entire projector relative to the wall -,,i/ the
striped image is exactly in focus. The wall is then at
position S'ofFi.-n.. 2 and thus establishes distance ds,.


Figure 4.
Projected
images of
convection
currents above
a tea candle.


* Measure the thickness andperiodicity of the stripes
projected on the wall to determine the ,,l, l. Ii. i
factor The stripes on the 1, 1 filter should exactly
match the stripes of the focused wall image.
The large filter is created, as is the small filter, by printing
onto transparency sheets from a computer graphics program.
The sheets are mounted onto a rigid frame. Additional appa-
ratus will be required to hold the frame in the proper position
during the demonstration. For instance, I built a stand that
accomplishes this from leftover pieces of foam-core board,
wooden toothpicks, and glue.
In preparing for the demonstration, some optical tuning is
required. The lens carriage should continue to be in its up-
permost position, whereas the projector will be located fur-
ther from the wall in the classroom than in the above experi-
ment. One must first ensure that the two stripe filters are in
focus with each other. This step requires patience and a steady
hand. Success comes when the projected image is uniformly
gray and all Moire patterns from the interacting filters have
been eliminated. Next, the free-convection object is placed
in the path between the small filter and the lens carriage (see
Figure 2). The object is then moved relative to the lens so
that the object's wall image is in focus.


Chemical Engineering Education


~











RESULTS AND STUDENT LEARNING
High-quality schlieren images require precise construction
and positioning of the optical elements. In this case, the pre-
cision is not as great as can be achieved in a laboratory, and
hence the "overhead projector" method is less sensitive to
density variations. For this reason, the setup here is only prac-
tical for imaging an object with large density variations, such
as a flame. Figure 4 shows three images obtained of the con-
vection currents above a tea candle. Two difficulties should
be noted. First, the pictures in Figure 4 have been rotated
180. That is, using the above setup results in a projected
schlieren image that is upside down-students will have to
adapt their perception to this fact. Second, careful position-
ing of the optical elements requires several minutes, so it is
preferable to set up the demonstration in the classroom prior
to the start of class. It is also a good idea to do a "dry run"
during a time when the classroom is not in use.
How can this demonstration reinforce student learning of
natural convection? The most obvious answer is that images
(particularly live moving images) of natural convection fluid
currents generate interest and excitement about the topic. In
this demonstration, students are able to visualize the dynamic
nature of free convection. While it is probably unrealistic in
an undergraduate class to attempt a quantitative analysis of
heat and mass transport for a diffusion flame, 41 the demon-
stration can serve as a launching point for discussion of gen-
eral concepts or a review of concepts already introduced. The
following questions can be posed to the class as a whole or to
small groups of students:

El Why would it be more difficult to use schlieren
imaging to view natural convection currents from
your hand, compared to currents from a candle
flame? (Answer: The schlieren technique depends on
fluid density ,it..i. .... which in turn depend on
fluid temperature ,irt i. The temperature
,irt i. i, i around a flame are much 1.. I:)
El How would the fluid currents around a candle flame
change if the candle were inside a quiescent-air-
filled spaceship orbiting the earth ? (Answer:
Natural convection depends on gravity. The convec-
tion currents would cease and the flame would be
spherically symmetric. Transport of reactants,
products, and heat will be due to ,iit ...i. '- and
conduction only.)
El Discuss your observations concerning the transition
from laminar to turbulent flow in the boundary layer
around a lit candle. What factors) seem to affect the
behavior of the transition? (Answer: Students should
observe that the transition position varies in time.
The smallest hydrodynamic disturbances, such as air
currents in the room, ,, i. t the transition point and
the motion of the boundary layer)


The demonstration is based on the
principle of schlieren imaging, commonly
used to visualize variations in density of gas
flows. [It] requires a few hours of preparation
time but very little in materials cost, assuming
an overhead projector is already available.


E Empirical correlations of natural convection treat it
as a steady-state process. Comment on the validity
of this assumption. (Answer: As with the currents
around the candle flame, natural convection is
nearly always a non-steady-state process, particu-
larly with the onset of turbulence. On the timescale
of most heat/mass transfer problems, however, one
can average the results in time to obtain reasonable
heat/mass transfer ... u., 1. i,1t )
The qualitative understanding that comes from direct ob-
servation of phenomena can serve as a framework students
can use to organize equations and quantitative problem solv-
ing. So far, I have used this schlieren demonstration only one
time in my class. The students were highly interested, and I
feel the demonstration and subsequent discussion were class-
room time well spent.
Videos of the projected images corresponding to Figure 4
are available at Ref. 5. As an aid to readers, electronic ver-
sions of the graphics used in Figure 3 are available at the
same website.
References 6 and 7 are websites for two leaders in the field
of schlieren imaging, Professor Gary Settles of Penn State
and Professor Andrew Davidhazy of Rochester Institute of
T-cliiilh.l.. Their sites contain a number of beautiful
schlieren images of natural convection that can complement
the live demonstration and lead to further discussion of how
dimensionless numbers and empirical correlations relate to
students' observations of natural convection currents.

REFERENCES
1. Incropera, Frank P., and David P. Dewitt, Fundamentals of Heat and
Mass Transfer 5th ed., John Wiley & Sons, New York, NY (2002)
2. Settles, Gary S., \ ,.'. .. . . Techniques: Visualizing
Phenomena in Transparent Media, Springer-Verlag, Heidelberg, Ger-
many (2001)
3. Katz, Eugenii, "August Toepler, website at ~eugeniik/history/toepler.html> (2003)
4. Turns, Stephen R., An Introduction to Combustion: Concepts andAp-
plications, 2nd ed., McGraw-Hill, New York, NY (2000)
5. Wheeler, Dean R., "Schlieren Classroom Demonstration, website at
(2004)
6. Settles, Gary S., "Penn State Gas Dynamics Lab," website at www.mne.psu.edu/psgdl> (2004)
7. Davidhazy, Andrew, "Basics of Focusing Schlieren Systems," web-
site at (1998)
[


Spring 2005











curriculum


COMPUTER SCIENCE

OR SPREADSHEET ENGINEERING?

An Excel/VBA-Based Programming and

Problem Solving Course


DANIEL G. CORONELL
Rose-Hulman Institute of Technology Terre Haute, IN 47803


Over the past two decades, chemical engineering prac-
tice has been profoundly influenced by advances in
computer hardware and software, stimulating debate
within the academic community on how students should be
prepared for computer applications in the "real world." At
the crux of this debate is the relative importance of including
a traditional introductory computer science course in the
chemical engineering curriculum. Without question, in the
"old days" the pathway for applying computers to the solu-
tion of engineering problems was to write your own program
from scratch, usually in Fortran.
Today, industry is much less likely to engage their engi-
neers with such tasks. The expectation is that commercial
software vendors will supply them with user-friendly soft-
ware packages that require little or no programming skills. A
recent surveym" by CACHE indicated that computing in the
workplace for entry-level chemical engineers is clearly on
the rise (over two-thirds of the approximately 300 respon-
dents spent at least one-half of their workday at their com-
puter). It was found that most of the time spent working on
the computer involved user-friendly commercial software
packages, with the most common application being Microsoft
Excel. Nearly three-quarters of the respondents were not ex-
pected by their employers to be competent in any program-
ming language. The most common programming language
being used, and the one most highly recommended for inclu-
sion in the chemical engineering curricula, was Visual Basic.
Based on these results, it might be argued that graduating
chemical engineers would be more suitably equipped to con-
tribute in an industrial setting if they were taught how to ef-
fectively use Excel rather than how to write a computer pro-
gram in a language they may never use again. The numerous
books,[2-5] trade journal articles,E6-81 software vendors,E9-121 and
consultantsE13-151 that demonstrate the use of Excel in engi-
neering analyses underscore this point. This notion, however,
overlooks the value of learning how to logically formulate a


problem-solving 1i dl -., 111.11 is inherent in any programming
course. Moreover, it omits the necessary exposure to pro-
gramming concepts (e.g., loops, decision constructs, etc.) for
the fraction of students who may be required to do some type
of programming in an R&D setting or in graduate school.
This paper describes a compromise approach that com-
bines instruction on the use of Excel as well as computer
programming concepts by way of Excel's macro program-
ming language, Visual Basic for Applications (VBA). The
benefit to students is that they can learn the practical aspects
of "spreadsheet engineering" as well as the more generally
applicable concepts of computer programming. Additionally,
they gain a clearer understanding of how the course material
applies to their future profession since the course is taught
within the chemical engineering department. The benefit to
the instructor is the ability to consolidate the presentation of
course material through the use of a single software package.
This paper describes the format and content of a freshman-
level course that has been designed to replace the more tradi-
tional introductory computer science course.

COURSE FORMAT
P, ..i ,,, ,,;,,.- and Computation for Chemical F,,;-in,. .
is a two-credit-hour course that chemical engineering majors
at Rose-Hulman Institute of Tl.in d.1 .-, are required to take
in the spring quarter of their freshman year. The class meets


@ Copyright ChE Division ofASEE 2005
Chemical Engineering Education


Dan Coronell received his BS from the Uni-
versity of Illinois-Urbana and his PhD from the
Massachusetts Institute of Technology, both
in chemical engineering. After graduation he
worked in the chemical, semiconductor, and
engineering software industries for over nine
years before joining the faculty at Rose-
Hulman Institute of Technology, where he is
presently Associate Professor.











two times per week for fifty-minute periods over a ten-week
quarter. At this point in the curriculum, students have typi-
cally completed two quarters of calculus and chemistry and
one quarter of physics. They are also concurrently enrolled
in a freshman-level design class that introduces them to many
concepts of importance to chemical .Ii;ll ii i '. The early
introduction of chemical engineering concepts into their cur-
riculum provided by the two courses is beneficial to the stu-
dents, as will be discussed below.
Prior to the first meeting of this newly redesigned course,
a survey was conducted to assess the level of expertise in
using Excel and experience with any programming language.
Approximately two-thirds of the 66 students that were origi-
nally registered for the two sections responded to the survey.
The first part of the survey asked the students to select one of
five different categories that best characterized their ability
to use Excel. The selection options included
Power user
Pretty comfortable using it to process data and make plots
Have used it before several times and know the basics
Have only started using it since my freshman year
Have never used it before
The results are summarized in Table 1. While all of the
respondents had used Excel to some extent, most of the course
material consisted of techniques and applications that the stu-
dents had never been exposed to in the past.
The second part of the survey asked students to identify
any programming languages they had previously learned in
coursework or through work experience. As can be seen in
Table 2 below, two-thirds of the respondents had no previous
programming experience. Note that a few respondents had
experience in more than one type of programming language.
The classroom instructional t. %liii l -'., at Rose-Hulman
greatly facilitated the execution of this type of course. Every
classroom is equipped with a laptop computer projector and
wireless network capabilities. In addition, each student at
Rose-Hulman is issued a laptop computer at the beginning of
their freshman year. The students were required to bring their

TABLE 1
Survey of Students' Level of Expertise Using Excel

Power Pretty Know Just Never Used
User Comfortable Basics Started Before
# of Respondents 2 17 13 10 0


TABLE 2
Survey of Students' Prior Programming Experience

Visual C/C" Java Pascal Matlab None
Basic C# HTML
# of Respondents 10 9 5 1 1 28


laptop computers to class each day. A typical 50-minute class
period was discretized into 20 minutes of traditional lecture,
20 minutes of computer laboratory, and 10 minutes of dis-
cussion and reflection.
The initial lecture period would usually include an instruc-
tor-led example problem with students following along on
their laptops, followed by a computer lab assignment on a
problem related to the lecture topic. The students were free
to work together and to ask questions during this time. The
last few minutes of class were used to obtain closure on the
subject matter where the computer lab solution would be pro-
vided, the relevance of the material would be reinforced, and
any remaining questions would be answered. All in-class
quizzes and homework assignments were submitted electroni-
cally as Excel workbooks.
While most of the students had not yet taken any core
chemical engineering courses, every opportunity was taken
to expose the students to the kinds of problems they would
see later in the curriculum. This served to benefit the stu-
dents in several ways. First, they became more engaged in
learning the programming and the problem-solving concepts
when it was demonstrated that these fundamentals could be
applied to chemical engineering-related problems. This was
true in spite of the fact that they possessed only a cursory
understanding of the underlying fundamentals at this point in
their education. Another benefit was that, early in the cur-
riculum, students were exposed to a sample of what the chemi-
cal engineering profession entails. It was observed that many
of the students were interested in chemical engineering for
reasons ranging from the desire to follow the path of a family
member or close friend to a desire to have a good paying job
when they graduated. Approximately 5% (3/66) of them ended
up changing their major after learning more about the chemical
engineering profession. In the following section, the specific
learning objectives and content of the course are described.

COURSE OBJECTIVES AND CONTENT

In a broader perspective, the objective of P1. -,,, ,,,;,,..-
and Computation for Chemical F,.; ... is to begin the pro-
cess of introducing the computer as an engineering problem-
solving tool. As described in the preceding section, the ap-
proach to satisfying this objective relies upon active learn-
ing, relevant example applications, and modern classroom
instructional tcillil'-'.,. This high-level objective of the
newly redesigned course was refined into the specific learn-
ing objectives of
Becoming proficient at using Excel to perform scientific
and engineering calculations and graphical analysis.
Understanding the essential elements of structured and
object-oriented programming as it applies to VBA.
Being able to construct customized VBA-based spread-
sheet functions to enhance the engineering problem-
solving capabilities of Excel.


Spring 2005











The first one-quarter of the course consisted of formal instruction on
spreadsheet techniques and tools. This is illustrated in Figure la, where the
students' progression of learning begins with basic operations in a work-
sheet cell and progresses outward to increasingly complex worksheet opera-
tions. The remaining three-quarters of the course was devoted to instruction
on VBA programming in Excel. Since VBA is a separate application that is
integrated into the Excel environment, this involved two distinct aspects-
learning the VBA programming language and learning how to interface with
Excel from a VBA program. The latter required the students to work with
Excel's so-called Object Model, a heirarchical, object-oriented interface to
the Excel application that facilitates manipulation of all the elements of an
Excel workbook.
A synopsis of the programming elements of VBA that were included in
the course is shown in Figure lb. VBA contains many of the same elements
that are common to other programming languages-variables, loops, deci-
sion constructs, etc. Thus, the students obtain a conceptual understanding
that enables them to more easily learn a different programming language,
such as C++ or Java. This was an important consideration since some of the
students will continue their education in graduate school where they may be
involved in computational research requiring programming skills in other
languages.

EXAMPLE APPLICATIONS
In the preceding section, the general features of Excel spreadsheets and
VBA programs that the students were exposed to, and which underly the
course learning objectives, were described. The students developed their skills
at using these tools by applying them to a number of engineering-related
problems. The types of applications that were included and the specific ex-
ample problem they were asked to solve are summarized in Table 3.
Most of the applications were first explored using a spreadsheet-only ap-
proach, then subsequently implemented in a VBA program. It is again em-
phasized that while the students did not possess a deep understanding of how
the design equations for a particular application were derived, their appre-
ciation for the usefulness of the computer skills they were acquiring was none-
theless heightened. Moreover, they finished the course with a better understanding
of what was ahead of them in the chemical engineering curriculum.
One of the applications listed in Table 3 is the numerical solution of ordi-
nary differential equations (ODEs). The students learned how to solve ODEs


Figure 1. Schematic illustrating sequence of topics pertaining to spread-
sheet (a) and VBA (b) instruction.


using both the explicit Euler method as well as
the 4th-order Runge-Kutta method. As an ex-
ample, the following differential equation repre-
senting the draining of a cylindrical tank was nu-
merically solved by applying the 4th-order Runge-
Kutta method, using both the spreadsheet and
VBA program implementations.

dh dholele 2g
dt dtank

In this equation, h is the height of fluid in the
tank, t is the cumulative draining time, dole is the
diameter of the drain hole located at the bottom
of the tank, dnk is the tank diameter, and g is the
gravitational acceleration constant. This equation
is widely known as Torricelli's formula, and pos-
sesses an exact solution. This enabled the stu-
dents to also explore the concepts of integration
step size and associated error, as well.
The two implementations are shown in Fig-
ure 2 below. The students solved this problem
using the spreadsheet implementation early in the
quarter, and subsequently revisited the problem
after learning how to create customized VBA
function procedures. This helped them to appre-
ciate the advantages of the VBA approach, in-
cluding the conciseness of the implementation


TABLE 3
Applications of Computer Skills
Included in Course

Application Implementation Example
Engineering formula Excel Pressure dynamics and
involving transcen- VBA release rate of choked
dental functions flow from a high-
pressure gas cylinder

Parameter estimation Excel Determination of first-
VBA order rate constant from
experimental data using
the integral method

Solution of linear Excel Steady-state material
systems of algebraic balance
equations

Solution of nonlinear Excel Determination of
algebraic equations VBA friction factor using the
Colebrook equation

Numerical integration Excel Sizing of a gas-liquid
VBA scrubber


Numerical solution of Excel
ordinary differential
equations


Draining of a tank using
Torricelli's formula


Chemical Engineering Education













and the ability to reuse the function to solve a different problem by
simply redefining the ODE in the VBA function. Additionally, the
VBA implementation reduces the possibility of introducing a typo-
graphical error since the Runge-Kutta terms do not have to be re-
typed for each problem.


SUMMARY AND CONCLUDING REMARKS

A newly redesigned freshman programming course for chemi-
cal engineers that supplants the traditional introductory computer
science course has been described in this paper. The course focuses
on the use of Excel spreadsheet and VBA programming techniques
to solve engineering-related problems in response to the needs of
industry as unveiled in a recent CACHE survey. The course also
serves as a metric for students to assess their interest and aptitude
for the chemical engineering profession at an earlier point in their
curriculum than previously allowed.

Some remaining issues will have to be addressed, one of which
includes the lack of suitable textbooks that relate to the course con-
tent. Many textbooks on Excel and VBA programming are avail-
able, but no textbook could be identified that focused on engineer-

a).
Excel worksheet for implementing spreadsheet and VBA-based solution to ODE.

Ld te Ed t T F ool Data PUP 2000 Windw Hp Acrob_
:Sm I a ee- -- 00 :o ria 10 a
J34 -
A B C D E F Ki G I J K
2 Hole Diameter (m) 00508
STank Dameter (m) 1 RK formulae typed into cells VBAfunction call
Initial Height (m) 1
Time Ste s)
/
SWorksheet Implementation VA E ct


11
12 . ...
13

80 0294683 -006204 -005868 -005887 -0 0555 0 29463 294683
90 0235908 -005551 -005214 -005235 -00496 023590 0235907
100 0183664 -004898 00 6 04584 -004243 0183664 0163
110 0 13795 -004245 -003905 -003933 -003589 013795 137 49
120 0098768 -003592 -003249 -003283 -002935 0098768 00987
130 0066117 -002939 -002592 -002635 -002279 0066117 006114
140 0039998 -002286 -001932 -001991 -00162 O039998 0039~
150 0020414 -001633 -001265 -001357 -000946 0020414 002040
160 007378 -000982 -000568 -00077 #NUMI 00737 007343

b).
VBA code called from worksheet cell formula.
Oplo Explilt
Function R.geKutt(t ks Double, As Double, d s Double) As Double
IThls function Integrates a single ODE using a 4 term Runge-Kutta method,.
IThe ODf Is defined In The prlate fun-tUoan dydt.
D. Im ki Double, k2 A Double, k3 Aa D-ole, k4 A Double.
kl = dt dvdt(, V) I
k2 t d-dt( 0.5 Y 0.5 I *k1
k3 dt dydt(t + 0.5 d, 0.5 k2)
k4 dt dydt( + dt, y + k3)
RungeKut. V + (kl + 2 1 k2 + 2 k + k1) / 1
End Funct. n
vteFuncon adyd( As Double, s Double Double
o dhole As Do-be, dtank A Doule
cons, g s ooue = 9.8066
dhole 0.0508
dtan- = 1
dydt -(dhole. / dank) 2 Sqr(2 g
End Function

Figure 2. Runge-Kutta solution of an ODE describing draining
of a tank using a spreadsheet (a) and a VBA program (b).

Spring 2005


ing-related applications. The students responded quite
positively to learning programming skills within the con-
text of solving engineering-related problems. A textbook
that is tailored to such a class would greatly facilitate the
continued offering of the course. Additionally, in order for
the students to sustain and leverage the skills obtained in
the course, a department-wide involvement to incorporate
Excel/VBA problem-solving methods where applicable
into their higher-level engineering courses must be initi-
ated and sustained. The familiar saying, "Use it or lose
it!" applies here.

It is also important to acknowledge that while spread-
sheets and Visual Basic programs are useful for solving
many relatively routine engineering problems as illustrated
in the preceding section, some problems require more so-
phisticated computational tools. This becomes apparent
to the students later in the curriculum as they take courses
in fluid mechanics, transport phenomena, thermodynam-
ics, reactor engineering, and design. Here they will learn
about software packages designed to perform computa-
tional fluid dynamics calculations, predict detailed fluid
properties, optimize process flowsheets, and more. Thus,
the Pi.. -i.,,, iin: and Computation for Chemical E,,..i-
neers course represents the commencement of their edu-
cation in using the computer as an engineering tool. The
real value of the approach outlined here is, perhaps, that
the students can more clearly and immediately see that
computers can be programmed to efficiently solve chemi-
cal engineering problems.

REFERENCES
1. Edgar, T., "Computing Through the Curriculum: An Integrated Ap-
proach for Chemical Engineering," CACHE Fall 2003 Newsletter,
cover.html>
2. Bloch, S.C., Excel for Engineers and Scientists, 2nd ed., Wiley, New
York, (2003)
3. Filby, G., Spreadsheets in Science and Engineering, Springer-Verlag,
New York, (1998)
4. Kral, I.H., The Excel Spreadsheet for Engineers and Scientists,
Pearson Education, New Jersey, (1997)
5. Orvis, W. J., Excel for Scientists and Engineers, 2nd ed., Sybex, San
Francisco, (1996)
6. Peress, J., "Working with Non-Ideal Gases," Chem. Eng. Prog., p.
39, March (2003)
7. Jevric, J., and M.E. Fayed, "Shortcut Distillation Calculations via
Spreadsheets," Chem. Eng. Prog., p.60, December (2002)
8. Anthony, J., "Elements of Calculation Style," Chem. Eng. Prog.,
p.50, November 2001.
9. Chemeng Software,
10. ChemSheet Software, ware/ChemSheet/IndexFrame.htm>
11. Excel Unit Conversion,
12. The Chemical Engineers' Resource Page, www.cheresources.com>
13. Beyond Technology,
14. Emagenit,
15. Spreadsheet World,
16. Sauer, S.G., "Freshman Design in Chemical Engineering," Chem.
End. Ed., 38, 222(2004) 7











curriculum


THE PARADOX OF PAPERMAKING



MARTIN A. HUBBE, ORLANDO J. ROJAS
North Carolina State University Raleigh, NC 27695-8005


Students in chemical engineering who enroll in courses
such as papermaking often find themselves startled
by the richness and breadth of phenomena that con-
currently take place in related processes. Gas, solid, and liq-
uid phases are put into contact in different states of disper-
sion where surface and colloidal forces, together with hydro-
dynamic effects, shape the final outcome, i.e., the familiar
sheet of paper. Even more perplexed is the instructor who,
while teaching, finds him/herself attempting to explain a se-
ries of events that is full of paradoxes.
To begin with, while librarians expect paper to last for hun-
dreds of years,E' 2] most paper gets thrown away or is recycled
within a matter of days or weeks. Whereas paper is one of the
least expensive manufactured items, its production involves
use of some of the most expensive systems of equipment.E3,4]
Paper is among the most recyclable and environmentally com-
patible products, made mainly from naturally renewable ma-
terials,E51 but at the same time the industry has faced great
pressure related to its environmental impact.E6-10]
Though each of the items just mentioned raises some inter-
esting questions, the focus of the present article is on some
especially paradoxical issues related to the process itself.
There are some apparent contradictions inherent in the pa-
permaking process that make it a fascinating field of science
and art. Even as we begin to understand the principles be-
hind what at first appears to be magic, we owe profound re-
spect to the craftspeople in China and I, \,. I. i..' who
discovered and developed this subtle and economically im-
portant process.


PARADOX ONE
Divide to Combine
Wood and paper are both solid materials, composed mainly
of polysaccharides-cellulose and hemicellulose.E131 Both
wood and paper contain at least 5% water, although wood
can contain considerably more in a living tree and before it is
dried. In addition, both wood and paper are composed of fi-
bers that firmly adhere to adjacent fibers.


As shown in Fig. 1, the first step in papermaking is to de-
stroy every one of those interfiber bonds in the original wood.
This is done at considerable expense and effort. The most
widely used process for converting wood into papermaking
pulp, the so-called kraft process, commonly involves disso-
lution of 50% to 60% of the solid material.141 What makes
the kraft process particularly impressive is the toughness, in-
solubility, and high resistance to chemical attack on the part
of lignin, which is the phenolic substance that holds the fi-
bers together in the wood. All of this is accomplished by a
process that recovers most of the chemicals used in cook-
ing, and also generates an excess of high-pressure steam
and electricity from the heat evolved from the unused
components of the fibers.[14,15]
Though less impressive from a chemical standpoint, the
other way of liberating wood fibers from each other also in-
volves drastic action. Mechanical approaches to turning wood
chips or logs into papermaking fibers require a huge amount
of i i -., usually between 5 and 10 megajoules per kilo-
gram of fibers, on a dry basis.[14,161
The next step, after converting the wood material to pulp,

Marty Hubbe isAssociate Professorin the De-
partment of Wood and Paper Science atNorth
Carolina State University. He received his BS
in Chemistry from Colby College in 1976, his
MS in paper technology from the Institute of
Paper Chemistry in 1979, and his PhD in
Chemistry from Clarkson University in 1984.
His interests include the colloidal chemistry of
papermaking, surface charges, and polyelec-
trolytes.

Orlando Rojas is Assistant Professor in the
Department of Wood and Paper Science at
North Carolina State University. He received
his BSc from Universidad de Los Andes (ULA,
Venezuela) in 1985, his MS in 1993, and his
PhD from Auburn University in 1998, all in
chemical engineering. His interests include in-
terfacial phenomena and surface and colloid
science and the study of adsorption behaviors
of surfactants and polymers at interfaces.


Copyright ChE Division ofASEE 2005


Chemical Engineering Education










involves adhering the fibers back together. A typical paper-
making fiber is about 1-3 mm long and has a length-to-thick-
ness ratio of about 50-100.1171 During the process of forming
a sheet of paper, these fibers have a tendency to lie in layers,
each fiber being approximately parallel to the plane of the
sheet. Hydrodynamic effects, as well as tension on the wet
sheet as it is being pressed and as it starts to be dried, can
further impose a preferential orientation in the direction of
manufacture.E18 191 It has been estimated that a typical fiber in
paper crosses about 20-40 similar fibers.E201 Adhesion at each
of these crossing points has a dominant effect on the strength
of the resulting paper.


PARADOX TWO
Add Water, Then Take It Away
Immense amounts of water are added to the papermaking
process, even if one just considers the initial separation of
wood into a suspension of fibers. Then, as illustrated in Fig.
2, the water is taken away again. Both the kraft process and
mechanical pulping processes involve dilution of the fibers
to a solids content of about 3% to 10%. It is usual to add
much more water just before the paper is formed into a sheet
and dried. Papermakers refer to this highly diluted condition
as the "headbox solids" or
"headbox consistency," since the
headbox is the last part of the pa-
per machine that is visited by the
fiber suspension before water is
taken out during the paper form-
ing process. The most common
values of headbox consistency together in fibe
lie within a range of about 0.3% wood
to 1.2%.E21 221 Taking 0.5% as an
example, this implies that the pa- ing te 1i A vnew fier tt
ing the interfiber attack
permaker needs to pump roughly tablish them again later
200 mass units of water for ev-
ery unit of fiber, on a dry basis.
Why do papermakers use such Fillers, etc.
high dilution? The answer can be
traced again to the high length-to-
thickness ratio of fibers, giving ood __.
them a tendency to become en-
tangled as "flocs" in a flowing sus- [
pension.[23-26] It has been proposed Suspension
that flocculation can generally be of wood
avoided by diluting the suspension pup ier
enough so that most fibers are able Recycled
to rotate about their center points paper
without touching another fiber. <- Dry ->
Based on the lengths and masses
of typical papermaking fibers, the Figure 2. A view of th
solids level required to approach matter of making the fi
this theoretical condition, even if dry them again.


//


persec
rs

aper
*men
'asp


P



White

We

e pat
bers


the fibers are lined up on an artificially regular array, would
be less than about 0.02% solids.E271

In actuality, the levels of headbox consistencies used in
most papermaking operations seldom are as low as these theo-
retical numbers. Rather, papermakers need to strike a com-
promise between the desire to minimize flocculation and the
expense and difficulty of recirculating so much water. Though
headbox consistencies in the range 0.3% to 1.2%, as men-
tioned earlier, imply very frequent collisions among fibers,
tending to produce some fiber flocs, the uniformity of the
resulting paper tends to be satisfactory for most end-uses.

The most massive and outwardly impressive part of a pa-
per machine is devoted to removal of almost all of that water
that was used to dilute the fibrous suspension. Though de-
tails of paper machine systems are discussed elsewhere,[4,14]
several features of this equipment are especially notable.
These include the forming fabric, which is essentially a con-
tinuous screen or pair of screens upon which the paper is
initially dewatered. Adjustments in the angle impingement
of the jet of fiber suspension onto the fabric, and also the
relative speeds of the jet and the fabric can be used to partly
break up the flocs of fiber, yielding more uniform paper.[281
As the wet paper proceeds down the moving fabric surface,
it experiences a series of pulses
of vacuum and pressure. These
pulses not only help in the pro-
cess of water removal, but they
also tend to improve paper's uni-
formity of formation.E28"29" Station-
d Fibers bound ary devices known as hydrofoils
together in and forming blades are often used
paper to pull water from the wet mat of

making process as break- fibers. Gradually increasing
ts in wood, just to rees- vacuum pulls yet more water from
aper. the paper. Most of the water is
removed in this stage, and the sol-
Polymer Colloidal silica ids content of the paper web may
|- 77 reach 15-20%. To remove more
water, the damp paper is pressed
r / against felt surfaces as it passes
makingg Paper through the nips between large
ocess machine solid rolls. Finally, in the dryer
section of the machine, the paper
process water typically passes around multiple,
\ rsteam-heated cylinders to evapo-
rate most of the remaining water.
water NBecause evaporation requires
New paper much more i.l i- compared to
t > <- Dry -> the previous dewatering steps, it
is important that the paper enter
permaking process as a the dryer part of the paper ma-
wet and then having to chine with as high a solids level
as practical. Usually about 4% to


Spring 2005










8% of moisture content is left in the final paper so that it will
be as close as practical to equilibrium with the expected rela-
tive humidity when it is used, a practice that tends to mini-
mize curl problems in the paper.[30]


PARADOX THREE
Swell with Water to Dehydrate and Si, ml,
Recently, the person in charge of making a relatively heavy
grade of paper on a modem machine wanted to know, "What
can I do to reduce the amount of water contained in the fi-
bers?" What was left unsaid was the fact that this papermaker
still wanted to achieve a high level of interfiber bonding within
the product. Past studies have shown a high correlation be-
tween a fiber's state of swelling, as represented by its water-
holding ability, and the tensile strength properties of paper
made from those fibers.31- 3] According to theory, a more
swollen fiber has a more flexible surface, and it is able to
develop a higher proportion of bonded area under a given set
of conditions for forming, pressing, and drying the paper
sheet.120,341 This situation is illustrated in Fig. 3, which shows
how papermaking fibers become swollen during the paper-
making process, but can end up "shrunk" relative to their
original perimeter.
The more swollen fiber can be more
difficult and more expensive to dry,
however. That is because it is very dif-
ficult to remove the last bit of water Rening
that is held within the cell walls of pa-
permaking fibers, except by evapora-
tion. Although papermakers apply in- Fiber not Inc
tense pressure as the wet paper sheet swollen sw(
passes between steel rolls or "extended off
nips,"[35,36] some water remains in the Figure 3. A paradox
cell walls of the compressed fi- ing: Fibers are mad
bers.t37,381 The average dimension of they shrink again ei
has dried.
micropores where such water is held as re
in a kraft pulp fiber has been estimated to be in the range of
about 1 to 50 nm.E39-411 If one models such capillaries as cylin-
ders, the pressure exerted by meniscus (capillary/surface ten-
sion) forces is predicted to be in the range 4 to 200 MPa, a
range that partly overlaps the range of pressures that paper-
makers use to squeeze water out of a paper sheet in press
nipsE141 before it is dried by evaporation. Papermakers' Holy
Grail, a visionary but seemingly impossible goal, would be
to find a type of fiber that has a highly conformable sur-
face in the wet state, but a low amount of water held within
the fiber walls.
Although the search for such fibers generally has led to
frustration, two contrasting solutions to this dilemma are
worth considering. One notable approach involves the use of
relatively high-yield fibers, such as the mechanical pulp fi-
bers mentioned in Paradox One. The lignin and hemicellu-


lose components, which account for over half of the dry mass
of such fibers, have softening points within a temperature
range of about 50 to 200 "C,[42'43] depending on moisture con-
tent, which is close to the temperature that paper reaches dur-
ing a typical drying operation.[441 Thermal deformation, al-
lowing fibers to develop a higher proportion of bonded area,
has been especially noted in the case where high-yield
fibers are subjected to certain modern drying practices
that achieve higher-than-typical combinations of moisture
and temperature.[45,461
Research has shown a fascinating interrelationship between
the strength of paper and its ability to scatter light and resist
that show-through of print images.120] The reason that these
two variables are connected is that the relative amount of
light scattering is roughly proportional to the air-solid inter-
facial area within paper. In areas where fibers are bonded
tightly together, light can pass between the two of them with-
out scattering. Thus, one of the penalties of relying on either
refining or plasticization as the chief means of increasing
paper's strength is that the paper tends to become more trans-
parent and might not meet the customer's specifications.


To minimize the


Drying


reased Fiber less
selling swollen
iber than at first
ical aspect ofpapermak-
te to swell in water, but
ven more after the paper


loss of opacity, papermakers can use a
completely different approach to in-
creasing the bondable nature of fiber
surfaces. Rather than making the
whole fiber more flexible, the common
approach is to add water-loving poly-
mers as dry-strength agents to the fi-
ber slurry. The function of these dry-
strength agents is to increase the te-
nacity of bonding within areas where
the fibers contact each other"47-49] and
possibly increase the area over which
bonding takes place. There has been a
debate as to whether additives such as
cationic starch or acrylamide polymers
can increase the relative area of bond-


ing between fibers,[50-52] but if that were true, then one would
expect the resulting paper to be more translucent, as discussed.
Rather, an analysis based on light-scattering tests revealed
very little increase in optically bonded area."531 Thus the main
contribution to paper strength, due to the polymeric additives,
is related to the strength per unit of bonded area. Apparently,
any effect of dry-strength polymers to fill in spaces between
rough surfaces of fibers must happen at a molecular scale,
smaller than the limits of detection of optical methods. We
have to keep in mind that the light-scattering method relies
on the fact that a fiber surface element appears bonded if
there is another fiber surface at a distance smaller than half
the wavelength of light. This doesn't guarantee that the two
fibers are bonded chemically, since the bonding distance is
shorter. Irrespective of the case under consideration it is con-
cluded that the interaction between light and the paper net-


Chemical Engineering Education










work is closely related to the bonding degree. Both light ab-
sorption and scattering are the same properties that define
the brightness and opacity of paper. Therefore the rela-
tionship between optical and mechanical strength in pa-
per is not surprising.


PARADOX FOUR
Make the I ,.. I, Flexible to Make the Paper Stiff
Although some producers of paper will argue that the pri-
mary benefit they provide for their customers is a surface on
which to print images or messages, there are many grades of
paper where "support" is a function that is equally important.
Paper bags provide a good example. Although many grocers
prefer plastic bags because of their handles, their resistance
to water, and their low cost, customers can clearly tell the
difference-only the paper version is stiff enough to stand
up by itself once it is opened. As another example, xerographic
copy paper has to meet a certain minimum stiffness level or
it tends to jam in the machine. Boxes made of paperboard
also need to have sufficient resistance to bending and crush-
ing in order to fulfill their role.
So what is the first thing that paper-
makers do to the fibers? As illustrated
in Fig. 4, they convert them to flexible stiff
hollow
ribbons. In the tree, fibers can be envi- fiber
sioned as little tubes with closed, pointy
ends. Based on the principles of me- Refini
chanics, the tubular shape offers a high
resistance to bending, relative to the
mass of solid material.1541 Instead of tak- Cvut-a
ing advantage of this inherent resistance __
to bending, papermakers subject the fi- Figure 4. Paperm
bers to a number of processes that make advantage of the
them more conformable. The combined strength ofhollow-,
effects of kraft pulping and refining convert them into
makes the fibers flexible enough to col-
lapse. Refining involves passage of fiber slurries between
rotating steel plates with raised bars. The fibers are re-
peatedly compressed and sheared as they pass between
these bars, causing internal delamination as well as fi-
brillation of the outer layers of the fibers."14,55561 A recent
study in our laboratory showed that refining increased the
flexibility of wet, unbleached softwood kraft fibers by a
factor of between 6 and 19.E571
Research has shed insight on how the orientations of fi-
bers, the bonds between them, and the degree to which the
paper is held in tension during drying relate to the final prop-
erties of the paper.[58-610 To simplify the analysis it was shown
that the in-plane mechanical properties of a thick sheet of paper
can be reproduced by laminating many thin sheets.[61-62] An ide-
alized model, involving 2-dimensional random networks of
fibers, is then able to explain many of paper's characteristics.


ng


way

aker
inhe
shap
ribbon


In the simplest network approach (fibers are assumed to be
randomly distributed and correlations between fibers are ne-
glected) it is found that the local value of the number of fiber
crossings can be described by simple probability distribu-
tions. From these distributions one can easily calculate the
average number of fibers crossing at any given point in the
network. This is the so-called coverage, c. The coverage can
be measured from sheet cross-sections by determining the
number of bonds that intersect a reference line and this gives
a precise measure of the effective number of fiber layers in a
sheet. Typical values of coverage for printing papers are 5-
20 (layers of fibers).
A more challenging issue to deal with quantitatively is
paper's directional nature. For instance, paper's strength in
the direction of manufacture tends to be considerably higher,
compared to the cross-directional strength.E63] Briefly stated,
the factors that mainly account for this directionality are (a) a
tendency of fibers to become aligned in the direction of manu-
facture due to hydrodynamic shear as the paper is being
formed,[63-65] and (b) forces exerted on the paper during the
process of drying.[63] Tensile forces exerted by the rotat-
ing dryer can keep the paper from shrinking, especially
in the direction of manufacture, add-
ing to the elastic modulus of paper
Flexible, in that direction.
ribbon-
like fiber There probably will never be a com-
Paper- pletely satisfactory explanation as to
making why papermakers so often fail to take

advantage of the inherent stiffness of
native, uncollapsed fibers. Ribbon-like
fibers, as used by papermakers, can be
advantageous in terms of achieving a
s do not take full high proportion of bonded area.1201 It
'rent stiffness and appears that the increased interfiber
edfibers, but rather bonding is so important that it offsets
ns the possible advantage of keeping the
fibers in their native shape. Perhaps the
next generation of papermakers will figure out a way to
achieve high levels of interfiber bonding without collapsing
most of the fibers into ribbons.


PARADOX FIVE
Disperse i ,n ii,;,, Well, but Retain the Fine Particles
The fifth paradox to consider is deeply ingrained in the art
of papermaking. The function of a dispersant chemical is to
help achieve and maintain a uniform suspension of fine par-
ticles-thus avoiding the formation of agglomerated mate-
rial. The latter could hurt the uniformity of the paper prod-
uct, cause abrasion, or form deposits on some of the paper-
making equipment. Some materials that need to be dispersed
before they are added to the papermaking process include
mineral fillers, sizing additives (see later), and certain bio-


Spring 2005











cides and colorants. Chemical products used to avoid undes-
ired agglomeration of the fine particles include phosphates,
low-mass acrylate copolymers, and a wide range of nonionic
surface-active agents (surfactants).[66,67] Such chemicals ad-
sorb onto the solid surfaces and increase the electrostatic
and/or steric repulsion forces,E661 keeping the particle from
colliding and sticking. It is worth noting that some dissolved
and colloidal materials originating from the wood also can
play the role of dispersants due to their negative charge.E681
As shown in Fig. 5, the papermaker's perspective changes
abruptly when the time comes to form the dispersed fibers
and finely divided substances into a wet sheet of paper. Typi-
cal mesh fabrics, upon which paper is formed, are composed
of polyester monofilaments.[69] Although there is a wide vari-
ety of forming fabric designs, including double- and triple-
layer fabrics, the openings between adjacent filaments is ap-
proximately 0.1 to 0.3 mm, which is big enough to allow
passage of nonfibrous materials. This
"fines" fraction may also contain, in Apply shear &
dispersants.
addition to some of the wood-derived
solids, mineral fillers and sizing "
emulsion particles. Although, in prin- ,
ciple, some of the fine particles may Undispersed Disp
be retained by mechanical filtration particulate .-. part
matter matt
in the mat of wet fibers, experience mar
has shown that the efficiency of such Figure 5. A schizoph
mechanical retention tends to be low ing: wanting everythi
in the absence of flocculating chemi- wanting the fine pai
cals.[70] Poor retention of these mate- when the sheet is bei
rials produces not only a lower pro-
ductivity in terms of mass balance, but also filtered water
that is more difficult to treat for recirculation.
Perhaps surprisingly, the kinds of chemical treatments that
have been found to be most effective for increasing the re-
tention efficiency during paper formation work according to
a different principle than do dispersants. Mere neutralization
or removal of repulsive forces between surfaces[711 does not
provide nearly the strength of attachments needed to resist
the strong hydrodynamic forces inherent in the formation of
paper on a modem machine.72-751 Strong forces tending to
detach fine particles from fibers develop as water is removed
from the sheet by gravity, and by the repeated vacuum and
pressure forces.[76-83] It is because of this that fine materi-
als tend to be washed out of those layers of a paper prod-
uct that were closest to the forming fabric during the pro-
duction process.[84,85]
The chemicals found to be most effective for retention of
fine particles are the very-high-mass acrylamide copolymers,
having molecular masses in the range of about 5 to 20 mil-
lion grams per mole.E70,86,871 This is roughly 1000 times larger
in molecular mass compared to common polymeric dispers-
ant molecules. The monstrous size of retention aid polymers
allows them to bridge between surfaces of adjacent solids,


*

ersed
iculate
:er

renic
ng w
article
ng f


extending beyond the range of repulsive forces, including
those components of the repulsive forces induced by dispers-
ant treatments. Various different bridging mechanisms have
been studied.[88-95] The effectiveness of very large molecules
has also been attributed to the fact that multiple points of
attachment occur simultaneously, so that adsorption of the
polymer onto a surface is very difficult to reverse.
It is reasonable to ask, "Do dispersants interfere with the
performance of retention aids?" In general, the answer is
"yes." Many studies have shown diminished effectiveness of
cationic acrylamide copolymer retention aids in systems that
contain substances that can act as dispersants.[96-98] This is
particularly observed in the case of wood-derived anionic
colloidal materials.[68,96-981 To overcome this kind of effect,
papermakers often use highly charged cationic materials such
as aluminum sulfate, polyaluminum chloride (PAC),
polyamines, polyethyleneimine (PEI), and similar chemicals.
In addition to their role as charge-
Add a retention neutralizers, such additives also can
aid polymer.
pl serve as anchoring sites for anionic
Retention aid molecules,[99-102] or as
Ssite-blockers to enhance the effec-
Agglomerated tiveness of cationic retention aid
particulate molecules. 1031
matter
Cationic retention aids exhibit a
aspect ofpapermak- surprising degree of compatibility
ell dispersed, but also with nonionic dispersants. The latter
's to adhere together often consist of long hydrophilic eth-
rmed ylene-oxide chains, having the re-

peating unit (-CH2-CH2-O-). These
are attached either to an alkyl or aromatic hydrocarbon group,
or to a water-hating propylene oxide chain. An example of
the compatibility between such nonionic dispersants and cat-
ionic retention aids can be seen in a patented system for con-
trol of wood pitch deposition in paper machine systems.[104]
This system consists of adding a nonionic surfactant to the
furnish to disperse the pitch particles (to keep them from
colliding and building up to objectionable size), and then
treating the slurry with a cationic acrylamide copolymer
retention aid.
At the opposite extreme, one can consider the use of a non-
ionic retention aid system based on polyethylene oxide (PEO)
and a cofactor.E92-951 Such systems can be almost unaffected
by changes in the amounts of anionic colloidal materials and
other anionic dispersants in the system. Although the strate-
gies mentioned in the previous two paragraphs are useful for
illustrating some principles, it is far more common for paper-
makers to follow a strategy of minimizing the amounts of
dispersants that are added to the papermaking system-know-
ing that their effects will need to be reversed later on when
the retention aid polymers are added. The goal is to keep the
amounts of dispersant no higher than the minimum needed
to maintain uniform suspensions of such materials as cal-


Chemical Engineering Education












. the focus of the present article is on some especially paradoxical issues related
to the process itself. There are some apparent contradictions inherent in the
papermaking process that make it a fascinating field of science and art.


cium carbonate filler. This strategy can explain at least part
of the success of on-site production of precipitated calcium
carbonate (PCC) filler.1105,1061 Relative to ground calcium car-
bonate (GCC), PCC requires relatively little dispersant as long
as it is made on site and kept agitated for the relatively short
time between its production and use.[107,108]


PARADOX SIX
Chemically Flocculate the I dl.. and then Disperse Them
As odd it may seem, one of the first things that often hap-
pens after the papermaker has flocculated the suspended ma-
terial with very-high-mass acrylamide copolymers, as just
described, is that the furnish passes through a screening de-
vice that rips apart 100% of the polymer-induced attachments
between fibers. This circumstance is illustrated in Fig. 6. Stud-
ies have shown that breakage of contacts between the fibers
can irreversibly degrade the high-mass polymeric
flocculants.1109-112 The main function of a pressure screen is
to prevent large objects, such as incompletely cooked bits of
wood, from getting into the product.]1131 The slots in the type
of screen typically used in these applications have widths of
about 0.15 to 0.45 mm, 1131 which is large enough to allow
passage of a single fiber, but too small to allow passage of
fibers that are bound together by polymers.
Although "pre-screen" addition of retention aid polymers,
as just mentioned, is very common, many papermakers choose
to maximize the efficiency of these flocculants by adding them
just after the screening operation."114 Depending on the type
of headbox and other details of the machinery, the papermaker
then selects a suitably low dosage of retention aid to achieve
almost the same result-redispersal of most of the fibers from
each other before the paper sheet is formed.


Add very- Apply
high mass hydrodynamic
flocculant. shear.




Dispersed Flocculated Dispersed
fibers and fibers and fibers with
fine fine particles
particles particles attached

Figure 6. Papermakers often add the retention aid poly-
mers just before the furnish is subjected to high hydrody-
namic shear, partly reversing the flocculating effect.


To add yet another layer to the riddle, many paper machine
systems (especially in the manufacture of printing papers)
use something called microparticles, which partly reflocculate
the papermaking furnish again.1 5-11"7 These additives include
colloidal silica dispersions and montmorillonite clay, a sus-
pension of extremely thin plate-like particles. The common
feature is that microparticles all have a very high ratio of
surface area to mass, usually in excess of 100 m2/g. One com-
mon strategy for microparticle use involves pre-screen addi-
tion of a cationic acrylamide retention aid, as just mentioned,
followed by postscreen addition of the microparticle addi-
tive.[115-116,118] When microparticles are added in this way, the
little particles are able to bridge between the fragments of
retention aid polymers remaining on the adjacent fiber sur-
faces and reconnect them. The fact that papermakers seem to
vacillate between inducing flocculation and then
deflocculation of the papermaking stock can make one won-
der what they are really trying to achieve.
One explanation for the papermaker's odd practice of floc-
culating fibers and then immediately deflocculating them, is
the fact that hydrodynamic forces are much better able to
detach larger objects from each other, compared to their abil-
ity to detach a small object, either from a larger object or
from other like-sized objects. 74,119-1211 It's a matter of lever-
age. Although only something like a screen device can en-
sure complete deflocculation of the papermaking furnish, if
only for a moment, hydrodynamic forces in the headbox of a
paper machine have the potential to achieve selective break-
age of polymer bridges. Modern paper machines often em-
ploy hydraulic headboxes, in which hydrodynamic shear and
extensional flow fields have been designed in such a way as
to maximize uniformity of the resulting paper.[122,1231 Recent
work suggests that it is possible, in principle, to select condi-
tions of retention aid treatment that are more than sufficient
to retain small particles, such as mineral fillers, on cellulosic
surfaces, but most contacts between fibers will be separated
from each other as the furnish passes through the high-shear
zones of the headbox.[74,121,124,125]


PARADOX SEVEN
Waterborne Treatments to Make Paper Water Resistant
Many different kinds of paper must be able to resist water
to perform their intended function, but the fibers themselves
are generally water loving. In a process called "internal siz-
ing," papermakers add "sizing agents" to the aqueous mix-
ture of fibers and other materials so that the resulting paper
becomes hydrophobic.[17'126'127] These sizing agents have to


Spring 2005










be either water-dispersible or water-soluble in order to be-
come well mixed with the papermaking stock. Science fic-
tion? No. This is commonly accepted practice within the pa-
per industry.
While there have been detailed studies of the molecular
mechanisms of different internal sizing systems,[126-132] little
of which will be repeated here, it is important to emphasize
two key molecular events that seem to underlie the seem-
ingly impossible transformation of water-loving fibers in an
aqueous environment to water-repellent paper once the same
materials are dried. One of these events is the orientation and
anchoring of sizing molecules, due to the ways in which these
molecules interact with fiber surfaces. The other event involves
the way some sizing molecules become distributed over the
surface of fibers when the paper is heated to evaporate the wa-
ter that remains after it has been formed and pressed.
The concept of "anchoring and orienting" can perhaps best
be illustrated by the case of rosin soap products. As the word
soap implies, rosin soap is a water-dispersible, sudsy mate-
rial. Although rosin products contain a mixture of different
compounds, most of them have between one and three wa-
ter-loving carboxylate groups per molecule. In addition, the
remainder of a typical rosin molecule consists of water-hat-
ing hydrocarbon material. When dispersed in water, the rosin
soap exists not as a true solution, but as micelles. In other
words, groups of rosin soap molecules associate with each
other so that the water-hating parts are generally facing each
other to avoid contact with the water. In order to achieve a
sizing effect, an aluminum compound, such as aluminum
sulfate, is added to the papermaking furnish.
As shown in Fig. 7, the aluminum ions interact with the
carboxylate groups, causing the rosin to precipitate onto the
fiber surfaces. It has been proposed that the alum keeps the
sizing molecules oriented on the fiber surfaces such that the
water-hating hydrocarbon portions face outwards from the
fiber surface.[130'133-1341

The other common types of internal sizing agents work
differently, and the key molecular events occur during dry-
ing at high temperature. If you were to add either rosin emul-
sion size or alkylketene dimer (AKD) sizing agents to a pa-
permaking furnish, and then gradually dry the paper at room
temperature overnight, very little hydrophobicity would de-
velop. Although many authors have used words such as
"spreading" to describe how emulsified sizing agents become
distributed over the exposed surfaces of paper during the dry-
ing process, recent evidence favors a different mechanism. It
is true that rosin acids, AKD, and alkenylsuccinic anhydride
(ASA) sizing agents all exist as liquids at the temperatures
found in the dryer sections of paper machines, but these drop-
lets of liquid tend to remain localized at the fiber surfaces
rather than spreading out as a monomolecular layer.[135-139] It
has been proposed that the lack of spreading is due to forma-
tion of so-called "precursor films" adjacent to the bulk of


sizing material."138'139 The very low surface i i-.. achieved
in areas covered by such films impedes spreading of the drop-
lets of hydrophobic material. In addition, studies have shown
that only a fraction of the surface area needs to be covered
with sizing molecules to achieve a high level of water resis-
tance.[140-142]
Despite the relatively low vapor pressures ofAKD and other
emulsified sizing agents, even at the temperatures adjacent
to drying cylinders on a paper machine, there is circumstan-
tial evidence of vapor-phase migration. For example, if one
forms a sheet of wet paper in the presence of sizing agents
and then dries that sheet in a stack with unsized paper sheets
in an oven, a significant sizing effect can become distributed
throughout the stack, with results depending on the location
of a sheet relative to the treated sheet.1140'143-1441 Perhaps the
answer to this puzzle involves the relatively short distances
over which the vapors of sizing agents need to migrate. The
distances that sizing agent vapors need to migrate are even
less if one considers the fact that the process of forming the
paper results in microsizing droplets or particles of sizing
material distributed in a semirandom manner over the sur-
face of each fiber.
A further perplexing phenomenon is observed when pa-
permakers add polymeric sizing compounds to the starch so-
lutions that are applied to the surface of dry paper at so-called
size press operations. These polymers, which include styrene
maleic anhydride (SMA) copolymers, are dispersible in the




101-9
Fiber Fiber

Water-loving Add micelles Add Water-hating
surface of fiber rosin soap. alum surface of fiber

Figure 7. One way that papermakers achieve the im-
possible-using a waterborne additive to convert
water-loving surfaces to water-resistant surfaces.

aqueous starch solution. Apparently the ratio of water-loving
maleic acid salts versus hydrophobic styrene groups is enough
to achieve either solubility or a micellization effect that closely
resembles solubility. When the starch film is dried, however,
droplets of water will not spread over the paper surface. To
explain this effect, it has been proposed that the sizing co-
polymers migrate to the surface of the starch film, as it dries,
and that hydrophobic styrene groups face outwards from the
paper surface."145 146]

CONCLUDING REMARKS

After considering these seven paradoxes, it becomes evi-
dent that making paper is not as simple as it may seem, and

Chemical Engineering Education












there is plenty of room to further our understanding. The sci-
ence of papermaking offers an abundance of opportunities
for fundamental inquiry on the biological, material, and
chemical fronts. At the educational level it is a subject where
one can put into practice all that is learned in allied subjects
of chemical engineering, including mass, I,- l .. and momen-
tum transfer, colloid and surface science, materials science,
and chemistry. Many career opportunities are available to new
chemical engineers who enjoy paradoxes. Possible career
roles for engineers can be as diverse as process engineering
and optimization, product development, research, technical
sales, and mill management. Although it is foreseen that the
nano-bio-techno waves will have an impact on papermaking
and paper composites, the main process by which paper is
made will probably remain the same, since all paradoxes co-
exist in perfect harmony. No wonder it took many centuries
for our papermaker predecessors to get to where we are now.

REFERENCES
1. Wilson, W.K., and E.J. Parks, "Comparison of Accelerated Aging of
Book Papers in 1937 with 36 years of Natural Aging," Restaurator 4,
1(1980)
2. Waterhouse, J.F, "Monitoring the Aging of Paper," in Paper Preser-
vation, TAPPI Press, Atlanta, GA, 53 (1990)
3. Yin, R., "Industry Characteristics and Investment Decisions: Alterna-
tive Approach to Pulp and Paper Production,"Tappi J., 81(1), 69 (1998)
4. Atkins, J., "The Modern Paper Machine. Part 2: Coated and Fine Pa-
per," Solutions, 86(12), 31 (2003)
5. Jorling, T., "The Forest Products Industry: A Sustainable Enterprise,"
Tappi J., 83(12), 32 (2000)
6. Axegard, P, O. Dahlman, I. Hanlind, B. Jacobson, and R. Morck, "Pulp
Bleaching and the Environment: The Situation in 1993," Nordic Pulp
Paper Res. J., 8(4), 365 (1993)
7. Munkittrick, K. R., M.R. Servos, J.H. Carey, and G.J. van der Kraak,
"Environmental Impacts of Pulp and Paper Wastewater: Evidence for
a Reduction in Environmental Effects at North American Pulp Mills
Since 1992," Water Sci. Technol., 35(2/3), 329 (1997)
8. M6bius, C. H., and Cordes-Tolle, "Paper Industry on the Way to Inte-
grated Environmental Protection: Wastewater Treatment," Papier
53(10A), V60 (1999)
9. Wahaab, R.A., "Evaluation of Aerobic Biodegradability of Some
Chemical Compounds Commonly Applied in Paper Industry," Bull.
Environ. Contam. Toxicol., 64, 558 (2000)
10. Anon., "Nutrient Forms in Pulp and Paper Mill Effluents and their
Potential Significance in Receiving Waters," NCASI Tech. Bull. 832,
25 (2001)
11. Hunter, D., Papermaking: The History and Technique of an Ancient
Craft, Dover Publications, New York, NY (1974)
12. Collings, T., and D. Milner, "New Chronology of Papermaking Tech-
nology," Paper Conservator 14, 58 (1990)
13. Lewin, M., and I.S. Goldstein, Wood Structure and Composition,
Marcel Dekker, New York, NY (1991)
14. Smook, G.A., Handbook for Pulp and Paper Technologists, 2nd ed.,
Angus Wilde Publications., Vancouver, BC, Canada (1992)
15. Aziz, S., and N. Arafat, "Pulp Manufacturing Energy Survey -TAPPI
Alkaline Committee," Proc. TAPPI 1997 Pulping Conf, 455, TAPPI
Press, Atlanta, GA (1997)
16. Law, K-N. "Insights on the Refining Mechanism," Tappi J., 1(1), 4
(2002)
17. Scott, WE., Principles of Wet End ( ......... TAPPI Press, Atlanta,
GA (1996)
18. Ross, R.F, and D.J. Klingenberg, "Simulation of Flowing Wood Fiber
Suspensions," J. Pulp Paper Sci., 24(12), 388 (1998)

Spring 2005


19. Niskanen, K., I. Kajanto, and P Pakarinen, "Paper Structure," in
Niskanen, K., Paper Physics, Ch. 1, 14, Fapet Oy, Helsinki (1998)
20. Page, D., 'A Theory for the Tensile Strength of Paper, Tappi, 52(4),
674 (1969)
21. Beirmann, C.J., Handbook of Pulping and Papermaking, Academic
Press, San Diego, CA (1996)
22. Weise, U., J. Terho, and H. Paulapuro, "Stock and Water Systems of
the Paper Machine," in Paulapuro, H., Ed., Papermaking. Part 1, Stock
Preparation and WetEnd, Ch. 5,125, FapetO' I I .I I ...I I .' -"-"
23. Waterhouse, J.F, "Effect of Papermaking Variables on Formation,"
Tappi J., 76(9), 129 (1993)
24. Kerekes, R.J., "Perspectives on Fiber Flocculation in Papermaking,"
1995 Intl. Paper Phys. Conf, 23, TAPPI Press, Atlanta, GA (1995)
25. Dodson, C.T.J., "Fiber Crowding, Fiber Contacts, and Fiber Floccula-
tion," Tappi J., 79(9), 211 (1996)
26. Beghello, L., and D. Eklund, "Some Mechanisms that Govern Fiber
Flocculation," Nordic Pulp Paper Res. J., 12(2), 119 (1997)
27. Kerekes, R.J., and C.J. Schell, "Characterization of Fiber Floccula-
tion Regimes by a Crowding Factor," J. Pulp Paper Sci., 18(1), J32
(1992)
28. Manson, D.W., "The Practical Aspects of Formation," Wet End Op-
erations Short Course Notes, TAPPI Press, Atlanta, GA (1996)
29. Hubbe, M.A., T. Tripattharanan, J.A. Heitmann, and R.A. Venditti,
"The 'Positive Pulse Jar' (PPJ): A Flexible Device for Retention Stud-
ies," Paperi Puu 86 (2004) accepted
30. Green, C., "Curl in Paper," Appita J., 53(4), 272 (2000)
31. Thode, E.E, J.G. Bergomi, and R.E. Unson, "The Application of a
Centrifugal Water-Retention Test to Pulp Evaluation," Tappi, 43(5),
505 (1960)
32. Jayme, G., and Bittel, "The Determination and Meaning of Water Re-
tention Value (WRV) of Various Bleached and Unbleached Pulps,"
Wochenbl. Papierfabr., 96(6), 180 (1968)
33. Anon., "Water Retention Value (WRV)," TAPPI Useful Method UM
256 (1981)
34. Robinson, J.V., "Fiber Bonding," in Casey, J. P, Ed., Pulp and Paper
( .. .... and Chemical Technology, 3rd ed., Vol. 2, 915, Wiley-
Interscience, New York, NY (1980)
35. Worsick, A., "Developments in Press Technology," Paper Technol.,
35(5), 30 (1994)
36. Wahlstr6m, B., "Wet Pressing in the 20th Century: Evolution, Under-
standing, and Future," Pulp Paper Can., 102(12), 81 (2001)
37. Maloney, T.C., and H. Paulapuro, "The Centrifugal Compression
Value," Tappi J., 82(6), 150 (1999)
38. Ahrens, F, N. Alaimo, H. Nanko, and T. Patterson, "Initial Develop-
ment of an Improved Water Retention Value Test and its Application
to the Investigation of Water Removal Potential," TAPPI99 Proc., 37,
TAPPI Press, Atlanta, GA (1999)
39. Stone, J.E., and A.M. Scallan, "A Structural Model for the Cell Wall
of Water-Swollen Wood Pulp Fibers based on Their Accessibility to
Macromolecules," Cellulose Chem. Technol., 2(3), 343 (1968)
40. Berthold, J., and L. Salmon, "Effects of Mechanical and Chemical
Treatments on the Pore-Size Distribution in Wood Pulps Examined by
Inverse-Size-Exclusion Chromatography," J. Pulp Paper Sci., 23(6),
J245 (1997)
41. Alince, T., and T.G.M. van de Ven, "Porosity of Swollen Pulp Fibers
Evaluated by Polymer Adsorption," in Baker, C. F, Ed., The Funda-
mentals ofPapermaking Materials, Vol. 2,771, Pira Int'l., Leatherhead,
Surrey, UK (1997)
42. Back, E.L., and N.L. Salmon, "Glass Transitions of Wood Compo-
nents Hold Implications for Molding and Pulping Processes," Tappi
J., 65(7), 107 (1982)
43. Salmon, N.L., P Kolseth, and A. de Ruvo, "Modeling the Softening
Behavior of Wood Fibers," J. Pulp Paper Sci., 11(4), J102 (1985)
44. Garvin, S.P, and P. Pantalea, "Measurement and Evaluation of Dryer
Section Performance," Proc. TAPPI Engineering Conf, Book 2, 125
(1976)
45. Kunnas, L., J. Lehtinen, H. Paulapuro, and A. Kiviranta, "The Effect
of Condebelt Drying on the Structure of Fiber Bonds," Tappi J., 76(4),












95 (1993)
46. Retulainen, E., "Condebelt Press Drying and Sustainable Paper Cycle,"
Paperi Puu, 85(6), 329 (2003)
47. Marton, J., and T. Marton, "Wet End Starch: Adsorption of Starch on
Cellulosic," Tappi J., 59(12), 121 (1976)
48. Zhang, J., R. Pelton, L. Wagberg, and M. Rundlof, "The Effect of
Charge Density and Hydrophobic Modification on Dextran-Based Pa-
per Strength Enhancing Polymers," Nordic Pulp Paper Res. J., 15(5),
440 (2000)
49. Pelton, R., J. Zhang, L. Wagberg, and M. Rundlof, "The Role of Sur-
face Polymer Compatibility in the Formation of Fiber/fiber Bonds in
Paper," Nordic Pulp Paper Res. J., 15(5), 400 (2000)
50. Hofreiter, B.T, "Natural Products for Wet-End Addition," in Casey, J.
P, Ed., Pulp and Paper ( '.. *. .. Chemical Technology, Vol. III,
Wiley-Interscience, 3rd ed., New York, NY (1980)
51. Spence, G.G., "Application of Wet- and Dry-Strength Additives," in
Spence, G.G., Ed., Wet- and Dry-Strength Additives -Application,
Retention, and Performance, TAPPI Press, 19, Atlanta, GA (1999)
52. i!l. i E, J. Daicic, and Fr6berg, J., "Surface Chemistry of Paper," in
Holmberg, K., Ed., Handbook of Applied Surface and Colloid Chem-
istry, Ch. 7., 123, Wiley, New York, NY (2001)
53. Howard, R.C., and C.J. Jowsey, "The Effect of Cationic Starch on the
Tensile Strength of Paper," J. Pulp Paper Sci., 15(6), J225 (1989)
54. Gere, J.M., and S.P Timoschenko, Mechanics of Materials, 3rd Ed.,
PWS Publishing Co., Boston, MA (1984)
55. Baker, C.F, "Good Practice for Refining the Types of Fiber Found in
Modern Paper Furnishes," Tappi J., 78(2), 147 (1995)
56. Batchelor, W.J., D.M. Martinez, R.J. Kerekes, and D. Ouellet, "Forces
on Fibers in Low-Consistency Refining: Shear Force," J. Pulp Paper
Sci., 23(1), J40 (1997)
57. Zhang, M., M.A. Hubbe, R.A. Venditti, and J.A. Heitmann, "Effects
of Sugar Addition Before Drying on the Wet-Flexibility of Redispersed
Kraft Fibers," J. Pulp Paper Sci., 30(1), 29 (2004)
58. Kim, C.Y, D.H. Page, F El-Hosseiny, and A.PS. Lancaster, "Me-
chanical-Properties of Single Wood Pulp Fibers. 3. Effect of Drying
Stress on Strength," J. Applied Polymer Sci., 19(6), 1549 (1975)
59. Zhang, G., J.E. Laine, and H. Paulapuro, "Characteristics of the
Strength Properties of a Mixture Sheet under Wet Straining Drying,"
Paperi Puu, 84(3), 169 (2002)
60. McDonald, J.D., L.I. Pikulik, and R. Daunais, "On-Machine Stress-
Strain Behavior of Newsprint," J. Pulp Paper Sci., 14(3), J53 (1988)
61. Kallmes, O., H. Corte, and G. Bernier, "The Structure of Paper. V. The
Bonding States of Fibers in Randomly Formed Papers," Tappi J., 46(8),
493 (1963)
62. Deng, M., and C.T.J. Dodson, Paper:An Engineered Stochastic Struc-
ture, Tappi Press, Atlanta, GA (1994)
63. Niskanen, K., I. Kajanto, and P Pakarinen, "Paper Structure," Ch. 1 in
Niskanen, K., Ed., Paper Physics, Fapet/Tappi, Atlanta, GA (1998)
64. Schulgasser, K., "Fiber Orientation in Machine-Made Paper," J. Ma-
terials Sci., 20(3), 859 (1985)
65. Kallmes, O., G. Bernier, and M. Perez, "A Mechanistic Theory for the
Load Elongation Properties of Paper," Pap. Technol. Ind., 18(7), 222,
(8) 243; (9), 283; (10), 328 (1977)
66. Hanu, W.M., "Dispersants," in Kirk-Othmer I . . of Chemi-
cal Technol., 4th Ed., Vol. 8, 293, Wiley-Interscience, NY (1993)
67. Lynn, J.L., Jr., and B.H. Bory, "Surfactants," in Kirk-Othmer Ency-
clopedia of Chemical Technol., 4th Ed., Vol. 23, 478, Wiley-
Interscience, NY (1993)
68. Sundberg, A., R. Ekman, B. Holmbom, and H. Gr6nfors, "Interac-
tions of Cationic Polymers with Components in Thermomechanical
Pulp Suspensions," Paperi Puu, 76(9), 593 (1994)
69. Kilpenlainen, R., S. Taipale, A. Marin, P Kortelainen, and S.
Metsaranta, "Forming Fabrics," in Paulapuro, H., Ed., Papermaking.
Part Stock Preparation and WetEnd, Ch. 7, 253, Fapet Oy, Helsinki,
Finland (2000)
70. Horn, D., and F Linhart, "Retention Aids," in Roberts, J. C., Ed., Pa-
per ( .. ... -. Ch. 4, 44, Blackie, Glasgow, UK (1991)


71. Walkush, J.C., and D.G. Williams, "The Coagulation of Cellulose Pulp
Fibers and Fines as a Mechanism of Retention," Tappi, 57(1), 112
(1974)
72. Britt, K.W., "Mechanisms of Retention during Paper Formation," Tappi
56(10), 46 (1973)
73. Britt, K.W., and J.E. Unbehend, "New Methods for Monitoring Re-
tention," Tappi, 59(2), 67 (1976)
74. Hubbe, M.A., "Retention and Hydrodynamic Shear," Tappi J., 69(8),
116 (1986)
75. Tripattharanan, T., M.W. Hubbe, R.A. Venditti, and J.A. Heitmann,
"Effect of Idealized Flow Conditions on Retention Aid Performance.
2. Polymer Bridging, Charged Patches, and Charge Neutralization,"
Appita J., 57 (2004) accepted
76. Lindberg, L., "Pulsed Drainage of Paper Stock," Svensk Papperstidn.
73(15), 451 (1970)
77. Walser, R., J.D. Eames, and W.M. Clark, "Performance Analysis of
Hydrofoils with Blades of Various Widths," Pulp Paper Mag. Can.,
71(8), T183 (1970)
78. Tam Doo, PA., R.J. Kerekes, and R.H. Pelton, "Estimates of Maxi-
mum Hydrodynamic Shear Stresses on Fiber Surfaces in Papermak-
ing," J. Pulp Paper Sci., 10(4), J80 (1984)
79. Britt, K.W., J.E. Unbehend, and R. Shidharan, "Observations on Wa-
ter Removal in Papermaking," Tappi J., 69(7), 76 (1986)
80. Kiviranta, A., and H. Paulapuro, "The Role of Fourdrinier Table Ac-
tivity in the Manufacture of Various Paper and Board Grades," Tappi
J., 75(4), 172 (1992)
81. Swerin, A., and L. Odberg, "Flocculation and Hoc Strength From
the Laboratory to the FEX Paper Machine," Papier 50(10A), V45
(1996)
82. Raisanen, K., S. Karrila, and A. Maijala, "Vacuum Dewatering Opti-
mization with Different Furnishes," Paperi Puu, 78(8), 461 (1996)
83. Baldwin, L., "High Vacuum Dewatering," Paper Technol., 38(4), 23
(1997)
84. Raisanen, K.O., H. Paulapuro, and S.J. Karrila, "The Effects of Reten-
tion Aids, Drainage Conditions, and Pretreatment of Slurry on High-
Vacuum Dewatering: A Laboratory Study," Tappi J., 78(4), 140 (1995)
85. Zeilinger, H., and M. Klein, "Modern Measuring Methods for the Cross-
Sectional Filler Distribution," Wochenbl. Papierfabr., 123(20), 903
(1995)
86. Schiller, A.M., and T. Suen, "Ionic Derivatives of Polyacrylamide,"
Ind. Eng. Chem., 48(12), 2132 (1956)
87. Norell, M., K. Johansson, and M. Persson, "Retention and Drainage,"
in Neimo, L., E., Papermaking C ... Ch. 3, 42, Fapet Oy, Helsinki,
Finland (1999)
88. La Mer, V.K., and T. Healy, "Adsorption-Flocculation Reactions of
Macromolecules at the Solid-Liquid Interface," Rev. Pure Applied
Chem., 13(Sept.), 112 (1963)
89. Swerin, A., and L. Odberg, "Some Aspects of Retention Aids," in Baker,
C.E, Ed., The Fundamentals of Papermaking Materials, Pira Interna-
tional, Leatherhead, UK, Vol. 1, 265 (1997)
90. Petaja, T., "Fundamental Mechanisms of Retention with Retention
Agents. Part 1. Electrolyte and Single Polymer Systems," Kemia-Kemi,
7(3), 110 (1980)
91. Petzold, G., H.-M. Buchhammer, and K. Lunkwitz, "The Use of Op-
positely Charged Polyelectrolytes as Flocculants and Retention Aids,"
Colloids Surf. A., 119(1), 87 (1996)
92. Lindstrom, T., and G. Glad-Nordmark, "Network Flocculation and
Fractionation of Latex Particles by Means of Polyethyleneoxide-
Phenolformaldehyde Resin Complex," J. Colloid Interface Sci., 97(1),
62 (1984)
93. Xiao, H., R. Pelton, andA. Hamielec, "Retention Mechanisms for Two-
Component Systems Based on Phenolic Resins and PEO or New PEO-
Copolymer Retention Aids," J. Pulp Paper Sci., 22(12), J475 (1996)
94. Van de Ven, T.G.M., and B. Alince, "Association-Induced Polymer
Bridging: New Insights into the Retention of Fillers with PEO," J.
Pulp Paper Sci., 22(7), J257 (1996)
95. Kratochvil, D., B. Alince, and T.G.M. Van de Ven, "Flocculation of


Chemical Engineering Education












Clay Particles with Poorly and Well-Dissolved Polyethylene Oxide,"
J. Pulp Paper Sci., 25(9), 331 (1999)
96. Lindstr6m, T., C. S6remark, C. Heinegard, and S. Martin-Lof, "The
Importance of Electrokinetic Properties of Wood Fiber for Papermak-
ing," Tappi, 57(12), 94 (1974)
97. Wagberg, L, and L. Odberg, "The Action of Cationic Polyelectrolytes
Used for the Fixation of Dissolved and Colloidal Substances," Nordic
Pulp Paper Res. J., 6(3), 127 (1991)
98. Nurmi, M., J. Byskata, and D. Eklund, "On the Interaction between
Cationic Polyacrylamide and Dissolved and Colloidal Substances in
Thermomechanical Pulp," Paperi Puu, 86(2), 109 (2004)
99. Moore, E.E., "Charge Relationships of Dual Polymer Retention Aids,"
Tappi 59 (6), 120-122 (1976)
100. Petaja, T., "Fundamental Mechanisms of Retention with Retention
Agents. Part 2. Dual Polymer Systems," Kemia-Kemi, 7(5), 261 (1980)
101. Wagberg, L., and T. Lindstrom, "Some Fundamental Aspects of Dual-
Component Retention Aid Systems," Nordic Pulp Paper Res. J., 2(2),
49 (1987)
102. Petzold, G., "Dual-Addition Schemes," in Faranato, R.S., and PL.
Dubin, Colloid-Polymer Interactions: From Fundamentals to Prac-
tice, Ch. 3, 83, Wiley Interscience, New York, NY (1999)
103. Swerin, A., G. Glad-Nordmark, and L. Odberg, "Adsorption and Floc-
culation in Suspensions by Two Cationic Polymers Simultaneous
and Sequential Addition," J. Pulp Paper Sci., 23(8), J389 (1997)
104. Capozzi, A.M., and D.S. Rend, "Particle Management: Effective Stickies
Control Approach," Proc TAPPI 994 Pulping Conference, 643, TAPPI
Press, Atlanta, GA (1994)
105. Gill, R.A., "The Behavior of On-Site Synthesized Precipitated Cal-
cium Carbonates and Other Calcium Carbonate Fillers on Paper Prop-
erties," Nordic Pulp Paper Res. J., 2(4), 120 (1989)
106. Fairchild, G.H., "Increasing the Filler Content of PCC-Filled Alkaline
Papers," Tappi J., 75(8), 85 (1992)
107. Sanders, N.D., and J.H. Schaefer, "Comparing Papermaking Wet-End
Charge-Measuring Techniques in Kraft and Groundwood Systems,"
Tappi J., 78(11), 142 (1995)
108. Suty, S., B. Alince, and T.G.M. van de Ven, "Stability of Ground and
Precipitated CaCO3 Suspensions in the Presence of Polyethylenimine
and Salt," J. Pulp Paper Sci., 22(9), J321 (1996)
109. Sikora, M.D., and R.A. Stratton, "The Shear Stability of Flocculated
Colloids," Tappi, 64(11), 97 (1981)
110. Tanaka, H., A. Swerin, and L. Odberg, "Transfer of Cationic Reten-
tion Aid from Fibers to Fine Particles and Cleavage of Polymer Chains
under Wet-End Papermaking Conditions," Tappi J., 76(5), 157 (1993)
111. Hubbe, M.A., "Reversibility of Polymer-Induced Fiber Flocculation
by Shear. 1. Experimental Methods," Nordic Pulp Paper Res. J., 15(5),
545 (2000)
112. Tripattharanan, T., M.A. Hubbe, R.A. Venditti, and J.A. Heitmann,
"Effect of Idealized Fow Conditions on Retention Aid Performance.
1. Cationic Acrylamide Copolymer," Appita J., 57 (2004) accepted
113. Bliss, T., "Screening in the Stock Preparation System," in TAPPIStock
Preparation Short Course Notes, TAPPI Press, Atlanta, GA (1996)
114. Hubbe, M.A., and F Wang, "Where to Add Retention Aid: Issues of
Time and Shear," Tappi J., 1(1), 28 (2002)
115. Langley, J.G., and E. Litchfield, "Dewatering Aids for Paper Applica-
tions," In Proc. TAPPIPapermakers Conf, Tappi Press, Atlanta, (1986)
116. Andersson, K., and E. Lindgren, "Important Properties of Colloidal
Silica in Microparticulate Systems," Nordic Pulp Paper Res. J., 11(1),
15 (1996)
117. Hubbe, M.A., "Microparticle Programs for Drainage and Retention,"
In Microparticles and Nanoparticles in Papermaking, TAPPI Press,
Atlanta, GA (2004)
118. Main, S., and P Simonson, "Retention Aids for High-Speed Paper
Machines," Tappi J., 82(4), 78 (1999)
119. McKenzie, A.W., "Structure and Properties of Paper. XVIII. The Re-
tention of Wet-End Additives," Appita, 21(4), 104 (1968)
120. Hubbe, M.A., "Detachment of Colloidal Hydrous Oxide Spheres from
Flat Solids Exposed to Flow. 2. Mechanism of Release," Colloids Surf.,


16(3-4), 249 (1985)
121. Hubbe, M.A., "Reversibility of Polymer-Induced Fiber Flocculation
by Shear. 1. Experimental Methods," Nordic Pulp PaperRes. J., 15(5),
545 (2000)
122. Kiviranta, A., and H. Paulapuro, "Hydraulic and Rectifier Roll
Headboxes in Boardmaking," Paper Technol., 31(11), 34 (1990)
123. Bonfanti, J-D., J.-C. Roux, and M. Rueff, "Hydraulic Headbox S -
Technology and Industrial Results," Wochenbl. Papierfabr., 128(20),
1372 (2000)
124. Hubbe, M.A., "Detachment of Colloidal Hydrous Oxide Spheres from
Fat Solids Exposed to Flow. 4. Effects of Polyelectrolytes," Colloids
Surf., 25(2-4), 325 (1987)
125. Rojas, O.J., and M.A. Hubbe, "The Dispersion Science of Papermak-
ing," J. Dispersion Sci. Technol., 25(6), 713 (2004)
126. Hodgson, K.T., "AReview of Paper Sizing Using Alkyl Ketene Dimer
versus Alkenyl Succinic Anhydride," Appita J., 47(5), 402 (1994)
127. Neimo, L., "Internal Sizing of Paper," in Neimo, L., Ed., Papermak-
ing ( .. .... .. Ch. 7, 151, Fapet Oy, Helsinki, Finland (1999)
128. Wasser, R.B., "The Reactivity of Alkenyl Succinic Anhydride: Its Per-
tinence with Respect to Alkaline Sizing," J. Pulp Paper Sci., 13(1),
J29 (1987)
129 L. Odberg, T. Lindstrom, B. Liedberg, and J. Gustavsson, J., "Evi-
dence for (3-Ketoester Formation during the Sizing of Paper with
Alkylketene Dimers," Tappi J., 70(4), 135 (1987)
130. Marton, J., "Mechanistic Differences between Acid and Soap Sizing,"
Nordic Pulp Paper Res. J., 4(2), 77 (1989)
131. Bottorff, K.J., "AKD Sizing Mechanism: AMore Definitive Descrip-
tion," Tappi J., 77(4), 105 (1994)
132. Isogai, A., "Mechanism of Paper Sizing by Alkylketene Dimers," J.
Pulp Paper Sci., 25(7), 251 (1999)
133. Strazdins, E., "Interaction of Rosin with some Metal Ions," Tappi J.,
46(7), 432 (1963)
134. Ehrhardt, S.M., and J.C. Gast, "Cationic Dispersed Rosin Sizes," Proc.
TAPPI 1998Papermakers Conf, 181, TAPPI Press, Atlanta,GA (1988)
135. Lee, H.N., "The Microscopical Mechanism of Rosin Sizing," Paper
Trade J., 103, T386 (1936)
136. Garnier, G., J. Wright, L. Godbout, and L. Yu, "Wetting Mechanism of
Alkyl Ketene Dimers on Cellulose Films," Colloids Surf. A, 145(1-3),
153 (1998)
137. Wang, F, H. Tanaka,T, Kitaoka, and M.A. Hubbe, "Distribution Char-
acteristics of Rosin Size and Their Effect on the Internal Sizing of
Paper," Nordic Pulp Paper Res. J., 15(5), 80 (2000)
138. Seppanen, R., and F. I-I. "Mechanism of Internal Sizing by Alkyl
Ketene Dimers (AKD): The Role of the Spreading Monolayer Precur-
sor and Autophobicity," Nordic Pulp Paper Res. J., 15(5), 452 (2000)
139. Shen, W., and I.H. Parker, "AStudy of the Non-Solid behavior of AKD
Wax," Appita J., 56(6), 442 (2003)
140. Swanson, J.W., and W. Cordingly, "Surface Chemical Studies on Pitch.
2. The Mechanism of the Loss of Absorbency of Self-Sizing in Papers
Made from Wood Pulps," Tappi J., 42(10), 812 (1959)
141. Davison, R.W., "The Chemical Nature of Rosin Sizing," Tappi J.,
47(10), 609 (1964)
142. Garnier, G., and L. Yu, "Wetting Mechanism of a Starch-Stabilized
Alkyl Ketene Dimer Emulsion: AStudy by Atomic Force Microscopy,"
J. Pulp Paper Sci., 25(7), 235 (1999)
143. Back, E.L., and S. Danielsson, "Hot Extended Press Nips as Gas-Phase
Reactors: Hydrophobization with ASA," Tappi J., 74(9), 167 (1991)
144. Yu, L., and G. Garnier, "Mechanisms of Internal Sizing with Alkyl
Ketene Dimers: The Role of Vapor Deposition," in Fundamentals of
Papermaking Materials, Vol. 2, 1021 (1997)
145. Batten Jr., G.L., "A Papermaker's Guide to Synthetic Surface Sizing
Agents," in Proc. TAPPI 1992 Papermakers Conf, 12, TAPPI Press,
Atlanta, GA (1992)
146. Garnier, G., M. Duskova-Smrckova, R. Vyhnalkova, T.G.M. van de
Ven, and J.F Revol, "Association in Solution and Adsorption at an
Air-Water Interface of Alternating Copolymers of Maleic Anhydride
and Styrene," Langmuir 16(8), 3757 (2000) 1


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classroom


THE POTATO CANNON

Determination of Combustion Principles

for Engineering Freshmen


HAZEL M. PIERSON, DOUGLAS M. PRICE
Youngstown State University Youngstown, OH 44555


First-semester engineering students bring with them a
spectrum of understanding of the engineering profes-
sion. They know that engineers design things, and they
have been told you need to be good at math and science to be
an engineer. While some are very committed to obtaining an
engineering degree, others are not too sure if engineering is
for them.
Engineering freshmen have taken courses in math and sci-
ence in high school and generally obtained good grades, but
they find their understanding of these subjects is limited as
they try to apply their knowledge to real problems. The same
is true of computing. They can manipulate the computer well,
but when they are asked to apply computing solutions to real
problems, they find their ability is limited.
In addition, many of these students are not prepared to in-
teract in teams and to get along socially with other students.
They come from many different high schools from all over
the country, and they may be the only student coming to our
college from their high school. In many instances they do not
know anyone on their first day at class.
Engineering curriculums have basically ignored these prob-
lems in the past. Freshmen engineering students found they
had a difficult schedule of math and science courses along
with all the social adjustments required in the transition be-
tween high school and college. Without a strong commitment
to obtaining an engineering degree, many capable engineer-
ing students would change majors or leave school prior to
the sophomore year. Also, often those sophomores who did
survive the engineering freshman year did not have the nec-
essary background and commitment for the rigorous sopho-
more-level engineering courses. At Youngstown State Uni-
versity, as is the case at many engineering schools, a fresh-
man engineering program was developed and instituted with
the goal of improving retention of freshman engineering stu-
dents, better preparing them for the remainder of the engi-
neering curriculum, and giving them a taste of engineering in
their freshman year.


GENERAL COURSE INFORMATION
A potato cannon project is part of the first-semester fresh-
man engineering course at Youngstown State University. The
design-based three-semester-hour course comprises two lec-
ture hours and three laboratory hours per week. The lecture
portion of the "Introduction to Engineering" course is con-
ducted in a design/analysis-based lecture format in which the
currently assigned project is used as a springboard for the
lecture topics. There are typically three or four out-of-class
design/analysis projects that span the semester. A brief intro-
duction is given on the entire design process, broken into six
steps:
1) Problem Identification
2) Preliminary Ideas
3) Refinement
4) Analysis
5) Decision
6) Implementation
This is done with the intention of making the students aware
there is a methodical approach to design and problem solv-
ing that does not rule out creativity. This format allows for
all aspects of any project they will encounter as an engineer
to be addressed, from the first brainstorming session, to a
prototype machine, to the final technical design report.

Hazel M. Pierson is currently Instructor of Mechanical Engineering and
Freshman Engineering at Youngstown State University Concurrently she
is finishing dissertation requirements for her PhD at the University ofAk-
ron. She received her BS in mechanical engineering at the University of
Texas at Austin in 1985 and her MA in mechanical engineering at Young-
stown State University in 1998. Her research interests are in the areas of
vibrations, rotor dynamics, and advanced stress analysis.
Douglas M. Price is Assistant Professor of Chemical Engineering and
Chemical Engineering Program Coordinatorat Youngstown State Univer-
sity He received his BS from Pennsylvania State University in 1984 and
his MA and PhD from the University of Notre Dame in 1986 and 1988, all
in chemical engineering. His research interests are in the areas of hetero-
geneous reaction optimization, biofuels, and biomaterials.
Copyright ChE Division ofASEE 2005
Chemical Engineering Education










While discussing the design process, the majority of time
is spent explaining the importance and application of the
analysis step. The goal is to show how engineers use math-
ematical formulas to predict and evaluate design performance.
Through the process, the students discover firsthand how the
application of math and science principals fits into engineer-
ing design and analysis as well as how to systematically com-
plete design and analysis at a level befitting an engineer.
The projects are a group venture with teams consisting of
four members each. The students are allowed to form their
own teams, and the vast majority of teams consist at least
partially of members who have had no prior interaction with
each other. To facilitate team formation and project execu-
tion, class time is taken to discuss team dynamics using the
Tuckman Model.1'

PROJECT INFORMATION
* Overview
Projects for the semester are chosen in such a way as to
present components from as many engineering disciplines as
possible. Historically, chemical engineering has been poorly
represented in the projects. In the fall of 2003, we decided to
reverse this trend-and thus, the potato cannon project was
born. Through this project, freshman engineering students
are given an opportunity to integrate the principles of com-
bustion chemistry and the physics of projectile motion.
Homemade potato cannons have been in use for many years,
but with the Internet making it easy to share design ideas,
they are once again arousing the curiosity of young inven-
tors. The potato cannon provides an ideal way to introduce
engineering principles to freshman students.
At the beginning of the project, the students are required to
conduct a Web search on potato cannon te.l cin i '- ., with an
emphasis on the scientific principles inherent in this type of
machine. This gives them a foundation for the project as well
as building upon the Web-search instruction that they have
received in their lab classes. Ultimately, the project requires
that the students determine the kinetic i i -. of a potato fired
from a cannon that is fueled by propane and air, and to
compare this ,I i.I- to theoretical predictions based on
combustion chemistry.
The project begins with a brief introduction in class using
a standard project assignment sheet. The students are informed
of the project's guidelines, of the grading parameters, and of
the project timetable. The Chemical Engineering Program
Coordinator then explains the ultimate goal of the project-
comparing the kinetic i i-.i of the potato as it leaves the
cannon with the theoretical amount of l i- i available from
combustion. The principles of combustion chemistry, as they
pertain to propane and methane, are presented and explained.
* Explanation of Combustion Chemistry
The combustion of propane in air is given by


C3H +5 02 3CO2 +4 H20 (1)
The lower and upper flammability limits of propane in air
at 25 C are 2.2 and 9.5% by volume, respectively.[2] This
gives the range of concentration of propane where an explo-
sion can occur at atmospheric pressure and 25 oC. At the tem-
peratures and pressures tested (10 to 25 oC and 1 atm), the
ideal gas law is applicable and the .Ii i released during the
combustion of propane as a function of volume percent of
propane within the range of the flammability limits can be
calculated. To do this, it is necessary to determine which com-
ponent, propane or oxygen, is the limiting reagent. Let xPropane
be the mole fraction of propane in air when it is in stoichio-
metric proportion to oxygen. The mole fraction of oxygen
present can now be calculated as

XOxygen = 0.21(1- Xropane) (2)
The ratio of the mole fraction of oxygen to that of propane
must be equal to the ratio of their respective stoichiometric
coefficients in the balanced chemical equation if they are to
be in stoichiometric proportion.

XOxygen 0_21(1 Xpropane )
5 (3)
XPropane XPropane

Solving Eq. (3), the mole fraction of propane is 0.0403 when
it is in stoichiometric proportion with oxygen. Assigning an
. i i, release value of zero below and above the lower and
upper flammability limits, respectively, the il-. of com-
bustion can be normalized on a unit volume of the fuel/air
mixture basis as shown in


Mole Fraction Propane


XPropane <0.022


0.022



0.0403

>0.095


Energy Release, Ec, kJ/liter


=0


XPropane kJ
224 liter 2220gole (4)
22.4
gmole


= 1 0.21 1- xpropane kJ
S 22.4 liter gmole

gmole
=0


* Potato Cannon Design
The potato cannon project does not include a student de-
sign component of the cannon itself, for safety and liability
reasons. For the actual in-class study and analysis, three can-
nons of varying combustion-chamber dimensions were used.
Aside from the different combustion-chamber sizes, the three
cannons were identical. All plastic components were made


Spring 2005











from Schedule 80 PVC pipe and fittings. A materials list for
the cannons is presented in Table 1 and a schematic of the 3-
inch-diameter by 12-inch-length combustion chamber can-
non is shown in Figure 1.


* Explanation of the Kinetic Energy of the Potato
The kinetic .In -i., Ek, of the potato leaving the barrel of
the cannon is given by

= mdg (5)
4 sin cosO

where m is the mass of the potato, d is the horizontal distance
the potato traveled, g is the gravitational acceleration and 0
is the angle of the barrel with respect to horizontal.
Dividing the kinetic, il i-. by the volume of the combus-
tion chamber to give a normalized I i- gives

Ek 4Ek (6)
7uD2L
where D is the diameter of the combustion chamber and L is
its length. The final equations of the derivation provide a
means to determine the kinetic i i in terms of easily mea-
surable variables: the mass of the potato, the angle of the
cannon, the horizontal distance of potato travel, and the geo-
metric size of the cannon barrel.
* Field Experiment
As was stated earlier, three cannons of varying combustion
chamber sizes were considered and analyzed in this project.
Figure 2 shows the completed cannons. For the experiment,
propane gas was quantitatively added via a calibrated syringe
to the combustion chamber which was previously filled with


TABLE 1
Material Supply List for Potato Cannons

Cannon Small Medium Large
Barrel 2" diameter by 24"
Combustion 3" diameter by 6" 3" diameter by 12" 4" diameter by 12"
Chamber 3" PVC end cap 3" PVC end cap 4" PVC end cap
3" to 2" reducer 3" to 2" reducer 4" to 3" reducer
3" to 2" bushing
General ball valves, piezo igniters, pins, PVC cement

inch
ball valve
Piezo 3-in dia to 2-in 2-in PVC pipe
igniter dia reducer 2-ft in length





3-in diaPVC PVC Pin for potato
end cap 3-india. PVCpipe positioning
1-ft in length
Figure 1. Schematic of potato cannon design.


air at ambient conditions. Potatoes of known mass were fired
from the cannon at three different elevation angles and the
linear distance traveled was recorded. To meter in a specific
amount of propane fuel, the students extracted propane from
the tank using a syringe (see Figure 3) and injected the pro-
pane into the combustion chamber.
The cannon was placed in a wooden cradle made of 3/4"
plywood. The cannons were fired at angles of 30-, 45-, and
60 from the ground. Figure 4 shows the cannon just prior to
cannon fire. Notice the distance of the student from the can-
non. This again was designed for safety purposes. The pulled
string was attached to a cantilevered thin sheet of metal.
When pulled, the metal actuated the piezoelectric igniter.


Figure 2. Three cannons used in the project.


Figure 3. Extracting fuel from a propane tank.


Chemical Engineering Education











Once the potato fired, the distance of horizontal travel
was measured using a Bushnell Yardage Pro Compact
600 Laser Range Finder.
* Results
The students were required to use the collected data taken
over a period of four days to calculate the kinetic i l i-
of the potatoes utilizing the mass, the distance, and the
angle. This kinetic I i- .- was normalized to the volume
of the combustion chamber and then compared to the vol-
ume percentage of propane in the combustion chamber


figure 4. ring the cannon.


5 0.07

0.06
S4
S0.05
uj3
0.04
E*
0.03
2 2
S0.02
S1
*1 0.01

0 ---- 0
0 2 4 6 8 10 12
Volume Percent Fuel

Figure 5. Energy generated during the combustion
of propane.

TABLE 2
Recruitment of Students into ChE Program

Enrolled in Percent of Retained
Academic ENGR 1550 Engineering Engineering Students
Year Enrollment Following Year Entering ChE Program
2001-2002 152 110 6.4%
2002-2003 139 88 9.1%
2003-2004 140 101 12.9%


prior to firing. Figure 5 shows the results of the firings of the
three potato cannons along with the theoretical i --'. release
based on the combustion i i-,..
During explosive combustion, approximately 1% to 10% of
the available chemical ici- is actually transferred into me-
chanical energy.E[3 Figure 5 shows the experimentally determined
combustible range for propane is approximately 2.5% to 9.8%.
This is in good agreement with the literature values. Figure 5
also shows that the kinetic ,I i-.-, based on the experimentally
measured firing distance is approximately 0.5% to 1.5% of the
calculated chemical. i -.l potential. This also is in good agree-
ment with literature values.

CONCLUSIONS
Table 2 shows the data on retention of engineering students
from the freshmen to the sophomore year and the percentage of
retained students entering the chemical engineering program.
Although further data collection is necessary to draw statisti-
cally significant conclusions, the percentage of engineering stu-
dents selecting chemical engineering as their major showed a
marked increase after the potato cannon project was initiated.
The potato cannon project was a positive growth experience
for the freshmen engineering students. It provided the students
an opportunity to use physical world knowledge that they al-
ready possessed, such as projectile motion. On the other hand, it
challenged the student by requiring them to now scientifically
identify and properly model these physical world occurrences.
They used math, science, and computing skills to solve a prob-
lem much like many "real" engineering problems. It also gave a
practical application to the computer skills they were simulta-
neously learning in their lab classes. In addition to this, the stu-
dents learn the pros and cons of teamwork, they develop lasting
friendships, and they have a lot of fun while testing and analyz-
ing the cannons. Students worked in the engineering laborato-
ries and worked to collect data accurately.
The students evaluated the course in a written class survey at
the end of the semester. They were asked their opinion concern-
ing how well each activity added to their understanding of the
field of engineering. Of the four design projects conducted
throughout the semester, the potato cannon project received the
most all-around favorable remarks. One of the most common
remarks was the students' amazement that the mathematical mod-
eling of the combustion actually correlated to the experiment.
Finally, they were required to write an engineering report docu-
menting their work and formulating conclusions from their re-
sults. This gave the students a good introduction into what engi-
neering is all about and what types of work engineers do.

REFERENCES
1. Tuckman, B.W., Psychological Bulletin, 63, p. 384 (1965)
2. Lewis, B., and G. von Elbe, Combustion, Flames and Explosions of Gases,
Academic Press (1987)
3. Crowl, D.A., and J.E Louvar, Chemical Process Safety: Fundamentals
with Applications, 2nd ed, Prentice Hall (2002) 1


Spring 2005











classroom
--- --- s________________________________


COMMUNITY-BASED PRESENTATIONS

IN THE UNIT OPS LABORATORY




BRIAN S. MITCHELL, VICTOR J. LAW
Tulane University New Orleans, LA 70118


The chemical engineering unit operations laboratory
has long been the primary venue for hands-on expo-
sure by undergraduate students to bench-top and pi-
lot-plant scale equipment. It has also provided an opportu-
nity to address otherwise-neglected accreditation-related top-
ics such as group activities, data analysis, statistical design
of experiments, and technical writing. As the call continues
for increased emphasis on the development of effective com-
munication skills in the undergraduate curriculum,E1-2] the use
of oral presentations in an integrated laboratory sequenceP31
and in laboratory and design courses[41 has been advocated,
in addition to the development of separate courses specifi-
cally tailored toward communication skills."1 The question
of where the technical content for these presentations should
come from, however, is an open one.
Often, technical presentations by undergraduate engineer-
ing students are based on their research projects or topics
selected (often by the instructor!) specifically for a course.
This provides an invaluable opportunity to develop and en-
hance presentation skills, but may limit exposure to a new
topic or the opportunity to apply one's new-found engineer-
ing knowledge to everyday situations. Unit operations pre-
sentations at Tulane University are designed to encourage
students to venture out into the community, to identify and
visit local industries, businesses, and public works that use
engineering tools, and to report their findings to their peers
and instructors. As will be described in this paper, these
sources for presentation material are ubiquitous and indepen-
dent of the community's proximity to traditional chemical
processing industry facilities. Identification of appropri-
ate topics, presentation format, outcome assessment, and
integration across the curriculum are described herein, but
we begin with a description of how the presentation itself
fits into the overall structure of the unit operations labo-
ratory course.


TULANE'S UNIT OPS LABORATORIES
The undergraduate chemical engineering laboratory expe-
rience at Tulane is similar to that found at many universities.
The sequence comprises two courses: the first offered in the
spring term of the junior year and the second during an inten-
sive three-week summer session immediately following the
first. Students, working in groups of 3-4, remain in these
groups for the duration of the laboratory course.
The technical presentations under consideration in this pa-
per are contained in the first course (UO Lab I), which fo-
cuses on bench-top scale apparatuses. The second course (UO
Lab II) primarily emphasizes pilot-plant scale equipment and
will not be described in further detail here. As outlined in
Table I, there are seven experiments in UO Lab I, including a
safety report and the technical presentation. After a few in-
troductory lectures on technical writing, plant safety, and the

Brian S. Mitchell is Professor of Chemical and
Biomolecular Engineering at Tulane University
He is also Associate Director of the Tulane In-
stitute for Macromolecular Engineering and
Science (TIMES). He received his BS from the
University of Illinois-Urbana in 1986 and his MS
and PhD degrees from the University of Wis- -
consin-Madison in 1987 and 1991, respectively,
all in chemical engineering. His research inter-
ests include nanostructured hybrid materials
processing and characterization.

Victor J. Law earned three degrees in chemi-
cal engineering from Tulane University (BS,
1960; MS, 1962; PhD, 1963) and has been a fac-
ulty member there for over forty years. His ar-
eas of specialization include process model-
ing, simulation, design, and control. He teaches
courses at Tulane that include UO Lab, numeri-
cal methods, process control, andprocess de-
sign. He is currently the coordinator for the
Tulane Practice School.

Copyright ChE Division ofASEE 2005


Chemical Engineering Education











theoretical background of the experiments, four half-
day (4-hour) lab sections are allotted to each experi-
ment. Note that the technical presentation receives the
same amount of laboratory time as the formal experi-
ments. It also receives the same weight in grading. The
primary logistical difference between the presentation
and the other experiments is that students may (and
often do) visit the host organization outside of the regu-
larly scheduled laboratory class hours, and may spend
the remaining laboratory hours making follow-up
visits, collecting relevant information, and prepar-
ing their presentation.

COMMUNITY-BASED PRESENTATIONS
Community-based presentations are the result of vis-
its to facilities or industries found in any university
community: water treatment, food processing, office
buildings (or sports stadiums), and health care. Since
most Tulane chemical engineering students have vis-
ited a chemical process facility through the AIChE stu-
dent chapter, or interned at one of the local companies,
they are encouraged to pursue a topic that gives them
an opportunity to see something new, such that chemi-
cal processing plants, while common in the New Or-
leans area, are some of the least-often visited facilities.
Some examples of facilities that have been reported
on, and examples of the technical content they provide,
are listed in Table 2 (specific company names have been
removed to better illustrate the universality of these
sources and their ready availability in a variety of col-
lege campus settings). It is worth noting that there are
additional goodwill benefits to be gained from univer-
sity-community interactions of this nature, particularly
if alumni are involved. The pedagogical utilities of these
presentations will be the focus here, however.
Each group of students is encouraged to be creative
in selecting a project topic, which has led to some very
interesting and informative presentations; < i.i.i.1-
ter drainage from the Louisiana Superdome and pro-


TABLE 1
Laboratory Experiments Comprising
Unit Operations Laboratory I

Laboratory No. Half-Day Periods
Safety Report 2
Batch Reactor 4
Turbulent-Flow Heat Exchanger 4
Flow and Heat Exchange in Fluidized Beds 4
Cross-Flow Heat Exchanger 4
Viscometry 4
Presentation 4


Unit operations presentations at Tulane University
are designed to encourage students to venture out
into the community, to identify and visit local
industries, businesses, and public works
that use engineering tools, and to
report their findings to their
peers and instructors.


duction of artificial sea water at the New Orleans Aquarium. There
must, of course, be a strong technical component to the topic and pre-
sentation, but the primary goals are to get the students out into the
local community and to interact with professional (not necessarily
chemical) engineers.
Topics must be cleared with the laboratory instructor, but the topic
selection criteria are few. During their visit, the students must
Speak with a technical professional
Ask technical questions
Take photographs, if allowed
Obtain process flow ,1i. .-, o',.. if allowed
Obtain detailed information on process equipment; e.g.,
capacity, material of construction, i'p. ,,, parameters,
vendor
Optionally consider the economics and/or environmental
impacts associated with the topic facility
There may be additional conditions specific to the site. For example,
a visit to virtually any facility first requires clearance and safety train-


TABLE 2
Example Presentation Topics

Location/Topic Example Unit Operation/Engineering Topics
Aquarium Fluid flow, water chemistry, filtration
Brewery Fermentation, filtration
Chemical process facility Variable
Chemical process industry vendor Variable
Chemical process research facility Variable
Country club Fluid flow, environmental impact
Dairy Heat transfer, fluid flow, packaging
Faculty research project Variable
Food processing facility Variable
Hospital Variable
Nuclear power plant Heat transfer, energy balance
Office building/Sports stadium Heat transfer, fluid flow (esp. rain handling)
Pumping station Fluid flow
Sewage plant Water treatment, filtration, biological reactions
Student health services Variable
Vineyard/Winery Fermentation, packaging
Water treatment facility Fluid flow, flocculation


Spring 2005











ing. These, too, are learning experiences. As described above,
the students may make their site visit outside of laboratory
class hours, but are otherwise expected to turn in their report
(in this case, make their oral presentation) on time, which is
one week after the completion of the final regularly sched-
uled laboratory period.
The conditions of the presentation are

The presentation should be about 20 minutes '. .,,
Each .., .,,'* member must present and describe at least
one slide or concept and there should be an equitable
,,I ;, in: of the presentation time ,ant. *-, .'' ,. ,. 'mem-
bers
The presentation must have technical content. This
could be theory behind a process, equipment specifica-
tions, materials-selection issues, environmental issues,
or economic consideration, as appropriate


The students must answer questions about their
presentation
There is no explicit or implicit requirement that the pre-
sentation be electronic in format, although such is often the
case (the vast majority of presentations are prepared using
Powerpoint or similar software). Regardless of the presenta-
tion medium, the students are evaluated on effective use of
visual aids, as described below. There are no requirements
for dress, other than students are encouraged to present them-
selves in a professional manner.
Particular emphasis is given to eliminating '"'i iili"ch words
during the oral presentation. Overuse of words such as "you
know" and "like" in contemporary speaking can easily make
their way into presentations. Students are warned that they
must eliminate, or at least minimize, the use of these phrases.
Similarly, students are encouraged to practice their presenta-
tions to the point that reliance on note cards is unnecessary.


Chemical Engineering Education


TABLE 3
Presentation Rubric

1 2 3 4
Attribute Not Acceptable Below Expectations Meets Expectations Exceeds Expectations Score

Clarity and readability Not clear or readable Difficulty reading Clear and readable Superior clarity and readability
Use of space VA cluttered Too little or too much Appropriate amount of VA very well laid out
information information
Format No consistent format Formatting errors Appropriate format
Color (if used) Colors too hard to Poor choice and use of colors Easily distinguishable colors Use of color enhances clarity
distinguish
Wording concise Slides full of text Slides too wordy Slides appropriate

Presentation Organization

Logical order of topics Totally disjointed, no Some items presented out of Organization as per Superior organization
organization order guidelines enhances communication
Appropriate use of time Far too long or far too short Somewhat too long or too short Appropriate length
Objective Not stated Poorly stated Clearly stated
Background and Neither stated Only one stated Background and significance Clear statement
significance explained stated
Theory (if applicable) No theoretical development Weak theoretical development Good theoretical development Clear theoretical development
Results Not explained Unclear Clear Clear as not to require
questioning
Discussion No explanations provided Few explanations Explanations for most results Explanations for all results
provided provided
Conclusions No conclusions Present, but not logical Present, logical, and clearly Present, logical, and superior
explained explanation

Other

Presentation mechanics Many distractions Some distractions No distractions Superior presentation
(voice, mannerisms,
poise)
Response to Questions Nonresponsive Incomplete Clear and direct Complete











The presentations are not videotaped, but this enhancement
could easily be incorporated.
By the time students have reached their junior year, they
have given at least one, and often times several, technical
presentations in their chemical engineering courses, such that
they are familiar with the mechanics of preparing an effec-
tive presentation. The emphasis in these presentations, then,
is on delivery and content.

PRESENTATION AND
OUTCOME EVALUATION
Student presentations are evaluated using a presentation
rubric, such as one available from Professor Joe Shaeiwitz at
West Virginia University.E61 The evaluation rubric used for
these presentations (Table 3) is currently used in many chemi-
cal engineering courses at Tulane, including the Tulane Prac-
tice School."7 This standardization of evaluation criteria is
an important tool in documenting ABET evaluation processes.
The criteria in this rubric are easily adapted to the course
and project at hand. For example, the technical content can
be more heavily weighted, if desired, or the use of computer
software or programs can be evaluated as a separate category.
The idea is to create a standardized set of minimum guide-
lines that the students will know they are being judged
against throughout their undergraduate experience. This
approach is invaluable in effectively integrating presen-
tations across the curriculum.
The effectiveness of these community-based presentations
in meeting ABET educational objectives and program out-
comes is assessed, in part, at the end of the semester with
electronic course evaluations. Course evaluations in Tulane's
School of Engineering are conducted online through Black-
board course software.
In addition to rating the instructor, laboratory teaching as-
sistants, and course content, the students are asked to evalu-
ate how certain outcomes/objectives were met. For the Unit
Operations Laboratory, ABET Outcomes a, b, e, f, and g are
listed, of which Outcome g:
This course met the stated objective that students will have
the ability to communicate cttr', rl/v.l
is the most germane to the community-based presentations.
Of course, this also includes written communication, which


TABLE 4
Student Course Evaluation Results Relevant to Commu-
nity-Based Presentations

Average Response (1=Strongly Agree; 5=Strongly Disagree)
Course Term ABET Outcome g Educational Objective #4
Spring, 2003 1.4 1.9
Spring, 2004 2.0 1.9


is heavily emphasized in the Unit Operation Lab. More ap-
propriate to evaluation of the effectiveness of presentations
is a specific educational objective for the Unit Operations
Laboratory (here arbitrarily labeled Objective #4):
This course met the stated objective that students have
learned to give oral presentations of technical material.
In the most recent version of course evaluations, student
responses and "point values" (for internal quantification pur-
poses only) to these questions are made from the following
options: 1 = Strongly Agree; 2 = Agree; 3 = Neutral; 4 =
Disagree; or 5 = Strongly Agree. So, for example, an average
response of 1.5 on this scale of 1 to 5 would indicate that the
"average" student agrees/strongly agrees that this objective/
outcome is being met. The most recent evaluations (2003 and
2004) are provided in Table 4. (Data are available for pre-
vious years that further support these conclusions, but a
different scoring system was used, which only serves to
confuse the issue).
Results indicate that students generally feel that both of
these outcomes/objectives are being met. There are currently
no data on how other constituencies (employers, parents, etc.)
rate the effectiveness of community-based presentations on
meeting these same objectives.

CONCLUSION
A method for incorporating community-based presentations
into the chemical engineering unit operation laboratory se-
quence has been described in this paper. These presentations
are based on visits to engineering-related facilities found in
most university communities. Presentations are treated
equivalently with experiments on a grading basis and are
evaluated using a standardized presentation rubric that is used
across the curriculum for all technical presentations. In addi-
tion to the development and refinement of communication
skills that the presentations provide, as confirmed by out-
come assessment, there is the potential for additional ben-
efits, including enhanced department visibility in the com-
munity, improved (non-giving related) contact with alumni,
and initiation of outreach activities.

REFERENCES
1. Felder, R.M., and R. Brent, "Designing and Teaching Courses to Sat-
isfy the ABET Engineering Criteria," J. Eng. Ed., 92[1],7 (2003)
2. Prausnitz, J.M., "Chemical Engineering and the Other Humanities,"
Chem. Eng. Ed., 32[1], 14 (1998)
3. Newell, J.A., S.P.K. Sternberg, and D.K. Ludlow, "Development of
Oral and Written Communication Skills Across An Integrated Labora-
tory Sequence," Chem. Eng. Ed., 31[2], 116 (1997)
4. Pettit, K.R., and R.C. Alkire, "Integrating Communication Training
into Laboratory and Design Courses," Chem. Eng. Ed., 28[3], 188
(1993)
5. Bendrich, G., "Just A Communications Course?," Chem. Eng. Ed.,
32[1], 84 (1998)
6.
7. Walz, J.Y., "The Chemical Engineering Practice School Program at
Tulane University," Chem. Eng. Ed., 29[3], 246 (1995) 1


Spring 2005











classroom


MAKING ROOM FOR GROUP WORK

Teaching Engineering

in a Modern Classroom Setting



ROBERT J. WILKENS, AMY R. CIRIC
University of Dayton Dayton, OH 45469-0246


he traditional lecture format of engineering courses
has many drawbacks. A 50- to 90-minute lecture pe-
riod exceeds the typical 20-minute attention span of a
college student.'1 Hartley and CameronE21 present data show-
ing a decline in note taking after the first ten minutes of lec-
ture. When questioned about their lack of notes, the students
said that they would fill in the gaps on personal time. For the
case presented, not only did they not follow up on their in-
tention to complete the notes, but 19 out of 22 also did not
even read through their notes.
While resources are available for improving note-taking
skills,E31 the passive structure of lecture does not encourage
teamwork or lifelong learning skills, and some students leave
lecture-oriented courses confident that they can solve the in-
class examples and little else. A number of group-learning
approaches have been suggested to augment lecture courses.
These include small- and large-group student-led discussions
and in-class assignments. A nice review of what to expect is
given by Felder and Brent.[4] These strategies can improve a
student's ability to handle ambiguity and complexity, to rec-
ognize assumptions, to improve their communication skills,
and to help them feel connected to a topic.51 Additionally,
shifting material from a lecture to a student-led discussion
format increases student confidence that they can learn on
their own, a prerequisite for lifelong learning.

Discussion-format classes have to be carefully structured
if they are to cover the same amount of material as a lecture-
format course. This paper will describe the use of creative
group-learning structures in an experimental methods course.
Specifically, these structures were employed during the sum-
mer of 2000 offering of the course Experimental Methods in
Chemical Fi,,.-i.. ,i I,- According to the University of Day-
ton Bulletin, the objective of this course serves as an "Intro-


duction to experimental methods, instrumentation, digital data
acquisition, data analysis, and report writing. Use of digital
computer is emphasized." The course is taught to second-
semester sophomores who are majoring in chemical engi-
neering. It is their second course in the major. While having a
stated objective of introducing the students to the engineer-
ing way of experimentation and to engineering instrumenta-
tion, it also serves the objective of maintaining student in-
volvement in the department until they have completed
the necessary mathematical background for the more ad-
vanced topics.
Historically, this course, when taught in a standard class-
room using a conventional lecture format, has received poor
student reviews. The course theme-how to conduct experi-
ments as a chemical engineer-leads to many varied topics,
from uncertainty analysis and probability to instrumentation
principles of operation to computer programming for data

Bob Wilkens is Assistant Professor of Chemi-
cal Engineering at the University of Dayton. He
received his BChE and MS from the University
of Dayton and his PhD from Ohio University,
all in chemical engineering. He worked as a
postdoctoral research engineer at Shell
Westhollow Technology Center in Houston,
Texas. His primary research areas include
multiphase fluid flow and agitation.


Amy Ciric is Associate Professor of Chemical
SEngineering at the University of Dayton. She
received BS degrees in chemical engineering
and in physics from Carnegie Mellon Univer-
sity and her PhD in chemical engineering from
Princeton University. Her research interests are
in process engineering, with a particular em-
phasis on synthesis, simulation, and optimiza-
tion.


Copyright ChE Division ofASEE 2005


Chemical Engineering Education











acquisition. Students had difficulty seeing the common theme
and tended to experience the course as a hodgepodge of in-
formation with no common thread.

BlighE61 reviewed and summarized hundreds of studies re-
garding the effectiveness of a straight lecture to alternative
methods. He found that the lecture is statistically equivalent
to other methods when the purpose is to transmit informa-
tion, but if the purpose is to promote thought (necessary for
problem-solving skills) or inspire interest (much needed for
this course), then discussion is significantly more effective
than a lecture. If the goal is to teach a skill (the computer
programming portion of the course), then practice of the skill
is superior to a lecture.

A special offering of the course was taught in an ideal class-
room for group work-the Studio in the Ryan C. Harris Learn-
ing Teaching Center at the University of Dayton. As part of
an innovative approach to encourage faculty members to ex-
plore new pedagogical styles, the University of Dayton es-
tablished the Ryan C. Harris Learning Teaching Center. In
the Learning Teaching Center, a classroom called the "Stu-
dio" was erected that incorporates classroom flexibility and
the latest tckllinl ,h '.. University faculty members use this
top-notch teaching facility for pedagogical exploration and
to test new tk el.i 'li n'.\ on a small scale before implementing
it in larger settings. The Studio, custom designed to foster
classroom discussion and groupwork, was the best place to
develop an improved pedagogical style for this course.

THE CLASSROOM

The classroom is designed to handle up to 24 students. The
room and the desks evoke memories of a kindergarten class-
room-only with bigger seats. The floor is carpeted, and in-
stead of desks, the students sit at specially designed tables
that can be moved around as necessary. An open closet runs
along one wall where coats and excess baggage can be placed.
Portable whiteboards and corkboards can be placed along any
wall or can be hung in the middle of the room by what can
best be described as a tic-tac-toe railing system overhead. In
one corer closet there is a combination TV/VCR along with
a standard overhead projection unit, and in the other corer
closet there is a notebook computer with wireless connection
to the Internet and a computer data projection unit. This sys-
tem is coupled with a SMART Board, which is much like a
giant touch screen for the computer. Notebook computers
are available for the classroom upon request. These also
have wireless connections to the Internet along with stan-
dard network ports.
Other unique aspects of this classroom involve its physical
setting-appointments both inside and outside of the Studio
are exquisite. Just outside of the room is a coffee bar. In addi-
tion, one of the most promising aspects is that the Learning
Teaching Center is in the basement of the library.

Spring 2005


Discussion-format classes have
to be carefully structured if they are
to cover the same amount of material as
a lecture-format course. This paper will
describe the use of creative group-
learning structures in an
experimental methods course.


TABLE 1
Summary of Comments About the LTC Studio


* Interaction room (sufficient space
to get in among the students)
* Extremely helpful LTC staff
* Availability of multimedia
* Wireless network
* Portability of whiteboards (they
could be physically moved)
* SMART Board use excites
students
* Students began showing up
progressively earlier


* Tables don't move as easily as
designed
* Whiteboards hanging on a track allows
them to swing when writing (requires
additional hand)
* Whiteboards should be able to cross
tracks (they cannot cross intersecting
support tracks)
* Whiteboards should be able to rotate
* Needed to arrive early to setup seating
* SMART Board screen must be cali-
brated to use as a touch screen-a
slight bump during the lecture gets it
out of calibration


Studio Evaluation
Notes about the Studio and its tnlili',n -l*,. were collected
from the instructor, the students, and communications with
other instructors who were using the classroom. These notes
have been summarized in Table 1. Although certain aspects
of the Studio could be improved upon, most were considered
to be a step in the right direction.

GROUP-DISCUSSION STRUCTURES
Brookfield and Preskill,E51 McKeachie,E[7 and Aronson and
Patnoe,E81 among others, have discussed ways to promote
classroom discussion. Five are particularly useful for engi-
neering education
S,,, ll..,- .'' discussion followed by ,,, ... '..,.l,'
discussion, then a lecture
Lecture with individual in-class practice (with
instructor's help)
Snowballfollowed by lecture
1/. i..i, jigsaw with no lecture
Straight lecture but open to questions
As previously mentioned, this was an off term (summer)

165











with 14 students. Thus, observations may be tainted by the
small class size or by the fact that all of the students had just
returned from their first cooperative education experience.
All techniques were either immediately followed or imme-
diately preceded by an appropriate homework assignment.
Also, each technique was followed by a large-group discus-
sion (entire class) to evaluate the style's effectiveness.
Small Groups
For the small-group discussion technique, the students were
first asked to read selected sections from the text about a new
topic prior to the next meeting. At the next meeting, the stu-
dents were asked to reflect on aspects of the reading that they
understood well and aspects that they found to be confusing.
The students were then divided into groups of three or four
and asked to create a group list. Finally, all of the lists were
summarized on a board in the front of the room and a large-
group discussion ensued.
What the students found was that, in general, they were all
confused about the same things. This was followed by a lec-
ture where additional focus and example problems were ap-
plied to the difficult material. All material was still covered
for completeness. Knowledge of their limitations helped the
students to focus on these parts of the notes.
As an added benefit, topics that were not well understood
by the minority were often cleared through the initial discus-
sion. As with all techniques, when finished the approach was
discussed in a large group to judge the effectiveness.

In-class Practice
While presenting aspects of computer programming, it was
decided that it was best to program live along with lecture.
The Studio provided a notebook PC to each student and one
for the instructor, which projected onto a SMART Board. The
programming had some lecture, a handout, and plenty of in-
class practice where the instructor and the teaching assistant
went from student to student to help them over the simpler
hurdles that so often stop programming in its tracks. This
structure was employed over a period of several weeks.


Snowball
Snowballing is much like
the small-group discussion
as applied to this course.
After reading, students pro-
gressively get into larger
groups until eventually the
entire class is involved in
the discussion. Lecture still
follows the discussion, with
focus on the areas of con-
cern. What distinguished
Snowball from Small
Group was the addition of


more group layers, much like a growing snowball.
!igsaw
A jigsaw is an approach where groups are formed to dis-
cuss one topic. Then they form new groups with one topic
expert in each (works best with a squared number of students
22 = 4, 32 = 9, 16, 25, 36, etc.). For this implementation, all
students were first asked to read the entire chapter (tempera-
ture instrumentation). Next, four groups were created and each
assigned to establish an area of topical expertise: thermal ex-
pansion techniques, thermocouple techniques, electrical re-
sistance techniques, or radiation techniques. They met for one
period in-class and then had until the next class period to
create a set of notes. They were also provided with refer-
ences to additional resources. At the following class, four
new groups were formed that included a topical expert from
each area. The students then gave lectures and examples to
each other using the portable whiteboards. This only took
one class period (1.5 hours) to present the information.

TABLE 2
Summary of End-of-Term Anonymous Student
Evaluations of Modified Course
(Select Questions)

Question Agree Neutral Disagree N/A
You like the required text 0 3 11 0

The book was a useful reference 3 9 2 0

The instructor is boring 3 8 3 0
You would recommend instructor to a friend 11 2 1 0

The course objective was clear 13 1 0 0

The course met the stated objective 13 1 0 0

As experienced co-ops, you feel that you've
learned tools that will be useful to your future 13 1 0 0

The instructor is clear about the subject area 9 1 0 0
The instructor understands the material 14 0 0 0

The instructor is well prepared for class 14 0 0 0


TABLE 3
Summary of End-of-Term Anonymous Student Evaluations for Previous Term (Select Questions)


Question
The textbook was an asset to the course
Instructor enthusiasm inspired interest


Strongly
Agree


1
0


You would recommend this instructor to another student 4
The instructor clearly communicated the course objectives 3
You learned a great deal from this course 3
Class discussion contributed to your understanding 1
Instructor encouraged classroom participation 2


Strongly Not
Agree Neutral Disagree Disagree Applicable


6 8 10
9 12 14
9 15 5


25
20


10 12 4 4 5
11 15 5 2 1


Chemical Engineering Education











Despite requests from the students, no lecture from the in-
structor accompanied the jigsaw notes (as a way to help as-
sess the improvement). A specialized homework assignment
was created to test how deep of an understanding was formed
in each area. The homework was assigned to each of the new
teams (i.e., not to individuals) to be turned in collectively.

Lecture and Other
Other teaching styles were used as necessary, but they were
not evaluated. The straight (traditional) lecture style was used,
primarily as a basis for comparison. All lectures included
examples, and students were encouraged to ask questions
when they needed clarification.
Another teaching format that was used but not evaluated
involved meeting in the chemical engineering laboratory and
collecting data. This was used at the end of the term to bring
all of the aspects of the course together with a case study.

STUDENT EVALUATION
Formal university evaluations are not required for courses
taught in the Studio, but the instructor created a special evalu-
ation form to help determine the success of the course. Table
2 summarizes the statements and responses. For comparison,
related questions from two previous sections are reported in
Table 3 (same instructor).
The responses to most of the questions reflected well on
the course. This is in stark contrast to evaluations received
for the previous instruction of this course. The response to
the question about the book is the same as previous; the stu-
dents did not like the text. It is also apparent that the instruc-
tor is not too exciting (before and after).
The most pertinent questions to the course modifications
are the next four. For these questions, 90% of the student
responses are at the highest level and 98% of the responses
are favorable. This marked a significant improvement to
whether or not the students would recommend the instructor
to someone else. The other areas marked a slight increase.

TABLE 4
Rank of Techniques Used in Classroom

Technique Topic Points
1. Lecture with individual in-class computers 66
practice (with instructor's help)
2. Small-group discussion followed by introduction, basic concepts 57
large-group discussion, then lecture data analysis
3. Straight lecture but open to questions electrical measurement,
flow measurement, data
acquisition 33
4. Snowball followed by lecture pressure measurement 32
5. Modified jigsaw with no lecture temperature measurement 16
6. Other 6


In the evaluation, the students were also asked to rank the
techniques used in the classroom. Five points are given for
the technique that the student liked best, four points for the
second, etc., with zero points given for the least-favorite
method. The total points received by all students are sum-
marized in Table 4.
The top-ranked technique was the one applied to computer
programming where the lecture was followed with in-class
practice such as examples or homework. The second-ranked
technique was small-group discussion followed by large-
group discussion and then lecture. The lowest-rated technique
was the modified jigsaw with no lecture.
The evaluation also contained several open-ended ques-
tions. One question asked the students to summarize topics
covered in the course about which they felt confident and
topics about which they felt confused. The topics about which
the most students indicated confusion were electrical mea-
surement, temperature measurement, and data acquisition
(straight lecture andjigsaw). The topics about which the most
students indicated confidence were computers, data analy-
sis, pressure measurement, and flow measurement (each a
different technique). Ironically, the students did best on the
jigsaw-taught topics as judged by homework and test scores.
The students were also asked to list the positive and nega-
tive aspects about the homework. Most agreed that while it
was difficult, it was quite relevant. During the course, as-
signments were alternated between being due before the topic
was covered in class and afterward. When asked which was
better, 1 preferred before, 8 preferred after, and 5 indicated
that they would like to alternate between the two scenarios.
Adjusting the timing of notes and homework can lead to an
increased student interest.
When asked what modified methods they might propose,
they responded with the following ideas:
Emphasize important topics to be covered in jigsaw
Add 1 lecture to theji:..-.,i,
Variety
Lecture followed by *i. i ;1, on problems in .i....,.
Conduct class as a i,.. it;,..

These ideas are certainly worth future exploration. Another
is to take the structure used for computer programming and
apply it to problem solving with the other material.

INSTRUCTOR COMMENTS
Throughout the semester, notes were made about the
progress of the class in journal fashion. Notes were made
prior to, during, and immediately following each class pe-
riod.
Notes prior to each class included a summary of announce-
ments along with a proposed list of topics and objectives for


Spring 2005











the day. Occasionally, the objectives were written on a side
whiteboard in the classroom for the students to consider for
the entire period. As a way to ensure equal participation among
the students, a list of students to "pick on" was also created
prior to the class. The instructor first called upon two of these
students to attempt to answer each question, for the entire
period, before asking the other students to answer. During
the course of the term, all of the students had their opportu-
nity to be "picked on." Note that the term "pick on" was
harsher than the implementation.
Notes made during each class included how the lecture notes
could be improved, who was late or missing from class, ob-
servations of the students, and summaries of student com-
ments about the course topics and formats (including a sum-
mary of large-group discussions).
Notes generated after the class period included an evalua-
tion of the period, what was covered (or not covered), and
ideas for future classes.
Table 5 summarizes the notes that are of general interest;
course-specific notes were deleted. This information es-
tablishes timelines and reinforces key concepts for the
term. It also helped to keep track of smaller observations
such as best seating arrangement (U-shape) for lecture or
large-group discussion.


CONCLUSIONS

A classroom designed for group work with notebook PC's
for each student, a SMART Board, and movable tables,
whiteboards, and corkboards made an excellent location for
exploring different cooperative-learning methods. The class-
room was used as a setting to evaluate (a) the effectiveness
of small-group discussions, in-class practices, snowballing,
and jigsaw discussions, (b) how these techniques were re-
ceived by students, and (c) the effect these techniques had on
student confidence.
Small-group discussions and in-class practices were well
received by the students. Small-group discussions were well
suited to the subject matter, and in-class practices gave the
students the most confidence about their abilities. Although
students developed the deepest understanding of the material
covered by the jigsaw method, they did not enjoy it and, para-
doxically, did not feel confident of their understanding of
the material. This matches the observations of Felder and
Brent,E41 "... cooperatively taught students tend to exhibit
higher academic achievement . [with] deeper under-
standing of learned material." If increased student confi-
dence is desired then it would benefit the instructor to fol-
low with a brief lecture.
Overall, a well-designed classroom can facilitate coopera-
tive learning methods, but preparing students for group work
remains essential. Part II of this worko101 will compare these
results to those in a traditional classroom setting.


TABLE 5
General Interest Notes (Roughly Chronological Order)

Students were slow to use whiteboards in the room
Term started quietly
Small-group discussion
Covered comparable material
Students happy to know that others were confused
Maybe assign review questions prior to reading assignment
Nice to have peers explain topics
Some students are already beginning to dominate conversation
U-shape of desk arrangement works well for large group
discussion and for lecture
It would be nice to set aside discussion time for such topics as the
impostor phenomenon91'
Students requested more practice problems
Could try an e-mail discussion to kick off the topic
Students are less likely to be shy in small-group discussion
In the future, let small groups solve example problems
Midway through the course, students speak out; still reluctant
about moving desks
During snowball approach, the four board writers were the
students who tended to dominate large-group discussion
Students enjoyed working through computer assignment in class
(independently, but with instructor help)
The jigsaw
I should have videotaped this
Approach would not work well without seat mobility
Having students discussing same topics simultaneously makes
instructor's evaluation job easier
The students did additional research, but they did not make it
apparent in presentations
Students recommend that I do this (jigsaw) "to" the next class
also
In future, try role reversal (student professor)
0 Attendance is exceptional


REFERENCES
1. Wankat P.C., and F.S. Oreovicz, Teaching Engineering, McGraw-Hill,
New York, NY(1993)
2. Hartley, J., and A. Cameron, "Some Observations on the Efficiency of
Lecturing," Educational Rev., 20, 30 (1967)
3. Hartley, J., and I.K. Davies, "Note-Taking: A Critical Review," Pro-
grammed Learning and Ed. Tech., 15, 207 (1978)
4. Felder, R.M., and R. Brent, "Cooperative Learning in Technical
Courses: Procedures, Pitfalls, and Payoffs," ERIC Document Repro-
duction Service, ED 377038 (1994)
5. Brookfield, S.D., and S. Preskill, Discussion as a Way of Teaching,
Jossey-Bass, San Francisco, CA (1999)
6. Bligh, D.A., What's the Use ofLectures?, Jossey-Bass, San Francisco,
CA (2000)
7. McKeachie, W.J., Teaching Tips, 8th ed., D.C. Heath, Lexington, MA
(1986)
8. Aronson, E., and S. Patnoe, The Jigsaw Classroom: 1..! .. Coop-
eration in the Classroom, 2nd ed., Longman, New York, NY (1997)
9. Felder, R.M., "Imposters Everywhere," ( ... i. i 22 168 (1988)
10. Ciric, A.R., and R.J. Wilkens, "Making Room for Group Work II:
Teaching Engineering in a Traditional Classroom Setting," to be sub-
mitted to Chemical Engineering Education, 2005 1


Chemical Engineering Education




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Spring 2005 81 Chemical Engineering Education Volume 39 Number 2Spring 2005 CHEMICAL ENGINEERING EDUCATION (ISSN 0009-2479) is published quarterly by the Chemical Engineering Division, American Society for Engineering Education, and is edited at the University of Florida. Correspondence regarding editorial matter, circulation, and changes of address should be sent to CEE, Chemical Engineering Department, University of Florida, Gainesville, FL 32611-6005. Copyright 2005 by the Chemical Engineering Division, American Society for Engineering Education. T he statements and opinions expressed in this periodical are those of the writers and not necessarily those of the ChE Division, ASEE, which body assumes no responsibility for them. Defective copies replaced if notified within 120 days of publication. Write for information on subscription costs and for back copy costs and availability. POSTMASTER: Send address changes to Chemical Engineering Education, Chemical Engineering Department., University of Florida, Gainesville, FL 32611-6005. Periodicals Postage Paid at Gainesville, Florida and additional post offices. EDITORIAL AND BUSINESS ADDRESS:Chemical Engineering Education Department of Chemical Engineering University of Florida Gainesville, FL 32611PHONE and FAX : 352-392-0861 e-mail: cee@che.ufl.eduEDITOR Tim Anderson ASSOCIATE EDITOR Phillip C. Wankat MANAGING EDITOR Carole Yocum PROBLEM EDITOR James O. Wilkes, U. Michigan LEARNING IN INDUSTRY EDITOR William J. Koros, Georgia Institute of Technology CHAIRMAN E. Dendy Sloan, Jr. Colorado School of Mines MEMBERS Pablo Debenedetti Princeton University Dianne Dorland Rowan University Thomas F. Edgar University of Texas at Austin Richard M. Felder North Carolina State University Bruce A. Finlayson University of Washington H. Scott Fogler University of Michigan Carol K. Hall North Carolina State University William J. Koros Georgia Institute of Technology John P. O'Connell University of Virginia David F. Ollis North Carolina State University Ronald W. Rousseau Georgia Institute of Technology Stanley I. Sandler University of Delaware Richard C. Seagrave Iowa State University C. Stewart Slater Rowan University Donald R. Woods McMaster University DEPARTMENT 82 Rowan University, C. Stewert Slater, Robert P. Hesketh, James A. Newell, Stephanie Farrell, Zenaida Otero Gephardt, Mariano J. Savelski, Kevin D. Dahm, Brian G. Lefebvre EDUCATOR 88 Alice Gast of the Massachusetts Institute of Technology, Channing R. Robertson, Kenneth A. Smith RANDOM THOUGHTS 93 Speaking of Everything-II, Richard M. Felder CLASSROOM 94 Micromixing Experiments in the Introductory Chemical Reaction Engineering Course, Kevin D. Dahm, Robert P. Hesketh, Mariano J. Savelski 100 Decision Analysis for Equipment Selection, J.J. Cilliers 116 Using Mathematica to Teach Process Units: A Distillation Case Study, Maria G. Rasteiro, Fernando P. Bernardo, Pedro M. Saraiva 134 Building Molecular Biology Laboratory Skills in ChE Students, Melanie McNeil, Ludmila Stoynova, Sabine Rech 138 A Simple Classroom Demonstration of Natural Convection, Dean R. Wheeler 156 The Potato Cannon: Determination of Combustion Principles for Engineering Freshmen, Hazel M. Pierson, Douglas M. Price 160 Community-Based Presentations in the Unit Ops Laboratory, Brian S. Mitchell, Victor J. Law 164 Making Room for Group Work: Teaching Engineering in a Modern Classroom Setting, Robert J. Wilkens, Amy R. Ciric LABORATORY 104 An Automated Distillation Column for the Unit Operations Laboratory, Douglas M. Perkins, David A. Bruce, Charles H. Gooding, Justin T. Butler CURRICULUM 110 Drawing the Connections Between Engineering Science and Engineering Practice, Faith A. Morrison 124 Incorporating Molecular and Cellular Biology into a ChE Degree Program, Kim C. O'Connor 142 Computer Science or Spreadsheet Engineering? An Excel/VBA-Based Programming and Problem Solving Course, Daniel G. Coronell 146 The Paradox of Papermaking, Martin A. Hubbe, Orlando J. Rojas CLASS AND HOME PROBLEMS 128 Cooperative Work that Gets Sophomores on Board, Charles H. Gooding 122 Call for Papers PUBLICATIONS BOARD

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82 Chemical Engineering Education In recruiting Rowan's faculty and the first class of students, the Founding Dean, James H. Tracey, said, "Build it and they will come." it was built, and they came! Doors were opened to engineering students in 1996, and the first class graduated in 2000. Today, Rowan University's undergraduate chemical engineering program is ranked third in the nation by U.S. News and World Report 's 2005 America's Best Colleges." This success can be attributed to the dedication and talent of the faculty, the high quality of its students, and its state-of-the-art facilities. The faculty have pioneered an innovative curriculum for students at Rowan that spans the engineering disciplines and is characterized by a "handson, minds-on" approach to engineering education.THE ROWAN GIFTRowan University's origins are as a teacher's college, and today it is still a leader in producing education majors for the state of New Jersey. Since its founding in 1923 as Glassboro Normal School, Rowan has had two major events of international significance. The first was in June of 1967 when President Lyndon Johnson and Soviet Primer Aleksei Kosygin held the first summit between the U.S. and the Soviet Uniona meeting that led to a thaw in the cold war. The second event occurred in June of 1992 when Henry and Betty Rowan gave $100 million to Glassboro State Collegethe largest contribution to a public university at that time. He gave this gift for the purpose of starting an "outstanding" engineering school to better serve the students of the southern New Jersey region. The institution was subsequently renamed in honor of the Rowans, and it achieved university status in 1997. Planning for the new and innovative engineering program began in 1993 with the formation of a National Advisory Council, a group of prominent engineers from around the country. Then in 1994, the founding Dean, James Tracey, was hired and joined Zenaida Otero Gephardt, who served as Assistant Dean to this fledgling enterprise. In 1995, C. StewartC. STEWART SLATER, ROBERT P. HESKETH, JAMES A. NEWELL, STEPHANIE FARRELL, ZENAIDA OTERO GEPHARDT, MARIANO J. SA VELSKI, KEVIN D. DAHM, AND BRIAN G. LEFEBVRERowan University Glassboro, New Jersey 08028Rowan University ChEdepartmentChE at . Henry M. Rowan Hall, home of the Chemical Engineering Department. V iew of the atrium and spiral staircase in Henry M. Rowan Hall.

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Spring 2005 83 Slater became the founding chair of chemical engineering, and new faculty was hired every succeeding year until it reached a complement of eight full-time faculty in 2000. Robert Hesketh, who joined the faculty in the fall of 1996, became chair in 2004. The first class graduated in May of 2000 and the department received accreditation by ABET the following year (retroactive to the first class). Dianne Dorland became Dean of the College of Engineering in 2000. Stewart Slater was an enthusiastic and energetic chair, traits that were essential in creating a new chemical engineering program. He believed engineering education should be transformed and he knew that if given a chance, he could lead Rowan's chemical engineering department into a new and exciting future. The synergy among the Rowan faculty, as a result, is cohesive and has produced one of the best undergraduate programs in the country. T oday, Rowan University has more than 9,500 students in 36 undergraduate majors, 26 master's degree programs, and a doctoral program in educational leadership. The College of Engineering offers bachelor and master of science degrees from the departments of chemical, civil and environmental, electrical and computer, and mechanical engineering. There are currently 112 chemical engineering undergraduate majors and 12 graduate students. Rowan is a selective, medium-sized state university located in southern New Jersey between Philadelphia and Atlantic City. The region is an eclectic mix of suburban and rural areas, and the home county of Gloucester is one of the fastest growing counties in the state. The average class size in chemical engineering is 14 and the student/faculty ratio is 10 to 1. All classes are taught by professors, which provides for an excellent student-centered learning environment.ACTIVE LEARNING AND A PROJECT-BASED CURRICULUM"Tell me and I forget, show me and I may remember, but involve me and I understand," a quote attributed to the statesman-inventor Benjamin Franklin, is a fundamental philosophy of the department. Students are involved in the learning process from the first day of the program. They participate through in-class cooperative problem solving, experiments and demonstrations, computer exercises, and small-scale and semester-long projects. This is accomplished through a curriculum that blends the fundamental chemical engineering knowledge with applications, design, and research in many of the emerging fields of technology. The hallmarks of the College of Engineering include a project-based curriculum, the teamwork approach to problem solving, emphasis on communication skills, hands-on laboratories and modern computer tools, safety and environmental issues, economics and entrepreneurship, and industrial partnerships.ENGINEERING CLINICSThe most innovative and unique feature of the engineering curriculum is the engineering clinic sequence. Loosely modeled after the medical school approach to teaching (first used in engineering by Harvey Mudd College), the eight-semester sequence gives students a real engineering experience on the very first day of their freshman year and culminates in a major project experience in their junior and senior years. Each section of the engineering clinic sequence involves students from all four of the engineering disciplines, and many of the clinic projects are funded by industry and faculty research grants. The Rowan program was one of the first in the country to focus on providing a one-year freshman experience with engineering experimentation, multidisciplinary teamwork, and communication skills. In the fall semester, students conduct experiments from each of the four engineering disciplines to learn about engineering measurements and to become familiar with engineering in general. Many innovative experiments have been developed in chemical engineering. For example, a fluidized bed polymer coating experiment introduces basic chemical engineering concepts by using a fluidized bed to demonstrate polymer coating and heat transfer, and a drug delivery experiment shows students some basic principles, such as rate control in the delivery of modern medicines. Students have even visited the campus cogeneration plant to examine the measurement techniques used in the production of steam and electricity for the campus. In the spring semester, students reverse-engineer a process or productexamples include an automatic drip coffee maker, a beer-brewing process, and the human body. The beer production project has been one the most popular projects; students start the semester investigating the brewing process and finish by designing a new brewing process. The Sophomore Clinic is a unique integrated course where professors in college writing and public speaking teach communication concepts through the use of an engineering project. These multidisciplinary design projects have focused on the design, optimization, and economic analysis of a baseball stadium, a NASA Mars mission, recycling, a stair climber for the disabled, a bridge design, and microbial fuel cells. The Junior and Senior Clinics are the most ambitious part of the program. There, multidisciplinary teams (3-4 studentsDoors were opened to engineering students in 1996, and the first class graduated in 2000. Today, Rowan University's undergraduate chemical engineering program is ranked third in the nation .

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84 Chemical Engineering Education Student at work in the bioprocessing and related bio areas research lab at Rowan. One of the most popular labs is the food product development lab where students can create and test their products. Fluidized bed for polymer coating experiment in the freshman clinic. on a team) work on real-world, open-ended projects in various areas that are linked to industry or to a grant from a state or federal agency. The majority of these projects run for an entire year (two semesters) and involve applied research, development, or design that solves some particular engineering problem. These projects emanate from a particular discipline, are led by that department's faculty, and typically involve an industrial mentor. The teams are matched by faculty project managers to achieve the best results in individual projects. Teams may combine various fields of expertise within a classical discipline (such as biochemical and polymer in chemical engineering) or combine other disciplines (such as science, business, and other engineering) as may be appropriate to the project goals. Students are required to meet weekly with a faculty advisor and/or an industrial mentor for project updates, they must write a final report or a paper/journal publication, and they must present an oral report at the end of each semester. A recent Junior/Senior Clinic project involved evaluation of novel separation processes for recovery of precious metals from process streams, sponsored by Johnson Matthey, Inc. The student team was composed of chemical engineering and chemistry students. The project outcomes included a literature review, critical ana lysis of equipment potential, experimental testing, modeling and verification, and economic process analysis. The results of the project were incorporated in the processing plant. Such association of students and industrial partners has often led to full-time jobs as well as internships. Another interesting Clinic partnership came as a result of the department's interaction with the Pillsbury division of General Mills. Pillsbury sponsored several Clinic projects for improvement and optimization of its dough line processes. One project focused on the analysis of raw materials, the second project optimized a process line, and the third investigated wastewater minimization. These projects also provide student teams with an opportunity to perform research that is more typically associated with graduate students and encourages them to pursue advanced degrees. Work on high-performance polymers and composites, done in the Clinics under the supervision of James Newell, has resulted in four papers being published in peerreviewed technical literature, and five of his undergraduate students have gone on to graduate study.ChE-FOCUSED COURSESThe chemical engineering curriculum consists of the fouryear engineering clinic sequence summarized above, coupled with a unique combination of chemical engineering subjects. Examination of the course names will reveal many of the core subjects, such as material and energy balances, fluid, heat, mass transfer, and thermodynamics, but these courses are not typical chemical engineering courses. Imagine trying to remove 14 credit hours from 131 credit hours, or more importantly 36 contact hours from the curriculum, to make room for a multidisciplinary project-based engineering clinic sequence! At Rowan, however, it has been proven that it is possible to make major changes in the chemical engineering curriculum. The process of transforming traditional chemical engineering courses began with the founding chair, Stewart Slater, and the curriculum continued to be evaluated and transformed as each new faculty member was hired. This process continues today through biannual evaluation meetings and involves in-depth participation of each of the eight faculty members. The faculty members evaluate the content of each course at meetings that last one to two days, and as a result, new and innovative topics have been integrated throughout the curriculum. Subjects and courses have been removed as

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Spring 2005 85 Grants from the NSF have funded lab experiments in novel areas such as this reverse osmosis membrane system. The high bay laboratory, shown here, gives students exposure to industrial processes such as a 25-ft distillation column and a specialty chemical pilot plant. well as added, constantly improving the curriculum. The process that is now in place allows the department to continually transform the curriculum to better prepare engineers for the future. The ability to constructively evaluate and make these changes is directly attributed to the good working relationship between all chemical engineering faculty members. Departmental faculty have also been successful in working with other colleges to reshape and improve traditional math, science, and general education courses, e.g ., the example of the sophomore clinics given above in which students are instructed by both communications faculty and engineering faculty on how to effectively communicate their results. In working with the biological science faculty, a new required course, "Biological Systems and Applications," has been created that integrates microbiology and other life science topics into the sophomore year. There has also been cooperation with the chemistry and math departments in creating unique courses for engineering students.ROWAN'S IMPACT ON ChE EDUCATIONThe Rowan department is influencing chemical engineering education by sharing its innovations with other educators through publication, presentations, and workshops. It has received numerous grants from the National Science Foundation, the U.S. Environmental Protection Agency, and the State of New Jersey to innovate the curriculum and to discover how engineering students really learn. For example, one of the NSF grants funded membrane experiments for the unit operations course as well as smallerscale membrane experiments for outreach activities. Another NSF grant funded micro-mixing and other experiments for a reaction engineering course. Some innovative food engineering experiments have been developed and are included in the freshman clinic and outreach, also with NSF support. EPA funding has helped incorporate green and sustainable engineering into the curriculum and to disseminate this to many other schools. The faculty have been strong advocates of an interactive classroom with cooperative learning, experiments and demos, and unique learning methods. James Newell has developed a game-show classparticipatory project using Hollywood Squares and Survivor to help students learn about material science and chemical principles, and the plant-design course has used a "business meeting" concept involving College of Business faculty and engineers from industry to review student design presentations. Kevin Dahm has taught process economic analysis with interactive economic simulation as a semester-long project. Zenaida Gephardt is leading the incorporation of experimental design in the curriculum. The department has been a leader in developing assessment tools designed to address ABET criteria. This work has expanded through NSF funding to use profiles of studentlearning preferences to develop metacognition in engineering students and to improve their performance in teams. Bio and pharmaceutical engineering focused innovations have occurred at many levels in Rowan's chemical engineering labs and courses. Stephanie Farrell has been a pioneer in invigorating the Freshman Engineering Clinic with bioengineering experimentsdrug delivery system testing, "Hands on the Human Body" biomedical experiments, and brewingprocess investigations, etc. Food product and process engineering has been a recent theme of the department. As a first step in response to the regional emphasis on food processing, Mariano Savelski developed a course that integrates applied food engineering coursework and food chemistry experiments. This course provides students with skills directly rel-

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86 Chemical Engineering EducationT ABLE 1Rowan's Chemical Engineering Team Robert P. Hesketh Professor and ChairBS, University of Illinois; PhD, University of DelawareReaction engineering Novel separation processes Dianne Dorland Professor and DeanBS, MS, South Dakota School of Mines; PhD,University of West Virginia Green engineering Management James A. Newell ProfesorBS, Carnegie-Mellon University; MS, Pennsylvaia State University; PhD, Clemson UniversityPolymer science and engineering C. Stewart Slater ProfessorBS, MS, Rutgers University; PhD, Rutgers UniversityMembrane separations Kevin D. Dahm Associate ProfessorBS, Worcester Polytechnic Institute; PhD, Massachusetts Institute of TechnologyReaction kinetics Process modeling Stephanie Farrell Associate ProfessorBS, University of Pennsylvania; MS, Stevens Institute; PhD, New Jersey Institute of TechnologyControlled release Pharmaceutical/food process technology Zenaida Otero Gephardt Associate ProfessorBS, Northwestern University; MS, University of Delaware; PhD, University of DelawareExperimental design Particle technology Mariano J. Savelski Associate ProfessorBS, University of Buenos Aires; ME, University of T ulsa; PhD, University of OklahomaDesign for pollution prevention Food process technology Supercritical fluids Brian G. Lefebvre Assistant ProfessorBE, U. of Minnesota; PhD, University of DelawareBiomolecular and protein engineering Bioseparations Marvin Harris Process Technician Susan Patterson Secretary The Rowan Chemical Engineering team: left to right, Susan Patterson, Zenaida Otero Gephardt, Brian G. Lefebvre, Kevin D. Dahm, Robert P. Hesketh, C. Stewart Slater, Mariano J. Savelski, Marvin Harris, James A. Newell, and Stephanie Farrell. evant to the evolving needs of the food processing industry. Rowan faculty have not only taught students in an innovative way, but have also helped improve the process of how chemical engineering is taught. In 1998, Stewart Slater and Robert Hesketh received funding from the NSF to conduct two workshops for other chemical engineering faculty on novel process science and engineering principles. The ASEE Summer School for Chemical Engineering Faculty and AIChE meetings have had Rowan leadership in workshops focusing on communication skills, assessment, experiential and inductive learning, and green engineering. Through these workshops, faculty at other schools have been impacted, and the Rowan innovations are now being used in educating chemical engineering students across the country. The faculty have also ventured into other parts of the world to spread the "Rowan way," as invited speakers at conferences and universities in Argentina, Australia, Brazil, Canada, Chile, China, Czech Republic, Mexico, Norway, Spain, and the United Kingdom.STATE-OF-THE-ART FACILITIESHenry M. Rowan Hall is the home of Rowan's Engineering College. This $29 million engineering building, completed in 1998, is equipped with the latest chemical engineering equipment and instrumentation. The 95,000 ft2 building is designed to facilitate problem-based learning with classrooms integrated with fully equipped modern laboratories. The high-bay facility and food product development lab (as well as the instructional and research laboratories) have pilot-scale equipment such as: an advanced distillation system designed for education with a 25-ft high column with full computer control; a specialty chemical pilot plant for the manufacture of flavors, fragrances, and other unique products; a reverse-osmosis system for water reuse and recovery in chemical processing; a climbing film evaporator that was used in pharmaceutical production; a supercritical fluid extraction system for the recovery of nutraceutical products; and clinical-grade cardiorespiratory, pulmonary function, and metabolic testing equipment. In a ddition to many other chemical engineering apparatus, these laboratories are supported by state-of-the-art analytical instrumentation.FACULTY LEADERSHIPFaculty members are leaders in chemical engineering education. Because of

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Spring 2005 87their varied backgrounds and prior experience, the Rowan team is well-respected by its peers in both scholarly and technical pursuits. Many of the faculty have received national awards and recognition. Four (Stephanie Farrell, Robert Hesketh, James Newell, and Stewart Slater) have received the Dow Outstanding New Faculty Award, and four (Kevin D. Dahm, Stephanie Farrell, Robert Hesketh, and James Newell) have been recognized with the Ray W. Fahien Award of ASEE. ASEE's Joseph J. Martin Award has been given to Rowan faculty four times, and James Newell and Kevin Dahm have won a PIC-III best paper award. In 2004, Stephanie Farrell was selected to receive ASEE's National Outstanding T eaching Medal, while Robert Hesketh was recently given ASEE's Robert G. Quinn award, recognizing his distinguished accomplishments in experiential education. Stewart Slater has received such honors as ASEE Fellow Member status, and the George Westinghouse, John Fluke, and Chester Carlson awards for innovation in engineering education. Faculty have also assumed leadership roles in professional societies, most notably the Dean of the College of Engineering, Dianne Dorland, was President of AIChE. Robert Hesketh and Stephanie Farrell have chaired the Undergraduate Education group of AIChE, and Robert helped create the AIChE National Chem-E-Car competition and has been its emcee. Stewart Slater has chaired the Chemical Engineering and Experimentation and Laboratory-Oriented Studies Divisions of ASEE. Mariano Savelski has also chaired the Division for Experimentation and Laboratory-Oriented Studies, and Stephanie Farrell is Chair of the Mid-Atlantic Section of ASEE.AWARD-WINNING STUDENTSIn the Department's short history, it students have distinguished themselves in many ways. When they start their career at Rowan, they have already passed through selective admissions requirements resulting in average SAT scores of 1240 and high school class ranking in the top 86 percentile. Every Rowan student works on multidisciplinary teams of students that are closely supervised by faculty, and many of these students have presented their work and won awards at regional and national meetings. Students have obtained internships and full-time employment in a wide variety of companies in the pharmaceutical, food, chemical, petrochemical, and materials technology areas. They have been accepted into leading graduate programs at a variety of universities such as Delaware, Princeton, Clemson, Virginia Tech, Lehigh, Massachusetts, and Colorado State. In addition to pursuing advanced study in chemical engineering, students have gone on to graduate business schools and several have entered medical school.INDUSTRIAL PARTNERSHIPSAnother unique characteristic of the Rowan chemical engineering program is its strong partnership with industry. Ever since it was founded, there was the belief that a program with active involvem ent in industry would be a win-win situation for industry, faculty, and students alike. Its location in the New Jersey, Pennsylvania, and Delaware tri-state region has been an asset since many of the well known (and less well known) names in the field are located within a couple hours drive. Partnerships with the department have developed in many ways. Involvement in the clinic program provides the most intimate interaction and has led to numerous successful projects. According to our industrial advisors, students who engage in an industrial clinic project and participate in an industrial summer internship program compare favorably to graduates with full-time job experience. For example, Johnson Matthey, Inc., the world's leader in precious metals processing, initially sponsored scholarships for the first engineering class in 1996. It has gone on to hire students for both parttime and full-time jobs and has provided continuous sponsorship of clinic projects since 1998. Industry has also helped shape the curriculum. The department has sought industry input for the program's objectives, curriculum, and assessment efforts though its Chemical Engineering Industrial Advisory Board. It also routinely looks to industry for guest lecturers and adjunct faculty.FUTURE DIRECTIONSThe College of Engineering continues to develop its programs in undergraduate education, particularly through the engineering clinics, and innovation in educational delivery. The delivery of experiential education will benefit from a new Technology Park that will house significant clinic activities in conjunction with developing technology ventures. T enants of the Park will have access to the research, development, and commercialization expertise of the Rowan University engineering and business faculty. External research and development funding from federal, state, and private sources to the College and Department has increased, fueled primarily by engineering's strength in its outreach to industry. The chemical engineering faculty obtained over a half million dollars in external funding last year. Many of these grants are in multidisciplinary areas of biotechnology, nanotechnology, advanced materials, sustainability, and engineering pedagogy. Chemical engineering has always been a dynamic field and while universities must adapt to the shifting marketplace, the department will not waver from its focus on producing skilled problem solvers who are capable of functioning in teams on diverse projects that expand beyond a single discipline, and who can effectively communicate their findings to many different audiences. Our commitment to developing these new engineers remains steadfast!

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88 Chemical Engineering EducationAlice P. Gast wanted to be a scientist ever since she was a little girl visiting her father's biochemistry laboratory. She almost diverged to become an archeologist at one point, and at another time an aptitude test told her to become an auto mechanic, but she went on to find the right home for her talents in chemical engineering. A ChemE since her freshman year in college, Alice says she loves the field and the collegiality of the community. What she didn't foresee, however, was that she would eventually become an academic administratora job she now finds even more challenging and rewarding. As Associate Provost and Vice President for Research at MIT, Alice holds one of the more interesting, important, and complex positions in American academic administration. The position reports to MIT's Provost, Robert A. Brown, and to President Susan Hockfield. It is Alice's responsibility to advise them on matters of research policy. Diverse policy issues in areas such as research integrity, intellectual property, international student visas, and the terms of research agreements are continuously evolving and require Alice's attention and influence. She also views her job as being a "champion of interdisciplinary research," and she can think of no better place to promote it than in the vibrant research environment of MIT. Reflecting on how she got this "dream job" she says that one thing simply led to another.PERSONAL BACKGROUNDThe seeds of scientific curiosity were planted early in Alice's life when she would go to her dad's lab and look at pictures from his electron microscope. Later, she found that being in junior high school was made tolerable by a circle of studious and like-minded friends . as well as by joining a track team. She says that growing up in California made "beach runs" de rigeur and that it was easier to be a serious student when one was a jock and a nerd at the same time. She remembers one time that she was embarrassed by her high school history teacher when a picture showing her executing a long-jump appeared in the local paper. He said "I could tell it was Alice because she is sitting down and her eyes are closed!" (Alice says she was simply honing that important academic talent of sleeping through lectures!) ChEeducatorAlice Gast of the Massachusetts Institute of Technology Copyright ChE Division of ASEE 2005CHANNING R. ROBERTSON Stanford University Stanford, CA 94305-5025KENNETH A. SMITH Massachusetts Inst. of Tech. Cambridge, MA 02139

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Spring 2005 89 Later, at USC, Alice enjoyed the flexibility of the program they offered, the excellent teachers there, and undergraduate research opportunities that abounded. She took courses in chemical engineering, chemistry, music, and historyand met Brad Askins, the boy next door. Brad was a history major at the time (another good influence) but later became a computer scientist. Alice says he has always been a source of inspiration for her. Another bonus is that she has her own technical support person in Brad and is thus able to gain insight into complex computer issues that are outside of her area of expertise. Alice and Brad moved to Princeton for grad school, experienced living with snow for the first time, adopted their cat, Stumpy, and found close friends to share their lives and ambitions with, friends like Chip Zukoski and Barbara Morgan. During this period, Alice also tremendously enjoyed conducting research with her mentors Bill Russel and Carol Hall. Later, a year in Paris as a postdoc turned into a great adventure and made serious Francophiles out of both Alice and Brad. She has since returned to France several times for sabbatical stays and more recently has spent time in Germany as a Humboldt Fellow. She relishes the opportunity to return to Europe from time to time to conduct research or to transact Institute business and to sharpen her language skills. Alice claims that her most effective training for university administration was in negotiating with her kids, Rebecca and David, when they were about four and two, respectively. At those ages, neither of them wanted to stay at a daycare facility in the morning and took a bit of onsite coaxing to accept the situation each daybut Alice was always quite anxious to leave before any of the other kids took the opportunity to decorate her attire with paint or sticky food. She found that the best approach was to "redirect" the kids attention so that they found something really interesting in the room, and thinking it was their own discovery, became engaged and forgot all about not wanting to stay. Alice says the same approach is true when you can get your colleagues to adopt a new and challenging idea and make it their own, truly engaging themthen you have done something worthwhile. Now that their kids are eight and ten, Alice and Brad find themselves enjoying recitals, soccer games, cross-country skiing, and biking adventures. The whole family is fortunate that Brad has a flexible work schedule and can shuttle the T op: Family visit to Paris for Stanford chemical engineering colleague Michel Boudart's 80th birthday. Above: Alice and fellow chemical engineer Chip Zukoski are longtime friends and Gordon Conference tennis partners. Alice and cold-weather friend, a new challenge for a California girl. Beloved bi-coastal family pet, Stumpy. Below: Alice's Stanford research group and kids gather at her Massachusetts home during a trip to set up Alice's MIT lab in February of 2003.

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90 Chemical Engineering Education Below: Press conference announcing the establishment of the Institute for Soldier Nanotechnologies (ISN) at MIT. Also pictured from the left are Provost Robert Brown, Dean of Engineering Thomas Magnanti, ISN Director Edwin Thomas, and Chemical Engineering Professor Paula Hammond. Left: At work and at playAlice is shown lecturing at a conference in Les Houches, France, and in a more relaxed setting exploring the tidepools in Baja, California.kids to the various activities they take part in. Family hikes and camping trips are the highlights of the year and take a high priority in the scheme of things.THE STANFORD DAYSAlice arrived in the chemical engineering department at Stanford to begin her academic career in late 1985 after returning from France, where she spent a year as a NSF NATO Postdoctoral Fellow at the Ecole Superieure de Physique et de Chimie Industrielles in Paris. She had been vigorously recruited by several universities and her champions at Stanford felt fortunate to have won the battle. During her sixteen years at Stanford, Alice established a world-wide reputation in the area of polymer solutions, colloidal dispersions, and interfacial behavior of proteins. She displayed an uncanny knack for developing and applying sophisticated tools to probe the intricacies of these complex systems, and often used statistical mechanics to interpret her experimental results. She was able to reveal the connections between molecular behavior and macroscopic manifestation in polymeric micelles, colloidal and protein crystallization processes, and polymer and protein adsorption phenomena in ways that were both foundational and revolutionary. To accomplish all of this, Alice had a certain magnetism that allowed her to attract the best available PhD students into her group. Her ability to mentor and guide students through the highs and lows of doing research is legendary. It has been claimed that students were also attracted to her group meetings, which featured fine French cheeses, water crackers, home made bread, and even, on occasion, some fine wine. And one cannot forget the many parties that she and Brad hosted at their home. Indeed, everyone looked forward to a celebration at the Gast household following another successful PhD defense by one of her students (she has had thirty PhD students in all). She was sometimes assisted by her colleague, Channing Rob ertson, who would entertain the kids with his reenactment of "the claw"something he pulled from a grade-B horror movie. It is fair to say that Alice's research group was a "family" of sorts, and created an atmosphere in which the very best was coaxed from the minds of many talented students. Alice was among the most popular teachers in the Stanford department. Her style was engaging and she set a high bar for the students. She loved to involve them in projects. Her "animal guts" project made the reactor design course much more interesting and entertaining for the students and offered numerous open-ended design problems for them to tackle. She would have the students demonstrate the fruits of their labor at a presentation for the entire department. Sometimes they cooked "gumbo" for their postfinal party (following Alice's family recipe, not the one in the excellent text by Scott Fogler). To recognize her efforts, Alice re-

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Spring 2005 91 As Associate Provost and Vice President for Research at MIT, Alice holds one of the more interesting, important, and complex positions in American academic administration.Alice in the role of tourist, posing with New York's Central Park as a backdrop.ceived a Camille and Henry Dreyfus Teacher Scholar A ward and was honored as Professor of the Year by Stanford's Society of Women Engineers. Alice's research accomplishments did not go unnoticed for long. In 1992 she received two prestigious awardsthe Allan P. Colburn Award from the AIChE and the National Academy of Science Award for Innovative Research. As could be expected, Alice found herself in great demand to give plenary talks, to organize conferences, and to serve on government panels. She did all these things with enthusiasm, but was always able to strike a balance between her family and her passion for research and teaching. Her fellow teachers viewed her as an extraordinary and remarkable faculty colleague in every sense of the word. As Stanford began to embark on a bold new interdisciplinary research enterprise, dubbed Bio-X, she was pegged by her colleague, Channing Robertson, to play a key role in the design process for the James H. Clark Center, the focal point for the effort. In so doing she worked with Sir Norman Foster, the primary architect, as well as a multitude of faculty and administrators, to bring about Stanford's showcase crossdisciplinary enterprise. It was a daunting task, given the number of stakeholders involved, and a divergence of opinion soon arose as to how the project should go forward. Alice deserves much credit for her ingenuity and the leadership she provided during those exhilarating, yet trying, times. As a result of the project, Stanford is positioned to play a leadership role in redefining the way in which multidisciplinary research is conducted in the future. Alice's legacy in this regard will never fade, and the Stanford community is forever indebted to her. As if her plate were not full enough, Alice somehow found time to work with the late Arthur Adamson (in the chemistry department at her alma mater, USC) in helping to revise the latest edition of the famous textbook, Physical Chemistry of Surfaces It was a common sight at Stanford to see Alice return to campus after her kids were tucked away at home, burning the midnight candle well into the next day as she toiled on revision after revision of the book. It was none other than a monumental labor of love for her. Because of her effort, generations of students will now have the benefit of her wisdom and her keen ability to communicate difficult topics in an understandable and palatable fashion. Alice's days at Stanford were full of joy, discovery, some failures, and many successes. All of her colleagues there remember them well. Alice is missed in ways that her colleagues find difficult to express and feel that MIT is incredibly fortunate to have such a treasure in its midst.THE MOVE TO MITAlice was difficult to uproot from Stanford, her California home. One day, in early 2001 her fellow chemical engineer, Bob Brown, the MIT Provost, called her to discuss the possibility of potential new challenge for herthat of Associate Provost and Vice President for Research at MIT. After reflecting seriously and at length about her love of graduate education and research, she decided to take the plunge into academic administration and accepted the challenge. Alice says that "It has been a wonderful ride and I am very grateful that such an opportunity arose." Alice found that some of the interesting issues that have always motivated her emerge in a totally unpredictable fashion and intersect with the government and industrial communities. She found she had to actively work with government and academic groups to improve the visa processes for international students and scholars. She has also been engaged in defending the ability of universities to freely publish their fundamental research results and to openly collaborate with students and colleagues from abroad. Because Washington is the source of both opportunities and problems for university research, and because all universities are subject to a similar set of opportunities and obstacles, Alice is frequently a participant in Washington activities of various sorts.

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92 Chemical Engineering EducationIn addition to policy issues, Alice enjoys being responsible for and promoting interdisciplinary research at MIT. The intellectual span of these interdisciplinary activities is considerable, ranging from the Plasma Science and Fusion Center to the Computational and Systems Biology Initiative, to the Institute for Soldier Nanotechnologies. In her oversight of important labs and centers, Alice brings the same talent as a supportive mentor that has always been evident in her interactions with students. She enjoys having the opportunity to work with laboratory directors in making their programs even more vibrant and exciting. Alice also enjoys meeting the critics and sponsors of the labs, centers, and programs she oversees, and communicating the Institute's support and appreciation for them. She is always willing to provide liaison with sponsors or to help a lab develop an exciting new program. Alice says the best part of her job is the opportunity to encourage new initiatives and to nurture new efforts. Although every situation is different, they often require that she assemble just the right combination of people with just the right intellectual skills to address the opportunity at hand, making sure they have the interpersonal skills that will lead to rapid development of a cohesive team. She is comfortable remaining in the background and allowing the team to determine its own destiny, providing enthusiastic support when it is needed. A good example of this process is the Institute for Soldier Nanotechnologies at MIT. This was MIT's response to a RFP from the Army, which promised a five-year grant at the level of $10M/year. As one might expect, competition was intense and many good proposals were submitted. One requirement of the proposal was creation of a new facilityand Alice and a team of faculty and project managers designed and constructed one in record time. She was at ease functioning as the project manager, balancing the budget while at the same time ensuring that the research needs of the program, faculty, and students were not compromised. Alice's support and collegiality during this process led to a great sense of accomplishment and satisfaction among her team members, who expressed their appreciation and their willingness to join her in any future endeavors. Another of Alice's areas that draws on her breadth of experience is the Office of Technology Licensing. Alice has worked hard to balance the interests of faculty, who receive compensation for the intellectual property that they generate, and the needs of the university, which provided the supportive environment and which actually owns and licenses the IP. She remarks that a few years ago, she "learned a lot about intellectual property from some very smart lawyers during an interesting consulting experience." One of Alice's challenges is working to keep the university and the funding communities focused on the proper role of university research as a vehicle for the education of young people. In addition, there is a fine line between research and development. In times of tight budgets or international economic tension, there is often the tendency to push university researchers toward technology development problems, just to "help out." But, as Alice points out, "All you end up doing is diminishing basic research at a time when industry and the country need it most." All of this may seem to be a major departure from her former activities as a teacher and scholar, but Alice views her research interests as interdisciplinary and she credits her mentors Bill Russel and Carol Hall with teaching her to apply concepts from one field to other areas. Her work at Stanford in helping to design the Clark Center and working with the Materials Center and the Synchrotron Laboratory were experiences that she has been able to draw on many times since arriving at MIT. Alice comments that she is always surprised to find how important past experiences and things learned along the way can be, and usually in unexpected ways. Her experience as an investigator at Stanford's Synchrotron Radiation Laboratory has come in handy more than once in working with some of MIT's laboratories, especially when some of the lab's investigators are not aware of her background. Alice's diverse experiences have also served her well in her work on behalf of international students and scholars. She gained valuable experience from her postdoctoral year in Paris working on fluid mechanics or something like it, as well as from the better part of a year (split over several trips) spent working on biophysical issues in Munich, as an Alexandar Von Humboldt Awardee. Not only did these experiences give her a first-hand understanding of what it is like to be a researcher in a foreign country dealing with different cultures and government systems, but she also made a number of close contacts who can now share insights on what it is like to deal with the U.S. Government when they come over here on international collaborations. Among her varied activities, Alice values most the days she spends with her research group in the Landau building at MIT. There she can work with talented undergraduate, graduate, and postdoctoral students and think about science and development of their research projects. She has always viewed her students as her best research "products" and has been fortunate to work with the best. All in all, Alice says she loves MIT and cannot think of a better place to be working as an advocate for research and interdisciplinary collaborations. "MIT is just this most amazing place," Alice is fond of saying, usually after discovering another area of fascinating research. Alice goes on, "MIT is probably one of the few places on the planet where my family would rather come in and meet me on a Friday night, to see something like a student robot competition, than have me come home to them."

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Spring 2005 93 There is always an easy solution to every human problemneat, plausible, and wrong. H.L. Mencken The problem is not that there are problems. The problem is expecting otherwise and thinking that having problems is a problem. Theodore Rubin If you had to identify, in one word, the reason why the human race has not achieved, and never will achieve, its full potential, that word would be "meetings." Dave Barry I went to a restaurant that serves "breakfast at any time." So I ordered French Toast during the Renaissance. Steven Wright Do unto yourself as your neighbors do unto themselves, and look pleasant. George Ade I went to a bookstore and asked the saleswoman, "Where's the self-help section?" She said if she told me, it would defeat the purpose. George Carlin Every prayer reduces itself to this: Great God, grant that two plus two not equal four. Ivan Turgenev The intellect of man is forced to choose Perfection of the life, or of the work W .B. Yeats Stu dents achieving oneness will move ahead to twoness. W oody Allen Middle age is having a choice between two temptations and choosing the one that'll get you home earlier. Dan Bennett 42.7 percent of all statistics are made up on the spot. Steven Wright The causes we know everything about depend on causes we know very little about, which depend on causes we know absolutely nothing about. T om Stoppard Buying the right computer and getting it to work properly is no more complicated than building a nuclear reactor from wristwatch parts in a darkened room using only your teeth. Dave Barry Hemingway said a long time agoand I subscribe to it that a smart writer quits for the day when he's really steaming, when he knows it's good and knows where it's going. If you can do that, you've fought half the next day's battle. James Michener How can I know what I think until I see what I say? W .H. Auden From the moment I picked your book up until I put it down I was convulsed with laughter. Some day I intend reading it. Groucho Marx If a politician tells you he's going to make a "realistic decision," you immediately understand that he's resolved to do something bad. Mary McCarthy The whole aim of practical politics is to keep the populace in a continual state of alarm (and hence clamorous to be led to safety) by menacing them with an endless series of hobgoblins, all of them imaginary. H.L. Mencken A fanatic is a man who does what he thinks the Lord would do if he knew the facts of the case. Finley Peter Dunne I have had a perfectly wonderful evening, but this wasn't it. Groucho Marx Having a dog teaches a boy fidelity, perseverance, and to turn around three times before lying down. Robert Benchley My esteem in this country has gone up substantially. It is very nice now that when people wave at me they use all their fingers Jimmy Carter I intend to live forever. So far, so good. Steven WrightSPEAKING OF EVERYTHING IIRICHARD M. FELDERNorth Carolina State University Raleigh, NC 27695Random Thoughts . . Copyright ChE Division of ASEE 2005 Richard M. Felder is Hoechst Celanese Professor Emeritus of Chemical Engineering at North Carolina State University. He received his BChE from City College of CUNY and his PhD from Princeton. He is coauthor of the text Elementary Principles of Chemical Processes(Wiley, 2000) and codirector of the ASEE National Effective Teaching Institute.

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94 Chemical Engineering Education MICROMIXING EXPERIMENTSIn the Introductory Chemical Reaction Engineering CourseKEVIN D. DAHM, ROBERT P. HESKETH, MARIANO J. SA VELSKIRowan University Glassboro, NJ 08028-1701In practice, the issue of mixing and chemical reactions is very important in the economic aspects of chemical reaction engineering. A major priority in industrial reactors[1] is to optimize the yield of desired products. This optimization is a function of reactor geometry, the chemical and physical characteristics of the reacting system, the degree of mixing, and the mode of supplying the reactor with reagents. Bourne and Gablinger[2] have shown how process chemistry developed in the laboratory can go awry when scaled to industrial reactors. An excellent example of the classic seriesparallel reaction using an azo dye chemistry is presented by Bourne and Gholap.[3] A chemist working on a bench scale will optimize this reaction to obtain very high reaction rates for the desired reaction. In the industrial scale reactor, micromixing becomes a limiting factor, negatively impacting the process chemistry.[4]As Etchells[5] noted, however, a typical undergraduate reactor design course focuses on ideal reactors. In the chapter on multiple reactions in the standard chemical reaction engineering text by Fogler,[6] it is assumed that the reactions are slow compared to the mixing of species. The classic examples for parallel reactions and series reactions are given, but these examples do not cover the basic concept of micromixing with respect to the reactants. It is only in the final chapter of this text that the concept of micromixing is introduced, and the presented mathematical theory is relatively complex for undergraduates. Idealized reactor models provide an excellent framework for a conceptual introduction to reaction engineering and reactor design, but they can be easily misused. In attempting to use ideal reactor models for the azo dye system, for example, one would overlook the impact of mixing on the reaction kinetics and on the formation of trace byproducts. A thorough treatment of the modeling of micromixing is beyond the scope of the introductory undergraduate chemical reaction engineering course, but the experiments described in this paper provide a qualitative and quantitative demonstration of the significance of the mixing effect and the limitations of the idealized reactor models, with minimal time investment. Baldyga and Bourne[7] summarize a number of experimental examples of product distributions sensitive to mixing. Examples of parallel or competitive reactions include DiazoKevin D. Dahm is Associate Professor of Chemical Engineering at Rowan University. He received his PhD in 1998 from Massachusetts Institute of Technology and his BS in 1992 from Worcester Polytechnic Institute. Prior to joining the faculty of Rowan University, he served as an Adjunct Professor of Chemical Engineering at North Carolina A&T State University and a postdoctoral researcher at the University of California at Berkeley. Mariano J. Savelski is Associate Professor of Chemical Engineering at Rowan University. He received his BS in 1991 from the University of Buenos Aires, his ME in 1994 from the University of Tulsa, and his PhD in 1999 from the University of Oklahoma. His technical research is in the area of process design and optimization. His prior academic experience includes two years as Assistant Professor in the Mathematics Department at the University of Buenos Aires, Argentina. Robert P. Hesketh is Professor of Chemical Engineering at Rowan University. He received his BS in 1982 from the University of Illinois and his PhD from the University of Delaware in 1987. After his PhD, he conducted research at the University of Cambridge, England. Robert's teaching and research interests are in reaction engineering, green engineering, and separations. Copyright ChE Division of ASEE 2005 ChEclassroom

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Spring 2005 95coupling with simultaneous reagent decomposition[8] and Iodate/iodine reaction with neutralization.[9] Examples of parallel-series reactions or competitive-consecutive reactions include Diamines with isocyantes or other acylating agents, nitrations of dibenzyl, durene, and alkyl benzenes and diazo couplings. The experiments described in this paper involve this pair of parallel competitive reactions, carried out in an aqueous solution: HBOHHBO IIOHIHO2 3 33 3 221 56332 + ++ ()++ +() The first reaction is essentially instantaneous, and can be modeled as an equilibrium reaction with K = 1.38 x 106 at ambient conditions.[10,11] The second reaction is essentially irreversible, with a rate that is first order in concentration of IO3 -, second order in Iand second order in H+. The rate constant has been modeled as a function of the ionic strength of the solution[9,10] and at the conditions of this reaction, k2 ~ 3.6 x 107 M-4sec-1. Thus the second reaction is fast, but orders of magnitude slower than the first reaction. So when H+ is added as the limiting reagent, a perfectly mixed system would produce essentially no I2. Production of a significant quantity of I2 is attributed to a local excess of H+; a condition in which all H2BO3 in a region is consumed and H+ remains to react with Iand IO3 -. Any I2 formed in solution will react further with IIII233 + () The concentration of the I3 ion can be measured accurately with spectrophotometry and Beer's law. Thus, the yield of reaction 2 is readily determined. Consequently, this reaction was deemed suitable for an undergraduate experiment because it meets several important criteria: The reagents are readily available, cheap, and r easonably safe, with water acting as the solvent. Quantitative results can be obtained with a fairly simple analytical method. The kinetics of both reactions have been studied.[9-11] Imperfect mixing has an effect on product distribution that is straightforward to quantify and explain. Finally, the iodine formed in solution has a striking yellow color. This is a perk compared to a solution that remains transparent throughout the reaction because the solution appears to be homogeneous. The yellow color grows darker as the reaction progresses but appears uniform at any given time. The fact that something can be well mixed macroscopically but poorly mixed on a molecular level is an important take-home message of this experiment.The experiment was integrated into a junior course on chemical reaction engineering in the Spring 2003 semester. The remainder of this paper describes the experimental apparatus itself, provides sample results, discusses the integration of the experiment into the course, and gives the results of a short quiz that was administered to assess the impact of the experiment.APPARATUSA team of Rowan undergraduate students designed and assembled the apparatus and developed an experimental procedure as an Engineering Clinic[12] project. There are two distinct experimental setups: one uses a 2-L reactor with baffles and a Lightnin Mixer (shown in Figure 1) and the other uses an ordinary 600-mL beaker with a magnetic stirring bar. In the first setup, a syringe pump is used to add the limiting reagent, sulfuric acid, at a controlled, known rate. In the second setup an Eppendorf pipet is used to add the acid all at once. Both experiments require stock solutions as summarized in Table 1. The purpose of the sodium hydroxide is to neutralize a portion of the boric acid, so that the H2BO3 ionT ABLE 1Reagent Stock SolutionsReagentConcentration (mol/l)MW (g/mol) H3BO30.60661.83 NaOH1.040.0 KIO30.0233214 KI1.167166 H2SO40.5098.04 Figure 1. 2-L reactor with Lightnin mixer.

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96 Chemical Engineering Educationwill be present with a concentration of 0.02 mol/L when the addition of sulfuric acid begins.EXPERIMENTAL PROCEDUREThe impeller speed of the mixer is the parameter that was varied, spanning the range outlined in Figure 3. The experimental procedure developed for the Lightnin Mixer is as follows: 1)Fill reactor with the 1080ml of DI water. 2)Add 225ml of the H3BO3 solution. 3)Add 30ml of the NaOH solution. 4)Add 150ml of the KIO3 solution. 5)Start mixer at 500 rpm (regardless of desired experimental speed) and allow solution to mix thoroughly. 6)Add 15ml of the KI solution. Let solution mix for several minutes to insure homogeneity. 7)Reset mixer to experimental speed. 8)Inject 10 ml of the sulfuric acid solution with the syringe pump, at a rate of 50 mL/ hr. 9)After injection is complete, wait approximately 2 minutes (to insure homogeneity of the solution) then turn off mixer. 10)Take samples from various points in the reactor. Because the first reaction is essentially instantaneous and the second essentially irreversible,{9,10] the composition does not change in the two minutes after the addition of acid is completed, but the mixing in step 9 ensures that the samples taken will be representative of the solution as a whole. The procedure for the beaker-stirring bar system is analogous. The total solution volume 300 mL rather than 1.5 L as in the Lightnin Mixer but the proportions of the reagents used are the same. The analysis of samples was completed using a Spec220, with the following procedure: 1)Set the wavelength to 353nm, the sensitivity to high, and the mode to Absorbance. 2)Fill one quartz cuvet with DI water and set the absorbance of this control sample to zero. 3)Take 1 mL of sample using Eppendorf pipet and inject into 10-mL volumetric flask. Fill the remainder of the 10-mL volume with DI water (mix well). 4)Pour the diluted sample into a quartz cuvet. Take to Spec220 and read the absorbance (reading should be between 0 and 1.999; if not, change the dilution as needed.)DATA ANALYSISA calibration curve relating I3 concentration to absorbance is shown in Figure 2. The I3 concentration is quantified by applying Beer's law C AI 34=() l The I2 and Iconcentrations can then be deduced from the following known equilibrium relationship for reaction (3):[13] LogKTKLogTKeq()=()+ ()()555735525755 /..[] Thus, one can deduce the extent of reaction 2, and by applying standard chemical reaction engineering principles of species balances and y = 4.1738E-05x R2 = 1.0000E+00 0.E+00 2.E-05 4.E-05 6.E-05 8.E-05 1.E-04 00.511.52 AbsorbanceConcentration I3(mol/L) 0 10 20 30 40 50 60 0 20040060080010001200 Impeller Speed (RPM)Selectivity Lightnin Mixer B eaker/Stir Bar Figure 3. Effect of increased mixing on selectivity of reaction 1 to reaction 2. Figure 2. Calibration curve for I3 ion concentration.

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Spring 2005 97 equilibrium relationships, one can compute the amounts of the added H+ that were consumed by reactions 1 and 2, respectively. These fractions are a function of the rate of micro-mixing. The product distribution can be quantified using the same method as Guichardon and Falk,[10] in which two limiting conditions are identified: Perfect Mixing in which the system acts like the perfectly mixed CSTR familiar to the students from early in the reaction engineering course. In this system, the yield of reaction 2 is insignificant under perfect mixing. T otal Segregation describes a system in which micro mixing is infinitely slow, so both reaction rates are essentially instantaneous by comparison. In this situation the rates of reaction 1 and 2 will be in proportion with the local concentrations of H2BO3 and I-, and independent of the kinetic rate constants of the reactions. Guichardon and Falk characterize the system by dividing the total volume of the reactor into a "perfectly mixed volume" VPM and a "totally segregated volume" VTS. The "micromixedness ratio," is defined as VPM/ VTS. Details of calculating for this system are given in their paper.[10] The calculation of however, was deemed beyond the scope of the one-period introduction to micromixing presented in this paper. Instead, the more familiar selectivity was used to quantify the results, and the total segregation and perfect mixing models were presented qualitatively as an explanation for the disparity between observed and predicted selectivity. Selectivity throughout this paper is defined as: S molesHconsumedbyreaction molesHconsumedbyreaction =()+ +1 2 6 Figure 3 shows the selectivity vs. impeller speed for both experimental setups. Note that in both cases an increase in impeller speed leads to an increase in selectivity. This observation helps demonstrate to the students that poor mixing is indeed the reason for the discrepancy between prediction and observation. The two experiments were carried out with different volumes to demonstrate the relationship between scale and mixing, which was cited in the introduction to this paper as a major motivation for teaching micromixing. The larger-scale experiment used a better impeller, a vessel with baffled walls, and a slow, controlled rate of addition of the limiting reagent, all factors that are known to produce better mixing. Quantitative modeling of the effects of these differences is possible with, for example, the E model of inhomogeneous turbulence.[6] While such a theoretical treatment is again beyond the scope of this module, students readily agree that qualitatively, the larger reactor is better designed to achieve good mixing. The data show, however, that the selectivity curves are in fact very similar for the two experimental setups, because the increase in scale offsets the benefits gained from using better equipment.CLASSROOM USE OF MICROMIXING EXPERIMENTThe Spring 2002 offering of chemical reaction engineering included one 75minute class period devoted to micromixing. The topics discussed in this period were: Why mixing rates and reaction rates can be interrelated Qualitative coverage of the concepts of perfect mixing and total segregation The "perfectly mixed" and "totally segregated" reactor models.At the conclusion of this period, the instructor explained that real reactors could be modeled as a combination of a "perfectly mixed" volume and a "totally segregated" volume. The purpose of this class period was to illustrate the shortcomings of the idealized reactor models that had been used throughout the semester. The presentation was in a lecture format and used sample data produced with POLYMATH,[14] but had no experimental component. During the Spring 2003 semester, the course included a 100-minute period devoted to micromixing. The topical coverage was the same as in the 2002 session, but this time, the experiment was integrated. Students were first shown the pair of competetive reactions and the initial composition of the reactor (excluding the H2SO4). The rate expression for reaction 2, as discussed in the introduction section, is rkHIIO22 22 37 =+()[][][] The rate expression for reaction 1 was presented as rkHHBOHBOK112 3 3318 =+ ()[][][]/ with K1 = 1.38 x 106 and k1 = 1017. (The value of k1 is not important so long as it is set sufficiently high that the reaction is in effect modeled as an instantaneous equilibrium reaction.). . the experiments described in this paper provide a qualitative and quantitative demonstration of the significance of the mixing effect and the limitations of the idealized reactor models, with minimal time investment.

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98 Chemical Engineering EducationA common teaching technique used throughout this course was for the instructor to pose a problem and then challenge the students to derive model equations describing the system. Once this was completed, the instructor would distrubute handouts showing a POLYMATH solution of the equations. In this case, the applicable design equation from Folger's text[6] is the semibatch equation dC dt r CC VB B BOB=+ ()()09 in which the addition term is 0 for all species except the acid, which is added gradually as the limiting reagent. When simultaneous species balances for the reaction system described here were solved, the selectivity was 3800. The students next proceeded to the laboratory, where the setup (steps 1-7) for an experiment with the Lightnin mixer had already been completed. Students recognized this as a semibatch reactora mixed vessel with all reactants initially present except for one that was slowly added. When the addition of acid was started, the solution immediately turned yellowqualitative evidence that iodine was present in significant quantities. The experiment and sample analysis was completed as a demonstration. The demonstration ended with the calculation of the overall selectivity, which was on the order of 101. The instructor then presented the data shown in Figure 3, saying "the experiment we just did would be one point on this graph." The data show that the baffled reactor with the Lightnin mixer provides a slightly higher selectivity (despite the larger scale) than an unbaffled beaker with a stir bar, and in both setups the selectivity of reaction 1 increases as the impeller speed increases. Both observations are evidence that mixing influences the reaction kinetics. The instructor then continued with a discussion of micromixing and the "perfectly mixed" and "totally segregated" models that had also been presented in the Spring of 2002. This model allows quantitative prediction of selectivities,[7] but the calculations were beyond the intended scope of this one-period introduction. Consequently, the ideas of perfect mixing and total segregation were presented as qualitative explanations of why mixing influences the kinetics of fast reactions. It is important to note that in both 2002 and 2003, the topical coverage of the introduction to micromixing was the same, and in both years students were responsible for the material and there was a 10-point question on micromixing on the final exam. The only difference in the presentations was the use of an experimental demonstration in the second year. The rest of the course was also substantially the same in both years and used the same syllabus and Fogler's book as the text. In the spring of 2004, micromixing was not covered at all in the chemical reaction engineering course. In this offering of the course (and in the previous two years), students were responsible for the derivation of the CSTR design equation on the first exam, so students were exposed to the asssumptions, including perfect mixing, behind the equation. In order to provide a contrast with previous years, however, micromixing was not covered through lecture or lab.ASSESSMENT OF EXPERIMENTThe anecdotal feedback on the micromixing experiment was favorable. Students appreciated seeing the real equipment and expressed surprise that a system that qualitatively looked well-mixed behaved so differently from an ideal reactor. The primary goal, however, was to prevent future misuse of the idealized reactor models by illustrating their shortcomings. In an attempt to assess the effectiveness of this, in September of 2002, 2003, and 2004, the following question was included in a non-graded "assessment quiz" that was administered to the senior classes.Our specialty chemical pilot plant includes a reactor that is a ~20-L kettle with a steam-heating jacket and an agitator. You are asked to model the reactor and a classmate has suggested using the CSTR design equation that you learned in chemical reaction engineering last spring. Is this appropriate? If your answer is "yes" or "no," explain why, and if it is "maybe," explain what factors it depends upon.There were three other questions on the quiz, covering Bernoulli's equation, vapor pressures and dew points. The students were told that the quiz was intended to assess retention of concepts from the junior year, but were not told there was a specific agenda of assessing the micromixing experiment. For each class this quiz was unannounced, was closedbook with no preparation of any kind, and was adminstered five months after the conclusion of the chemical reaction engineering course.T ABLE 2Student Responses to Whether or Not It is Appropriate to Use CSTR Design Equation for 20-L Agitated ReactorDate"Yes""No""Maybe"September 20024017 September 20031014 September 20044111 T ABLE 3Factors Cited by Students Who Responded "Maybe"DateSteady-State or NotMixingSeptember 2002134 September 2003125 September 200470

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Spring 2005 99The student responses to this question are summarized in T ables 2 and 3. All three years, most students said "maybe," with some mention of whether the process was "continuous" or "steady-state," (as opposed to "batch or semi-batch") being most commonly cited as the determining criteria. The fraction of students, however, who specifically mentioned "perfect mixing" in their response increased from 19% (4 of 21) to 33% (5 of 15) in the second year, and was zero for the 2004 control group, who were not exposed to micromixing. The students who answered "yes," in all cases used the rationale that because the reactor has an agitator, it must be a CSTRexactly the sort of error that this introduction to micromixing was intended to prevent. The number of students who responded this way dropped from 19% (4 of 21) to 7% (1 of 15) the second year, and was 23% (4 of 17) in the control group. A Chi-squared analysis of the differences between the three classes cited in the last paragraph was performed. This showed:The second class (lecture and lab) performed better on the quiz than the first (lecture only) class but the improvement was not statistically significant at 95% confidence (p~0.3).The first class (lecture only) performed better than the control group. This difference was also not statistically significant at 95% confidence (p~0.1).The differences between the second class (lecture and lab) and the control group was statistically significant to (p~0.02). Thus, the quiz indicates that an introduction to micromixing achieved the goals of improving retention and illustrating the limitations of the idealized reactor models, but no statistical conclusion can be drawn regarding whether the improvement was primarily attributable to the lecture, the lab, or both.SUMMARY AND CONCLUSIONSThe traditional chemical reaction engineering course is taught using idealized reactor models, such as the CSTR and the PFR models, with little discussion of mixing. This paper presents a micromixing experiment and its use in an introductory chemical reaction engineering course. While a thorough coverage of mixing and chemical kinetics is beyond the scope of most introductory chemical reaction engineering courses, this experiment introduces students to the field and illustrates the limitations of the idealized reactor models. A quiz was administered to the students five months after the course was completed. The results suggested that an introduction to micromixing using this experiment is helpful for illustration and retention of the concepts.ACKNOWLEDGEMENTSSupport for the laboratory development activity described in this paper was provided for by a grant (DUE0088501) from the National Science Foundation through the Division for Undergraduate Education. The authors gratefully acknowledge the following undergraduate students who contributed to this project: Robert McKeown, Andrew Dunay, David Urban, Danielle Baldwin, William Engisch, and Shaun Rendall.REFERENCES1.Belkhiria, S., T.Meyer, A.Renken, "Study of Micromixing in Polymerization Reactions and Its Application in Experimental Copolymerization," in Industrial Mixing Technology: Chemical and Biological Applications E.L.Gaden, Jr., G.B.Tatterson, R.V.Calabrese, W .R.Penney, eds., AIChE Symp. Ser., Vol. 90, No. 299 (1994) 2.Bourne, J.R., H. Gablinger, "Local pH Gradients and the Selectivity of Fast Reactions. II. Comparisons Between Model and Experiments," Chem. Eng. Sci., 44 (6), 1347 (1989) 3.Bourne, J.R., R.V. Gholap, "Approximate Method for Predicting the Product Distribution of Fast Reactions in Stirred-Tank Reactors," Chem. Eng. J. and Biochem. Eng. J., 59 (3), 293 (1995) 4.Baldyga, J., J.R. Bourne, S.J. Hearn, "Interaction Between Chemical Reactions and Mixing on Various Scales," Chem. Eng. Sci., 52 (4), 457 (1997) 5.Etchells, A., "Notes on Mixing in the Process Industries: Lecture and Short Course Material," DuPont USA, Wilmington, DE (1998) 6.Fogler, H. Scott, Elements of Chemical Reaction Engineering, 3rd ed., Prentice Hall PTR, New Jersey (1999) 7.Baldyga, J., and J.R. Bourne, T urbulent Mixing and Chemical Reactions John Wiley & Sons, Chichester (1999) 8.Nienow A.W., S.M. Drain, A.P. Boyes, R. Mann, A.M. El-Hamouz, and K.J. Carpenter, "A New Pair of Reactions to Characterise Imperfect Macromixing and Partial Segregation in a Stirred Semi-Batch Reactor," Chem. Eng. Sci., 47, 2825 (1992) 9.Fournier, M.C., L. Falk, and J. Villermaux, "A New Parallel Competing Reaction System for Assessing Micromixing Efficiency: Experimental Approach," Chem. Eng. Sci ., 51 5053 (1996) 10.Guichardon, P., and L. Falk, "Characterization of Micromixing Efficiency by the Iodide-Iodate Reaction System. Part I: Experimental Procedure," Chem. Eng. Sci., 55 4233 (2000) 11 Guichardon, P., L. Falk, and J. Villermaux, "Characterization of Micromixing Efficiency by the Iodide-Iodate Reaction System. Part II: Kinetic Study," Chem. Eng. Sci., 55 4245 (2000) 12.Schmalzel, J., A. Marchese, and R. Hesketh, "What's Brewing in the Engineering Clinic?" Hewlett Packard Engineering Educator 2( 1 ) 6 (1998) 13.Palmer, D.A., R.W. Ramette, and R.E. Mesmer, "Triodide Ion Formation Equilibrium and Activity Coefficients in Aqueous Solution," J. Solution Chem. 13 9, (1984) 14.Shacham, M., N. Brauner, and M.B. Cutlip, "Efficiently Solve Complex Calculations," Chem. Eng. Prog., 99, 10 (2003) While a thorough coverage of mixing and chemical kinetics is beyond the scope of most introductory chemical reaction engineering courses, this experiment introduces students to the field and illustrates the limitations of the idealized reactor models.

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100 Chemical Engineering Education Process design is the synthesis of a complete chemical operation as an assembly of unit operations. A key part of the design process is the selection, specification, and design of each unit operation so that the equipment will perform the specific function required. The equipment used in a chemical plant can be divided into two classes: proprietary and nonproprietary. Proprietary equipment is designed and manufactured by specialist companies, and its detailed design is not normally the responsibility of the chemical engineer. The chemical engineer is, however, required to select and size the equipment required for a specific duty, to consult with vendors to ensure suitability, and to carry out any customization that may be required.[1]This paper will focus on equipment selection to meet the design requirements. Process design and equipment selection by its very nature requires engineering judgment and subjective analysis, and is therefore a typical "semi-structured" task[2] in which neither judgment alone nor a rigorous procedure by itself is adequate. Equipment selection falls between structured (programmed) and unstructured (non-programmed) decisionmaking,[3] the complexity being principally a result of the large number of interacting criteria that have to be considered. In multiple-criteria decision-making problems, the engineer must combine conflicting measures to assess the desirability of different decision alternativesin this case equipment types. Often, much of the knowledge and design experience in an engin eering organization is not in a tractable form, but is based on the experience of individuals. This requires knowledge management[4] to develop some form of "institutional memory." Selection of proprietary equipment therefore involves three aspects: first, a thorough knowledge of the types of available equipment and their characteristics; second, a methodology to balance multiple criteria, which may include a combination of technical, legal, economic, and social aspects for selecting the most appropriate among the available choices; and finally, a sensitivity analysis to ensure that the choice is robust. When educating students on solving a specific aspect of chemical engineering that involves design and, more specifically, the selection of proprietary equipment, the pedagogic focus is often on introducing and explaining the types of equipment available and their operating characteristics. This descriptive focus is further evident in numerous design and process engineering textbooks that describe in detail the equipment and its sizing, but only give fleeting reference to making a selection from different types that may all be suitable. Selection is often based on flowcharts that eliminate alternatives, or on tables of properties. In general, any analysis of the sensitivity of the selection to changing conditions or requirements is neglected. From the point of view of both student and lecturer, theDECISION ANALYSIS FOR EQUIPMENT SELECTIONJ.J. CILLIERSThe University of Manchester Manchester M60 1QD, United Kingdom Copyright ChE Division of ASEE 2005 In this paper, a novel pedagogic approach . is offered in which students are taught how to develop a multi-criteria selection procedure and then how to implement such a system in practice. Jan Cilliers is Professor of Chemical Engineering the University of Manchester. Originally from South Africa, where he completed his BSc, MSc and PhD studies, he joined the University 10 years ago. In 2001 he graduated with an MBA from the Manchester Business School. It was during those studies that he developed an interest in decision-making methods and its application to teaching. His academic research focuses on froth and foam physics, in particular for application to mineral separations. ChEclassroom

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Spring 2005 101description of equipment application and sizing, while often interesting, is of less long-term and general value than either a robust methodology for making a selection between alternatives or for evaluating the robustness of that selection. The question is, however, how to teach the methodologies of equipment selection and analysis without neglecting the essential descriptive aspects. In this paper, a novel pedagogic approach to this dilemma is offered in which students are first taught how to develop a multi-criteria selection procedure and then how to implement such a system in practice. Multiple criteria decision analysis (MCDA) is a methodology for making decisions, such as equipment selection, in a rigorous and justifiable way. A particularly straightforward MCDA technique for equipment selection is "value tree analysis," which treats decision-making as a weighting problem in which the criteria are structured hierarchically and weighted by their importance. The value of the various equipment choices is then calculated from the weighted sum of the criteria. A particular benefit is that sensitivity analyses can be performed to ensure decision robustness. Value tree analysis as applied to equipment selection will be discussed in greater detail later in the paper. It is suggested here that by framing the equipment descriptions within a decision-making and analysis framework, a deeper understanding of the difficulties involved in making multi-criteria decisions will be imparted to the students, while the specific knowledge required to make sensible choices is emphasized. The example used in this paper deals with the selection of appropriate equipment for pollution abatement by removal of particulates from gases. The use of computer-aided learning for design was tested previously[5] when a knowledgebased system was used to evaluate student designs after the event. The approach used in this study is significantly different, howeverthe student's task is to develop a decision system for a specific application, and learning occurs through collation and transformation of equipment information into a useable and relevant form. The use of MCDAand in particular quantitative value tree analysisfor making design decisions is, of course, not new. Ulrich,[6] for example, gives a very clear description of its use in selecting chemical engineering process alternatives. It is of interest that he considers the method useful for indicating the superiority of one alternative over another, but does not consider the sensitivity of the choice to changes in priority. Sensitivity analysis is strongly emphasized in the teaching example given here.EQUIPMENT SELECTION USING CONVENTIONAL AND MULTICRITERIA DECISION ANALYSIS Conventional Selection Procedures Conventionally, the selection of gas-cleaning equipment for pollution abatement is largely qualitative and highly subjective. As an example, Table 1, abridged from Muir,[7] shows the problem attributes to consider and the qualitative measures within each attribute. Although not shown here in full, two tables of attributes to consider are given, with 11 primary and 14 secondary attributes. When using a table-based approach to make equipment selection, the less-suitable equipment is progressively eliminated until a final choice is made from the remaining selections. It is evident that it will be difficult to make and justify a choice between types of equipment based solely on such tables. In part, this is due to the highly qualitative measuresT ABLE 1Qualitative Equipment Selection Criteria (A limited selection taken from Ref. 7)Smallest particle sizeGas temperatureUser preferences to be collectedinlet to collector(if practical) Attributes 1-10Sub>400 C NearDryLow Initial micronmicronDewpointProductCost Alternatives CyclonesCareBeware Care W et Electrostatic Precipitator Beware BewareUnlikely Aggregate Filter Care Care Key Can generally cope with the process requirements if well designed Care Special attention required in plant design and operation to prevent problems Beware Could lead to severe operational difficulties; alternatives that avoid the problem are normally sought Unlikely On purely economic grounds, alternatives are generally favored if suitable

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102 Chemical Engineering Educationused in each attribute considered and the fact that they cannot readily be weighted by their importance to the particular design problem. Further, and of increasing importance, is the need for decisions to be justifiable. Qualitative selection procedures make objective justification of choices at a later date difficult. Multi-Criteria Decision Analysis (MCDA) In multi-criteria decision analysis using a value tree, the objective is the final choicein this case the most suitable type of equipment for the specific situation. Each type of equipment is an alternative and is described by a number of attributes as shown in Table 1. Each attribute has a real value, for example its capital cost. Attribute values are scaled using a value function to bring them to a common relative value range, usually between 0 and 1. The value functions can be linear or nonlinear and can be positively or negatively correlated with the attribute values. For example, a high real-capital cost can be scaled linearly to have a low relative attribute value, while a high realoperating cost may be scaled nonlinearly. In the simplest form, the decision problem is defined by weighing the importance of each attribute to the specific situation. For example, both capital cost and technical complexity may be rated very low when retrofitting gas-cleaning equipment to an old plant. The objective is achieved by considering the weighted sum of attributes for each alternative. A critical and largely neglected aspect of equipment selection and design is the sensitivity of the decision to changing circumstances and process conditions. For example, when selecting equipment for pollution mitigation where public health may be at risk, choosing equipment that fulfills only current legal requirements is highly risky. Changes in legislation, economics, and process conditions may lead to significant changes in specifications that must be met; choosing equipment with excess capability in the short-term may be a better long-term economic and political decision. Sensitivity analysis is not readily performed when confronted with highly qualitative selection criteria, such as shown in Table 1. When using MCDA, sensitivity analyses can be performed by considering the effect of changing each weight in turn on the decision made. The use of a robust decision-making procedure makes the potential for improving selection greater and the use of MCDA more attractive, not only for the design process itself but also for teaching and demonstrating the importance of sensitivity analysis during the design process. For teaching purposes, the procedure for developing an MCDA system was formalized into a highly structured, procedural approach, summarized as "The 5 Stages to Multi-Criteria Decision Analysis": 1.For each alternative (equipment), allocate a numerical value to each of the attributes (e.g., capital cost) 2.Scale the attribute values to a common range by applying an appropriate scaling function 3.In the context of the problem under consideration, allocate importance weightings to each of the attributes 4.Calculate the total weighted attribute scores for each alternative. The highest scoring alternative(s) form the basis of the initial selection 5.Perform a sensitivity analysis to assess the robustness of the decision The 5-stage procedure and its application to pollution-abatement equipment selection will be described in greater detail in the following sections.STRUCTURE OF THE TEACHING EXERCISEThe teaching module consists of two three-hour sessions. Previously, these were divided as follows:Session 1 Introduction to gas pollution problems, processes, and equipment Performance description: quantitative measures Other selection criteria: qualitative measures Session 2 Detailed equipment descriptions Equipment selection by elimination Selection of equipment: industrial examplesIt was decided that all the above material should be retained under the MCDA-based format. Since, in addition, decision making and MCDA had to be introduced, the following structure was implemented:Session 1 Introduction to gas pollution problems Detailed introduction to processes and equipment Performance description: quantitative measures Self-study: Detailed equipment descriptions Session 2 Other selection criteria: qualitative measures 5 Steps to an MCDA system Decision support systems: example (restaurants) On-line MCDA demonstrations: Restaurant selection Gas-cleaning equipment selection Student MCDA development exerciseIt can be seen that in the MCDA framework the basic descriptive element has been retained, but the detailed descriptions are relegated to self-study. Note further that a simple example is used to introduce the MCDA concepts and that this is augmented with an on-line demonstration. A further demonstration shows an MCDA for equipment selection. The module concludes with a computer exercise in which

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Spring 2005 103the students have to develop an MCDA of their own, on a topic of their own choosing. Examples of systems that have been implemented, in addition to equipment selection, are the selection of computers, cars, and jobs.THE TEACHING AND LEARNING EXPERIENCEThis section describes in more detail the teaching of the MCDA approach following the 5-stage format and its application to the pollution abatement problem. Some of the interesting problems and findings that were encountered are detailed, and the difference in the learning experience it brings to the students is illustrated. A class example of selecting a restaurant to suit a particular occasion is also detailed. The 5 Stages to MCDA The first two steps of the procedure are: Stage 1 Score each alternative (equipment) against each of the lowest-level attributes. Stage 2 Bring the score of each alternative to a comparable scale by applying an appropriate scaling function. The first two stages lead to development of an equipment database where the various pieces of information about the same attributes for all the available types of equipment are collated and brought to a common scale. During a teaching course, this defines the scope of the lectures and ensures that all the appropriate information is available for all the equipment to be discussed. Since the more tedious, descriptive material could be relegated to self-study in this way, the class time could be devoted to more interactive and exciting demonstrations, which is more satisfying for both students and lecturer. The MCDA approach also gives a clear structure in which the need for (and importance of) quantitative performance measures can be explained. Particular emphasis is needed on converting qualitative data to quantitative values and on the transformations required to bring all the data to a common scale. Referring again to Table 1, the qualitative measures associated with the efficiency of removing specific particle sizes can be quantified by introducing the partition curve, its calculation and interpretation. Similarly, the equipment capital and operating costs become true financial costs but must be scaled to a common throughput rate. T ransforming the other qualitative measures in Table 1 ( e.g ., gas inlet temperature, dry product) is more difficult and involves some subjectivity, but it can be seen that, in general, the qualitative criteria can be transformed to 0% or 100%, i.e ., the equipment is either unsuitable or suitable based on that attribute alone. Emphasis is given at this stage of the lectures to the concept of the "institutional memory" and knowledge management.[4] Using MCDA, an internally consistent database of equipment and their attributes is generated as a result of the above two stages, which captures this expertise in a form that is consistent and directly useable by the whole organization. It is of interest that, for the students, the least difficulty was with the mathematical transformations used for scaling, while the greatest was with allocating quantitative values to qualitative information as shown in Table 1. Stage 3 Allocate importance weightings to each of the attributes. This is done in the context of the process under consideration. Stage 3 is the first point at which the process design requirements are considered. Here an "importance weighting" is allocated to the scaled score, which quantifies its importance to each possible equipment choice. By explicitly making the distinction between the scaling (Stage 2) and weighting (Stage 3), the scoring of an attribute and its significance is decoupled, separating the process selection from the equipment that can be used. In the pollution abatement example, two highly disparate process examples were used for illustration: sawdust from a sawmill and catalyst dust in the offgas from a refinery. The students generally have either visited such plants or are able to visualize the problems. The sawmill produces a relatively coarse dust and requires a low-cost/low-maintenance solution in which the dust has to be kept dry. In contrast, the dust in the refinery may be extremely hazardous and therefore requires equipment with a high efficiency, and neither cost nor moisture is important. These two process examples clearly illustrate the importance weightings, as (for most attributes) the needs are very differe nt. For example, in Table 1, the importance ranking for the attributes of "submicron" and "dry product" will be at opposite ends of the scale for the sawmill and the refinery. Stage 4 The weighted attribute scores are added to give an overall score for each alternative. The highest scoring alternative(s) form the basis of the initial selection. At this stage the attribute values of all the equipment choices are weighted by the importance to the sawmill and refinery. Considering the alternatives given in Table 1, the appropriate equipment choice for each application is very clear. The mathematical function used for making the selection was also found to be of great interest. Conventionally, a simpleContinued on page 109.

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104 Chemical Engineering EducationAN AUTOMATED DISTILLATION COLUMNFor the Unit Operations LaboratoryDOUGLAS M. PERKINS, DA VID A. BRUCE, CHARLES H. GOODING, JUSTIN T. BUTLERClemson University Clemson SC 29634Douglas M. Perkins is a recent chemical engineering graduate from Clemson University. During his undergraduate career he worked closely with Dr. Bruce on designing and building multiple experiments for the Unit Operations Laboratory as well as being the lead student designer/ builder of the batch distillation column. David A. Bruce is Associate Professor in the Department of Chemical Engineering at Clemson University. He earned his BS degrees in Chemistry and Chemical Engineering and his PhD in Inorganic Chemistry from Georgia Institute of Technology. His research interests include heterogeneous catalysts with controlled pore geometries, advanced oxidation processes, and quantum and molecular mechanics modeling. Charles H. Gooding is Professor of Chemical Engineering at Clemson University. He earned his BS and MS degrees at Clemson and his PhD at North Carolina State University, all in chemical engineering. His teaching and research interests are in chemical process design, analysis, and control. Justin T. Butler is a recent chemical engineering graduate from Clemson University. He aided in building/designing the batch column.Distillation is one of the most common separation processes; hence, it is important for undergraduates to have some hands-on exposure to this unit operation during the course of their studies. Additionally, working with batch distillation towers provides students with an opportunity to experience and learn about a dynamic process that is widely used in the pharmaceutical and specialty chemical industries. It is equally important for undergraduate students to work with automated processes, since similar control features are commonly implemented in industry to reduce labor costs, provide greater processing flexibility, and improve process safety and product purity. For these reasons, an automated batch distillation column was designed and constructed on-site for the Clemson Unit Operations Laboratory (UO Lab). The pilot-scale tower uses sieve plates to separate a mixture of 2-propanol (IPA) and 1propanol (NPA). Some background information about the Clemson curriculum should be mentioned before going into more depth about this particular experiment. First, the senior-level UO Lab course consists of groups of students (typically three to four students per group) conducting four experiments during the course of the semester. Lab groups develop their own experimental procedures to accomplish the assigned objectives. They are given three three-hour lab periods to conduct each experiment, and the results of these experiments are presented either in writing or orally in front of a panel of their peers and professors. Having three lab periods to perform each experiment provides students with the ability to explore different aspects of a particular process and to collect enough data to explore statistical variations. Additionally, the process control course, while providing students with both the practical aspects and fundamental mathematical principles of control, has no lab associated with it. Therefore, students can only simulate how a change in a manipulated variable affects a process control variable using software such as Control Station.[1] Thus, the senior-level UO Lab course incorporates process control concepts into several of the classical unit operations so that students gain hands-on experience working with and tuning controllers in automated chemical processes. Ultimately, this better prepares them for work with complex, real-world processes than would conducting experiments with idealized processes, such as simple tanks in series.EQUIPMENTThough the basic design for the batch distillation apparatus was developed by Clemson faculty, the detailed design and most of the construction was accomplished by undergraduates involved in the project.[2] This afforded the students an opportunity to gain hands-on knowledge about metal machining and process engineering. The apparatus required approximately six months and $25,000 to build. The key components of the apparatus (shown in Figure 1) includeA 180-liter jacketed vessel (Owens Mechanical & Fabrica Copyright ChE Division of ASEE 2005 ChElaboratory

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Spring 2005 105The IPA/NPA system also exhibits relatively ideal behavior as indicated by the vapor-liquid equilibrium (VLE) data shown in Figure 2. This figure includes both experimentally measured data[3] and compositions predicted by a Margules activity coefficient model.[4] Binary parameters calculated by Gmehling[4] for other activity coefficient models are shown in Table 1 along with the mean deviations associated with each model. As can be seen in the table, all of the activity coefficient models do an excellent job at describing the VLE data for this non-azeotropic system. Another key design feature was the choice to use gravity, rather than a pump, to return reflux flow to the column. This necessitated that the pressure drop across all flow measuring/control devices be kept to a minimum. For this reason, Coriolis flow meters were chosen both for their accuracy and their lo w-pressure drop character istics. An added bonus in using the Cotion), which serves as the reboiler A 4-in. diameter glass distillation tower (Labglass) with six aluminum sieve plates vertically spaced 6 in. apart A single-pass shell-and-tube heat exchanger using water coolant in the tube side Coriolis flow meters (Micromotion CMF025) and pneumatic control valves (Fisher Rosemount 5100 valves with 3661 positioners) on both the reflux and distillate lines Data acquisition and control hardware and software (National Instruments).All vapor lines are 2-in NPT pipe and all liquid lines are 1/2-in NPT steel pipe. Additional information, such as vendor addresses, a wiring diagram, and a more detailed equipment list, are available upon request from Professor Bruce.DESIGN METHODOLOGYThe chemical system as well as several key components of the batch column were chosen to be similar to those previously used in another pilotscale distillation apparatus in the UO Lab. This was done because the previously built column had proven to be very safe to operate and there were well-established performance characteristics, such as optimal flow rates, heat duty for the condenser, and stage efficiencies. Specifically, the IPA/NPA binary system was chosen because: 1) the chemicals are relatively inexpensive; 2) they have low toxicity; 3) they have high short-term exposure limits (> 250 ppm); 4) fires can be extinguished by water, dry chemical powder, or CO2; 5) they have moderate vapor pressures (< 45 torr) at STP conditions; and 6) mixture compositions are easily analyzed by gas chromatography.T ABLE 1VLE Binary Parameters for Activity Coefficient Models of the 2-propanol/1-propanol System[4]Mean Activity Binary ParametersDeviation from CoefficientAIPA-NPAANPA-IPAExperimental ModelVapor Fractions Margules0.1321-0.06210.0046 V an Laar0.010025765.38000.0090 W ilson818.3291-481.05900.0048 UNIQUAC-399.2278575.09560.0050 Figure 1. Schematic for batch distillation apparatus. Figure 2. V apor-liquid equilibrium data for mixtures of 2-propanol and 1-propanol at 1 atm. Curve corresponds to compositions predicted using the Margules parameters listed in T able 1 and (*) represent experimental data collected by Ballard and Van Winkle, 1952.

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106 Chemical Engineering Educationriolis flow meters is that they can not only measure mass flow rate, but also volumetric flow rate, density, and temperature of the fluid in the pipes. The reflux and distillate control valves were selected for their ability to control low flows with a very small pressure drop across the valve. At first, an actuated ball valve was considered to allow for the low-pressure drop requirements, but after talking with several vendors it became apparent that a ball valve would not be a viable option, due to sizing difficulties. The selected needle valves were chosen based on their ability to meet the above criteria, specifically, a lowpressure drop across the valve and integral positioners for adjusting the needle. The Labview data acquisition and control software (National Instruments) was chosen because it has several key features that make it attractive for use in the UO Lab. These include low cost, widespread use across campus, user-friendly graphical programming language, and most importantly, preprogrammed algorithms for PID control of specified measurables. Labview can also log data that is acquired during an experiment ( e.g. temperatures, flow rates, and pressures) and store them in an Excel spreadsheet. This not only allows students to have more time during the lab period to observe column dynamics, but it also allows for post-lab analysis to be conducted virtually instantaneously. Another important aspect of Labview is the graphical user interface, which allows students to look at pictorial representations of numbers ( e.g., a virtual thermometer) instead of simply looking at the raw data/numbers. This interface also allows for plots of time variations in process variables to be continuously displayed so that students can easily observe when the process or a measured variable reaches steady state. Finally, safety limits can be programmed into the software, meaning that a student would not be capable of running the column under dangerous conditions, such as an over-pressurized reboiler. If a student did try to run the column at an unsafe condition, Labview would override the student's attempt and bring the column back within safe operating limits. A copy of the distillation control program used in Labview can be obtained from Professor Bruce.MODES OF OPERATIONThere are four basic modes of operation and control for the column: total reflux, constant distillate flow rate, constant distillate composition, and fixed reflux ratio. For all modes of operation, the liquid level in the sight glass is maintained at a setpoint using either the distillate or the reflux valve. Additionally, the column is currently operated so as to maintain a constant reboiler steam pressure (4-6 psi) for all modes of operation. Future exper iments may examine the possibility of manipulating the steam pressure to control the reflux or distillate rate. Initially, the column is started in total reflux. This is the simplest mode of column operation and involves control of only the reboiler steam pressure and liquid level in the sight glass. This mode allows the rising vapor and falling liquid to heat the tower. Once the column has reached steady state, the overall tray efficiency can be determined from composition analysis of samples collected from the top and bottom of the column. By varying the setpoint of the reboiler steam pressure, it is possible to determine how tray efficiency varies with vapor flow rate. The column can be operated in three other modes. Constant reflux ratio is used least often because it requires that the distillate and reflux valves be adjusted to maintain a constant fluid level in the sight glass as well as a fixed reflux ratio. Noise and interaction make this mode difficult to tune and operate in a satisfactory manner. Rather than filter the signals from the two Coriolis flow meters to improve control, a simpler yet related mode of operation has been used more commonly by the students. This mode of operation maintains a constant distillate flow rate, which is essentially the same as maintaining a fixed reflux ratio if the steam pressure remains constant and the composition of the pot does not vary significantly over the course of the lab period. The control scheme for constant distillate flow is very straightforward; the reflux valve maintains a constant fluid level in the sight glass, while the distillate valve controls the distillate flow rate. Common operating conditions maintain a distillate flow of 5 kg/hr and a reflux ratio of approximately 3. Running the column at a constant distillate flow rate allows the students to see how column temperatures and both the distillate and reboiler composition change over time. The final mode of operation is constant distillate composition. This is accomplished by adjusting the distillate flow rate to keep the temperature at the top of the column constant, while using the reflux valve to control the fluid level in the sight glass. The purity of the distillate product is checked periodically by GC to adjust the temperature setpoint or ensure that the composition is not varying.ASSIGNMENTSAs described earlier, each student group has three lab periods to work with the distillation column. Essentially, this allows for three different experiments to be run by each group. During the first day, students typically run the column in total reflux with preset controller tuning parameters and note changes in column operation and the visual appearance of liquid hold-up on the trays at different reboiler duties ( i.e. different reboiler steam pressures). Three or four conditions can be tested after the initial 30to 45-minute start-up time for the column to reach pseudo steady state. Temperatures are monitored and samples of liquid and vapor are collected

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Spring 2005 107for GC analysis from the sample ports indicated in Figure 1. On the second day the students start the column at total reflux and then shift to either a constant distillate flow or constant distillate composition mode to accomplish a particular assigned objective. The third day is typically devoted to basic closed-loop tuning exercises on the control loops (reboiler steam pressure, sight glass fluid level, distillate flow, or distillate composition). The controller tuning assignment can be made somewhat more challenging by making it the first-day task with little or no guidance on where to start.RESULTS/DISCUSSIONExperience during the first two semesters of operation has confirmed some of the design objectives, while at the same time revealing a few surprises. Overall the column has performed very well. The six trays yield approximately 4 equilibrium stages with the pot functioning as a 5th. The 60 to 70% range of tray efficiencies is consistent with predictions of various correlations for overall plate efficiency.[5] The constant distillate rate scheme can provide a distillate composition ranging from 60 to 80% IPA with an initial pot composition of approximately 25% IPA. The constant composition scheme can provide a small amount of product up to 70% IPA with the expected tradeoff between product quantity and purity. During initial column operation, the severity of reset windup[6] in the control loops was not anticipated. The basic controller logic provided by Labview did not include antiwindup, and the column was started with each loop configured for PI control. As a result, both the steam pressure and sight glass level control loops substantially overshot their setpoints, and the students were puzzled as to why the control loops "didn't work." It is relatively easy to program antiwindup measures into Labview, but the faculty decided not to do this. Having the students experience setpoint offset and reset windup first-hand rather than just hearing the principles behind them in class is thought to be highly beneficial. The students are initially told to turn off integral action before starting the program, and leave it off until each control variable nears its setpoint. This allows them to observe the offset, which disappears when integral action is added. Later they are told to make substantial changes in setpoint, which allows them to observe reset windup when the controller fails to reverse the control action until the controlled variable is well past the setpoint. Another anomaly in the column is a tendency to drift and exhibit hysteresis during total reflux operation. This means that the "steady state" conditions seemingly change during the course of a lab. In essence, students believe that they have reached a steady-state condition as evidenced by constant fluid level in the sight glass and apparently constant temperatures and flow rates, but closer observation shows that the temperatures and flow rates tend to drift slowly. Also the apparent steady-state temperatures and flow rates one achieves at a particular reboiler duty/steam pressure may actually depend on the history of the steam pressures used since startup. The main reason for this anomalous behavior is thought to be heat loss from the uninsulated column. Essentially, each glass section has to heat up to the temperature of the vapor and liquid inside the column before it can correctly be considered to be at steady state. To minimize this drift and cut down on startup time, students are initially told to start the reboiler with a high steam pressure of 10 psig until condensate begins to leave the condenser, and then return the steam pressure to the desired operating condition. Once the column has reached steady state, the response time for the controlled process variables is rather fast. The reboiler steam pressure, distillate flow rate, and sight glass fluid level respond fully to a change in setpoint in less than a minute. When the steam pressure is changed, however, it takes approximately 5 to 30 minutes for the column to reach a new steady state, depending on the magnitude of the change. When controlling the exiting vapor temperature (distillate composition) at the top of the column, the response time is approximately one to two minutes depending on the size of the change in setpoint. An example of batch column performance when operated in constant distillate flow rate mode is shown in Figure 3. The column was initially allowed to reach steady state conditions at total reflux before data collection began. Specifically, Figure 3 shows how changes in distillate flow rate and sight glass level setpoints affect the sight glass level, reflux mass flow rate, temperature on the top tray of the tower, and distillate mass flow rate. The following changes in setpoint were used for this study: 1) at 48 seconds, the distillate flow rate setting was increased from 0 to 5 kg/h; 2) at 86 seconds, the distillate flow rate was increased further to 10 kg/h; 3) at 402 seconds, the sight glass level setpoint was changed from 28 to 27 inches; 4) at 546 and 599 seconds, the sight glass level setting was increased by 1 inch; and 5) at 734 seconds the distillate flow rate was changed from 10 to 7 kg/h. As mentioned earlier, the column rapidly adjusts to changes in both distillate flow rate and sight glass level; however, the temperature within the column and purity of the distillate stream are much slower to respond, as evidenced by the slow rise in temperature of the top tray of the tower. This increase in temperature is the result of less separation in the tower, which is caused by the reduction in reflux ratio. Additionally, it can be observed that the sight glass level controller is tuned much more tightly than one would normally operate in industry. Most industrial operators would prefer to let the level adjust slowly and not subject the column to dramatic changes in reflux flow rate that could affect product purity. The undergraduate students who built this batch column certainly gained from the experience by designing and build-

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108 Chemical Engineering Education Figure 3. Non-steady-state operational data from the batch distillation tower.ing a real process. The students were involved in, and for the most part headed up, the design of the column from the beginning. They learned how to communicate with equipment vendors, how to recognize the need for and implement design changes during construction, and how to make other daily engineering decisions based on their classroom experience. Finally, these students learned that start-up of a new process is as much about troubleshooting as it is about testing the capabilities of the equipment. In essence, the student builders were able to see what they would likely do as an entry-level process engineer, while at the same time solidifying the application of classroom theories in all aspects of the design. UO Lab students who operate the automated batch distillation apparatus benefit in several ways. All of our lab experiments require the students to investigate background information and prepare a brief literature review on the subject, to design an experiment (logically, if not statistically), to write an operating procedure, to evaluate their procedure for safe operation, to present their plans for approval before running the experiment, to op erate the equipment, to collect data, to analyze their data, and to prepare a final report. And, of course, all of these experiences involve teamwork. This particular experiment involves one of the most common unit operations used by chemically related industries. The experiment is driven primarily from a computer interface, much like the control room environment students will encounter in industry; unlike industry, however, the actual apparatus is only five feet away. The glass column allows the students to observe tray phenomena, such as weeping and entrainment flooding. Specific assignments can be varied so that the students learn how to achieve an operating or production objective, such as a specified distillate purity. The control environment provides hands-on experience with numerous concepts that might remain abstract if taught only in the classroom or even if supplemented with computer simulations. Some of the concepts we have explored already include offset, reset windup, control valve saturation, loop interaction, and nature and magnitude of disturbances. There are surely others that experience and ingenuity will reveal.CONCLUSIONSThe batch column performs in a manner similar to that of a typical industrial column with an overall tray efficiency ranging from 60 to 70%, a distillate composition ranging from 60 to 80% IPA for the constant distillate mode when there is 25% IPA initially in the still pot, and up to 70% IPA for the constant composition mode. The inherent characteristics ( i.e., graphically based interface) of the Labview software make operating the column easy. Once the students gain a little experience with the controllers, they are able to manipulate and optimize the process in a control room environment, while at the same time observing common tray phenomena and the effects of different operating conditions on column performance. Finally, the students are able to gain insights into aspects of process control that might otherwise elude them in class work or simulation assignments alone.ACKNOWLEDGMENTSThe authors would like to thank lab technologist Bill Colburn for the many hours he spent helping program the software and piping water and steam to the column. Additionally, they would like to thank the National Science Foundation (CAREER-9985022) and Dow Chemical Company for financial support.REFERENCES1. Cooper, D., Control Station (Computer software), Control Station Tech (2001) 2.Bruce, D.A., R.W. Rice, and C.H. Gooding, "Educational Outcomes from Having Undergraduates Design and Build Unit Operations Lab Equipment", to be submitted to Chem. Eng. Ed. (2005) 3.Ballard, L.H., and M. Van Winkle, "Vapor-Liquid Equilibria at 760 mm. Pressure," Ind. Eng. Chem. 44 2450 (1952) 4.Gmehling, J., and V. Onken, V apor-Liquid Equilibrium Data Collection Dechema, New York (1977) 5.Seader, J.D., and E.J. Henley, Separation Process Principles John W iley & Sons, New York (1998) 6. Riggs, J.B., Chemical Process Control 2nd ed., Ferret Publishing, Lubbock, TX, (2001)

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Spring 2005 109weighted sum is used. In cases where any choice is completely inappropriate, however, the form does not reflect this. Therefore, it must be emphasized that, since the MCDA methodology evaluates all the equipment available, completely unsuitable equipment may still appear as a possibility based on other attributes, and the answers must be interpreted intelligently. Ulrich[6] describes an elegant approach to interpreting the results in which the attributes are divided into "wants" and "musts." Equipment that does not satisfy the "musts" is eliminated before considering the remaining alternatives. Again, this modification was not difficult to explain and was readily understood. Stage 5 A sensitivity analysis is performed. Sensitivity analysis was found to be difficult to convey adequately without the benefit of a demonstration. An online demonstration during the lecture is highly effective for illustrating the importance and benefit of sensitivity analysis. The further benefit of performing this on-line is that the number of equipment alternatives is far greater, and the best choice is less obvious. The importance and utility of sensitivity analysis can be shown using the refinery case study. For example, either filters or electrostatic precipitators (Table 1) may be a suitable solution for the problem. The optimal choice, however, can be changed by changing the importance weighting given to submicron particles. This may be the result of future changes in legislation or adverse publicityboth graphic illustrations. Additional T eaching Example: Choosing a Restaurant If required, the 5-step procedure can be illustrated quickly and simply using the example of selecting a restaurant. This is a particularly good class example, as it allows vivid scenarios to be painted, e.g ., dinner with a partner or the boss, a quick meal before theater, etc. Further, the institutional memory concept became very clear, and the students suggested that it could be used as the basis for an Internet restaurant selection facility. With relatively few attributes ( e.g ., cost, quality, and service) and a small number of restaurant types ( e.g., fast food, steakhouse, and expensive), a simple sensitivity analysis can be performed during the lecture. A number of complex issues are also highlighted using the restaurant examplein particular the importance of clarity in attribute specification. For example, the attribute "Duration of meal" could refer to either long or short, and is better stated as "Meal takes long," which may be weighted high or low. This example attribute can also be confused with "Service quality," which is best incorporated as a further attribute. On-line demonstrations and exercise An excellent set of on-line decision support tools has been developed by the Helsinki University of Technology and is available at no cost on the Internet.[8] From this toolbox, WEBHIPRE was used for on-line demonstrations. The output from WEB-HIPRE is highly visual, particularly in regard to the sensitivity analysis, which aids understanding. Further, the system is intuitive to use, and the students can readily develop their own systems during the exercise. Course assessment Examining the course has been made more flexible with the MCDA approach. Instead of relatively predictable descriptive examination questions, MCDA can be used either as a project assessment, or more flexibly in a conventional examination. Student feedback to date has been very positive, and the course rating has improved markedly. It is clear that the students find the approach novel and useful, and the teaching enjoyable.CONCLUSIONSThe use of MCDA as a framework for teaching the selection of equipment for gas pollution abatement was very successful. In particular, two aspects were highlighted that otherwise would not have beenthe development of an "institutional memory" and the importance and utility of sensitivity analysis. The students enjoyed the class, and the use of interactive computer techniques was found to be exciting. It has been stated[9] that a hard problem addressed with support for successfully solving and reflecting on the problem will lead to deep, transferable knowledge and skills. It is believed that the MCDA approach gives the support required, and that this approach is particularly appropriate for the teaching of "hard problem" design-type courses.REFERENCES1.Sinnott, R.K., Coulson & Richardson's Chemical Engineering, Volume 6 Pergamon Press, Oxford, UK (1993) 2.Keen, P.G.W., and M.S. Scott Morton, Decision Support Systems: An Organizational Perspective Addison-Wesley, MA (1978) 3.Simon, H.A., The New Science of Management Decision, Harper and Row, New York, NY (1960) 4.Macintosh, A., I. Filby, and J. Kingston, "Knowledge Management T echniques: Teaching and Dissemination Concepts, Intl. J. Human Computer Studies 51 3, 549 (1999) 5.Toll, D.G., and R.J. Barr, "A Computer-Aided Learning System for the Design of Foundations," Advances in Eng. Software 29 7, 637 (1998) 6.Ulrich, G.D., A Guide to Chemical Engineering Process Design and Economics John Wiley & Sons, New York, NY (1984) 7.Muir, D.M., Dust and Fume Control A User Guide IChemE, Rugby, UK (1992) 8. 9.Guzdial, M., et al. "Computer Support for Learning Through Complex Problem Solving," Communications of the ACM 39 4, 43 (1996) Decision Analysis for Equipment SelectionContinued from page 103.

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110 Chemical Engineering Education Drawing the Connections BetweenENGINEERING SCIENCE AND ENGINEERING PRACTICEFAITH A. MORRISONMichigan Technological University Houghton, MI 49931-1295Change is a fact of life, and engineers make their careers out of bringing about changes in their surroundings. In today's chemical engineering departments we hear of the need for changes in our institutions and methods. Alumni, employers, and researchers in the field bring back news of the need for new priorities for the curriculum the need for students to have more teamwork experience, to develop better communication skills and critical thinking skills,[1] and to acquire specialized knowledge in emerging areas such as bioand nanotechnology. In addition, there is continuing pressure for better preparation of graduates in each of the established, and diverse, fields in which chemical engineers find employment. The passive approach to these demands would be to pack more and more into the chemical engineering curriculum, extending the undergraduate years and demanding more of the students. This runs counter to other institutional and national priorities, however, that demand high four-year graduation rates and low overall costs for undergraduate education. Finding a solution to a problem amid seemingly contradictory requirements is the exact task that the practicing engineer faces on a daily basis. We can find a solution to the pedagogical dilemma posed above by following the same engineering problem-solving processes we seek to develop in our students. We should begin by defining the problem as we perceive it and exploring the context in which the problem presents itself. We then can bring our own expertise and experience and the expertise and experience of others to bear on the problem, seeking clarification and (hopefully) a solution. Finally, we test the proposed solution and evaluate its effects, feeding back our observations into a refined solution as we iterate and hopefully converge to the best solution. What is the best way now and in the future to educate a chemical engineer? To address this question we need to reflect a bit on what a chemical engineer iswhat abilities and expertise is a chemical engineer expected to have? How are these abilities different from those of other engineers and scientists? How has the field of chemical engineering survived throughout a century of tremendous change? What are the strengths and weaknesses of the chemical engineering education we currently deliver? Before there were chemical engineers, there were mechanical engineers who worked in the chemical process industry along with industrial chemists who had become experts in large-scale production. The industrial need for individuals with chemical and engineering expertise suggested (to some) the establishment of a new discipline. Chemical engineering thus had very practical and industrial roots and an instant identity crisisare the practitioners chemists or are they engineers? And, if they are something altogether new, how are they different from the chemists and engineers who have been doing the job up until now? The answer for the early founders of our discipline was that chemical engineers were specialists in the chemical process industriesin particular, experts on unit operations. The Copyright ChE Division of ASEE 2005 Faith Morrison is Associate Professor of Chemical Engineering at Michigan Tech, where she has taught for 15 years. She is also the author of Understanding Rheology (Oxford, 2001), an undergraduate textbook on nonNewtonian flows, and is the undergraduate advisor for chemical engineering at Michigan T ech. Her research is in polymer rheology and viscoelastic phenomena. This paper is dedicated to Professor Philip W. Morrison of Case W estern Reserve University, who passed away in 2002. ChEcurriculum

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Spring 2005 111organization of chemical processes around a finite set of unit operations established both an identity and a pedagogy that could carry the new field forward. The unit-operations paradigm served the field well through W orld War II, but the maturing of the commodity chemical industries through the 1950s led to some new challenges for the discipline. Faced with a dwindling need for chemical engineers to do classical chemical-plant engineering, the field adapted to new technologies (polymers, electronics, nuclear power) and claimed them as fields addressed by chemical engineering. This was possible because a new paradigm was adopted in engineering educationthe engineering-science paradigm. By moving down in length-scale from the processunit scale (unit operations) to the molecular scale (transport phenomena, chemical kinetics, thermodynamics), chemical engineers could broaden the number of fields to which they could apply their analytical skills and methods. In the last 100 years, therefore, chemical engineers have established themselves as problem solvers in the field of chemical processes, including both large-scale chemical manufacturing processes and molecular chemical processes. The key to the survival of the discipline was the ability to adapt to changing economies and technologies while retaining a fundamental, and valued, expertise. How do we currently educate a chemical engineer? While the chemical engineering curriculum varies from place to place, there is a general structure, shown in Figure 1. Industry-specific content is addressed in the practice courses (unit operations, design, controls) and is also addressed in the curriculum by including elective courses that allow students to follow their interests. These elective courses ( e.g ., polymer engineering, environmental engineering, business, biochemistry, bioprocess engineering, etc.) are sometimes offered from within the chemical engineering department, but are often courses taught outside of chemical engineering. Within one of the fundamental courses there may also be some exposure to industry-specific content, depending on how the particular instructor implements his or her course. Many of the more recently published textbooks also go to some lengths to include individual problems or case studies that draw from a wide range of industries. Due to the emphasis of most textbooks, however, it is also possible (even probable) to complete an entire undergraduate chemical engineering degree without considering any chemical processes outside of the commodity-chemical or petroleum industries. What are the challenges and changes that must be addressed? If technology and society remained stagnant, no changes in an effective curriculum would be needed. Two questions should be asked, therefore: Is our curriculum effective as is? What changes in technology and in society have taken place, or are anticipated to take place, that might affect the chemical engineering curriculum? To address the effectiveness of our curriculum, we need to assess the experiences of our students, our alumni, and their employers. The good news is that chemical engineers are still in demand in industry, the current employment downturn not withstanding. Salaries for chemical engineers still top the list of engineering salaries, and employers have often shown a preference for classically trained chemical engineers over more specialized engineers ( e.g ., environmental, biomedical, materials) because of the versatility of the chemical engineers. There is room for improvement, however, as reflected in alumni surveys and in discussions with industrial advisors. At Michigan Technological University we have surveyed our alumni and industrial partners and some of the common concerns are given in Figure 2. High on the list of comments is Fundamentals Physics, chemistry, math, liberal arts, general education Mass/energy balances Thermodynamics T ransport phenomena Chemical reaction kinetics/reactor design Practice Process Control Staged operations Unit operations Process design ElectivesT echnical (chemistry, biology), engineering One particular kind of practice (petroleum or commodity chemical processing) Figure 1. Outline of the current chemical engineering curriculum, organized into fundamentals, practice, and electives. The key to the survival of the discipline [is] the ability to adapt to changing economies and technologies while retaining a fundamental, and valued, expertise . . Today's chemical engineering degree represents something of value to employers, but changing technologies and changing conditions in the workplace put new demands on the education of a chemical engineer.

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112 Chemical Engineering Education Common Curricular Feedback Don't know bioengineering and other cutting-edge fields Don't use math after graduation T oo much petroleum processing in curriculum Electives are taken for convenience instead of as part of a deliberate educational plan No time for undergraduate research T eamwork Communication skills Need more emphasis onCritical thinking Learning versus teaching Lifelong learning Figure 2. Summary of some curricular feedback received from alumni and industrial partners.that alumni and industrial partners would like to see an increase in teamwork experience and an improvement in communication skills, critical-thinking skills, and learning skills in chemical engineering graduates. Richard Felder has reported similar responses from NC State alumni.[2]Changes in technology and in society challenge the curriculum as well. New technologies, including biotechnology and nanoscale engineering, are a vibrant part of chemical engineering research and a potential source for growth in chemical engineering employment. Fundamental changes have also taken place at colleges and universities in the last twenty years. Research is now a central activity at most universities, and for public universities the proportion of support coming from state governments has fallen to an average of only 32% of total expenditures.[3] The university degree has never been more popular, howevera fact that itself brings its own challenges since there are increasing numbers of underprepared students in need of remedial work and special attention. These changes at universities have been accompanied by double-digit tuition inflation, reflecting the broadened mission of the university and the decrease in state support for the universities' missions. Paradoxically, decreasing public funding for universities has been accompanied by calls for tuition controls, for sanctions for universities with poor four-year graduation rates, and for reduction or elimination of remedial programs.[4,5]Thus, we face a dilemma. Today's chemical engineering degree represents something of value to employers, but changing technologies and changing conditions in the workplace put new demands on the education of a chemical engineer. In addition, our universities themselves have gone through a fundamental change, increasing their research emphasis, broadening their missions to include less-well-prepared students, all the while facing financial challenges. How can we preserve what is right about chemical engineering education while adjusting to these new realities?CONTENT VERSUS PROCESSAt the end of the day, the chemical engineering curriculum is a list of courses (experiences) that are required by an academic department. These courses have contentsubjects that are presented, explained, practiced, and mastered. Part of the educational process requires that the student master the content of the courses. Often this is the part on which we concentrate. The debates over chemical engineering curricula are usually discussions of content. Another part of a student's education is the experience of confronting the material and structure of a coursethe process of mastering the content. The educational process includes interactions with faculty and peers, managing time, working in groups, and developing and implementing a learning strategy for a course. We do not test on the mastery of process. Or perhaps we do, indirectly, since students who succeed in mastering content usually do so because they have mastered processthey are able to determine the goals of the course, and they plan their conduct to allow them to succeed. As the education scholar Jerome Bruner[6] notes, "To instruct someone. . is not a matter of getting him to commit results to mind. Rather, it is to teach him to participate in the process that makes possible the establishment of knowledge." As we assess and redesign the chemical engineering curriculum, we may ask ourselves, "Do we need to revamp the content? Or should we concentrate only on process and presume that whatever technical content is covered or omitted will be addressed in the graduate's subsequent career?" A graduate who has mastered the education process, in fact, sounds very much like the ideal engineer: a person who is able to learn new topics, work in teams, communicate effectively, focus on goals, and develop strategies to solve problems. To a certain extent, we have always relied on content not mattering too much, since it has always been important for engineers to be able to adapt to new technologies (lifelong learning).

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Spring 2005 113Shall we conclude then, that, within reasonable bounds, content does not matter? We can examine two case studies to explore these questions.Case IIs Content Important? Developing Writing Skills in Engineering I had been frustrated by the quality of unit operations laboratory reports, and I volunteered to teach the technical communications course to see what could be done to improve it. The previous instructors had shown the students how to write a proposal and then asked them to write a proposal of their own. The topic of the proposal could be anything they wishedit did not need to be technical. I wanted to see if this could be improved upon. I formulated the hypothesis that the students needed more technical content in their writing exercises in order to gain proposal-writing skills. In my section of the course, I asked the students to write an essay on why fluid mechanics is important to chemical engineers. The results of this assignment were uniformly terrible. The students were unable to "find" the answer to the question, so they simply wrote appropriatelength texts consisting of paraphrases from various textbooks and submitted them as their essays. They appeared to not know how to write even cogent sentences. Frustrated with this outcome, I gave them a focused lecture on a new subject and asked them to write an essay explaining back to me the content that I provided. Specifically, I gave a lecture on how to produce good technical writing and asked the students to write an essay explaining the important features of good technical writing. The results of the second assignment were uniformly excellent. Each essay began with the appropriate introduction and statement of the problem. The three key content components on which I had lectured were listed. A final paragraph was constructed that summarized the essay. What was the difference in the two assignments? In the first assignment, I gave them an open-ended problemthey had to first find the content that they needed to report on in the assigned essay. The students did not know why fluid mechanics is important to chemical engineers, however, and they did not know how to find out In the second assignment, I spoon-fed them the content ahead of time, and they repeated it back to me using writing skills that they possessed. For the first assignment, critical thinking and problem-solving skills were essential and apparently lacking in the class. What had looked like a writing-skill deficit had turned out to be a deficit in critical-thinking/problem-solving skills. Conclusion: Content in this case the decision to confront the students with a specific question that required analysis, reflection, and discovery rather than simple disgorgement of presented materialcan be critical. We may be guilty of content errors in our chemical engineering curriculum. For example, we show students how to make tray-by-tray calculations on a distillation column. We then ask them to make such calculations. They succeed. When they arrive at their senior year in unit operations laboratory however, they may fail to recognize that the open-ended or ill-defined problem they have been asked to solve requires a tray-by-tray calculation on a distillation column. We may not have taught them how to determine what calculations are necessary.Case IIIs Content Important? The Process of Problem Solving. There was once a television commercial that touted the Internet as the place to find the answers to any questions one might have. In the advertisement they listed a question of fact that was quite obscure, and, using an Internet browser, they found the answer in seconds. The implication was that any question you might formulate could be answered easily if you have an Internet connection. We all have enough Internet experience to know that this is not true. Going to an obscure site and formulating a question that is answered by that site is a far cry from having a specific need and actually finding a reliable answer to the question. In order to do the latter effectively, you need problemsolving skills and experience. To find information effectively, one must learn the process of finding information. The process is something like the following: A process for finding information or solving a problem:1.Know where to start 2.Slog through unfamiliar nomenclature 3.Struggle with missing background (on your part) in the subject 4.Return to fundamentals for a refresher 5.Seek out experts presuming you can determine what kind of expert you need 6.Postulate a solution (a location for your information) 7.Evaluate the accuracy of the solution, appropriateness of assumptions 8.Return to the appropriate step and repeat, depending on what you find and decideIn the case of the Internet search engine advertisement, they made finding something on the Web look incredibly easy because they skipped every one of these steps. They knew the answer they wanted ahead of time and went right to it. This is analogous to assigning homework or exam problems that are just like the examples in the bookstudents become accustomed to this practice and come to believe that the practice of engineering will be an exercise of finding a previously solved problem that is similar to the problem presented to them. Conclusion: Skipping process prevents learning.

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114 Chemical Engineering EducationReturning to our topic, is content important? The answer we arrive at is yes. And no. Content is important (Case Study I) in that it must be real, open-ended, specific, and, although we did not discuss it, it must integrate physical and chemical principles that are fundamental to the types of problems that are faced by chemical engineers. Content is not important in the specifics, however (Case Study II), since problem-solving process is generic and common to all types of engineering (and nonengineering) problems. We cannot teach chemical engineering without specifics, i.e., without choosing content. But an engineering graduate who studies petroleum processes should be able to design a lysine fermentation process with recourse to additional materials and by consulting knowledgeable expertsif that graduate has mastered critical thinking and problem solving. And likewise, an engineering graduate who studied fermentation reactors should be able, with some backfilling of missing or forgotten techniques, to confront distillation-column design.A PROPOSAL: RENEWED EMPHASIS ON INTEGRATIONThere has been much discussion on improvements to engineering education in the last decade, including calls for more integration of engineering practice,[7] adoption of cooperative learning methods,[8] expansion of the engineering degree to a five-year degree,[9] changes in faculty reward structures,[10]and insertion into the curriculum of international experience and the studies of ethics,[11] government regulation,[12] and many other subjects.[13-15] These ideas have merit, but wholesale change is expensive, time consuming, and often unrewarded. We have discussed the question, what is the best way now and in the future to educate a chemical engineer? In addressing this question we have found good things about the current method. We have also identified some challenges to maintaining the quality of the chemical engineering curriculum. Finally, we have discussed the curriculum as being composed of two componentscontent and process. Content and process are delivered together, and it is in the specifics of how this is done that we see an opportunity to address some of the challenges identified above. The typical chemical engineering curriculum in 2005 requires roughly two years of science and mathematics study followed by a year of discipline-specific engineering science followed by a capstone senior experience. Engineering practice, therefore, is left until senior year (or late in the junior year), in large measure because of the need to build on the prerequisite material. To improve this curriculum we need to strengthen the exposure to engineering practice, make room for new subjects, and bolster teamwork and communication skills. These challenges can mostly be addressed by attending to the integration of chemical engineering practice into the delivery of the existing subjects. All courses can strengthen students' mastery of chemical engineering practice by increasing attention to problem-solving process. While it is true that sophomores and juniors are not ready to tackle full-fledged engineering design, the problem-solving process used in chemical engineering senior design is the generic problem-solving process we discussed above. This process can be integrated into the first-year, sophomore, and junior courses by using open-ended problems and by assigning homework that stretches students beyond the "pattern recognition" response. Such problembased learning methods[16,17] have been advocated by many on a wide scale, but it is also possible to implement it piecemeal to good effect. Elective courses in engineering can broaden students' exposure to new fields while also strengthening their problemsolving/critical thinking skills. To do this, engineering/technical electives need to be designed to emphasize the problem-solving process. Engineering/technical electives need to make explicit the connections between engineering-science background material (math, sciences, introductory engineering subjects) and the types of problems that are tackled in the elective. New textbooks that emphasize integrated problem-solving process can be written and adopted. An instructor's greatest ally when designing a course is a well-written textbook. The textbook is not just a compilation of notes on a subject, however. An instructor dedicated to integrating problem-solving process into a course may do so with almost any text, but the whole process is made much easier if the textbook is designed with the problem-solving process in mind. Integration exercises can be added to all courses. Integration exercises[18] are activities or classroom exercises that serve to bring together subjects that have been studied independently. Classroom exercises could integrate mass and energy balance concepts, staged-operations concepts, and various mathematical and chemical concepts into one whole. The result will be a greater understanding of chemical processes and a greater appreciation of how all the pieces of a chemical engineering education fit together. Co-ops and undergraduate research can be emphasized. Co-ops and undergraduate research are two classic ways in which students have gained exposure to engineering practice and problem solving. These are excellent sources of integration between engineering science and engineering practice and should be encouraged. Academic advising can be recognized as an important piece also in integrating engineering science and engineering practice. Beyond helping students to plan their schedules, academic advisors can discuss with students the trade-offs of various choices for engineering/technical electives as well as

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Spring 2005 115the potential benefits to taking a minor or masters in a particular subfield. The discussion with the advisor is an integration exercise in itself. It can challenge the student as to what are his/her goals in making these choices, and it can challenge the student to articulate those goals effectively. Finally, the senior design class, both traditional and nontraditional, can be retained and refined as the mainstay of integration of engineering science and engineering practice in the chemical engineering curriculum. T raditional senior design has students pulling together all their background studies to design chemical plants, typically in the commodity chemicals industry. More nontraditional approaches could range from choosing less classical design problems all the way to alternate design experiences such as working on interdisciplinary design teams with other majors, such as in the Engineering Enterprise Program we have at Michigan Tech.[19]SUMMARY AND CONCLUSIONSAn engineering problem-solving approach has been applied to the problem of evaluating and seeking to improve the chemical engineering curriculum. Various demands on the curriculum may be seen as different views of the same desire: the desire for a chemical engineering graduate to be wellversed in the processes of problem solving that can be applied to any of the diverse fields employing chemical engineers. To educate engineers in these processes, we must use specific, real systems for study and calculation, and the need to specialize in this way may seem to narrow the education of the engineer. This need not be the case, however, if proper notice is taken of the processes used to solve the problem, and if the proper connections are drawn between the engineering science background common to all chemical engineering problems and the specific chemical engineering practice confronted in the classroom. As Bruner[6] notes, "To instruct someone. . is not a matter of getting him to commit results to mind. Rather, it is to teach him to participate in the process that makes possible the establishment of knowledge." Engineering graduates from Michigan Technological University have long been valued by employers for their ability to "hit the ground running." In the current decade, however, the number of fields in which a chemical engineering graduate can find employment is impossibly broadour graduates cannot possibly "hit the ground running" in every field. We need to change our approach so that our graduates "hit the ground jogging"no matter the field in which they land, they should land in motion, and they should be able to rapidly ramp up as they acquire the specific knowledge they need to succeed in their chosen field. The key to "hitting the ground jogging" is an education that emphasizes learning the process of engineering problem solving through a deliberate and widespread integration of fundamental knowledge (engineering science) with practical application (engineering practice).ACKNOWLEDGEMENTSMany thanks to the colleagues who read and gave feedback on previous drafts of this paper.REFERENCES1.Hannon, Kerry, "Educators are Struggling to Prepare Well-Rounded Engineers for Today's Workplace," Prism 12 (9), May-June 2003: 2.Felder, Richard, "Random Thoughts: The Alumni Speak," Chem. Eng. Ed. 34 (3), 238 (2000) 3. Selingo, Jeffrey, "The Disappearing State in Public Higher Education," Chron. Higher Ed., 49 (25) A22, February 28 (2003) 4.Burd, Stephen, "Colleges Catch a Glimpse of Bush Policy on Higher Education, and Aren't Pleased," Chron. Higher Ed., A25 March 8, (2002) 5.Burd, Stephen, "Education Department Wants to Create Grant Program Linked to Graduation Rates," Chron. Higher Ed., 49 (17), A31 January 3 (2003) 6. Bruner, Jerome S., The Process of Education Harvard University Press (1966) 7.Cussler, E., "What Happens to Chemical Engineering Education," ConocoPhillips Lecture Series in Chemical Engineering given at Oklahoma State University, Stillwater, OK, March 1, (2002): 8.Johnson, Roger T., and David W. Johnson, "The Cooperative Learning Center at the University of Minnesota," 9.The push for a 5-year degree was felt at Michigan Tech from both industrial advisory board members and from faculty members concerned that room needed to be found for new topics and also in recognition of the reality that many students were taking 5 years to obtain their BS degree. 10.Felder, Richard, "The Myth of the Superhuman Professor," ConocoPhillips Lecture Series in Chemical Engineering given at Oklahoma State University, Stillwater, OK, May 1, (1992) 11 Grose, Thomas K., "Opening a New Book," ASEE Prism, 13 (6), 21 February (2004) 12.Creighton, Linda, "School for Wonks," ASEE Prism 13 (6), 37, February (2004) 13.Meyers, Carolyn, and Edward W. Ernst, "NSF 95-65 Restructuring Engineering Education: A Focus on Change," Report of an NSF Workshop on Engineering Education, August 16, (1995) 14.Augustine, Norman R., Rebuilding Engineering Education," Chron. Higher Ed., May 24 (1996) 15.Subrata, Sengupta, "The Center For Engineering Education and Practice: Rethinking Engineering Education" accessed February 16, 2004; the Center is associated with the College of Engineering and Computer Science at University of Michigan Dearborn. 16. University of Delaware, Web site on Problem Based Learning, and references cited therein. 17.Felder, Richard M., "Changing Times and Paradigms," Chem. Eng. Ed., 38 (1), 32 (2004) 18.Wenger, Win, "The Other End of Bruner's Spiral: A Proposed Educative Procedure for Easy Integration of Knowledge. A Learning Model for Summer School in College or High School," Project Renaissance, (301) 948 (1987) accessed September 25, 2003. 19.Michigan Tech's Enterprise Program gives teams of students the opportunity to participate in real-world settings to solve engineering problems supplied by industry partners. The program prepares students for the challenges that await them after their education, and gives new perspectives to sponsors, businesses, and organizations who participate. On the Web at

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116 Chemical Engineering EducationToday it is well accepted that courses on process units should incorporate some kind of computational and/or simulation tools in order to perform the intensive calculations often required in the analysis and design of process equipment. A common approach in the past, also followed at the University of Coimbra, was to propose a design project where the students had to construct their own programs in a structured language such as Fortran. Nowadays, process simulators, such as Aspen Plus or HYSYS,[1-4] or general-purpose computational platforms, such as Mathematica, MATLAB, or spreadsheet programs,[5-8] are widely accepted tools throughout the chemical engineering curriculum, particularly in the teaching of process units. When compared with Fortran programming, these higher-level computational tools have the obvious advantage of allowing complex calculations with less programming effort. In addition, their graphical interface can be used as a teaching/learning platform, allowing exploratory simulations and quick visualization of the corresponding results. Process simulators, however, have a potential pedagogical drawbackstudents may eventually use them as black boxes, without really understanding the physico-chemical model embedded in the simulator. Wankat and Dahm recognize this limitation and propose a cautious use of process simulators, leading students to physically interpret simulation results.[3,4]On the other hand, if a general-purpose platform is used, students have to write down the process model equations and program their basic solution strategy. Therefore, it is the opinion of the authors that this kind of tool is more adequate to support a basic process units course. Process simulators can also be used, but mainly for inductive presentation of concepts[2,4] and to compare solutions and methods.[8] A more intensive use of simulators should be left for later instruction in a senior design course. In the case study presented in this paper, we have chosen Mathematica, a very powerful general-purpose platform, to support the teaching of distillation in a process units course. Similar experiences have been reported using spreadsheet programs,[7,8] which have the advantage of being easier to learn. Mathematica is much more powerful, however, and has a comprehensible working environment that makes it possible to introduce its key capabilities using engineering problems as a starting point, as will be explained later. In a previous evaluation, made from the viewpoint of an undergraduate student seeking to solve four simple chemical engineering problems, Mathematica received the highest rating, ahead of MATLAB, Maple, and Excel.[6]Mathematica has been used in our process units course for the last two academic years (2001/2002 and 2002/2003), and in particular, it was used to teach distillation operations. Two initial computer classes introduce students to some key Mathematica capabilities, using vapor-liquid equilibrium cal-USING MATHEMATICA TO TEACH PROCESS UNITSA Distillation Case StudyMARIA G. RASTEIRO, FERNANDO P. BERNARDO, PEDRO M. SARAIVAUniversity of Coimbra 3030-290 Coimbra, PortugalMaria G. Rasteiro is Associate Professor in the Chemical Engineering Department at Coimbra University. She received a PhD in Chemical Engineering/Unit Operations in 1988. Her research interests are in the fields of process units, particle technology, and multiphase processes as well as in improving teaching and learning in engineering education. She is a member of ASEE and of the Working Party on Particle Characterization from EFCE. Fernando P. Bernardo is a Teaching Assistant at the University of Coimbra and is currently preparing his PhD in the area of Chemical Product and Process Design. He has collaborated in courses on applied computation and numerical methods as well as transfer phenomena and process units. Pedro M. Saraiva is Associate Professor in the Department of Chemical Engineering, University of Coimbra. He received his PhD in 1993 from Massachusetts Institute of Technology. His research interests are in the areas of process systems engineering, applied statistics, and quality management. ChEclassroom Copyright ChE Division of ASEE 2005

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124 Chemical Engineering Education Chemical engineers have the unique opportunity and challenge to translate recent advances in the biological sciences into useful products. There has been tremendous growth in the understanding of living systems at the molecular and cellular level, typified by insight into the human genome,[1] tissue repair with stem cells,[2] and the molecular basis for many diseases.[3] Educational programs that provide chemical engineers with a strong foundation in molecular and cellular biology (MCB) can produce a workforce capable of both biological discovery and product development. This training can ultimately foster interdisciplinary collaboration and accelerate productivity. The chemical engineering curriculum provides an excellent platform on which to develop an interdisciplinary educational program that exposes engineers to MCB. With its historical roots in chemistry, chemical engineering has retained its ties to the molecular sciences, and as a result, kinetics, transport phenomena, and other core concepts in the chemical engineering curriculum can be readily adapted to the molecular-based advances that are prevalent in the biological sciences today, such as cell signaling[4] and drug resistance in tumors.[5] Moreover, the quantitative-systems view to problem solving t hat is a hallmark of an engineering education is particularly relevant to emerging biological disciplines that require analysis of large data sets or complex reaction pathways, with metabolic engineering[6] as a prominent example. If past performance is an indicator of future achievements, chemical engineers will make great strides in the development of biotechnology. From the manufacturing of penicillin during World War II and the first artificial kidney in the 1960s, to current production of pharmaceuticals and fabrication of living tissue equivalents,[7-9] chemical engineers have been instrumental in the development of biological products that have touched lives on a global scale and revolutionized the health-care industry. Consequently, the initial industrial employment of chemical engineers in the biotechnology and pharmaceutical sector has risen over the past five years for graduates at the bachelor's, master's, and doctoral levels (see Figure 1). The current figures of 12.5% (BS), 16.3% (MS), and 18.3% (PhD) of industrial employment most likely represent lower limits since the chemical, food, and environmental sectors require bioengineers as well.[10]Anticipating the direction of growth in the biological sciences and the resulting hiring trend, the National Research Council recommended development of innovative interdisciplinary programs in a "Frontiers in Chemical Engineering" report published in 1988.[7] This call for change has been echoed over the years by numerous sources.[8,9,11] In response, chemical engineering departments are developing new bioengineering courses, incorporating biology into existing engineering courses, exposing students to bioengineering research and laboratory experiments, and/or changing the name of their departments.[11,12]For the past decade, Tulane University has offered a combined degree program that integrates chemical engineering and MCB. The program was initiated at the graduate level and then extended to undergraduates in response to student demand. At the cornerstone of this program is a strong foundation in both chemical engineering and the biological sciences that is research intensive at both the graduate and undergraduate levels. In celebration of its tenth anniversary, the program is described herein as one department's response to the growing need for interdisciplinary curricula and as a reference for other departments to address this issue.INCORPORATING MOLECULAR AND CELLULAR BIOLOGY INTO A ChE DEGREE PROGRAMKIM C. O'CONNORT ulane University New Orleans, LA 70118 Kim O'Connor is a Professor of Chemical and Biomolecular Engineering at Tulane University and is a graduate of Rice University (BS 82) and the California Institute of T echnology (PhD 87). Her postdoctoral training is in molecular and cellular biology, and her research interests are cellular and tissue engineering. She founded and directs the Graduate Combined Degree Program, and was Co-Director and Interim Director of the Interdisciplinary MCB Program. Copyright ChE Division of ASEE 2005 ChEcurriculum

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Spring 2005 125PROGRAM ORGANIZATIONT ulane University is composed of three campuses: the University, Health Sciences Center, and Primate Center. While graduate programs are offered on all Tulane campuses, only the University provides undergraduate education. The Combined Degree Program is offered by the Department of Chemical and Biomolecular Engineering (CBE) on the University campus in conjunction with the Interdisciplinary MCB Program that spans the three Tulane campuses (Figure 2). Administration of the Combined Degree Program is under the direction of a CBE faculty member who is also a member of the Interdisciplinary MCB Program. The CBE Department has ten faculty members, five of whom are engaged in bioengineering research. As shown in the organizational chart in Figure 2, the Interdisciplinary MCB Program encompasses four different schools. There are over 100 MCB faculty with a broad range of expertise and with primary appointments in one of twenty departments and four centers. The CBE Department is one of the participating departments on the Tulane University campus. Membership criteria for the faculty include productivity and funding level in MCB research. This large program is governed by a steering committee of appointed faculty representatives from each of the participating departments/ units, and is under the leadership of two CoDirectors and a Director selected by MCB faculty in a general election.GRADUATE EDUCATIONThe Combined Degree Program was approved by Tulane in Fall, 1993, and offered first at the graduate level in Spring, 1994. Applicants must satisfy the admission requirements of both the CBE Department and Interdisciplinary MCB Program to be admitted to the Combined Degree Program. Graduate students achieve a critical understanding of biology and engineering principles underlying their field of research through CBE and MCB coursework, lab rotations and independent research. Upon completing the program requirements, students earn a Master of Science degree with thesis through the Interdisciplinary MCB Program and a Doctor of Philosophy degree through the CBE Department. This typically requires five years of study. Curriculum Doctoral students in the CBE Department are required to complete a series of core courses and electives for 48 credit hours. In the Combined Degree Program, some of the electives are replaced with graduate-level bioengineering and MCB courses (see Table 1). The bioengineering component includes capstone courses in biomolecular engineering that integrate molecular-based biology and chemical engineering. Lecture topics include kinetics of the apoptotic pathway, computational approaches to tissue engineering, and delivery of gene therapies, as well as more established topics such as enzyme kinetics, bioreactor design, and transport of metabolites. New bioengineering courses are under development, and existing courses are updated regularly. In addition to MCB courses in biochemistry, cell biology, and genetics, the core curriculum includes a two-part course titled "Research Methods" that consists of faculty research seminars and a lab rotation (Table 1). During the Fall semester, the 100+ MCB faculty make a series of short presentations to introduce Combined Degree and MCB graduate stu0 4 8 12 16 20 9899-'0000-'0101-'0202-'03 YearPercentage Figure 1. Employment trends in the biotechnology and pharmaceutical sector for BS ( ), MS ( ), and PhD ( ) chemical engineers upon graduation. Data is presented as a percentage of initial placement in all industrial sectors. Source: AIChE Career Services.[10] Department Chemical & Biomolecular Eng. Sc hool of Engineering Departments Cell & Mole cu lar Biology Chemistry Physics Psyc hology Scho ol of Arts & Sciences University Bioc hemistry Microbiology/Immunology Pat hology Phar macology Physio logy Structur al & Cellul ar Biology Basic Scie nce Depts. Medicine OB/GYN O phthalmology Ot olaryngology Pediatrics Urology Clinical Depts. School of Medicine Depart ments Envir onmental Health Sciences Epidem iology Tropical Medicine Scho ol of Public Health Bioe nvironmental Research Cance r Gene Therapy Centers Health Sciences Center Primate Center Steering Commi ttee Co-Directors Director Figure 2. Organizational chart of the Interdisciplinary MCB Program for faculty and students in the biological sciences at T ulane University, Health Sciences Center, and Primate Center.

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126 Chemical Engineering EducationT ABLE 1Curriculum Requirements for MS in Molecular & Cellular Biology and PhD in Chemical Engineering Field Course Chemical Engineering Advanced Reactor Design T ransport Phenomena I or II Thermodynamics or Applied Statistical Mechanics Biomolecular Engineering T wo of the following: Biochemical Engineering Gene Therapy Advances in Biotechnology Biology Biochemistry Advanced Cell Biology Research Methods Molecular Genetics or Biochemical Genetics T echnical Electives Electives in Engineering, Science, and/or Medicine dents to the biological sciences and to specific research opportunities within the Interdisciplinary MCB Program. In the following semester, Combined Degree students complete a rotation in the laboratory of a MCB faculty member other than their dissertation advisor. Students earn a letter grade for their productivity on a well-defined research project. A graduatelevel MCB laboratory course can be substituted for the rotation. Traditional chemical engineering graduate students directly enter their research advisor's laboratory. Rotations provide an opportunity for Combined Degree students to broaden their knowledge of the biological sciences and learn specific experimental techniques required for their own dissertation research. In consultation with their dissertation advisor, Combined Degree students choose electives related to their field of interest from courses offered by CBE Department, Interdisciplinary MCB Program, and other graduate programs at Tulane. Topics include numerical methods, molecular basis of disease, and biostatistics. Also, students can earn a limited number of elective credits for independent study in the laboratory on their dissertation topic. When graduate students enter the Combined Degree Program with a bachelor's degree in an area other than chemical engineering, they are required to become proficient with the fundamental principles required of chemical engineers by completing undergraduate courses on unit operations and either reactor design, process control, or process design. These requirements can be modified based on each student's specific background. Undergraduate courses do not count toward the credit requirement for advanced degrees. Graduate students with a bachelor's degree in engineering can opt to take undergraduate biology courses to overcome deficiencies. Research The Combined Degree Program requires that graduate students 1) demonstrate the ability to conduct independent research that results in a novel contribution to their field of study or an original interpretation of existing knowledge, 2) document their findings in a master's thesis and doctoral dissertation, and 3) defend this scholarly work in an oral exam administered by MCB faculty for the master's degree and CBE faculty for the doctorate. Of the two documents, the former focuses on the fundamental biology of the research project, whereas the doctoral dissertation addresses the engineering applications. Students are encouraged to defend their thesis by the third year of graduate study and their dissertation by the fifth year. Both the thesis and dissertation can be under the direction of a single research advisor if the professor is a member of the CBE Department and Interdisciplinary MCB Program. Alternatively, MCB faculty can direct the master's thesis as long as a CBE faculty member directs the doctoral dissertation. The latter can arise from a research collaboration between two faculty. Consider, for example, a research project to improve survival of mammalian cells under harsh culturing conditions in a bioreactor. A MCB faculty member can direct a fundamental study of protein expression and cell signaling along critical pathways under different reactor conditions, and a CBE faculty can direct kinetic modeling of the pathways and develop corrective strategies based on the simulations.UNDERGRADUATE EDUCATIONIn 1997, the Combined Degree Program was extended to the undergraduate level at the request of undergraduates who worked with Combined Degree graduate students in the laboratory and wanted a similar education. From their freshman year until graduation, the undergraduates are engaged in a comprehensive learning experience in the classroom and through co-curricular activities. The curriculum provides knowledge of the principles and applications of chemical engineering and the biological sciences. Co-curricular activities are designed to reinforce and supplement classroom instruction. Upon completing the four-year program, students can earn a Bachelor of Science degree in chemical engineering with a second major or minor in the biological sciences from the Department of Cell and Molecular Biology within the Interdisciplinary MCB Program (see Figure 2). Curriculum At Tulane, bioengineering training in the CBE Department currently has four components at the undergraduate level: a sophomore-level bioengineering course, Practice School, concentration of technical electives, and double major/minor in the biological sciences. All undergraduates entering the CBE Department are required to complete an introductory bioengineering course that teaches biology fundamentals, engineering applications, and problem-solving skills (Table 2). In addition, all CBE seniors are required to participate in a one-semester internship, called Practice School. Students have the option to fulfill internship requirements with bioengineering projects at the Tulane Health Sciences Center that involve

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Spring 2005 127 Continued on page 133.T ABLE 2Curriculum Requirements for BS in Chemical Engineering with Second Major (*) or Minor ( ) in Cell and Molecular Biology Field Course Chemical EngineeringMaterial and Energy Balances Thermodynamics I and II T ransport Phenomena I and II Numerical Methods for ChEs Unit Operations Lab I and II Separation Processes Kinetics and Reactor Design Process Design Process Control Practice School I and II Other EngineeringIntro. Eng. and Computer Science Software Design and Programming Intro. Chemical Engineering Intro. Biomolecular Engineering Chemistry & PhysicsGeneral Chemistry + Lab I and II General Physics + Lab I and II Organic Chemistry + Lab I and II Advanced Chemistry (Biochemistry * ) MathCalculus I, II, and III Applied Math T echnical ElectivesBioengineering elective Four courses required General Biology *  for chemical Genetics*  engineering Cell Biology*  curriculum Molecular Biology*  Cell Biology Lab* or Molecular Biology Lab* Neuroscience* or Dev. Biology* T wo* (one ) of the following: Biology Elective 1 and 2 (Lab) Biology Elective 3 (Lecture or Lab) Liberal Arts: 6 coursesHumanities/Social Science Distribution independent research and/or computer programming under CBE and MCB faculty supervision. The curriculum has been designed to allow CBE students to focus their technical electives in a specialized area. The biomolecular engineering concentration includes graduate bioengineering courses that are co-listed at the undergraduate level and MCB courses. This concentration has the flexibility to enable CBE students to obtain a second major or minor in the biological sciences. The core courses for a biology major are general biology, genetics, cell biology, molecular biology, biochemistry, cell or molecular biology laboratory, and neuroscience or developmental biology. Biochemistry is one of the courses that fulfills the advanced chemistry requirement in the chemical engineering curriculum (Table 2). In addition, three electives are required for the biology major: two laboratories and either a lecture or another laboratory. Independent research gained in a co-curricular activity counts as an elective. To avoid overloading their course schedules, students either enter the program with advanced placement credit or are encouraged to fulfill requirements for introductory courses over the summer. For a minor in the biological sciences, the MCB core and elective component are reduced to general biology, genetics, cell biology and molecular biology, and two biology electives. The technical electives and advanced chemistry course in the chemical engineering curriculum fulfill the majority of these requirements. Undergraduates are encouraged to satisfy at least one biology elective with a laboratory to be exposed to MCB experimental techniques. Co-Curricular Activities Undergraduates are encouraged to participate in co-curricular activities that reinforce and supplement classroom instruction. A popular choice is independent research in the laboratory of a faculty member in the CBE Department or another department participating in the Interdisciplinary MCB Program (Figure 2). Research supplements the traditional academic curriculum by exposing students to the practice of science and engineering. In so do ing, it helps students think creatively, develop problem-solving and time-management skills, work in groups, and learn the importance of patience and perseverance when solving difficult research problems. There are several co-curricular activities for students preparing for medical school. Clinical faculty allow chemical engineering students to participate in rounds to their patients and volunteer in the surgical suites at the Tulane Health Sciences Center. On the University campus, under graduates volunteer in public health projects and in an emergency medical program to administer prehospital care and ambulance service to students. Summer provides an opportunity for students to continue their learning experiences without time constraints imposed by coursework. Activities include research at a university, employment in industry or a national laboratory, and training programs at medical schools.STUDENTSThe Combined Degree Program has produced a diverse cadre of talented students. At the doctoral level, 66% of the graduates have been US citizens; 34% female. Unfortunately, none of the graduates to date have been minorities. They enter the Combined Degree Program with a 3.5 undergraduate GPA, 590 verbal GRE score, and 740 quantitative GRE, on average. Comparable statistics for enrolled graduate students in the School of Engineering at Tulane reveal that 51% were US citizens, 27% were women and 6% were minorities in 2004. Graduate students entering the School of Engineering in 2004 had an average score of 3.4 for undergraduate GPA, 570 verbal GRE, and 740 quantitative GRE. At the undergraduate level, 83% of the Combined Degree students have come from high schools outside of Louisiana, 33% have been female, and 51% have been minorities. The students are frequently in the top decile of their senior class and have had an average SAT score of 1380. In comparison, approximately 70% of Tulane Engineering freshman are out-of-state, and 65% were in the top decile of their senior class in 2004.

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128 Chemical Engineering Education COOPERATIVE WORK THAT GETS SOPHOMORES ON BOARDCHARLES H. GOODINGClemson University Clemson, SC 29634-0909 Copyright ChE Division of ASEE 2005 ChEclass and home problems The object of this column is to enhance our readers' collections of interesting and novel problems in chemical engineering. Problems of the type that can be used to motivate the student by presenting a particular principle in class, or in a new light, or that can be assigned as a novel home problem, are requested, as well as those that are more traditional in nature and that elucidate difficult concepts. Manuscripts should not exceed fourteen double-spaced pages and should be accompanied by the originals of any figures or photographs. Please submit them to Professor James O. Wilkes (e-mail: wilkes@umich.edu), Chemical Engineering Department, University of Michigan, Ann Arbor, MI 48109-2136. The chemical engineering curriculum at most universities begins with a mass and energy balance course. In some cases this is preceded by a general engineering course that covers concepts such as unit conversions, graphical data representation, and basic statistics. One of the challenges in these lower-level courses is to help students grasp big-picture issues that faculty often take for granted. Some examples are The importance of error, uncertainty, significance, cause and effect, and/or quantitative relationships among real process data. "What do you mean error'? I thought they did the experiment carefully." "Why should I use a linear fit if the polynomial gives a higher R2?" Understanding, at least in a rudimentary way, how process equipment works. "In problem 4.11, what do they mean by . ." "How do I know if it's adiabatic or not?" Understanding something about the diversity, breadth, and connections among companies that employ chemical engineers. "Why would I want to spend the rest of my life making tetrahydrofuran?" "Advil comes from oil? No way!" Cooperative learning is a proven technique for helping students learn through discovery and discussion.[1] Simple cooperative assignments can be particularly useful in the first two courses to deal with the issues cited above. Three examples are presented in this paper. The problem statements and basic rationale are explained, and typical solutions are shown in part. These assignments not only help students understand important basic concepts, but also help them begin to think likeCharles H. Gooding is Professor of Chemical Engineering at Clemson University. He received BS and MS degrees from Clemson and a PhD from North Carolina State University. He teaches the introductory course in material and energy balances, unit operations laboratory, process control, and process design. Simple cooperative assignments can be particularly useful in the first two courses . . Three examples are presented in this paper.

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Spring 2005 129 chemical engineers. Moreover, these examples work best as team exercises with written and oral reporting requirements, which can contribute to the development of productive relationships among the students and to developing or refining their communication and presentation skills.EXAMPLE 1 ACCESSING AND USING DATA FROM A REAL PROCESSClemson University is fortunate to have an Energy Systems Laboratory (ESL), which was developed to provide realtime energy usage and equipment performance data for simulation, modeling, and analysis by students and faculty. The ESL is located adjacent to the Central Energy Plant. It provides physical and virtual access to operating data from three gas turbines and extensive data on other utility systems and equipment that are under the purview of University Facilities. The capstone microturbine virtual interface is the most convenient ESL tool for students and faculty to use. The physical facility consists of a 30-kW gas-fired turbine and an integrated heat exchanger, which recovers part of the sensible heat from the turbine exhaust gases and transfers it into the campus steam system. Data from this facility can be accessed and used as a virtual lab by anyone who has a web connection. The user first encounters a photograph of the facility and then the schematic of the gas turbine and heat exchanger, shown in Figure 1. Real-time operating data can be accessed by clicking the "Refresh" button and waiting a few moments. As shown in the figure, data are available on the feed gas, exhaust gas, water, and power generation to support several types of engineering analysis. Historical data can also be obtained on any of the process variables shown. We usually start this assignment by giving freshman or sophomore students a tutorial that sends them individually to the microturbine web site to view and print a copy of Figure 1 with typical operating data shown in the blocks. They bring this to the next class meeting, which is held at the ESL. There they see a full-scale c utaway mock-up of a gas turbine and hear a brief lecture on turbine operations and energy conversion. This is followed immediately by a short walk to see the Figure 1. Capstone microturbine schematic with typical data.

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130 Chemical Engineering Education 182 184 186 188 190 192 050 100150200250300350400 Sample time, minutesWa ter temperature out, oF mean = 186.2 oF std dev = 1.5 oF range = 184.0 to 190.5 oF y = 0.084x 6.5263 24.0 25.0 26.0 27.0 370375380385390395 Fuel flow, SCFMPower generated, kW y = power, kW x = fuel flow, SCFM slope = 0.084 kW/SCFM intercept = -6.53 kW Figure 3. Microturbine power generated vs. fuel flow rate. Figure 2. Heat exchanger outlet water temperature vs. time.actual microturbine and heat exchanger facility for further observation, explanation, and questions and answers. The goals of this ESL assignment at the freshman level are to introduce students to energy conversion, to have them explore and gain a rudimentary understanding of the equipment operation, and to have them conduct basic exercises in data presentation and analysis. The first homework requires them to write a short narrative description of the integrated energy conversion facility after visiting it and to answer questions such as What kind of gas enters the turbine and where does it come from? What does SCFH mean? Where does the air for combustion enter the turbine? Is the air flow rate metered? What type of energy is measured by the "energy meter"? What do the bowties on the thin lines in the schematic represent? In the second ESL assignment the freshman students are given access to an Excel spreadsheet that contains data from the microturbine and heat exchanger tabulated at regular intervals over several hours. They are instructed to plot a specified process variable versus time (see Figure 2) and to plot against one another two variables that should be correlated (see Figure 3). For the single-process variable plotted on the ordinate against time they calculate statistics such as mean, range, and standard deviation, and then brainstorm and explain several physical reasons why the standard deviation is not equal to zero, i.e., what are the influences on this process variable, how is it measured, and why does the measured value change with time? For the correlated-process variables they fit a simple linear model and discuss the physical interpretation of the slope and intercept and the goodness of fit. The objectives of these exercises are to develop the students' basic skills in data representation and their understanding of statistical and modeling concepts such as measurement error, random variation, and cause and effect. After students study mass balances, data from this facility can be used further for a real-world comprehensive assignment. They are told to start from the data set such as the one shown in Figure 1 and determine the composition of the exhaust gas and the amount of excess air used in the turbine. They soon learn that another engineering skill is needed to accomplish thismaking reasonable assumptions and approximations. In this case the students must assume something about the composition of the fuel gas, e.g., that it is 100% methane or that it has some average natural gas composition. When they have completed the material balances, students can conduct energy balances on the facility. Again using data from Figure 1, they can determine the fraction of the chemical energy from the fuel that is converted into electricity in the microturbine, the fraction that is transferred to the water in the heat exchanger, the fraction lost up the stack, and the fraction lost elsewhere. This assignment is an excellent springboard for introducing concepts of alternative energy conversion, conservation strategies, thermodynamic limitations, environmental consequences, and economics. Complete discussion of these topics may have to wait until the students encounter other courses, but the seeds of interest can certainly be planted at the sophomore, or even the freshman, level.

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Spring 2005 131 The apparatus shown above is used to remove moisture from solids. Wet material is placed on a rack inside the dryer. Room air is pushed by an electric fan through a heat exchanger and then through the dryer. The heat exchanger consists of small tubes inside a larger cylinder. The air passes through the tubes, and steam is fed into the outer cylinder. In the dryer, moisture evaporates into the hot air, leaving a dry solid after a period of time. Material balance Air enters the fan and passes through the heat exchanger and dryer, then back into the room. Steam condenses in the heat exchanger and leaves as water. Moisture is evaporated from the solids and leaves as water vapor with the air. The solids put into the dryer are taken out later (minus the moisture). Energy balance Steam put into the heat exchanger loses thermal energy to the air. Electrical energy put into the fan, raises the pressure of the air. The air cools when it heats the solids and evaporates the moisture. Fan Heat Exchanger Dryer Room Air Steam Condensate xxxxxxxxxxx wet solids Figure 4.EXAMPLE 2 WHAT IS IT AND HOW DOES IT WORK?This simple assignment is designed to help students in the mass and energy balance course understand common chemical engineering processes that are used frequently in homework problems and quizzes. Early in the semester, teams of two or three students are assigned an unnamed apparatus in the Unit Operations Laboratory and told to complete the following tasks: 1.Prepare a simple drawing of the apparatus. The drawing doesn't have to show nonfunctional details or be artistic, but it should be sufficient to help you explain how the device works. Make a rough sketch when you are in the lab, and then use that to make a neater drawing later for inclusion in your written submission and to use in your oral presentation. 2.Figure how the device works and write a brief narrative description to accompany your drawing. Explain the material and energy balance aspects of the process as well as you understand them at this point in your studies. Describe what goes in where and what comes out where during typical operation. Explain how energy gets into the system and where and how it is converted to another form or where it comes out. 3.Prepare and present a three-minute oral summary on your results. Students are encouraged to ask upper-class chemical engineering students in the Unit Ops Lab to help them understand how an apparatus works. They are also referred to the ChE library to consult Perry's Chemical Engineer's Handbook, the Kirk-Othmer Encyclopedia of Chemical Technology, and the assortment of textbooks and periodicals stored there. They discover not only that descriptive help is available, but also that there are cutaway pictures and diagrams in these references that will help them understand the equipment. The sketch and narrative summary in the example shown in Figure 4 are typical of those handed in for this assignment. Although the description doesn't include sufficient detail to ensure that correct mass and energy balances would follow, it reflects a reasonable understanding of the process. After examining process equipment and discussing how it works, sophomores are much better equipped to decipher written and verbal process descriptions in their classes and to correctly lay out process flow diagrams.EXAMPLE 3 CHEMICAL GENEALOGYIn this assignment each team investigates the "genealogy" of a family of related chemicals. They are assigned a chemical intermediate ( e.g., acrylonitrile, ethylene oxide, styrene), which is defined for them as a compound that is made (perhaps in multiple steps) from naturally occurring materials and is then used to make other compounds, until ultimately the products become part of consumer goods. Each team must conduct a literature research and complete the following tasks: 1.Identify the "parents" and one set of "grandparents" of the assigned intermediate. In other words, identify an industrially relevant reaction route that produces the intermediate, and then pick one of the reactants of that reaction and determine how it is made. 2.Investigate one "child" and one "grandchild" of the

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132 Chemical Engineering EducationGiven chloroform as the initial assignment, one team identified methyl chloride as a parent, chlorodifluoromethane as a child, tetrafluoro-ethylene as a grandchild, and poly-tetrafluoroethylene as a great-grandchild. They brought a PTFE coated pan to class and presented the following information on step one of the genealogy: Reaction CH3Cl + 2Cl2 = CHCl3 + 2HCl Reactor configuration and conditions Chloroform is produced in the gas phase reaction of methyl chloride and chlorine, with hydrogen chloride as a by-product. Methylene chloride and carbon tetrachloride are also produced in the successive substitution reaction. Usually the reactants are preheated and fed into a cylindrical metal tank with methyl chloride in excess. The exothermic reaction is very fast (residence time of about 10 seconds), and the products leave at about 470 oC and 1500 kPa. Separations The chemicals leaving the reactor are separated in a series of distillation columns. Unreacted methyl chloride and methylene chloride are recycled to the reactor. HCl and CCl4 are sold as by-products or used elsewhere in the plant. The annual production rate of chloroform in the U.S. is about 300 million kg. The market value is about $1/kg. Dow Chemical Company is a major producer. Figure 5.intermediate; i.e., identify one product that is made from the intermediate and one product that is made from that product. 3.Identify one member of the chemical family that can be identified as a tangible product and bring it to class (safely!). The "grandchild" might be the most likely candidate, but the product can contain any member of the family. This product must be something that is commonly used or can be purchased for less than $5. 4.For each of the four steps in the genealogy ("births," to take the analogy a bit farther), teams do the following: a.Write the primary reaction involved. Make sure it is balanced. b.Describe the industrial-scale reaction conditions (e.g., physical layout of reactor equipment; temperature and pressure of operation) c.Describe the separations that follow the reaction to purify the product. d.Determine the annual production rate in the U.S. (or globally) of the primary product. Name at least one company that produces a substantial amount of it. e.Determine the unit value of the primary product ($/kg). 5.For each of the four steps in the genealogy, gather and organize the information so that it fits on a single overhead or PowerPoint slide, using no fonts smaller than 16 points. Bring to class the four slides and a hard-copy report that consists of the four slides plus a list of references, identifying what was obtained from each. Each team must present a five-minute oral summary of its work in class. The genealogy assignment gives students a glimpse of the structure, breadth, and connections in industries that employ chemical engineers. It reinforces their study of organic chemistry and introduces them to future chemical engineering topics such as reaction and separation equipment and economics. To afford some flexibility, teams are allowed to shift the position of their starting compound to the second or fourth position in the lineage if they wish. Other options include restricting the in-class "show-and-tell" product to a certain category such as personal care products or pharmaceuticals. A typical assignment is shown in Figure 5. Chemical and Engineering News is a good source of ideas and variations on this assignment.SUMMARYMost students entering chemical engineering curricula today have had no hands-on experience other than a high school chemistry lab, have had no exposure to process equipment, and have only a vague idea of what constitutes the chemical industry and what chemical engineers actually do. These assignments introduce students to real issues and concepts that chemical engineers confront every day. They complement engineering fundamentals that are taught early in the curriculum, making these courses less abstract and more interestingwhich rewards both the students and the professor. The assignments also foster teamwork and contribute to the development of communication skills.REFERENCES1. Felder, R.M., and R. Brent, Cooperative Learning in Technical Courses: Procedures, Pitfalls, and Payoffs ERIC Document Reproduction Service, ED 377038 (1994). (This reference and numerous others on cooperative learning are available at .)

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Spring 2005 133Molecular and Cellular BiologyContinued from page 127. Their SAT scores ranged from 1070 (25th percentile) to 1490 (75th percentile). Twenty-five percent of the bachelor's degrees awarded by the School of Engineering were to women in 2004, and 24% were to minorities. Enrollment in the CBE Department at Tulane ranges from 7 to 11 new graduate students per year and 17 to 25 undergraduates per class. Combined Degree students represent 15% of the entering graduate class in 2004, and 10 to 20% of the sophomores. Since the Department changed its name in 2003 to reflect the bioengineering in its curriculum, our enrollment has increased. Upon graduation, Combined Degree students have earned on average a 3.7 GPA over 5.5 years in the graduate program and 3.9 GPA over 4 years in the undergraduate program. For the School of Engineering as a whole, the comparable time to fulfill degree requirements is 5 years for the doctorate and 4 years for a bachelor's degree. During their graduate studies, Combined Degree students produced 4 peer-reviewed publications on average. Sixty percent of these graduate students entered industry upon graduation; 40% remained in academia. They have obtained positions at leading institutions such as Johns Hopkins, Johnson & Johnson, Memorial-Sloan Kettering Cancer Institute, and Merck. Their contributions to the field of bioengineering to date include development and delivery of anti-cancer therapeutics, drug formulation, and tissue engineering. Upon earning a bachelor's degree from T ulane, 83% of Combined Degree students enrolled in medical school at, for example, Columbia, Johns Hopkins, and Yale.IMPACT ON BIOLOGISTSWhile chemical engineers are the focus of this article, biology faculty and students also benefit from an interdisciplinary learning experience. There are numerous opportunities for dialog between the two groups in the classroom and laboratory, as well as through co-curricular activities, research collaborations that result in or are the product of student training, and leadership activities in the Interdisciplinary MCB Program. For example, a faculty member of the CBE Department has served as Director of the Interdisciplinary MCB Program and, in this capacity, was responsible for graduate MCB training across the three Tulane campuses. Collaborations have formed between faculty in the CBE Department and Departments of Biochemistry, Medicine, Pathology, Ophthalmology and Surgery, to name a few. In addition, biologists work side by side with engineers in the laboratory on research projects and for lab rotations. These forms of exchange expose biologists to an engineer's perspective on problem solving. Not only is the approach inherently more quantitative, but also an engineer is trained to consider a system as a whole and the interactions between its components. This quantitative systems view is relevant in an age of bioinformatics and molecular-based biology.COMPARISON WITH OTHER PROGRAMSA survey of the twenty leading chemical engineering departments in the United States as ranked by U. S. News and W orld Report reveals that 40% of the departments have interdisciplinary programs in bioengineering at the graduate level. Seventy-five percent of the departments provide a bioengineering curriculum for undergraduates. These programs were developed recently, two of which will be introduced in 2005. In 30% of the departments, graduate students have the opportunity to participate in interdepartmental programs in the biological sciences, biotechnology or bioengineering. The amount of biology and bioengineering in the undergraduate curriculum varies widely among the chemical engineering departments. The bioengineering curriculum at the undergraduate level is in the form of a course, concentration, certificate program, minor or double major. A biology requirement is being introduced to the chemical engineering curriculum in a limited number of departments. Features of the Tulane Combined Degree Program are the continuity of interdisciplinary training at the undergraduate and graduate levels, depth of training in chemical engineering and the biological sciences, scope of the Interdisciplinary MCB Program, and longevity of the program.ACKNOWLEDGMENTSThe academic experiences of the following students have been instrumental in the evolution of the Combined Degree Program: Nancy Cowger, Richard Enmon, Carrie Giordano, Shamik Jain, Jim Muhitch, Hong Song, Sandeep Sule, Julie T alavera, Murthy Tata and Nina Watson.REFERENCES1.Baltimore, D., "Our Genome Unveiled," Nature 409 814 (2001) 2.Prockop, D.J., C.A. Gregory, and J.L. Spees, "One Strategy for Cell and Gene Therapy: Harnessing the Power of Adult Stem Cells to Repair Tissue," Proc. Natl. Acad. Sci. USA 100 11917 (2003) 3.Parekh, R., "Proteomics and Molecular Medicine," Nat. Biotechnol. 17 19 (1999) 4.Asthagiri, A.R., and D.A. Lauffenburger, "Bioengineering Models of Cell Signaling," Ann. Rev. Biomed. Eng ., 2 31 (2000) 5.Jain, R.K., "Delivery of Molecular and Cellular Medicine to Solid T umors," J. Control. Release 53 49 (1998) 6.Stephanopoulos, G., and J. Kelleher, "How to Make a Superior Cell," Science 292 2024 (2001) 7. Frontiers in Chemical Engineering: Research Needs and Opportunities National Academy Press, Washington, DC (1988) 8. Putting Biotechnology to Work: Bioprocess Engineering, National Academy Press, Washington, DC (1992) 9.Rudolph, F.B., and L.V. McIntire, Biotechnology: Science, Engineering and Ethical Challenges for the Twenty-First Century, Joseph Henry Press, Washington, DC (1996) 10."Initial Placement of Chemical Engineering Graduates," and , AIChE Career Services (2003) 11 .V arma, A., "Future Directions in ChE Education: A New Path to Glory," Chem. Eng. Ed ., 37 284 (2003) 12.Westmoreland, P.H., "Chemistry and Life Sciences in a New Vision of Chemical Engineering," Chem. Eng. Ed ., 35 248 (2001)

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134 Chemical Engineering EducationHistorically, chemical engineering graduates have been hired predominantly by the chemical process industry and petrochemical industry, a fact indicated by the focus of applications in the chemical engineering curriculum.[1] Nowadays, however, chemical engineering graduates are also heavily recruited for jobs in the pharmaceutical, semiconductor, and environmental industries.[2] This diversity of job opportunities is expected to increase as new technologies, such as nanotechnology, smart drug design, and bioinformatics, continue to evolve. Since the 1980s, chemical engineering educators have been encouraged to modify the curriculum to include new technologies, such as biotechnology and semiconductor processing.[3-4] In particular, the biotechnology area has been receiving increased attention since many of the high-tech applications of biotechnology (such as drug engineering, drug discovery and pharmaceutical production based on recombinant DNA processes) have become established in the marketplace. As these processes have been scaled up for production, the participation of chemical engineers has become a necessity. Many underlying chemical engineering principles, such as reactor design and mass transfer, can be transferred to the biotechnology industry, but educators have begun to realize that biology itself must be incorporated into the chemical engineering curriculum in order for chemical engineering graduates to be competitive in industry.[2,5,6] This situation is similar to a prior shift to focus on chemistry in the curriculum when chemical engineering graduates were predominantly hired in the chemical process and petrochemical industries. In fact, a number of chemical engineering departments have changed their names to the "Chemical and Biology Engineering Department"[7-11] or similar designations, in recognition of the increased importance of biology in many of the jobs their graduates will one day be hired for. However, constraints such as ABET requirements, significant General Education requirements (along with a push to keep the units required for the degree as low as possible), and even the current applications focused on in many popular chemical engineering textbooks, have posed challenges to increasing the biology content to acceptable levels.[12]Although some chemical engineering departments have introduced basic biology into the curriculum, it has become increasingly important for chemical engineers hired by biotechnology companies to have some understanding of molecular biology, an advanced topic. One of the best ways to help students achieve this understanding is by successfully completing molecular biology experiments. Not only do students gain the hands-on skills required for successful molecular biology protocols, but they also must explain what they did and what their results mean in laboratory reports. Chemical engineering students at San Jose State University are exposed to these experiments in a biochemical engineering laboratory course developed by Drs. Komives (ChE), McNeil (ChE), and Rech (Biological Sciences). The course is a senior-level course open to chemical engineering students, biochemistry students, and biology students. Chemical engineering students are required to have a biochemistry course and biochemical engineering lecture course prior toBUILDING MOLECULAR BIOLOGY LABORATORY SKILLS IN ChE STUDENTSMELANIE MCNEIL, LUDMILA STOYNOVA, SABINE RECHSan Jose State University San Jose CA 95192Melanie A. McNeil is Professor of Chemical Engineering at San Jose State University. She teaches courses in chemical engineering kinetics and reactor design, biochemical engineering, heat transfer, fluids, safety and ethics, and statistics. Her research experience includes nanowire synthesis, RNA/peptide binding interactions, development of sequence search algorithms, and enzyme kinetics. Sabine Rech is Assistant Professor in the Department of Biological Sciences at San Jose State University. She obtained a BS in Biology from Santa Clara University, an MA in Microbiology from San Jose State University, and a PhD in microbiology from UC Davis. She is teaching courses in general microbiology, microbial physiology, and microbial diversity. Her research interests include the isolation of natural products, gene expression in environmentally important bacteria, and the study of microbial diversity in the soils of salt marshes in the process of restoration. Ludmila Stoynova is a research technician and a part-time lecturer in the Department of Chemistry at San Jose State University. She has a BS degree in Chemistry from Sofia University, Bulgaria, and an MS degree in Chemistry from San Jose State University. She teaches an introductory biochemistry laboratory class. Her research is concentrated on the nuclear vitamin D3 receptor, a ligand-dependent transcription factor. Copyright ChE Division of ASEE 2005 ChEclassroom

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Spring 2005 135enrolling in the laboratory. The first half of this laboratory course is focused on molecular biology experiments such as polymerase chain reaction, ligation, and bacterial transformation, while the latter half is focused on enzyme kinetics, fermentation, and protein purification. The nature of molecular biology is that small volumes (microliter levels) are used and the results of a given experiment are often not known until two or three experiments later, corresponding to two or three weeks later in a laboratory course. Thus, it is imperative to quickly and effectively train chemical engineers in basic biological techniques such as micropipetting, sterile techniques, streaking and spreading samples on agar plates, and loading DNA-containing samples on an agarose gel. In addition, our laboratory course attracts a multidisciplinary population of students from biology, biochemistry, and chemical engineering. A number of the science students have some or most of the required laboratory skills. In order to avoid redundancy for the experienced science students, and because the laboratory curriculum does not allow multiple days to train chemical engineering students, we have developed a one-day Biology Laboratory Skills-Building session for students. On the first day of class, students answer a questionnaire regarding their prior laboratory experience and are given protocols for each procedure they will complete during the skillsbuilding session that is held during the first day of the laboratory. They are arranged into twoor three-member teams and are instructed to meet with their team prior to the first laboratory session so they will arrive prepared to complete the activities. Every attempt is made to include at least one student experienced in the necessary laboratory techniques on each team.BIOLOGY LABORATORY SKILLS-BUILDING SESSIONThe course is set up as two lecture hours directly followed by a three-hour laboratory session. Due to the nature of some of the experiments,[13] however, the laboratory portion often takes the entire five hours. This is the case for the Biology Laboratory Skills-Building Session. Table 1 lists the skillsbuilding stations that students complete during the first official laboratory session of the semester. It is not enough for the students to blindly perform each activity. Instead, they are allowed to make mistakes at the various stations so they can figure out what the most common mistakes might be and how to identify them. The students must also answer a set of questions associated with each stationquestions that have been written to help the students identify common errors or common pitfalls associated with a given protocol. The activities and questions associated with each station are described in Table 1. The answers to most of the protocol questions can be answered by the students with reference to the protocol sheet they were given on the first day of class.STATION ACTIVITIESThe instructions for activities and questions associated with each station are as follows: 1. MicropipettingEach group should check each other out to confirm that each member understands the use of micropipettes. Be able to demonstrate the answer to the following questions and record your answers in your laboratory notebook: a.How do you set the volume required? b.Which tips go on which pipettes for which range of volumes? c.How do you pipette a certain aliquot of solution? Note how you might get aerosols, suction against the tube bottom, or air bubblesnone of which you want. d.How do you release the aliquot? e.How should the micropipettes be stored? f.In which direction should you NOT hold loaded micropipettes ( our students have often been observed holding the micropipette in directions such that the chamber can become contaminated )? g.What aspects of sterile technique should you keep in mind while micropipetting? 2. AutoclavingEach group should autoclave 500 ml of DI water, in a labeled capped bottle (label should include contents, composition, date, one team member's initials, and course number). a.Which settings should you use? b.How do you program the autoclave? c.How do you add the water used for steam? d.How long should you autoclave? e.How should your container of water be autoclaved e.g. with a lid? f.How do you remove items after autoclaving? g.How do you know if the autoclave has reached sterilization temperature? h.How do you know if the contents are sterile? i.What aspects of sterile technique should you keep in mind while autoclaving? 3. Gel LoadingEach gel contains two sets of 16-well lanes. Each group can use ONE set of 16, although you don't have to use them all if all group members are confident on their loading technique sooner. Pipette 150 L of sterilized water into an Eppendorf tube using a STERILE pipette tip. Add 10 L of loading dye.T ABLE 1 Biology Laboratory Skills-Building Stationsl. MicropipettingAll groups at once 2. AutoclavingTwo groups at a time, one at each autoclave 3. Gel loadingTwo groups at a time, one at each gel 4. Material data safety sheets (MSDSs)One group at each computer 5. Agarose gel preparationTwo groups at a time 6. Sterile techniques and agar plate streakingEach group separately 7. Station clean upEach group separately

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136 Chemical Engineering Education Fingertip flick to mix. Load 10 L at a time into each gel. Make sure your tip is in the well. The dye is heavy so it will sink. If you haven't loaded before, hit the bottom of one of the lanes just to see what it feels like. a.What is best technique for you to steady your hand when you load? b.Are you satisfied with the way your sample loaded in the well? c.Where are the tips disposed? d.What aspects of sterile technique should you keep in mind while loading the gel? 4. Material Data Safety Sheets (MSDSs)Each group will download two MSDSs from the Internet and will give a brief report on any safety hazards associated with that chemical at the end of the lab period. Group 1 Ethidium bromide, Tris Group 2 EDTA, agarose Group 3 Glacial acetic acid, LB medium Group 4 DMSO, glucose 5. Agarose Gel PreparationThe instructor will demonstrate preparation of the agarose gel. Note: Some glassware is reserved for making the gel since residual amounts of ethidium bromide may contaminate the glassware. a.How do you tell when the gel solution has been microwaved long enough.? b.How do you tell when to pour the gel? c.How do you tape the gel plate? d.When is the ethidium bromide added and in what amount? e.Where are the ethidium bromide-contaminated tips etc. collected? 6. Sterile technique and agar plate streaking Each group will get four LB agar Petri dishes. Label the dishes so they can be identified (content, date, one members initials, and course number) Where should you label, top, bottom, and/or side? TELL THE INSTRUCTOR YOUR ANSWER BEFORE LABELING. Each member should practice streaking using the technique shown on the handout given in the first class. One member should streak with unsterilized tap water, one with unsterilized DI water and one with the water you just sterilized in this lab. REMEMBER to use sterile techniques when pouring your sterilized water. Review your sterile techniques protocol. Put your dishes upside down in a 37 C incubator, after they have been streaked. Use the Internet to find out the difference between streaking and spreading techniques. The fourth dish is to show you why you need to use sterile techniques. Group 1 open up the dish and talk over it, then close it up and incubate it. Group 2 swab the doorknob with a cotton tip, then lightly streak your dish, and then incubate it. Group 3 have each member swab their hand, each with their own cotton swab, then lightly streak each swab on your dish, and then incubate the dish. Group 4 swab the computer keyboard, then lightly streak your dish, and then incubate it. These dishes should incubate for 24-36 hours. If someone in your group cannot come in to put the dishes in the refrigerator, e-mail the instructor and she will take care of that step. All groups should review all 4 of these plates after incubation. Label them well. 7. Station Clean-up When you are done, clean up your station. Review the cleanup protocol you were given on the first day.a.What clean-up protocol do you need to follow? b.Where do the waste chemicals go? c.Where do the waste plastic supplies go?DISCUSSION AND CONCLUSIONSThe activities included in the Biology Laboratory SkillsBuilding session were designed to serve several purposes. We recognized that each subsequent molecular biologyrelated laboratory would occupy essentially all of the student's concentration due to the detailed nature of the protocols and the number of samples, controls, and calibration standards that would be tested. It has been our experience that students can concentrate on one new activity at a time. All of the molecular biology experiments were new, and thus areas such as safety or sterile techniques tend to be ignored if they were first introduced at the same time as the new molecular biology protocol. The Biology Laboratory Skills-Building session was designed to introduce students to safety, sterile techniques, and basic protocols (preparing an agar gel, micropipetting, autoclaving) before their concentration was focused on the new molecular biology protocols (ligation, digestion, transformation, etc.). For instance, the MSDSs that they had to download were selected for chemicals that had the most safety hazards to consider and for chemicals that were used most often. The questions assigned to each activity were designed to have the students address important issuesfor instance, how to dispose of ethidium bromide-contaminated items or what not to do with a loaded micropipette. The inclusion of this skills-building session has not eliminated all problems associated with the lack of molecular biology skills common to chemical engineering students without prior experience. For instance, during the transformation experiment later in the semester, some students gouged their agar as they roughly spread their transformed bacteria. This resulted in zero colony growth. Also, sterile techniques were often treated with less diligence than was optimal. Students were very appreciative of the initial training session, however. All students were visibly impressed with the colonies

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Spring 2005 137that grew on their agar after the first laboratory session. The colonies obtained off swabs from their skin, the doorknob, and the computer keyboard were multicolored and profuse, making a vivid impression on the students. During the semester, anytime they relaxed their attention, one reference back to these colonies inspired them to renew their sterile techniques. It should be noted that it takes a fairly long period of time for many students to gain an appreciation and mastery of biology laboratory skills such as sterile techniques, micropipetting, and culturing. When SJSU science and engineering faculty compared the skill levels of students in their laboratory courses, the general consensus was that microbiology students have higher skills than biochemistry students, who have higher skills than biochemical engineering students. Not surprisingly, the higher skill level corresponds to the greater amount of time these topics are focused on in the typical curriculum (lecture and laboratory) in microbiology, biochemistry, and chemical engineering. Other universities may be able to offer one, two, or three biology-related courses in their chemical engineering curriculum, but even that number will not be sufficient to build up skills to the level required in industry. It is an acceptable start, howeverespecially given the constraints (ABET, unit load, textbook examples, etc.) chemical engineering departments face as they try to incorporate additional biology into the curriculum.[6,7,12]We have found that the experienced science students were invaluable during the skills-building session. It would be hard to imagine one instructor and one graduate student assistant being able to work with every group at every station in enough depth to make sure the students were being properly trained. W ith at least one experienced student on every team, there was enough experience and attention to make sure the lessexperienced students were adequately trained. If experienced students are not available at other universities (for instance if such a class was open only to chemical engineering students), it might be more productive to take two sessions to make sure all the students had enough time to gain adequate competency in these critical basic skills. Molecular biology-related experiments, such as ligation and transformation, are complex and time intensive. Lack of the basic biology laboratory skills can be a major reason for the failure in obtaining desired results ( e.g., failed transformation) in molecular biology-related experiments. Students tend to be very disappointed if they spend a few weeks on a experiment only to find out it has failed. Thus, it is worthwhile to spend time at the beginning to build the basic biology laboratory skills so students can focus on the multitude of steps needed to successfully complete their subsequent molecular biologyrelated experiments. Since it can be difficult for a chemical engineering department to have all the equipment and supplies necessary to run in-depth molecular biology experiments, we thought it might be useful to mention that the Bay Area Biotechnology Education Consortium (BABEC) has developed some kit experiments that are sold through Bio-Rad. The experiments are described on the BABEC website at . Incorporating the Biology Laboratory SkillsBuilding session along with one or more of these kit experiments (several of which are designed to be done in sequence, if desired) would be a low-cost means of giving chemical engineering students hands-on exposure to important molecular biology skills. In conclusion, incorporating a Biology Laboratory SkillsBuilding session prior to the start of molecular biology experiments has resulted in student teams, predominantly populated with students having low biology laboratory skills, successfully completing complex molecular biology experiments. Issues such as safety, sterile techniques, and basic biology laboratory skills (making an agarose gel, micropipetting, autoclaving) were emphasized, allowing these skills to be developed early so the students could then concentrate on the new concepts introd uced by each molecular biology protocol introduced in subsequent experiments (ligation, transformation, etc.). We would like to thank NSF, California State University Program for Education and Research in Biotechnology (CSUPERB), and the Department of Chemical and Materials Engineering for providing support for the development of the ChE 194 laboratory course.REFERENCES1."75 Years of Progress-A History of AIChE 1908-1983," AIChE (1983) 2.Committee on Challenges for the Chemical Sciences in the 21st Century, National Research Council, "Beyond the Molecular Frontier: Challenges for Chemistry and Chemical Engineering," April 23, 2003, accessed on December 20, 2004 3. Frontiers in Chemical Engineering: Research Needs and Opportunities (Amundson Report), National Academy Press, Washington, D.C. (1988) 4.Veggeberg, S., "The Interface Of Biology And Chemical Engineering," The Scientist, 7 (3), 15, February 8 (1995) 5.Georgakis, C., "Revolutions: All Sorts...But Mostly Scientific," CAST Comm., Summer 2002, accessed January 5, 2005 6."Integration of Chemical and Biological Engineering in the Undergraduate Curriculum: A Seamless Approach," July 2003, accessed January 5, 2005 7. 8. 9. 10. 11 12.Ydstie, B. Erik, "New Frontiers in Chemical Engineering: Impact on Undergraduate Curriculum Workshop," WPI May 7, 2004 accessed January 5, 2005 13.Komives, C., S. Rech, and M. McNeil, Chem. Eng. Ed., 38 (3), 212, (2004)

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138 Chemical Engineering Education A Simple Classroom Demonstration ofNATURAL CONVECTIONDEAN R. WHEELERBrigham Young University Provo, UT 84602 Copyright ChE Division of ASEE 2005 ChEclassroomNatural or free convection results when there is a fluid density gradient in a system with a density-based body force such as the gravitational force. In an otherwise quiescent fluid, a density gradient can be caused by temperature gradients and/or species concentration gradients. Natural-convection currents enhance heat and mass transfer relative to conduction and diffusion in a quiescent fluid.[1]This is an important process for engineers to understand. For instance, natural convection is a key process in the passive cooling of people, machinery, and computer chips, and in the volatilization of exposed liquids in an indoor or windless environment. The topic of natural convection is typically covered during two or three classroom hours in a junior-level heat and mass transport course. One of the difficulties in such math-intensive courses is helping students get a qualitative and physical understanding of the phenomena. It is easy for students to get lost in dimensionless numbers and correlations when they don't have basic engineering sense. One way to remedy this is for students to observe the relevant phenomena and to discuss their observations and how they relate to the equations. This article explains a simple way to demonstrate natural convection in the classroom using an overhead projector. The demonstration is based on the principle of schlieren imaging, commonly used to visualize variations in density of gas flows. The demonstration requires a few hours of preparation time but very little in materials cost, assuming an overhead projector is already available. It could be prepared by the instructor or by students as part of a class-related project. In the discussion below, I assume the reader is more familiar with the principles of natural convection than with schlieren imaging. Therefore, I focus on the principle behind the schlieren technique, the preparation required for the demonstration, and the results that one can expect.SCHLIEREN IMAGINGSchlieren images, along with shadowgraphs and interferometry, are a means of visualizing density variations in transparent media.[2] These techniques work on the principle that the index of refraction of a fluid depends on its density. The path and phase of a light wave passing through the fluid therefore depends on its density and its spatial derivatives. Schlieren optics as such was invented in 1864 by August Toepler, a German chemist and physicist ( schlieren means "streaks" in German).[3] The technique has been extensively used to visualize shock waves in supersonic flight. The wavy appearance of the Dean R. Wheeler completed a BS at Brigham Y oung University (1996) and a PhD at the University of California, Berkeley (2002), both in chemical engineering. Returning to his Utah roots, he began teaching as an assistant professor at Brigham Young University in 2003. His research area is electrochemical engineering, with ongoing projects to optimize processes in lithium batteries and in metal electrodeposition. Figure 1. The principle of schlieren imaging. Rays of light, moving from bottom to top, encounter a filter, a refractive object, a second filter, and then the image plane. Density gradients in the refractive object bend light rays such that some are screened out by the second filter, resulting in intensity variations on the imaging surface.

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Spring 2005 139 fluid density gradient. Conversely, if the fluid object has a uniform density gradient, the image will be uniformly gray.DEMONSTRATION SETUPHow can one adapt the schlieren technique for classroom use? Figure 2 shows how the optics that are part of an overhead projector can be used to project a schlieren image of an object onto a screen. The schematic is a view from above, which means that the overhead projector is turned on its side. This is necessary so that vertically traveling fluid currents around the free-convection object are largely orthogonal to the light path. The optical principles of this setup, including the use of striped filters, is the same as in Figure 1, except that a focusing lens increases the brightness of the projected image by collecting and distributing the light from the projector lamp. The smaller filter (point S) is attached to the surface of the overhead projector, and both filters have their stripes in a vertical orientation. In order for the setup in Figure 2 to work, the optical planes associated with points O and O must be "in focus" with each other, as must the planes associated with points S and S. Assuming the lens is ideal, this means that 11111 1 ddddfO O S S+=+=() where dX indicates optical distance between the lens and point X, and f is the focal length of the lens. Because the projector lens is mounted on a movable carriage, we have a great deal of freedom in positioning the various optical elements. Figure 3 shows the two striped filters used in my optical setup. They were made by creating the black-and-white striped patterns in a computer graphics program, laser printing onto transparent sheets, and attaching the sheets onto frames con-Figure 2. View of the optical setup from above. Point L indicates the overhead-projector carriage lens. Points S and S indicate the small and large stripe filters, respectively. Points O and O indicate the free-convection object and its projected schlieren image, respectively.horizon above a hot road is a simple example of schlieren imaging of natural convection. Figure 1 illustrates the principle of schlieren imaging. A series of two filters with periodically alternating transparent and opaque stripes is used in combination with a light source. The fluid to be imaged has a gradient in its index of refraction, which causes spatial variations in the amount of light that passes through both filters. This produces an image in which light and dark areas correspond to variations in the Figure 3. Schematic of the small and large stripe filters. The dotted lines indicate boundaries of single-page transparencies that are taped onto frames made of foam-core board.

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140 Chemical Engineering Education Figure 4. Projected images of convection currents above a tea candle.structed from foam-core board purchased from the art supplies section of the campus bookstore. The smaller filter has a size comparable to the free-convection object to be imaged and has black stripes of thickness 0.5 mm and periodicity of 1 mm. (Because of the vagaries of my laser printer, it was necessary to make the black stripes 0.67 mm thick in the graphics program to affect a printed thickness close to 0.5 mm.) The larger filter is basically an enlarged image of the smaller filterin this case enlarged by a factor of 3.7. The enlargement factor is equal to the ratio of optical distances dS/dS. It is advantageous to make the large filter as small as the optics allow and customize it for the overhead projector to be used. To determine the optimal large filter Make the small filter, place it on the overhead projector surface, and project its image onto a wall. Move the lens carriage to its uppermost (furthest) position relative to the surface. This maximizes distance dS and hence minimizes dS, according to Eq. (1). Move the entire projector relative to the wall until the striped image is exactly in focus. The wall is then at position S of Figure 2 and thus establishes distance dS. Measure the thickness and periodicity of the stripes projected on the wall to determine the enlargement factor. The stripes on the large filter should exactly match the stripes of the focused wall image. The large filter is created, as is the small filter, by printing onto transparency sheets from a computer graphics program. The sheets are mounted onto a rigid frame. Additional apparatus will be required to hold the frame in the proper position during the demonstration. For instance, I built a stand that accomplishes this from leftover pieces of foam-core board, wooden toothpicks, and glue. In preparing for the demonstration, some optical tuning is required. The lens carriage should continue to be in its uppermost position, whereas the projector will be located further from the wall in the classroom than in the above experiment. One must first ensure that the two stripe filters are in focus with each other. This step requires patience and a steady hand. Success comes when the projected image is uniformly gray and all MoirŽ patterns from the interacting filters have been eliminated. Next, the free-convection object is placed in the path between the small filter and the lens carriage (see Figure 2). The object is then moved relative to the lens so that the object's wall image is in focus.

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Spring 2005 141The demonstration is based on the principle of schlieren imaging, commonly used to visualize variations in density of gas flows. [It} requires a few hours of preparation time but very little in materials cost, assuming an overhead projector is already available. RESULTS AND STUDENT LEARNINGHigh-quality schlieren images require precise construction and positioning of the optical elements. In this case, the precision is not as great as can be achieved in a laboratory, and hence the "overhead projector" method is less sensitive to density variations. For this reason, the setup here is only practical for imaging an object with large density variations, such as a flame. Figure 4 shows three images obtained of the convection currents above a tea candle. Two difficulties should be noted. First, the pictures in Figure 4 have been rotated 180 That is, using the above setup results in a projected schlieren image that is upside downstudents will have to adapt their perception to this fact. Second, careful positioning of the optical elements requires several minutes, so it is preferable to set up the demonstration in the classroom prior to the start of class. It is also a good idea to do a "dry run" during a time when the classroom is not in use. How can this demonstration reinforce student learning of natural convection? The most obvious answer is that images (particularly live moving images) of natural convection fluid currents generate interest and excitement about the topic. In this demonstration, students are able to visualize the dynamic nature of free convection. While it is probably unrealistic in an undergraduate class to attempt a quantitative analysis of heat and mass transport for a diffusion flame,[4] the demonstration can serve as a launching point for discussion of general concepts or a review of concepts already introduced. The following questions can be posed to the class as a whole or to small groups of students: Why would it be more difficult to use schlieren imaging to view natural convection currents from your hand, compared to currents from a candle flame? (Answer: The schlieren technique depends on fluid density differences, which in turn depend on fluid temperature difference. The temperature differences around a flame are much larger.) How would the fluid currents around a candle flame change if the candle were inside a quiescent-airfilled spaceship orbiting the earth ? (Answer: Natural convection depends on gravity. The convection currents would cease and the flame would be spherically symmetric. Transport of reactants, products, and heat will be due to diffusion and conduction only.) Discuss your observations concerning the transition from laminar to turbulent flow in the boundary layer around a lit candle. What factor(s) seem to affect the behavior of the transition? (Answer: Students should observe that the transition position varies in time. The smallest hydrodynamic disturbances, such as air currents in the room, affect the transition point and the motion of the boundary layer.) Empirical correlations of natural convection treat it as a steady-state process. Comment on the validity of this assumption. (Answer: As with the currents around the candle flame, natural convection is nearly always a non-steady-state process, particularly with the onset of turbulence. On the timescale of most heat/mass transfer problems, however, one can average the results in time to obtain reasonable heat/mass transfer coefficients.) The qualitative understanding that comes from direct observation of phenomena can serve as a framework students can use to organize equations and quantitative problem solving. So far, I have used this schlieren demonstration only one time in my class. The students were highly interested, and I feel the demonstration and subsequent discussion were classroom time well spent. V ideos of the projected images corresponding to Figure 4 are available at Ref. 5. As an aid to readers, electronic versions of the graphics used in Figure 3 are available at the same website. References 6 and 7 are websites for two leaders in the field of schlieren imaging, Professor Gary Settles of Penn State and Professor Andrew Davidhazy of Rochester Institute of T echnology. Their sites contain a number of beautiful schlieren images of natural convection that can complement the live demonstration and lead to further discussion of how dimensionless numbers and empirical correlations relate to students' observations of natural convection currents.REFERENCES1.Incropera, Frank P., and David P. Dewitt, Fundamentals of Heat and Mass Transfer, 5th ed., John Wiley & Sons, New York, NY (2002) 2.Settles, Gary S., Schlieren and Shadowgraph Techniques: Visualizing Phenomena in Transparent Media, Springer-Verlag, Heidelberg, Germany (2001) 3.Katz, Eugenii, "August Toepler ," website at (2003) 4.Turns, Stephen R., An Introduction to Combustion: Concepts and Applications, 2nd ed., McGraw-Hill, New York, NY (2000) 5.Wheeler, Dean R., "Schlieren Classroom Demonstration ," website at (2004) 6.Settles, Gary S., "Penn State Gas Dynamics Lab," website at (2004) 7.Davidhazy, Andrew, "Basics of Focusing Schlieren Systems," website at (1998)

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142 Chemical Engineering EducationCOMPUTER SCIENCE OR SPREADSHEET ENGINEERING?An Excel/VBA-Based Programming and Problem Solving CourseOver the past two decades, chemical engineering practice has been profoundly influenced by advances in computer hardware and software, stimulating debate within the academic community on how students should be prepared for computer applications in the "real world." At the crux of this debate is the relative importance of including a traditional introductory computer science course in the chemical engineering curriculum. Without question, in the "old days" the pathway for applying computers to the solution of engineering problems was to write your own program from scratch, usually in Fortran. T oday, industry is much less likely to engage their engineers with such tasks. The expectation is that commercial software vendors will supply them with user-friendly software packages that require little or no programming skills. A recent survey[1] by CACHE indicated that computing in the workplace for entry-level chemical engineers is clearly on the rise (over two-thirds of the approximately 300 respondents spent at least one-half of their workday at their computer). It was found that most of the time spent working on the computer involved user-friendly commercial software packages, with the most common application being Microsoft Excel. Nearly three-quarters of the respondents were not expected by their employers to be competent in any programming language. The most common programming language being used, and the one most highly recommended for inclusion in the chemical engineering curricula, was Visual Basic. Based on these results, it might be argued that graduating chemical engineers would be more suitably equipped to contribute in an industrial setting if they were taught how to effectively use Excel rather than how to write a computer program in a language they may never use again. The numerous books,[2-5] trade journal articles,[6-8] software vendors,[9-12] and consultants[13-15] that demonstrate the use of Excel in engineering analyses underscore this point. This notion, however, overlooks the value of learning how to logically formulate a problem-solving strategy that is inherent in any programming course. Moreover, it omits the necessary exposure to programming concepts ( e.g., loops, decision constructs, etc. ) for the fraction of students who may be required to do some type of programming in an R&D setting or in graduate school. This paper describes a compromise approach that combines instruction on the use of Excel as well as computer programming concepts by way of Excel's macro programming language, Visual Basic for Applications (VBA). The benefit to students is that they can learn the practical aspects of "spreadsheet engineering" as well as the more generally applicable concepts of computer programming. Additionally, they gain a clearer understanding of how the course material applies to their future profession since the course is taught within the chemical engineering department. The benefit to the instructor is the ability to consolidate the presentation of course material through the use of a single software package. This paper describes the format and content of a freshmanlevel course that has been designed to replace the more traditional introductory computer science course.COURSE FORMATProgramming and Computation for Chemical Engineers is a two-credit-hour course that chemical engineering majors at Rose-Hulman Institute of Technology are required to take in the spring quarter of their freshman year. The class meetsDANIEL G. CORONELLRose-Hulman Institute of Technology Terre Haute, IN 47803 ChEcurriculum Copyright ChE Division of ASEE 2005Dan Coronell received his BS from the University of Illinois-Urbana and his PhD from the Massachusetts Institute of Technology, both in chemical engineering. After graduation he worked in the chemical, semiconductor, and engineering software industries for over nine years before joining the faculty at RoseHulman Institute of Technology, where he is presently Associate Professor.

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Spring 2005 143two times per week for fifty-minute periods over a ten-week quarter. At this point in the curriculum, students have typically completed two quarters of calculus and chemistry and one quarter of physics. They are also concurrently enrolled in a freshman-level design class that introduces them to many concepts of importance to chemical engineers16. The early introduction of chemical engineering concepts into their curriculum provided by the two courses is beneficial to the students, as will be discussed below. Prior to the first meeting of this newly redesigned course, a survey was conducted to assess the level of expertise in using Excel and experience with any programming language. Approximately two-thirds of the 66 students that were originally registered for the two sections responded to the survey. The first part of the survey asked the students to select one of five different categories that best characterized their ability to use Excel. The selection options included Power user Pretty comfortable using it to process data and make plots Have used it before several times and know the basics Have only started using it since my freshman year Have never used it beforeThe results are summarized in Table 1. While all of the respondents had used Excel to some extent, most of the course material consisted of techniques and applications that the students had never been exposed to in the past. The second part of the survey asked students to identify any programming languages they had previously learned in coursework or through work experience. As can be seen in T able 2 below, two-thirds of the respondents had no previous programming experience. Note that a few respondents had experience in more than one type of programming language. The classroom instructional technology at Rose-Hulman greatly facilitated the execution of this type of course. Every classroom is equipped with a laptop computer projector and wireless network capabilities. In addition, each student at Rose-Hulman is issued a laptop computer at the beginning of their freshman year. The students were required to bring their laptop computers to class each day. A typical 50-minute class period was discretized into 20 minutes of traditional lecture, 20 minutes of computer laboratory, and 10 minutes of discussion and reflection. The initial lecture period would usually include an instructor-led example problem with students following along on their laptops, followed by a computer lab assignment on a problem related to the lecture topic. The students were free to work together and to ask questions during this time. The last few minutes of class were used to obtain closure on the subject matter where the computer lab solution would be provided, the relevance of the material would be reinforced, and any remaining questions would be answered. All in-class quizzes and homework assignments were submitted electronically as Excel workbooks. While most of the students had not yet taken any core chemical engineering courses, every opportunity was taken to expose the students to the kinds of problems they would see later in the curriculum. This served to benefit the students in several ways. First, they became more engaged in learning the programming and the problem-solving concepts when it was demonstrated that these fundamentals could be applied to chemical engineering-related problems. This was true in spite of the fact that they possessed only a cursory understanding of the underlying fundamentals at this point in their education. Another benefit was that, early in the curriculum, students were exposed to a sample of what the chemical engineering profession entails. It was observed that many of the students were interested in chemical engineering for reasons ranging from the desire to follow the path of a family member or close friend to a desire to have a good paying job when they grad uated. Approximately 5% (3/66) of them ended up changing their major after learning more about the chemical engineering profession. In the following section, the specific learning objectives and content of the course are described.COURSE OBJECTIVES AND CONTENTIn a broader perspective, the objective of Programming and Computation for Chemical Engineers is to begin the process of introducing the computer as an engineering problemsolving tool. As described in the preceding section, the approach to satisfying this objective relies upon active learning, relevant example applications, and modern classroom instructional technology. This high-level objective of the newly redesigned course was refined into the specific learning objectives of Becoming proficient at using Excel to perform scientific and engineering calculations and graphical analysis. Understanding the essential elements of structured and object-oriented programming as it applies to VBA. Being able to construct customized VBA-based spreadsheet functions to enhance the engineering problemsolving capabilities of Excel.T ABLE 1Survey of Students' Level of Expertise Using ExcelPowerPrettyKnowJustNever Used UserComfortableBasicsStartedBefore# of Respondents21713100 T ABLE 2Survey of Students' Prior Programming ExperienceV isualC/C++JavaPascalMatlabNone BasicC#HTML# of Respondents10951128

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144 Chemical Engineering Education T ABLE 3Applications of Computer Skills Included in Course ApplicationImplementationExampleEngineering formulaExcelPressure dynamics and involving transcen-VBArelease rate of choked dental functionsflow from a highpressure gas cylinder Parameter estimationExcelDetermination of firstVBAorder rate constant from experimental data using the integral method Solution of linearExcelSteady-state material systems of algebraicbalance equations Solution of nonlinearExcelDetermination of algebraic equationsVBAfriction factor using the Colebrook equation Numerical integrationExcelSizing of a gas-liquid VBAscrubber Numerical solution ofExcelDraining of a tank using ordinary differentialTorricelli's formula equations Figure 1. Schematic illustrating sequence of topics pertaining to spreadsheet (a) and VBA (b) instruction.The first one-quarter of the course consisted of formal instruction on spreadsheet techniques and tools. This is illustrated in Figure 1a, where the students' progression of learning begins with basic operations in a worksheet cell and progresses outward to increasingly complex worksheet operations. The remaining three-quarters of the course was devoted to instruction on VBA programming in Excel. Since VBA is a separate application that is integrated into the Excel environment, this involved two distinct aspects learning the VBA programming language and learning how to interface with Excel from a VBA program. The latter required the students to work with Excel's so-called Object Model, a heirarchical, object-oriented interface to the Excel application that facilitates manipulation of all the elements of an Excel workbook. A synopsis of the programming elements of VBA that were included in the course is shown in Figure 1b. VBA contains many of the same elements that are common to other programming languagesvariables, loops, decision constructs, etc Thus, the students obtain a conceptual understanding that enables them to more easily learn a different progamming language, such as C++ or Java. This was an important consideration since some of the students will continue their education in graduate school where they may be involved in computational research requiring programming skills in other languages.EXAMPLE APPLICATIONSIn the preceding section, the general features of Excel spreadsheets and VBA programs that the students were exposed to, and which underly the course learning objectives, were described. The students developed their skills at using these tools by applying them to a number of engineering-related problems. The types of applications that were included and the specific example problem they were asked to solve are summarized in Table 3. Most of the applications were first explored using a spreadsheet-only approach, then subsequently implemented in a VBA program. It is again emphasized that while the students did not possess a deep understanding of how the design equations for a particular application were derived, their appreciation for the usefulness of the computer skills they were acquiring was nonetheless heightened. Moreover, they finished the course with a better understanding of what was ahead of them in the chemical engineering curriculum. One of the applications listed in Table 3 is the numerical solution of ordinary differential equations (ODEs). The students learned how to solve ODEs using both the explicit Euler method as well as the 4th-order Runge-Kutta method. As an example, the following differential equation representing the draining of a cylindrical tank was numerically solved by applying the 4th-order RungeKutta method, using both the spreadsheet and VBA program implementations. dh dt d d ghhole k= tan 22 In this equation, h is the height of fluid in the tank, t is the cumulative draining time, dhole is the diameter of the drain hole located at the bottom of the tank, dtank is the tank diameter, and g is the gravitational acceleration constant. This equation is widely known as Torricelli's formula, and possesses an exact solution. This enabled the students to also explore the concepts of integration step size and associated error, as well. The two implementations are shown in Figure 2 below. The students solved this problem using the spreadsheet implementation early in the quarter, and subsequently revisited the problem after learning how to create customized VBA function procedures. This helped them to appreciate the advantages of the VBA approach, including the conciseness of the implementation

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Spring 2005 145 Figure 2. Runge-Kutta solution of an ODE describing draining of a tank using a spreadsheet (a) and a VBA program (b).and the ability to reuse the function to solve a different problem by simply redefining the ODE in the VBA function. Additionally, the VBA implementation reduces the possibility of introducing a typographical error since the Runge-Kutta terms do not have to be retyped for each problem.SUMMARY AND CONCLUDING REMARKSA newly redesigned freshman programming course for chemical engineers that supplants the traditional introductory computer science course has been described in this paper. The course focuses on the use of Excel spreadsheet and VBA programming techniques to solve engineering-related problems in response to the needs of industry as unveiled in a recent CACHE survey. The course also serves as a metric for students to assess their interest and aptitude for the chemical engineering profession at an earlier point in their curriculum than previously allowed. Some remaining issues will have to be addressed, one of which includes the lack of suitable textbooks that relate to the course content. Many textbooks on Excel and VBA programming are available, but no textbook could be identified that focused on engineering-related applications. The students responded quite positively to learning programming skills within the context of solving engineering-related problems. A textbook that is tailored to such a class would greatly facilitate the continued offering of the course. Additionally, in order for the students to sustain and leverage the skills obtained in the course, a department-wide involvement to incorporate Excel/VBA problem-solving methods where applicable into their higher-level engineering courses must be initiated and sustained. The familiar saying, "Use it or lose it!" applies here. It is also important to acknowledge that while spreadsheets and Visual Basic programs are useful for solving many relatively routine engineering problems as illustrated in the preceding section, some problems require more sophisticated computational tools. This becomes apparent to the students later in the curriculum as they take courses in fluid mechanics, transport phenomena, thermodynamics, reactor engineering, and design. Here they will learn about software packages designed to perform computational fluid dynamics calculations, predict detailed fluid properties, optimize process flowsheets, and more. Thus, the Programming and Computation for Chemical Engineers course represents the commencement of their education in using the computer as an engineering tool. The real value of the approach outlined here is, perhaps, that the students can more clearly and immediately see that computers can be programmed to efficiently solve chemical engineering problems.REFERENCES1.Edgar, T., "Computing Through the Curriculum: An Integrated Approach for Chemical Engineering," CACHE Fall 2003 Newsletter, 2.Bloch, S.C., Excel for Engineers and Scientists, 2nd ed., Wiley, New Y ork, (2003) 3. Filby, G., Spreadsheets in Science and Engineering Springer-Verlag, New York, (1998) 4. Kral, I.H., The Excel Spreadsheet for Engineers and Scientists Pearson Education, New Jersey, (1997) 5.Orvis, W. J., Excel for Scientists and Engineers 2nd ed., Sybex, San Francisco, (1996) 6.Peress, J., "Working with Non-Ideal Gases," Chem. Eng. Prog. p. 39, March (2003) 7.Jevric, J., and M.E. Fayed, "Shortcut Distillation Calculations via Spreadsheets," Chem. Eng. Prog. p.60, December (2002) 8.Anthony, J., "Elements of Calculation Style," Chem. Eng. Prog. p.50, November 2001. 9.Chemeng Software, 10.ChemSheet Software, 11.Excel Unit Conversion, 12. The Chemical Engineers' Resource Page, 13.Beyond Technology, 14.Emagenit, 15.Spreadsheet World, 16.Sauer, S.G., "Freshman Design in Chemical Engineering," Chem. End. Ed. 38 222(2004)

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146 Chemical Engineering Education THE PARADOX OF PAPERMAKINGMARTIN A. HUBBE, ORLANDO J. ROJASNorth Carolina State University Raleigh, NC 27695-8005Marty Hubbe is Associate Professor in the Department of Wood and Paper Science at North Carolina State University. He received his BS in Chemistry from Colby College in 1976, his MS in paper technology from the Institute of Paper Chemistry in 1979, and his PhD in Chemistry from Clarkson University in 1984. His interests include the colloidal chemistry of papermaking, surface charges, and polyelectrolytes. Copyright ChE Division of ASEE 2005 Orlando Rojas is Assistant Professor in the Department of Wood and Paper Science at North Carolina State University. He received his BSc from Universidad de Los Andes (ULA, V enezuela) in 1985, his MS in 1993, and his PhD from Auburn University in 1998, all in chemical engineering. His interests include interfacial phenomena and surface and colloid science and the study of adsorption behaviors of surfactants and polymers at interfaces. Students in chemical engineering who enroll in courses such as papermaking often find themselves startled by the richness and breadth of phenomena that concurrently take place in related processes. Gas, solid, and liquid phases are put into contact in different states of dispersion where surface and colloidal forces, together with hydrodynamic effects, shape the final outcome, i.e., the familiar sheet of paper. Even more perplexed is the instructor who, while teaching, finds him/herself attempting to explain a series of events that is full of paradoxes. To begin with, while librarians expect paper to last for hundreds of years,[1,2] most paper gets thrown away or is recycled within a matter of days or weeks. Whereas paper is one of the least expensive manufactured items, its production involves use of some of the most expensive systems of equipment.[3,4]Paper is among the most recyclable and environmentally compatible products, made mainly from naturally renewable materials,[5] but at the same time the industry has faced great pressure related to its environmental impact.[6-10]Though each of the items just mentioned raises some interesting questions, the focus of the present article is on some especially paradoxical issues related to the process itself. There are some apparent contradictions inherent in the papermaking process that make it a fascinating field of science and art. Even as we begin to understand the principles behind what at first appears to be magic, we owe profound respect to the craftspeople in China and elsewhere[11,12] who discovered and developed this subtle and economically important process.P ARADOX ONEDivide to Combine W ood and paper are both solid materials, composed mainly of polysaccharidescellulose and hemicellulose.[13] Both wood and paper contain at least 5% water, although wood can contain considerably more in a living tree and before it is dried. In addition, both wood and paper are composed of fibers that firmly adhere to adjacent fibers. As shown in Fig. 1, the first step in papermaking is to destroy every one of those interfiber bonds in the original wood. This is done at considerable expense and effort. The most widely used process for converting wood into papermaking pulp, the so-called kraft process, commonly involves dissolution of 50% to 60% of the solid material.[14] What makes the kraft process particularly impressive is the toughness, insolubility, and high resistance to chemical attack on the part of lignin, which is the phenolic substance that holds the fibers together in the wood. All of this is accomplished by a process that recovers m ost of the chemicals used in cooking, and also generates an excess of high-pressure steam and electricity from the heat evolved from the unused components of the fibers.[14,15]Though less impressive from a chemical standpoint, the other way of liberating wood fibers from each other also involves drastic action. Mechanical approaches to turning wood chips or logs into papermaking fibers require a huge amount of energy, usually between 5 and 10 megajoules per kilogram of fibers, on a dry basis.[14,16]The next step, after converting the wood material to pulp, ChEcurriculum

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Spring 2005 147involves adhering the fibers back together. A typical papermaking fiber is about 1-3 mm long and has a length-to-thickness ratio of about 50-100.[17] During the process of forming a sheet of paper, these fibers have a tendency to lie in layers, each fiber being approximately parallel to the plane of the sheet. Hydrodynamic effects, as well as tension on the wet sheet as it is being pressed and as it starts to be dried, can further impose a preferential orientation in the direction of manufacture.[18,19] It has been estimated that a typical fiber in paper crosses about 20-40 similar fibers.[20] Adhesion at each of these crossing points has a dominant effect on the strength of the resulting paper.P ARADOX TWOAdd Water, Then Take It Away Immense amounts of water are added to the papermaking process, even if one just considers the initial separation of wood into a suspension of fibers. Then, as illustrated in Fig. 2, the water is taken away again. Both the kraft process and mechanical pulping processes involve dilution of the fibers to a solids content of about 3% to 10%. It is usual to add much more water just before the paper is formed into a sheet and dried. Papermakers refer to this highly diluted condition as the "headbox solids" or "headbox consistency," since the headbox is the last part of the paper machine that is visited by the fiber suspension before water is taken out during the paper forming process. The most common va lues of headbox consistency lie within a range of about 0.3% to 1.2%.[21,22] T aking 0.5% as an example, this implies that the papermaker needs to pump roughly 200 mass units of water for every unit of fiber, on a dry basis. Why do papermakers use such high dilution? The answer can be traced again to the high length-tothickness ratio of fibers, giving them a tendency to become entangled as "flocs" in a flowing suspension.[23-26] It has been proposed that flocculation can generally be avoided by diluting the suspension enough so that most fibers are able to rotate about their center points without touching another fiber. Based on the lengths and masses of typical papermaking fibers, the solids level required to approach this theoretical condition, even if the fibers are lined up on an artificially regular array, would be less than about 0.02% solids.[27]In actuality, the levels of headbox consistencies used in most papermaking operations seldom are as low as these theoretical numbers. Rather, papermakers need to strike a compromise between the desire to minimize flocculation and the expense and difficulty of recirculating so much water. Though headbox consistencies in the range 0.3% to 1.2%, as mentioned earlier, imply very frequent collisions among fibers, tending to produce some fiber flocs, the uniformity of the resulting paper tends to be satisfactory for most end-uses. The most massive and outwardly impressive part of a paper machine is devoted to removal of almost all of that water that was used to dilute the fibrous suspension. Though details of paper machine systems are discussed elsewhere,[4,14]several features of this equipment are especially notable. These include the forming fabric, which is essentially a continuous screen or pair of screens upon which the paper is initially dewatered. Adjustments in the angle impingement of the jet of fiber suspension onto the fabric, and also the relative speeds of the jet and the fabric can be used to partly break up the flocs of fiber, yielding more uniform paper.[28]As the wet paper proceeds down the moving fabric surface, it experiences a series of pulses of vacuum and pressure. These pulses not only help in the process of water removal, but they also tend to improve paper's uniformity of formation.[28,29] Stationary devices known as hydrofoils and forming blades are often used to pull water from the wet mat of fibers. Gradually increasing vacuum pulls yet more water from the paper. Most of the water is removed in this stage, and the solids content of the paper web may reach 15-20%. To remove more water, the damp paper is pressed against felt surfaces as it passes through the nips between large solid rolls. Finally, in the dryer section of the machine, the paper typically passes around multiple, steam-heated cylinders to evaporate most of the remaining water. Because evaporation requires much more energy compared to the previous dewatering steps, it is important that the paper enter the dryer part of the paper machine with as high a solids level as practical. Usually about 4% to Fibers bound together in wood Fibers bound together in paper Dispersed fibers Papermaking process Paper machine White water Fillers, etc. Wood Recycled paper Suspension of wood pulp fibers Polymer Process water Colloidal silica New paper Dry Wet Dry Figure 2. A view of the papermaking process as a matter of making the fibers wet and then having to dry them again. Figure 1. A view of the papermaking process as breaking the interfiber attachments in wood, just to reestablish them again later as paper.

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148 Chemical Engineering Education8% of moisture content is left in the final paper so that it will be as close as practical to equilibrium with the expected relative humidity when it is used, a practice that tends to minimize curl problems in the paper.[30]P ARADOX THREESwell with Water to Dehydrate and Shrink Recently, the person in charge of making a relatively heavy grade of paper on a modern machine wanted to know, "What can I do to reduce the amount of water contained in the fibers?" What was left unsaid was the fact that this papermaker still wanted to achieve a high level of interfiber bonding within the product. Past studies have shown a high correlation between a fiber's state of swelling, as represented by its waterholding ability, and the tensile strength properties of paper made from those fibers.[31-33] According to theory, a more swollen fiber has a more flexible surface, and it is able to develop a higher proportion of bonded area under a given set of conditions for forming, pressing, and drying the paper sheet.[20,34] This situation is illustrated in Fig. 3, which shows how papermaking fibers become swollen during the papermaking process, but can end up "shrunk" relative to their original perimeter. The more swollen fiber can be more difficult and more expensive to dry, however. That is because it is very difficult to remove the last bit of water that is held within the cell walls of papermaking fibers, except by evaporation. Although papermakers apply intense pressure as the wet paper sheet passes between steel rolls or "extended nips,"[35,36] some water remains in the cell walls of the compressed fibers.[37,38] The average dimension of micropores where such water is held in a kraft pulp fiber has been estimated to be in the range of about 1 to 50 nm.[39-41] If one models such capillaries as cylinders, the pressure exerted by meniscus (capillary/surface tension) forces is predicted to be in the range 4 to 200 MPa, a range that partly overlaps the range of pressures that papermakers use to squeeze water out of a paper sheet in press nips[14] before it is dried by evaporation. Papermakers' Holy Grail, a visionary but see mingly impossible goal, would be to find a type of fiber that has a highly conformable surface in the wet state, but a low amount of water held within the fiber walls. Although the search for such fibers generally has led to frustration, two contrasting solutions to this dilemma are worth considering. One notable approach involves the use of relatively high-yield fibers, such as the mechanical pulp fibers mentioned in Paradox One. The lignin and hemicellulose components, which account for over half of the dry mass of such fibers, have softening points within a temperature range of about 50 to 200 C,[42,43] depending on moisture content, which is close to the temperature that paper reaches during a typical drying operation.[44] Thermal deformation, allowing fibers to dev elop a higher proportion of bonded area, has been especially noted in the case where high-yield fibers are subjected to certain modern drying practices that achieve higher-than-typical combinations of moisture and temperature.[45,46]Research has shown a fascinating interrelationship between the strength of paper and its ability to scatter light and resist that show-through of print images.[20] The reason that these two variables are connected is that the relative amount of light scattering is roughly proportional to the air-solid interfacial area within paper. In areas where fibers are bonded tightly together, light can pass between the two of them without scattering. Thus, one of the penalties of relying on either refining or plasticization as the chief means of increasing paper's strength is that the paper tends to become more transparent and might not meet the customer's specifications. To minimize the loss of opacity, papermakers can use a completely different approach to increasing the bondable nature of fiber surfaces. Rather than making the whole fiber more flexible, the common approach is to add water-loving polymers as dry-strength agents to the fiber slurry. The function of these drystrength agents is to increase the tenacity of bonding within areas where the fibers contact each other[47-49] and possibly increase the area over which bonding takes place. There has been a debate as to whether additives such as cationic starch or acrylamide polymers can increase the relative area of bonding between fibers,[50-52] but if that were true, then one would expect the resulting paper to be more translucent, as discussed. Rather, an analysis based on light-scattering tests revealed very little increase in optically bonded area.[53] Thus the main contribution to paper strength, due to the polymeric additives, is related to the strength per unit of bonded area. Apparently, any effect of dry-strength polymers to fill in spaces between rough surfaces of fibers must happen at a molecular scale, smaller than the limits of detection of optical methods. We have to keep in mind that the light-scattering method relies on the fact that a fiber surface element appears bonded if there is another fiber surface at a distance smaller than half the wavelength of light. This doesn't guarantee that the two fibers are bonded chemically, since the bonding distance is shorter. Irrespective of the case under consideration it is concluded that the interaction between light and the paper netFiber not swollen Increased swelling of fiber Fiber less swollen than at first Refining Drying Figure 3. A paradoxical aspect of papermaking: Fibers are made to swell in water, but they shrink again even more after the paper has dried.

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Spring 2005 149work is closely related to the bonding degree. Both light absorption and sca ttering are the same properties that define the brightness and opacity of paper. Therefore the relationship between optical and mechanical strength in paper is not surprising.P ARADOX FOURMake the Fibers Flexible to Make the Paper Stiff Although some producers of paper will argue that the primary benefit they provide for their customers is a surface on which to print images or messages, there are many grades of paper where "support" is a function that is equally important. Paper bags provide a good example. Although many grocers prefer plastic bags because of their handles, their resistance to water, and their low cost, customers can clearly tell the differenceonly the paper version is stiff enough to stand up by itself once it is opened. As another example, xerographic copy paper has to meet a certain minimum stiffness level or it tends to jam in the machine. Boxes made of paperboard also need to have sufficient resistance to bending and crushing in order to fulfill their role. So what is the first thing that papermakers do to the fibers? As illustrated in Fig. 4, they convert them to flexible ribbons. In the tree, fibers can be envisioned as little tubes with closed, pointy ends. Based on the principles of mechanics, the tubular shape offers a high resistance to bending, relative to the mass of solid material.[54] Instead of taking advantage of this inherent resistance to bending, papermakers subject the fibers to a number of processes that make them more conformable. The combined effects of kraft pulping and refining makes the fibers flexible enough to collapse. Refining involves passage of fiber slurries between rotating steel plates with raised bars. The fibers are repeatedly compressed and sheared as they pass between these bars, causing internal delamination as well as fibrillation of the outer layers of the fibers.[14,55,56] A recent study in our laboratory showed that refining increased the flexibility of wet, unbleached softwood kraft fibers by a factor of between 6 and 19.[57]Research has shed insight on how the orientations of fibers, the bonds between them, and the degree to which the paper is held in tension during drying relate to the final properties of the paper.[58-60] To simplify the analysis it was shown that the in-plane mechanical properties of a thick sheet of paper can be reproduced by laminating many thin sheets.[61-62] An idealized model, involving 2-dimensional random networks of fibers, is then able to explain many of paper's characteristics. In the simplest network approach (fibers are assumed to be randomly distributed and correlations between fibers are neglected) it is found that the local value of the number of fiber crossings can be described by simple probability distributions. From these distributions one can easily calculate the average number of fibers crossing at any given point in the network. This is the so-called coverage, c The coverage can be measured from sheet cross-sections by determining the number of bonds that intersect a reference line and this gives a precise measure of the effective number of fiber layers in a sheet. Typical values of coverage for printing papers are 520 (layers of fibers). A more challenging issue to deal with quantitatively is paper's directional nature. For instance, paper's strength in the direction of manufacture tends to be considerably higher, compared to the cross-directional strength.[63] Briefly stated, the factors that mainly account for this directionality are (a) a tendency of fibers to become aligned in the direction of manufacture due to hydrodynamic shear as the paper is being formed,[63-65] and (b) forces exerted on the paper during the process of drying.[63] T ensile forces exerted by the rotating dryer can keep the paper from shrinking, especially in the direction of manufacture, adding to the elastic modulus of paper in that direction. There probably will never be a completely satisfactory explanation as to why papermakers so often fail to take advantage of the inherent stiffness of native, uncollapsed fibers. Ribbon-like fibers, as used by papermakers, can be advantageous in terms of achieving a high proportion of bonded area.[20] It appears that the increased interfiber bonding is so important that it offsets the possible advantage of keeping the fibers in their native shape. Perhaps the next generation of papermakers will figure out a way to achieve high levels of interfiber bonding without collapsing most of the fibers into ribbons.P ARADOX FIVEDisperse Everything Well, but Retain the Fine Particles The fifth paradox to consider is deeply ingrained in the art of papermaking. The function of a dispersant chemical is to help achieve and maintain a uniform suspension of fine particlesthus avoiding the formation of agglomerated material. The latter could hurt the uniformity of the paper product, cause abrasion, or form deposits on some of the papermaking equipment. Some materials that need to be dispersed before they are added to the papermaking process include mineral fillers, sizing additives (see later), and certain bioStiff, hollow fiber Refining Cut-away views Flexible, ribbonlike fiber Papermaking Figure 4. Papermakers do not take full advantage of the inherent stiffness and strength of hollow-shaped fibers, but rather convert them into ribbons.

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150 Chemical Engineering Educationcides and colorants. Chemical products used to avoid undesired agglomeration of the fine particles include phosphates, low-mass acrylate copolymers, and a wide range of nonionic surface-active agents (surfactants).[66,67] Such chemicals adsorb onto the solid surfaces and increase the electrostatic and/or steric repulsion forces,[66] keeping the particle from colliding and sticking. It is worth noting that some dissolved and colloidal materials originating from the wood also can play the role of dispersants due to their negative charge.[68]As shown in Fig. 5, the papermaker's perspective changes abruptly when the time comes to form the dispersed fibers and finely divided substances into a wet sheet of paper. Typical mesh fabrics, upon which paper is formed, are composed of polyester monofilaments.[69] Although there is a wide variety of forming fabric designs, including doubleand triplelayer fabrics, the openings between adjacent filaments is approximately 0.1 to 0.3 mm, which is big enough to allow passage of nonfibrous materials. This "fines" fraction may also contain, in addition to some of the wood-derived solids, mineral fillers and sizing emulsion particles. Although, in principle, some of the fine particles may be retained by mechanical filtration in the mat of wet fibers, experience has shown that the efficiency of such mechanical retention tends to be low in the absence of flocculating chemicals.[70] Poor retention of these materials produces not only a lower productivity in terms of mass balance, but also filtered water that is more difficult to treat for recirculation. Perhaps surprisingly, the kinds of chemical treatments that have been found to be most effective for increasing the retention efficiency during paper formation work according to a different principle than do dispersants. Mere neutralization or removal of repulsive forces between surfaces[71] does not provide nearly the strength of attachments needed to resist the strong hydrodynamic forces inherent in the formation of paper on a modern machine.[72-75] Strong forces tending to detach fine particles from fibers develop as water is removed from the sheet by gra vity, and by the repeated vacuum and pressure forces.[76-83] It is because of this that fine materials tend to be washed out of those layers of a paper product that were closest to the forming fabric during the production process.[84,85]The chemicals found to be most effective for retention of fine particles are the very-high-mass acrylamide copolymers, having molecular masses in the range of about 5 to 20 million grams per mole.[70,86,87] This is roughly 1000 times larger in molecular mass compared to common polymeric dispersant molecules. The monstrous size of retention aid polymers allows them to bridge between surfaces of adjacent solids, extending beyond the range of repulsive forces, including those components of the repulsive forces induced by dispersant treatments. Various different bridging mechanisms have been studied.[88-95] The effectiveness of very large molecules has also been attributed to the fact that multiple points of attachment occur simultaneously, so that adsorption of the polymer onto a surface is very difficult to reverse. It is reasonable to ask, "Do dispersants interfere with the performance of retention aids?" In general, the answer is "yes." Many studies have shown diminished effectiveness of cationic acrylamide copolymer retention aids in systems that contain substances that can act as dispersants.[96-98] This is particularly observed in the case of wood-derived anionic colloidal materials.[68,96-98] To overcome this kind of effect, papermakers often use highly charged cationic materials such as aluminum sulfate, polyaluminum chloride (PAC), polyamines, polyethyleneimine (PEI), and similar chemicals. In addition to their role as chargeneutralizers, such additives also can serve as anchoring sites for anionic retention aid molecules,[99-102] or as site-blockers to enhance the effectiveness of cationic retention aid molecules.[103]Cationic retention aids exhibit a surprising degree of compatibility with nonionic dispersants. The latter often consist of long hydrophilic ethylene-oxide chains, having the repeating unit (-CH2-CH2-O-). These are attached either to an alkyl or aromatic hydrocarbon group, or to a water-hating propylene oxide chain. An example of the compatibility between such nonionic dispersants and cationic retention aids can be seen in a patented system for control of wood pitch deposition in paper machine systems.[104]This system consists of adding a nonionic surfactant to the furnish to disperse the pitch particles (to keep them from colliding and building up to objectionable size), and then treating the slurry with a cationic acrylamide copolymer retention aid. At the opposite extreme, one can consider the use of a nonionic retention aid system based on polyethylene oxide (PEO) and a cofactor.[92-95] Such systems can be almost unaffected by changes in the amounts of anionic colloidal materials and other anionic dispersants in the system. Although the strategies mentioned in the previous two paragraphs are useful for illustrating some principles, it is far more common for papermakers to follow a strategy of minimizing the amounts of dispersants that are added to the papermaking systemknowing that their effects will need to be reversed later on when the retention aid polymers are added. The goal is to keep the amounts of dispersant no higher than the minimum needed to maintain uniform suspensions of such materials as calUndispersed particulate matter Apply shear & dispersants. Dispersed particulate matter Add a retention aid polymer. Agglomerated particulate matter Figure 5. A schizophrenic aspect of papermaking: wanting everything well dispersed, but also wanting the fine particles to adhere together when the sheet is being formed.

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Spring 2005 151cium carbonate filler. This strategy can explain at least part of the success of on-site production of precipitated calcium carbonate (PCC) filler.[105,106] Relative to ground calcium carbonate (GCC), PCC requires relatively little dispersant as long as it is made on site and kept agitated for the relatively short time between its production and use.[107,108]P ARADOX SIXChemically Flocculate the Fibers and then Disperse Them As odd it may seem, one of the first things that often happens after the papermaker has flocculated the suspended material with very-high-mass acrylamide copolymers, as just described, is that the furnish passes through a screening device that rips apart 100% of the polymer-induced attachments between fibers. This circumstance is illustrated in Fig. 6. Studies have shown that breakage of contacts between the fibers can irreversibly degrade the high-mass polymeric flocculants.[109-112] The main function of a pressure screen is to prevent large objects, such as incompletely cooked bits of wood, from getting into the product.[113] The slots in the type of screen typically used in these applications have widths of about 0.15 to 0.45 mm,[113] which is large enough to allow passage of a single fiber, but too small to allow passage of fibers that are bound together by polymers. Although "pre-screen" addition of retention aid polymers, as just mentioned, is very common, many papermakers choose to maximize the efficiency of these flocculants by adding them just after the screening operation.[114] Depending on the type of headbox and other details of the machinery, the papermaker then selects a suitably low dosage of retention aid to achieve almost the same resultredispersal of most of the fibers from each other before the paper sheet is formed. To add yet another layer to the riddle, many paper machine systems (especially in the manufacture of printing papers) use something called microparticles, which partly reflocculate the papermaking furnish again.[115-117] These additives include colloidal silica dispersions and montmorillonite clay, a suspension of extremely thin plate-like particles. The common feature is that microparticles all have a very high ratio of surface area to mass, usually in excess of 100 m2/g. One common strategy for microparticle use involves pre-screen addition of a cationic acrylamide retention aid, as just mentioned, followed by postscreen addition of the microparticle additive.[115-116,118] When microparticles are added in this way, the little particles are able to bridge between the fragments of retention aid polymers remaining on the adjacent fiber surfaces and reconnect them. The fact that papermakers seem to vacillate between inducing flocculation and then deflocculation of the papermaking stock can make one wonder what they are really trying to achieve. One explanation for the papermaker's odd practice of flocculating fibers and then immediately deflocculating them, is the fact that hydrodynamic forces are much better able to detach larger objects from each other, compared to their ability to detach a small object, either from a larger object or from other like-sized objects.[74,119-121] It's a matter of leverage. Although only something like a screen device can ensure complete deflocculation of the papermaking furnish, if only for a moment, hydrodynamic forces in the headbox of a paper machine have the potential to achieve selective breakage of polymer bridges. Modern paper machines often employ hydraulic headboxes, in which hydrodynamic shear and extensional flow fields have been designed in such a way as to maximize uniformity of the resulting paper.[122,123] Recent work suggests that it is possible, in principle, to select conditions of retention aid treatment that are more than sufficient to retain small particles, such as mineral fillers, on cellulosic surfaces, but most contacts between fibers will be separated from each other as the furnish passes through the high-shear zones of the headbox.[74,121,124,125]P ARADOX SEVENW aterborne Treatments to Make Paper Water Resistant Many different kinds of paper must be able to resist water to perform their intended function, but the fibers themselves are generally water loving. In a process called "internal sizing," papermakers add "sizing agents" to the aqueous mixture of fibers and other materials so that the resulting paper becomes hydrophobic.[17,126,127] These sizing agents have to Dispersed fibers and fine particles Add veryhigh mass flocculant. Flocculated fibers and fine particles Apply hydrodynamic shear. Dispersed fibers with particles attached Figure 6. Papermakers often add the retention aid polymers just before the furnish is subjected to high hydrodynamic shear, partly reversing the flocculating effect. . the focus of the present article is on some especially paradoxical issues related to the process itself. There are some apparent contradictions inherent in the papermaking process that make it a fascinating field of science and art.

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152 Chemical Engineering Educationbe either water-dispersible or water-soluble in order to become well mixed with the papermaking stock. Science fiction? No. This is commonly accepted practice within the paper industry. While there have been detailed studies of the molecular mechanisms of different internal sizing systems,[126-132] little of which will be repeated here, it is important to emphasize two key molecular events that seem to underlie the seemingly impossible transformation of water-loving fibers in an aqueous environment to water-repellent paper once the same materials are dried. One of these events is the orientation and anchoring of sizing molecules, due to the ways in which these molecules interact with fiber sur faces. The other event involves the way some sizing molecules become distributed over the surface of fibers when the paper is heated to evaporate the water that remains after it has been formed and pressed. The concept of "anchoring and orienting" can perhaps best be illustrated by the case of rosin soap products. As the word soap implies, rosin soap is a water-dispersible, sudsy material. Although rosin products contain a mixture of different compounds, most of them have between one and three water-loving carboxylate groups per molecule. In addition, the remainder of a typical rosin molecule consists of water-hating hydrocarbon material. When dispersed in water, the rosin soap exists not as a true solution, but as micelles. In other words, groups of rosin soap molecules associate with each other so that the water-hating parts are generally facing each other to avoid contact with the water. In order to achieve a sizing effect, an aluminum compound, such as aluminum sulfate, is added to the papermaking furnish. As shown in Fig. 7, the aluminum ions interact with the carboxylate groups, causing the rosin to precipitate onto the fiber surfaces. It has been proposed that the alum keeps the sizing molecules oriented on the fiber surfaces such that the water-hating hydrocarbon portions face outwards from the fiber surface.[130,133-134]The other common types of internal sizing agents work differently, and the key molecular events occur during drying at high temperature. If you were to add either rosin emulsion size or alkylketene dimer (AKD) sizing agents to a papermaking furnish, and then gradually dry the paper at room temperature overnight, very little hydrophobicity would develop. Although many authors have used words such as "spreading" to describe how emulsified sizing agents become distributed over the exposed surfaces of paper during the drying process, recent evidence favors a different mechanism. It is true that rosin acids, AKD, and alkenylsuccinic anhydride (ASA) sizing agents all exist as liquids at the temperatures found in the dryer sections of paper machines, but these droplets of liquid tend to remain localized at the fiber surfaces rather than spreading out as a monomolecular layer.[135-139] It has been proposed that the lack of spreading is due to formation of so-called "precursor films" adjacent to the bulk of sizing material.[138,139] The very low surface energy achieved in areas covered by such films impedes spreading of the droplets of hydrophobic material. In addition, studies have shown that only a fraction of the surface area needs to be covered with sizing molecules to achieve a high level of water resistance.[140-142]Despite the relatively low vapor pressures of AKD and other emulsified sizing agents, even at the temperatures adjacent to drying cylinders on a paper machine, there is circumstantial evidence of vapor-phase migration. For example, if one forms a sheet of wet paper in the presence of sizing agents and then dries that sheet in a stack with unsized paper sheets in an oven, a significant sizing effect can become distributed throughout the stack, with results depending on the location of a sheet relative to the treated sheet.[140,143-144] Perhaps the answer to this puzzle involves the relatively short distances over which the vapors of sizing agents need to migrate. The distances that sizing agent vapors need to migrate are even less if one considers the fact that the process of forming the paper results in microsizing droplets or particles of sizing material distributed in a semirandom manner over the surface of each fiber. A further perplexing phenomenon is observed when papermakers add polymeric sizing compounds to the starch solutions that are applied to the surface of dry paper at so-called size press operations. These polymers, which include styrene maleic anhydride (SMA) copolymers, are dispersible in the aqueous starch solution. Apparently the ratio of water-loving maleic acid salts versus hydrophobic styrene groups is enough to achieve either solubility or a micellization effect that closely resembles solubility. When the starch film is dried, however, droplets of water will not spread over the paper surface. To explain this effect, it has been proposed that the sizing copolymers migrate to the surface of the starch film, as it dries, and that hydrophobic styrene groups face outwards from the paper surface.[145,146]CONCLUDING REMARKSAfter considering these seven paradoxes, it becomes evident that making paper is not as simple as it may seem, and Water-loving surface of fiber Fiber Add micelles of rosin soap. Add alum. Al Fiber Water-hating surface of fiber Al Al Al Al Al Al Al Figure 7. One way that papermakers achieve the impossibleusing a waterborne additive to convert water-loving surfaces to water-resistant surfaces.

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Spring 2005 153there is plenty of room to further our understanding. The science of papermaking offers an abundance of opportunities for fundamental inquiry on the biological, material, and chemical fronts. At the educational level it is a subject where one can put into practice all that is learned in allied subjects of chemical engineering, including mass, energy and momentum transfer, colloid and surface science, materials science, and chemistry. Many career opportunities are available to new chemical engineers who enjoy paradoxes. Possible career roles for engineers can be as diverse as process engineering and optimization, product development, research, technical sales, and mill management. Although it is foreseen that the nano-bio-techno waves will have an impact on papermaking and paper composites, the main process by which paper is made will probably remain the same, since all paradoxes coexist in perfect harmony. No wonder it took many centuries for our papermaker predecessors to get to where we are now.REFERENCES1.Wilson, W.K., and E.J. Parks, "Comparison of Accelerated Aging of Book Papers in 1937 with 36 years of Natural Aging," Restaurator, 4 1(1980) 2.Waterhouse, J.F., "Monitoring the Aging of Paper," in Paper Preservation TAPPI Press, Atlanta, GA, 53 (1990) 3.Yin, R., "Industry Characteristics and Investment Decisions: Alternative Approach to Pulp and Paper Production," T appi J., 81 (1), 69 (1998) 4.Atkins, J., "The Modern Paper Machine. Part 2: Coated and Fine Paper," Solutions, 86 (12), 31 (2003) 5.Jorling, T., "The Forest Products Industry: A Sustainable Enterprise," T appi J., 83 (12), 32 (2000) 6. Axegard, P., O. Dahlman, I. Hanlind, B. Jacobson, and R. Morck, "Pulp Bleaching and the Environment: The Situation in 1993," Nordic Pulp Paper Res. J., 8 (4), 365 (1993) 7.Munkittrick, K. R., M.R. Servos, J.H. Carey, and G.J. van der Kraak, "Environmental Impacts of Pulp and Paper Wastewater: Evidence for a Reduction in Environmental Effects at North American Pulp Mills Since 1992," W ater Sci. Technol., 35 (2/3), 329 (1997) 8.Mšbius, C. H., and Cordes-Tolle, "Paper Industry on the Way to Integrated Environmental Protection: Wastewater Treatment," Papier, 53 (10A), V60 (1999) 9. W ahaab, R.A., "Evaluation of Aerobic Biodegradability of Some Chemical Compounds Commonly Applied in Paper Industry," Bull. Environ. Contam. Toxicol., 64 558 (2000) 10.Anon., "Nutrient Forms in Pulp and Paper Mill Effluents and their Potential Significance in Receiving Waters," NCASI Tech. Bull. 832 25 (2001) 11 Hunter, D., Papermaking: The History and Technique of an Ancient Craft Dover Publications, New York, NY (1974) 12.Collings, T., and D. Milner, "New Chronology of Papermaking Technology," Paper Conservator, 14 58 (1990) 13. Lewin, M., and I.S. Goldstein, W ood Structure and Composition Marcel Dekker, New York, NY (1991) 14.Smook, G.A., Handbook for Pulp and Paper Technologists 2nd ed., Angus Wilde Publications., Vancouver, BC, Canada (1992) 15.Aziz, S., and N. Arafat, "Pulp Manufacturing Energy Survey TAPPI Alkaline Committee," Proc. TAPPI 1997 Pulping Conf. 455, TAPPI Press, Atlanta, GA (1997) 16.Law, K-N. "Insights on the Refining Mechanism," T appi J., 1 (1), 4 (2002) 17.Scott, W.E., Principles of Wet End Chemistry TAPPI Press, Atlanta, GA (1996) 18.Ross, R.F., and D.J. Klingenberg, "Simulation of Flowing Wood Fiber Suspensions," J. Pulp Paper Sci., 24 (12), 388 (1998) 19. Niskanen, K., I. Kajanto, and P. Pakarinen, "Paper Structure," in Niskanen, K., Paper Physics Ch. 1, 14, Fapet Oy, Helsinki (1998) 20.Page, D., A Theory for the Tensile Strength of Paper, T appi, 52 (4), 674 (1969) 21.Beirmann, C.J., Handbook of Pulping and Papermaking Academic Press, San Diego, CA (1996) 22.Weise, U., J. Terho, and H. Paulapuro, "Stock and Water Systems of the Paper Machine," in Paulapuro, H., Ed., Papermaking. Part 1, Stock Preparation and Wet End Ch. 5, 125, Fapet Oy, Helsinki, Finland (2000) 23.Waterhouse, J.F., "Effect of Papermaking Variables on Formation," T appi J., 76 (9), 129 (1993) 24.Kerekes, R.J., "Perspectives on Fiber Flocculation in Papermaking," 1995 Intl. Paper Phys. Conf. 23, TAPPI Press, Atlanta, GA (1995) 25.Dodson, C.T.J., "Fiber Crowding, Fiber Contacts, and Fiber Flocculation," T appi J., 79 (9), 211 (1996) 26.Beghello, L., and D. Eklund, "Some Mechanisms that Govern Fiber Flocculation," Nordic Pulp Paper Res. J., 12 (2), 119 (1997) 27.Kerekes, R.J., and C.J. Schell, "Characterization of Fiber Flocculation Regimes by a Crowding Factor," J. Pulp Paper Sci., 18 (1), J32 (1992) 28.Manson, D.W., "The Practical Aspects of Formation," W et End Operations Short Course Notes, T APPI Press, Atlanta, GA (1996) 29.Hubbe, M.A., T. Tripattharanan, J.A. Heitmann, and R.A. Venditti, "The Positive Pulse Jar' (PPJ): A Flexible Device for Retention Studies," Paperi Puu 86 (2004) accepted 30.Green, C., "Curl in Paper," Appita J., 53 (4), 272 (2000) 31.Thode, E.F., J.G. Bergomi, and R.E. Unson, "The Application of a Centrifugal Water-Retention Test to Pulp Evaluation," T appi, 43 (5), 505 (1960) 32.Jayme, G., and BŸttel, "The Determination and Meaning of Water Retention Value (WRV) of Various Bleached and Unbleached Pulps," W ochenbl. Papierfabr., 96 (6), 180 (1968) 33.Anon., "Water Retention Value (WRV)," T APPI Useful Method UM 256 (1981) 34.Robinson, J.V., "Fiber Bonding," in Casey, J. P., Ed., Pulp and Paper Chemistry and Chemical Technology 3rd ed., Vol. 2, 915, WileyInterscience, New York, NY (1980) 35.Worsick, A., "Developments in Press Technology," Paper Technol., 35 (5), 30 (1994) 36.Wahlstršm, B., "Wet Pressing in the 20th Century: Evolution, Understanding, and Future," Pulp Paper Can., 102 (12), 81 (2001) 37. Maloney, T.C., and H. Paulapuro, "The Centrifugal Compression V alue," T appi J., 82 (6), 150 (1999) 38.Ahrens, F., N. Alaimo, H. Nanko, and T. Patterson, "Initial Development of an Improved Water Retention Value Test and its Application to the Investigation of Water Removal Potential," T APPI 99 Proc. 37, T APPI Press, Atlanta, GA (1999) 39.Stone, J.E., and A.M. Scallan, "A Structural Model for the Cell Wall of Water-Swollen Wood Pulp Fibers based on Their Accessibility to Macromolecules," Cellulose Chem. Technol., 2 (3), 343 (1968) 40.Berthold, J., and L. SalmŽn, "Effects of Mechanical and Chemical T reatments on the Pore-Size Distribution in Wood Pulps Examined by Inverse-Size-Exclusion Chromatography," J. Pulp Paper Sci., 23 (6), J245 (1997) 41.Alince, T., and T.G.M. van de Ven, "Porosity of Swollen Pulp Fibers Evaluated by Polymer Adsorption," in Baker, C. F., Ed., The Fundamentals of Papermaking Materials, V ol. 2, 771, Pira Int'l., Leatherhead, Surrey, UK (1997) 42.Back, E.L., and N.L. SalmŽn, "Glass Transitions of Wood Components Hold Implications for Molding and Pulping Processes," T appi J., 65 (7), 107 (1982) 43.SalmŽn, N.L., P. Kolseth, and A. de Ruvo, "Modeling the Softening Behavior of Wood Fibers," J. Pulp Paper Sci., 11 (4), J102 (1985) 44.Garvin, S.P., and P.F. Pantalea, "Measurement and Evaluation of Dryer Section Performance," Proc. TAPPI Engineering Conf. Book 2, 125 (1976) 45.Kunnas, L., J. Lehtinen, H. Paulapuro, and A. Kiviranta, "The Effect of Condebelt Drying on theStructure of Fiber Bonds," T appi J., 76 ( 4),

PAGE 67

154 Chemical Engineering Education 95 (1993) 46. Retulainen, E., "Condebelt Press Drying and Sustainable Paper Cycle," Paperi Puu, 85 (6), 329 (2003) 47.Marton, J., and T. Marton, "Wet End Starch: Adsorption of Starch on Cellulosic," T appi J., 59 (12), 121 (1976) 48.Zhang, J., R. Pelton, L. W‰gberg, and M. Rundlšf, "The Effect of Charge Density and Hydrophobic Modification on Dextran-Based Paper Strength Enhancing Polymers," Nordic Pulp Paper Res. J., 15 (5), 440 (2000) 49.Pelton, R., J. Zhang, L. W‰gberg, and M. Rundlšf, "The Role of Surface Polymer Compatibility in the Formation of Fiber/fiber Bonds in Paper," Nordic Pulp Paper Res. J., 15 (5), 400 (2000) 50.Hofreiter, B.T, "Natural Products for Wet-End Addition," in Casey, J. P ., Ed., Pulp and Paper Chemistry and Chemical Technology Vol. III, W iley-Interscience, 3rd ed., New York, NY (1980) 51.Spence, G.G., "Application of Wetand Dry-Strength Additives," in Spence, G.G., Ed., W etand Dry-Strength Additives Application, Retention, and Performance TAPPI Press, 19, Atlanta, GA (1999) 52.Tiberg, F., J. Daicic, and Fršberg, J., "Surface Chemistry of Paper," in Holmberg, K., Ed., Handbook of Applied Surface and Colloid Chemistry Ch. 7., 123, Wiley, New York, NY (2001) 53.Howard, R.C., and C.J. Jowsey, "The Effect of Cationic Starch on the T ensile Strength of Paper," J. Pulp Paper Sci., 15 (6), J225 (1989) 54.Gere, J.M., and S.P. Timoschenko, Mechanics of Materials 3rd Ed., PWS Publishing Co., Boston, MA (1984) 55.Baker, C.F., "Good Practice for Refining the Types of Fiber Found in Modern Paper Furnishes," T appi J., 78 (2), 147 (1995) 56.Batchelor, W.J., D.M. Martinez, R.J. Kerekes, and D. Ouellet, "Forces on Fibers in Low-Consistency Refining: Shear Force," J. Pulp Paper Sci., 23 (1), J40 (1997) 57.Zhang, M., M.A. Hubbe, R.A. Venditti, and J.A. Heitmann, "Effects of Sugar Addition Before Drying on the Wet-Flexibility of Redispersed Kraft Fibers," J. Pulp Paper Sci., 30 (1), 29 (2004) 58.Kim, C.Y., D.H. Page, F. El-Hosseiny, and A.P.S. Lancaster, "Mechanical-Properties of Single Wood Pulp Fibers. 3. Effect of Drying Stress on Strength," J. Applied Polymer Sci., 19 (6), 1549 (1975) 59. Zhang, G., J.E. Laine, and H. Paulapuro, "Characteristics of the Strength Properties of a Mixture Sheet under Wet Straining Drying," Paperi Puu, 84 (3), 169 (2002) 60.McDonald, J.D., L.I. Pikulik, and R. Daunais, "On-Machine StressStrain Behavior of Newsprint," J. Pulp Paper Sci., 14 (3), J53 (1988) 61.Kallmes, O., H. Corte, and G. Bernier, "The Structure of Paper. V. The Bonding States of Fibers in Randomly Formed Papers," T appi J., 46 (8), 493 (1963) 62.Deng, M., and C.T.J. Dodson, Paper: An Engineered Stochastic Structure Tappi Press, Atlanta, GA (1994) 63.Niskanen, K., I. Kajanto, and P. Pakarinen, "Paper Structure," Ch. 1 in Niskanen, K., Ed., Paper Physics Fapet/Tappi, Atlanta, GA (1998) 64.Schulgasser, K., "Fiber Orientation in Machine-Made Paper," J. Materials Sci., 20 (3), 859 (1985) 65.Kallmes, O., G. Bernier, and M. Perez, "A Mechanistic Theory for the Load Elongation Properties of Paper," Pap. Technol. Ind., 18 (7), 222, (8) 243; (9), 283; (10), 328 (1977) 66.Hanu, W.M., "Dispersants," in Kirk-Othmer Encyclopedia of Chemical Technol. 4th Ed., Vol. 8, 293, Wiley-Interscience, NY (1993) 67.Lynn, J.L., Jr., and B.H. Bory, "Surfactants," in Kirk-Othmer Encyclopedia of Chemical Technol. 4th Ed., Vol. 23, 478, WileyInterscience, NY (1993) 68.Sundberg, A., R. Ekman, B. Holmbom, and H. Gršnfors, "Interactions of Cationic Polymers with Components in Thermomechanical Pulp Suspensions," Paperi Puu, 76 (9), 593 (1994) 69. KilpenlŠinen, R., S. Taipale, A. Marin, P. Kortelainen, and S. MetsŠranta, "Forming Fabrics," in Paulapuro, H., Ed., Papermaking. Part 1, Stock Preparation and Wet End, Ch. 7, 253, Fapet Oy, Helsinki, Finland (2000) 70.Horn, D., and F. Linhart, "Retention Aids," in Roberts, J. C., Ed., Paper Chemistry Ch. 4, 44, Blackie, Glasgow, UK (1991) 71.Walkush, J.C., and D.G. Williams, "The Coagulation of Cellulose Pulp Fibers and Fines as a Mechanism of Retention," T appi, 57 (1), 112 (1974) 72. Britt, K.W., "Mechanisms of Retention during Paper Formation," T appi 56 (10), 46 (1973) 73.Britt, K.W., and J.E. Unbehend, "New Methods for Monitoring Retention," T appi, 59 (2), 67 (1976) 74.Hubbe, M.A., "Retention and Hydrodynamic Shear," T appi J., 69 (8), 1 16 (1986) 75.Tripattharanan, T., M.W. Hubbe, R.A. Venditti, and J.A. Heitmann, "Effect of Idealized Flow Conditions on Retention Aid Performance. 2. Polymer Bridging, Charged Patches, and Charge Neutralization," Appita J., 57 (2004) accepted 76.Lindberg, L., "Pulsed Drainage of Paper Stock," Svensk Papperstidn. 73 (15), 451 (1970) 77.Walser, R., J.D. Eames, and W.M. Clark, "Performance Analysis of Hydrofoils with Blades of Various Widths," Pulp Paper Mag. Can., 71 (8), T183 (1970) 78.Tam Doo, P.A., R.J. Kerekes, and R.H. Pelton, "Estimates of Maximum Hydrodynamic Shear Stresses on Fiber Surfaces in Papermaking," J. Pulp Paper Sci., 10 (4), J80 (1984) 79.Britt, K.W., J.E. Unbehend, and R. Shidharan, "Observations on Water Removal in Papermaking," T appi J., 69 (7), 76 (1986) 80.Kiviranta, A., and H. Paulapuro, "The Role of Fourdrinier Table Activity in the Manufacture of Various Paper and Board Grades," T appi J., 75 (4), 172 (1992) 81.Swerin, A., and L. …dberg, "Flocculation and Floc Strength From the Laboratory to the FEX Paper Machine," Papier, 50 (10A), V45 (1996) 82.RŠisŠnen, K., S. Karrila, and A. Maijala, "Vacuum Dewatering Optimization with Different Furnishes," Paperi Puu, 78 (8), 461 (1996) 83.Baldwin, L., "High Vacuum Dewatering," Paper Technol., 38 (4), 23 (1997) 84.RŠisŠnen, K.O., H. Paulapuro, and S.J. Karrila, "The Effects of Retention Aids, Drainage Conditions, and Pretreatment of Slurry on HighV acuum Dewatering: A Laboratory Study," T appi J., 78 (4), 140 (1995) 85. Zeilinger, H., and M. Klein, "Modern Measuring Methods for the CrossSectional Filler Distribution," W ochenbl. Papierfabr., 123 (20), 903 (1995) 86.Schiller, A.M., and T. Suen, "Ionic Derivatives of Polyacrylamide," Ind. Eng. Chem., 48 (12), 2132 (1956) 87.Norell, M., K. Johansson, and M. Persson, "Retention and Drainage," in Neimo, L., E., Papermaking Chemistry, Ch. 3, 42, Fapet Oy, Helsinki, Finland (1999) 88.La Mer, V.K., and T. Healy, "Adsorption-Flocculation Reactions of Macromolecules at the Solid-Liquid Interface," Rev. Pure Applied Chem., 13 (Sept.), 112 (1963) 89. Swerin, A., and L. …dberg, "Some Aspects of Retention Aids," in Baker, C.F., Ed., The Fundamentals of Papermaking Materials Pira International, Leatherhead, UK, Vol. 1, 265 (1997) 90.PetŠjŠ, T., "Fundamental Mechanisms of Retention with Retention Agents. Part 1. Electrolyte and Single Polymer Systems," Kemia-Kemi, 7 (3), 110 (1980) 91.Petzold, G., H.-M. Buchhammer, and K. Lunkwitz, "The Use of Oppositely Charged Polyelectrolytes as Flocculants and Retention Aids," Colloids Surf. A., 119 (1), 87 (1996) 92.Lindstršm, T., and G. Glad-Nordmark, "Network Flocculation and Fractionation of Latex Particles by Means of PolyethyleneoxidePhenolformaldehyde Resin Complex," J. Colloid Interface Sci., 97 (1), 62 (1984) 93. Xiao, H., R. Pelton, and A. Hamielec, "Retention Mechanisms for TwoComponent Systems Based on Phenolic Resins and PEO or New PEOCopolymer Retention Aids," J. Pulp Paper Sci., 22 (12), J475 (1996) 94.Van de Ven, T.G.M., and B. Alince, "Association-Induced Polymer Bridging: New Insights into the Retention of Fillers with PEO," J. Pulp Paper Sci., 22 (7), J257 (1996) 95.Kratochvil, D., B. Alince, and T.G.M. Van de Ven, "Flocculation of

PAGE 68

Spring 2005 155 Clay Particles with Poorly and Well-Dissolved Polyethylene Oxide," J. Pulp Paper Sci., 25 (9), 331 (1999) 96.Lindstršm, T., C. Sšremark, C. HeinegŒrd, and S. Martin-Lšf, "The Importance of Electrokinetic Properties of Wood Fiber for Papermaking," T appi, 57 (12), 94 (1974) 97.WŒgberg, L, and L. …dberg, "The Action of Cationic Polyelectrolytes Used for the Fixation of Dissolved and Colloidal Substances," Nordic Pulp Paper Res. J., 6 (3), 127 (1991) 98.Nurmi, M., J. Byskata, and D. Eklund, "On the Interaction between Cationic Polyacrylamide and Dissolved and Colloidal Substances in Thermomechanical Pulp," Paperi Puu, 86 (2), 109 (2004) 99.Moore, E.E., "Charge Relationships of Dual Polymer Retention Aids," T appi 59 (6), 120-122 (1976) 100. PetŠjŠ, T., "Fundamental Mechanisms of Retention with Retention Agents. Part 2. Dual Polymer Systems," Kemia-Kemi, 7 (5), 261 (1980) 101.WŒgberg, L., and T. Lindstršm, "Some Fundamental Aspects of DualComponent Retention Aid Systems," Nordic Pulp Paper Res. J., 2 (2), 49 (1987) 102.Petzold, G., "Dual-Addition Schemes," in Faranato, R.S., and P.L. Dubin, Colloid-Polymer Interactions: From Fundamentals to Practice Ch. 3, 83, Wiley Interscience, New York, NY (1999) 103.Swerin, A., G. Glad-Nordmark, and L. …dberg, "Adsorption and Flocculation in Suspensions by Two Cationic Polymers Simultaneous and Sequential Addition," J. Pulp Paper Sci., 23 (8), J389 (1997) 104. Capozzi, A.M., and D.S. Rend, "Particle Management: Effective Stickies Control Approach," Proc TAPPI 1994 Pulping Conference 643, TAPPI Press, Atlanta, GA (1994) 105.Gill, R.A., "The Behavior of On-Site Synthesized Precipitated Calcium Carbonates and Other Calcium Carbonate Fillers on Paper Properties," Nordic Pulp Paper Res. J., 2 (4), 120 (1989) 106.Fairchild, G.H., "Increasing the Filler Content of PCC-Filled Alkaline Papers," T appi J., 75 (8), 85 (1992) 107.Sanders, N.D., and J.H. Schaefer, "Comparing Papermaking Wet-End Charge-Measuring Techniques in Kraft and Groundwood Systems," T appi J., 78 (11), 142 (1995) 108.Suty, S., B. Alince, and T.G.M. van de Ven, "Stability of Ground and Precipitated CaCO3 Suspensions in the Presence of Polyethylenimine and Salt," J. Pulp Paper Sci., 22 (9), J321 (1996) 109.Sikora, M.D., and R.A. Stratton, "The Shear Stability of Flocculated Colloids," T appi, 64 (11), 97 (1981) 1 10.Tanaka, H., A. Swerin, and L. …dberg, "Transfer of Cationic Retention Aid from Fibers to Fine Particles and Cleavage of Polymer Chains under Wet-End Papermaking Conditions," T appi J., 76 (5), 157 (1993) 11 1.Hubbe, M.A., "Reversibility of Polymer-Induced Fiber Flocculation by Shear. 1. Experimental Methods," Nordic Pulp Paper Res. J., 15 (5), 545 (2000) 1 12.Tripattharanan, T., M.A. Hubbe, R.A. Venditti, and J.A. Heitmann, "Effect of Idealized Flow Conditions on Retention Aid Performance. 1. Cationic Acrylamide Copolymer," Appita J., 57 (2004) accepted 1 13. Bliss, T., "Screening in the Stock Preparation System," in T APPI Stock Preparation Short Course Notes TAPPI Press, Atlanta, GA (1996) 1 14.Hubbe, M.A., and F. Wang, "Where to Add Retention Aid: Issues of T ime and Shear," T appi J., 1 (1), 28 (2002) 1 15.Langley, J.G., and E. Litchfield, "Dewatering Aids for Paper Applications," In Proc. TAPPI Papermakers Conf ., Tappi Press, Atlanta, (1986) 1 16.Andersson, K., and E. Lindgren, "Important Properties of Colloidal Silica in Microparticulate Systems," Nordic Pulp Paper Res. J., 11 (1), 15 (1996) 1 17.Hubbe, M.A., "Microparticle Programs for Drainage and Retention," In Microparticles and Nanoparticles in Papermaking TAPPI Press, Atlanta, GA (2004) 1 18.Main, S., and P. Simonson, "Retention Aids for High-Speed Paper Machines," T appi J., 82 (4), 78 (1999) 1 19.McKenzie, A.W., "Structure and Properties of Paper. XVIII. The Retention of Wet-End Additives," Appita, 21 (4), 104 (1968) 120.Hubbe, M.A., "Detachment of Colloidal Hydrous Oxide Spheres from Flat Solids Exposed to Flow. 2. Mechanism of Release," Colloids Surf., 16 (3-4), 249 (1985) 121.Hubbe, M.A., "Reversibility of Polymer-Induced Fiber Flocculation by Shear. 1. Experimental Methods," Nordic Pulp Paper Res. J., 15 (5), 545 (2000) 122. Kiviranta, A., and H. Paulapuro, "Hydraulic and Rectifier Roll Headboxes in Boardmaking," Paper Technol., 31 (11), 34 (1990) 123.Bonfanti, J-D., J.-C. Roux, and M. Rueff, "Hydraulic Headbox S T echnology and Industrial Results," W ochenbl. Papierfabr., 128 (20), 1372 (2000) 124.Hubbe, M.A., "Detachment of Colloidal Hydrous Oxide Spheres from Flat Solids Exposed to Flow. 4. Effects of Polyelectrolytes," Colloids Surf ., 25 (2-4), 325 (1987) 125.Rojas, O.J., and M.A. Hubbe, "The Dispersion Science of Papermaking," J. Dispersion Sci. Technol., 25 (6), 713 (2004) 126.Hodgson, K.T., "A Review of Paper Sizing Using Alkyl Ketene Dimer versus Alkenyl Succinic Anhydride," Appita J., 47 (5), 402 (1994) 127.Neimo, L., "Internal Sizing of Paper," in Neimo, L., Ed., Papermaking Chemistry Ch. 7, 151, Fapet Oy, Helsinki, Finland (1999) 128.Wasser, R.B., "The Reactivity of Alkenyl Succinic Anhydride: Its Pertinence with Respect to Alkaline Sizing," J. Pulp Paper Sci., 13 (1), J29 (1987) 129L. …dberg, T. Lindstršm, B. Liedberg, and J. Gustavsson, J., "Evidence for -Ketoester Formation during the Sizing of Paper with Alkylketene Dimers," T appi J., 70 (4), 135 (1987) 130.Marton, J., "Mechanistic Differences between Acid and Soap Sizing," Nordic Pulp Paper Res. J., 4 (2), 77 (1989) 131.Bottorff, K.J., "AKD Sizing Mechanism: A More Definitive Description," T appi J., 77 (4), 105 (1994) 132.Isogai, A., "Mechanism of Paper Sizing by Alkylketene Dimers," J. Pulp Paper Sci., 25 (7), 251 (1999) 133.Strazdins, E., "Interaction of Rosin with some Metal Ions," T appi J., 46 (7), 432 (1963) 134.Ehrhardt, S.M., and J.C. Gast, "Cationic Dispersed Rosin Sizes," Proc. TA PPI 1998 Papermakers Conf. 181, TAPPI Press, Atlanta,GA (1988) 135.Lee, H.N., "The Microscopical Mechanism of Rosin Sizing," Paper T rade J., 103 T386 (1936) 136.Garnier, G., J. Wright, L. Godbout, and L. Yu, "Wetting Mechanism of Alkyl Ketene Dimers on Cellulose Films," Colloids Surf. A, 145 (1-3), 153 (1998) 137.Wang, F., H. Tanaka,T, Kitaoka, and M.A. Hubbe, "Distribution Characteristics of Rosin Size and Their Effect on the Internal Sizing of Paper," Nordic Pulp Paper Res. J., 15 (5), 80 (2000) 138.SeppŠnen, R., and F. Tiberg, "Mechanism of Internal Sizing by Alkyl Ketene Dimers (AKD): The Role of the Spreading Monolayer Precursor and Autophobicity," Nordic Pulp Paper Res. J., 15 (5), 452 (2000) 139.Shen, W., and I.H. Parker, "A Study of the Non-Solid behavior of AKD W ax," Appita J., 56 (6), 442 (2003) 140.Swanson, J.W., and W. Cordingly, "Surface Chemical Studies on Pitch. 2. The Mechanism of the Loss of Absorbency of Self-Sizing in Papers Made from Wood Pulps," T appi J., 42 (10), 812 (1959) 141.Davison, R.W., "The Chemical Nature of Rosin Sizing," T appi J., 47 (10), 609 (1964) 142.Garnier, G., and L. Yu, "Wetting Mechanism of a Starch-Stabilized Alkyl Ketene Dimer Emulsion: A Study by Atomic Force Microscopy," J. Pulp Paper Sci., 25 (7), 235 (1999) 143.Back, E.L., and S. Danielsson, "Hot Extended Press Nips as Gas-Phase Reactors: Hydrophobization with ASA," T appi J., 74 (9), 167 (1991) 144.Yu, L., and G. Garnier, "Mechanisms of Internal Sizing with Alkyl Ketene Dimers: The Role of Vapor Deposition," in Fundamentals of Papermaking Materials Vol. 2, 1021 (1997) 145.Batten Jr., G.L., "A Papermaker's Guide to Synthetic Surface Sizing Agents," in Proc. TAPPI 1992 Papermakers Conf. 12, TAPPI Press, Atlanta, GA (1992) 146.Garnier, G., M. Duskova-Smrckova, R. Vyhnalkova, T.G.M. van de V en, and J.F. Revol, "Association in Solution and Adsorption at an Air-Water Interface of Alternating Copolymers of Maleic Anhydride and Styrene," Langmuir, 16 (8), 3757 (2000)

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156 Chemical Engineering EducationFirst-semester engineering students bring with them a spectrum of understanding of the engineering profession. They know that engineers design things, and they have been told you need to be good at math and science to be an engineer. While some are very committed to obtaining an engineering degree, others are not too sure if engineering is for them. Engineering freshmen have taken courses in math and science in high school and generally obtained good grades, but they find their understanding of these subjects is limited as they try to apply their knowledge to real problems. The same is true of computing. They can manipulate the computer well, but when they are asked to apply computing solutions to real problems, they find their ability is limited. In addition, many of these students are not prepared to interact in teams and to get along socially with other students. They come from many different high schools from all over the country, and they may be the only student coming to our college from their high school. In many instances they do not know anyone on their first day at class. Engineering curriculums have basically ignored these problems in the past. Freshmen engineering students found they had a difficult schedule of math and science courses along with all the social adjustments required in the transition between high school and college. Without a strong commitment to obtaining an engineering degree, many capable engineering students would change majors or leave school prior to the sophomore year. Also, often those sophomores who did survive the engineering freshman year did not have the necessary background and commitment for the rigorous sophomore-level engineering courses. At Youngstown State University, as is the case at many engineering schools, a freshman engineering program was developed and instituted with the goal of improving retention of freshman engineering students, better preparing them for the remainder of the engineering curriculum, and giving them a taste of engineering in their freshman year.GENERAL COURSE INFORMATIONA potato cannon project is part of the first-semester freshman engineering course at Youngstown State University. The design-based three-semester-hour course comprises two lecture hours and three laboratory hours per week. The lecture portion of the "Introduction to Engineering" course is conducted in a design/analysis-based lecture format in which the currently assigned project is used as a springboard for the lecture topics. There are typically three or four out-of-class design/analysis projects that span the semester. A brief introduction is given on the entire design process, broken into six steps: 1) Problem Identification 2) Preliminary Ideas 3) Refinement 4) Analysis 5) Decision 6) Implementation This is done with the intention of making the students aware there is a methodical approach to design and problem solving that does not rule out creativity. This format allows for all aspects of any project they will encounter as an engineer to be addressed, from the first brainstorming session, to a prototype machine, to the final technical design report.THE POTATO CANNONDetermination of Combustion Principles for Engineering FreshmenHAZEL M. PIERSON, DOUGLAS M. PRICEY oungstown State University Youngstown, OH 44555Hazel M. Pierson is currently Instructor of Mechanical Engineering and Freshman Engineering at Youngstown State University. Concurrently, she is finishing dissertation requirements for her PhD at the University of Akron. She received her BS in mechanical engineering at the University of T exas at Austin in 1985 and her MA in mechanical egineering at Youngstown State University in 1998. Her research interests are in the areas of vibrations, rotor dynamics, and advancd stress analysis. Douglas M. Price is Assistant Professor of Chemical Engineering and Chemical Engineering Program Coordinator at Youngstown State University. He received his BS from Pennsylvania State University in 1984 and his MA and PhD from the University of Notre Dame in 1986 and 1988, all in chemical engineering. His research interests are in the areas of heterogeneous reaction optimization, biofuels, and biomaterials. Copyright ChE Division of ASEE 2005 ChEclassroom

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Spring 2005 157While discussing the design process, the majority of time is spent explaining the importance and application of the analysis step. The goal is to show how engineers use mathematical formulas to predict and evaluate design performance. Through the process, the students discover firsthand how the application of math and science principals fits into engineering design and analysis as well as how to systematically complete design and analysis at a level befitting an engineer. The projects are a group venture with teams consisting of four members each. The students are allowed to form their own teams, and the vast majority of teams consist at least partially of members who have had no prior interaction with each other. To facilitate team formation and project execution, class time is taken to discuss team dynamics using the T uckman Model.[1]PROJECT INFORMATION Overview Projects for the semester are chosen in such a way as to present components from as many engineering disciplines as possible. Historically, chemical engineering has been poorly represented in the projects. In the fall of 2003, we decided to reverse this trendand thus, the potato cannon project was born. Through this project, freshman engineering students are given an opportunity to integrate the principles of combustion chemistry and the physics of projectile motion. Homemade potato cannons have been in use for many years, but with the Internet making it easy to share design ideas, they are once again arousing the curiosity of young inventors. The potato cannon provides an ideal way to introduce engineering principles to freshman students. At the beginning of the project, the students are required to conduct a Web search on potato cannon technology, with an emphasis on the scientific principles inherent in this type of machine. This gives them a foundation for the project as well as building upon the Web-search instruction that they have received in their lab classes. Ultimately, the project requires that the students determine the kinetic energy of a potato fired from a cannon that is fu eled by propane and air, and to compare this energy to theoretical predictions based on combustion chemistry. The project begins with a brief introduction in class using a standard project assignment sheet. The students are informed of the project's guidelines, of the grading parameters, and of the project timetable. The Chemical Engineering Program Coordinator then explains the ultimate goal of the project comparing the kinetic energy of the potato as it leaves the cannon with the theoretical amount of energy available from combustion. The principles of combustion chemistry, as they pertain to propane and methane, are presented and explained. Explanation of Combustion Chemistry The combustion of propane in air is given by CHOCOHO382225341 + +() The lower and upper flammability limits of propane in air at 25 C are 2.2 and 9.5% by volume, respectively.[2] This gives the range of concentration of propane where an explosion can occur at atmospheric pressure and 25 C. At the temperatures and pressures tested (10 to 25 C and 1 atm), the ideal gas law is applicable and the energy released during the combustion of propane as a function of volume percent of propane within the range of the flammability limits can be calculated. To do this, it is necessary to determine which component, propane or oxygen, is the limiting reagent. Let xPropanebe the mole fraction of propane in air when it is in stoichiometric proportion to oxygen. The mole fraction of oxygen present can now be calculated as xxOxygenopane= ()()02112 .Pr The ratio of the mole fraction of oxygen to that of propane must be equal to the ratio of their respective stoichiometric coefficients in the balanced chemical equation if they are to be in stoichiometric proportion. x x x xOxygen opane opane opane Pr Pr Pr. = ()=()0211 53 Solving Eq. (3), the mole fraction of propane is 0.0403 when it is in stoichiometric proportion with oxygen. Assigning an energy release value of zero below and above the lower and upper flammability limits, respectively, the energy of combustion can be normalized on a unit volume of the fuel/air mixture basis as shown inMole Fraction PropaneEnergy Release, Ec kJ/liter x x x liter gmole kJ gmole x x liter gmole kJ gmoleopane opane opane opane opane Pr Pr Pr Pr Pr. .. .. . <= <<= ()<<= () >= 0 0220 0 02200403 224 22204 0 04030095 1 5 0211 224 2220 0 0950 Potato Cannon Design The potato cannon project does not include a student design component of the cannon itself, for safety and liability reasons. For the actual in-class study and analysis, three cannons of varying combustion-chamber dimensions were used. Aside from the different combustion-chamber sizes, the three cannons were identical. All plastic components were made

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158 Chemical Engineering EducationT ABLE 1Material Supply List for Potato CannonsCannon Small Medium Large Barrel 2" diameter by 24" Combustion 3" diameter by 6"3" diameter by 12"4" diameter by 12" Chamber 3" PVC end cap3" PVC end cap4" PVC end cap 3" to 2" reducer3" to 2" reducer4" to 3" reducer 3" to 2" bushing General ball valves, piezo igniters, pins, PVC cement Figure 1. Schematic of potato cannon design. Figure 2. Three cannons used in the project. Figure 3. Extracting fuel from a propane tank.from Schedule 80 PVC pipe and fittings. A materials list for the cannons is presented in Table 1 and a schematic of the 3inch-diameter by 12-inch-length combustion chamber cannon is shown in Figure 1. Explanation of the Kinetic Energy of the Potato The kinetic energy, Ek, of the potato leaving the barrel of the cannon is given by E mdgk=()4 5 sincos where m is the mass of the potato, d is the horizontal distance the potato traveled, g is the gravitational acceleration and is the angle of the barrel with respect to horizontal. Dividing the kinetic energy by the volume of the combustion chamber to give a normalized energy gives E E DLk k=()4 62 where D is the diameter of the combustion chamber and L is its length. The final equations of the derivation provide a means to determine the kinetic energy in terms of easily measurable variables: the mass of the potato, the angle of the cannon, the horizontal distance of potato travel, and the geometric size of the cannon barrel. Field Experiment As was stated earlier, three cannons of varying combustion chamber sizes were considered and analyzed in this project. Figure 2 shows the completed cannons. For the experiment, propane gas was quantitatively added via a calibrated syringe to the combustion chamber which was previously filled with air at ambient conditions. Potatoes of known mass were fired from the cannon at three different elevation angles and the linear distance traveled was recorded. To meter in a specific amount of propane fuel, the students extracted propane from the tank using a syringe (see Figure 3) and injected the propane into the combustion chamber. The cannon was placed in a wooden cradle made of 3/4" plywood. The cannons were fired at angles of 30-, 45-, and 60 from the ground. Figure 4 shows the cannon just prior to cannon fire. Notice the distance of the student from the cannon. This again was designed for safety purposes. The pulled string was attached to a cantilevered thin sheet of metal. When pulled, the metal actuated the piezoelectric igniter.

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Spring 2005 159 T ABLE 2Recruitment of Students into ChE ProgramEnrolled inPercent of Retained AcademicENGR 1550EngineeringEngineering Students Y earEnrollmentFollowing YearEntering ChE Program 2001-20021521106.4% 2002-2003139889.1% 2003-200414010112.9% Figure 5. Energy generated during the combustion of propane. Figure 4. Firing the cannon.Once the potato fired, the distance of horizontal travel was measured using a Bushnell Yardage Pro Compact 600 Laser Range Finder. Results The students were required to use the collected data taken over a period of four days to calculate the kinetic energy of the potatoes utilizing the mass, the distance, and the angle. This kinetic energy was normalized to the volume of the combustion chamber and then compared to the volume percentage of propane in the combustion chamber prior to firing. Figure 5 shows the results of the firings of the three potato cannons along with the theoretical energy release based on the combustion energy. During explosive combustion, approximately 1% to 10% of the available chemical energy is actually transferred into mechanical energy.[3] Figure 5 shows the experimentally determined combustible range for propane is approximately 2.5% to 9.8%. This is in good agreement with the literature values. Figure 5 also shows that the kinetic energy based on the experimentally measured firing distance is approximately 0.5% to 1.5% of the calculated chemical energy potential. This also is in good agreement with literature values.CONCLUSIONST able 2 shows the data on retention of engineering students from the freshmen to the sophomore year and the percentage of retained students entering the chemical engineering program. Although further data collection is necessary to draw statistically significant conclusions, the percentage of engineering students selecting chemical engineering as their major showed a marked increase after the potato cannon project was initiated. The potato cannon project was a positive growth experience for the freshmen engineering students. It provided the students an opportunity to use physical world knowledge that they already possessed, such as projectile motion. On the other hand, it challenged the student by requiring them to now scientifically identify and properly model these physical world occurrences. They used math, science, and computing skills to solve a problem much like many "real" engineering problems. It also gave a practical application to the computer skills they were simultaneously learning in their lab classes. In addition to this, the students learn the pros and cons of teamwork, they develop lasting friendships, and they have a lot of fun while testing and analyzing the cannons. Students worked in the engineering laboratories and worked to collect data accurately. The students evaluated the course in a written class survey at the end of the semester. They were asked their opinion concerning how well each activity added to their understanding of the field of engineering. Of the four design projects conducted throughout the semester, the potato cannon project received the most all-around favorable remarks. One of the most common remarks was the students' amazement that the mathematical modeling of the combustion actually correlated to the experiment. Finally, they were required to write an engineering report documenting their work and formulating conclusions from their results. This gave the students a good introduction into what engineering is all about and what types of work engineers do.REFERENCES1.Tuckman, B.W., Psychological Bulletin 63 p. 384 (1965) 2.Lewis, B., and G. von Elbe, Combustion, Flames and Explosions of Gases Academic Press (1987) 3.Crowl, D.A., and J.F. Louvar, Chemical Process Safety: Fundamentals with Applications 2nd ed, Prentice Hall (2002)

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160 Chemical Engineering Education The chemical engineering unit operations laboratory has long been the primary venue for hands-on exposure by undergraduate students to bench-top and pilot-plant scale equipment. It has also provided an opportunity to address otherwise-neglected accreditation-related topics such as group activities, data analysis, statistical design of experiments, and technical writing. As the call continues for increased emphasis on the development of effective communication skills in the undergraduate curriculum,[1-2] the use of oral presentations in an integrated laboratory sequence[3]and in laboratory and design courses[4] has been advocated, in addition to the development of separate courses specifically tailored toward communication skills.[5] The question of where the technical content for these presentations should come from, however, is an open one. Often, technical presentations by undergraduate engineering students are based on their research projects or topics selected (often by the instructor!) specifically for a course. This provides an invaluable opportunity to develop and enhance presentation skills, but may limit exposure to a new topic or the opportunity to apply one's new-found engineering knowledge to everyday situations. Unit operations presentations at Tulane University are designed to encourage students to venture out into the community, to identify and visit local industries, businesses, and public works that use engineering tools, and to report their findings to their peers and instructors. As will be described in this paper, these sources for presentation material are ubiquitous and independent of the community's proximity to traditional chemical processing industry facilities. Identification of appropriate topics, presentation format, outcome assessment, and integration across the curriculum are described herein, but we begin with a description of how the presentation itself fits into the overall structure of the unit operations laboratory course.TULANE'S UNIT OPS LABORATORIESThe undergraduate chemical engineering laboratory experience at Tulane is similar to that found at many universities. The sequence comprises two courses: the first offered in the spring term of the junior year and the second during an intensive three-week summer session immediately following the first. Students, working in groups of 3-4, remain in these groups for the duration of the laboratory course. The technical presentations under consideration in this paper are contained in the first course (UO Lab I), which focuses on bench-top scale apparatuses. The second course (UO Lab II) primarily emphasizes pilot-plant scale equipment and will not be described in further detail here. As outlined in T able I, there are seven experiments in UO Lab I, including a safety report and the technical presentation. After a few introductory lectures on technical writing, plant safety, and theCOMMUNITY-BASED PRESENTATIONS IN THE UNIT OPS LABORATORYBRIAN S. MITCHELL, VICTOR J. LAWT ulane University New Orleans, LA 70118Brian S. Mitchell is Professor of Chemical and Biomolecular Engineering at Tulane University. He is also Associate Director of the Tulane Institute for Macromolecular Engineering and Science (TIMES). He received his BS from the University of Illinois-Urbana in 1986 and his MS and PhD degrees from the University of Wisconsin-Madison in 1987 and 1991, respectively, all in chemical engineering. His research interests include nanostructured hybrid materials processing and characterization. V ictor J. Law earned three degrees in chemical engineering from Tulane University (BS, 1960; MS,1962; PhD,1963) and has been a faculty member there for over forty years. His areas of specialization include process modeling, simulation, design, and control. He teaches courses at Tulane that include UO Lab, numerical methods, process control, and process design. He is currently the coordinator for the T ulane Practice School. Copyright ChE Division of ASEE 2005 ChEclassroom

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Spring 2005 161 theoretical background of the experiments, four halfday (4-hour) lab sections are allotted to each experiment. Note that the technical presentation receives the same amount of laboratory time as the formal experiments. It also receives the same weight in grading. The primary logistical difference between the presentation and the other experiments is that students may (and often do) visit the host organization outside of the regularly scheduled laboratory c lass hours, and may spend the remaining laboratory hours making follow-up visits, collecting relevant information, and preparing their presentation.COMMUNITY-BASED PRESENTATIONSCommunity-based presentations are the result of visits to facilities or industries found in any university community: water treatment, food processing, office buildings (or sports stadiums), and health care. Since most Tulane chemical engineering students have visited a chemical process facility through the AIChE student chapter, or interned at one of the local companies, they are encouraged to pursue a topic that gives them an opportunity to see something new, such that chemical processing plants, while common in the New Orleans area, are some of the least-often visited facilities. Some examples of facilities that have been reported on, and examples of the technical content they provide, are listed in Table 2 (specific company names have been removed to better illustrate the universality of these sources and their ready availability in a variety of college campus settings). It is worth noting that there are additional goodwill benefits to be gained from university-community interactions of this nature, particularly if alumni are involved. The pedagogical utilities of these presentations will be the focus here, however. Each group of students is encouraged to be creative in selecting a project topic, which has led to some very interesting and informative presentations; e.g. rainwater drainage from the Louisiana Superdome and production of artificial sea water at the New Orleans Aquarium. There must, of course, be a strong technical component to the topic and presentation, but the primary goals are to get the students out into the local community and to interact with professional (not necessarily chemical) engineers. T opics must be cleared with the laboratory instructor, but the topic selection criteria are few. During their visit, the students must Speak with a technical professional Ask technical questions T ake photographs, if allowed Obtain process flow diagrams, if allowed Obtain detailed information on process equipment; e.g., capacity, material of construction, operating parameters, vendor Optionally consider the economics and/or environmental impacts associated with the topic facility There may be additional conditions specific to the site. For example, a visit to virtually any facility first requires clearance and safety train-T ABLE 1Laboratory Experiments Comprising Unit Operations Laboratory ILaboratoryNo. Half-Day PeriodsSafety Report2 Batch Reactor4 T urbulent-Flow Heat Exchanger4 Flow and Heat Exchange in Fluidized Beds4 Cross-Flow Heat Exchanger4 V iscometry4 Presentation4 T ABLE 2Example Presentation TopicsLocation/TopicExample Unit Operation/Engineering TopicsAquariumFluid flow, water chemistry, filtration BreweryFermentation, filtration Chemical process facilityVariable Chemical process industry vendorVariable Chemical process research facilityVariable Country clubFluid flow, environmental impact DairyHeat transfer, fluid flow, packaging Faculty research projectVariable Food processing facilityVariable HospitalVariable Nuclear power plantHeat transfer, energy balance Office building/Sports stadiumHeat transfer, fluid flow (esp. rain handling) Pumping stationFluid flow Sewage plantWater treatment, filtration, biological reactions Student health servicesVariable V ineyard/WineryFermentation, packaging W ater treatment facilityFluid flow, flocculation Unit operations presentations at Tulane University are designed to encourage students to venture out into the community, to identify and visit local industries, businesses, and public works that use engineering tools, and to report their findings to their peers and instructors.

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162 Chemical Engineering Education T ABLE 3Presentation Rubric1234 AttributeNot AcceptableBelow ExpectationsMeets ExpectationsExceeds ExpectationsScore Clarity and readabilityNot clear or readableDifficulty readingClear and readableSuperior clarity and readability Use of spaceVA clutteredToo little or too muchAppropriate amount ofVA very well laid out information information FormatNo consistent formatFormatting errorsAppropriate format Color (if used)Colors too hard toPoor choice and use of colorsEasily distinguishable colorsUse of color enhances clarity distinguish W ording conciseSlides full of textSlides too wordySlides appropriate Presentation Organization Logical order of topicsTotally disjointed, noSome items presented out ofOrganization as perSuperior organization organization order guidelines enhances communication Appropriate use of timeFar too long or far too shortSomewhat too long or too shortAppropriate length ObjectiveNot statedPoorly statedClearly stated Background andNeither statedOnly one statedBackground and significanceClear statement significance explained stated Theory (if applicable)No theoretical developmentWeak theoretical developmentGood theoretical developmentClear theoretical devel opment ResultsNot explainedUnclearClearClear as not to require questioning DiscussionNo explanations providedFew explanationsExplanations for most resultsExplanations for all results provided provided ConclusionsNo conclusionsPresent, but not logicalPresent, logical, and clearlyPresent, logical, and superior explained explanation Other Presentation mechanicsMany distractionsSome distractionsNo distractionsSuperior presentation (voice, mannerisms, poise) Response to QuestionsNonresponsiveIncompleteClear and directComplete ing. These, too, are learning experiences. As described above, the students may make their site visit outside of laboratory class hours, but are otherwise expected to turn in their report (in this case, make their oral presentation) on time, which is one week after the completion of the final regularly scheduled laboratory period. The conditions of the presentation are The presentation should be about 20 minutes long Each group member must present and describe at least one slide or concept and there should be an equitable sharing of the presentation time among group members The presentation must have technical content. This could be theory behind a process, equipment specifications, materials-selection issues, environmental issues, or economic consideration, as appropriate The students must answer questions about their presentation There is no explicit or implicit requirement that the presentation be electronic in format, although such is often the case (the vast majority of presentations are prepared using Powerpoint or similar software). Regardless of the presentation medium, the students are evaluated on effective use of visual aids, as described below. There are no requirements for dress, other than students are encouraged to present themselves in a professional manner. Particular emphasis is given to eliminating "crutch" words during the oral presentation. Overuse of words such as "you know" and "like" in contemporary speaking can easily make their way into presentations. Students are warned that they must eliminate, or at least minimize, the use of these phrases. Similarly, students are encouraged to practice their presentations to the point that reliance on note cards is unnecessary.

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Spring 2005 163T ABLE 4Student Course Evaluation Results Relevant to Community-Based Presentations A verage Response (1=Strongly Agree; 5=Strongly Disagree) Course Term ABET Outcome g Educational Objective #4Spring, 20031.41.9 Spring, 20042.01.9 The presentations are not videotaped, but this enhancement could easily be incorporated. By the time students have reached their junior year, they have given at least one, and often times several, technical presentations in their chemical engineering courses, such that they are familiar with the mechanics of preparing an effective presentation. The emphasis in these presentations, then, is on delivery and content.PRESENTATION AND OUTCOME EVALUATIONStudent presentations are evaluated using a presentation rubric, such as one available from Professor Joe Shaeiwitz at W est Virginia University.[6] The evaluation rubric used for these presentations (Table 3) is currently used in many chemical engineering courses at Tulane, including the Tulane Practice School.[7] This standardization of evaluation criteria is an important tool in documenting ABET evaluation processes. The criteria in this rubric are easily adapted to the course and project at hand. For example, the technical content can be more heavily weighted, if desired, or the use of computer software or programs can be evaluated as a separate category. The idea is to create a standardized set of minimum guidelines that the students will know they are being judged against throughout their undergraduate experience. This approach is invaluable in effectively integrating presentations across the curriculum. The effectiveness of these community-based presentations in meeting ABET educational objectives and program outcomes is assessed, in part, at the end of the semester with electronic course evaluations. Course evaluations in Tulane's School of Engineering are conducted online through Blackboard course software. In addition to rating the instructor, laboratory teaching assistants, and course content, the students are asked to evaluate how certain outcomes/objectives were met. For the Unit Operations Laboratory, ABET Outcomes a, b, e, f, and g are listed, of which Outcome g:This course met the stated objective that students will have the ability to communicate effectively.is the most germane to the community-based presentations. Of course, this also includes written communication, which is heavily emphasized in the Unit Operation Lab. More appropriate to evaluation of the effectiveness of presentations is a specific educational objective for the Unit Operations Laboratory (here arbitrarily labeled Objective #4):This course met the stated objective that students have learned to give oral presentations of technical material.In the most recent version of course evaluations, student responses and "point values" (for internal quantification purposes only) to these questions are made from the following options: 1 = Strongly Agree; 2 = Agree; 3 = Neutral; 4 = Disagree; or 5 = Strongly Agree. So, for example, an average response of 1.5 on this scale of 1 to 5 would indicate that the "average" student agrees/strongly agrees that this objective/ outcome is being met. The most recent evaluations (2003 and 2004) are provided in T able 4. (Data are available for previous years that further support these conclusions, but a different scoring system was used, which only serves to confuse the issue). Results indicate that students generally feel that both of these outcomes/objectives are being met. There are currently no data on how other constituencies (employers, parents, etc.) rate the effectiveness of community-based presentations on meeting these same objectives.CONCLUSIONA method for incorporating community-based presentations into the chemical engineering unit operation laboratory sequence has been described in this paper. These presentations are based on visits to engineering-related facilities found in most university communities. Presentations are treated equivalently with experiments on a grading basis and are evaluated using a standardized presentation rubric that is used across the curriculum for all technical presentations. In addition to the development and refinement of communication skills that the presentations provide, as confirmed by outcome assessment, there is the potential for additional benefits, including enhanced department visibility in the community, improved (non-giving related) contact with alumni, and initiation of outreach activities.REFERENCES1.Felder, R.M., and R. Brent, "Designing and Teaching Courses to Satisfy the ABET Engineering Criteria," J. Eng. Ed ., 92 [1],7 (2003) 2.Prausnitz, J.M., "Chemical Engineering and the Other Humanities," Chem. Eng. Ed. 32 [1], 14 (1998) 3.Newell, J.A., S.P.K. Sternberg, and D.K. Ludlow, "Development of Oral and Written Communication Skills Across An Integrated Laboratory Sequence," Chem. Eng. Ed. 31 [2], 116 (1997) 4.Pettit, K.R., and R.C. Alkire, "Integrating Communication Training into Laboratory and Design Courses," Chem. Eng. Ed. 28 [3], 188 (1993) 5.Bendrich, G., "Just A Communications Course?," Chem. Eng. Ed. 32 [1], 84 (1998) 6. 7.Walz, J.Y., "The Chemical Engineering Practice School Program at T ulane University," Chem. Eng. Ed., 29 [3], 246 (1995)

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164 Chemical Engineering Education ROBERT J. WILKENS, AMY R. CIRICUniversity of Dayton Dayton, OH 45469-0246MAKING ROOM FOR GROUP WORKT eaching Engineering in a Modern Classroom SettingThe traditional lecture format of engineering courses has many drawbacks. A 50to 90-minute lecture period exceeds the typical 20-minute attention span of a college student.[1] Hartley and Cameron[2] present data showing a decline in note taking after the first ten minutes of lecture. When questioned about their lack of notes, the students said that they would fill in the gaps on personal time. For the case presented, not only did they not follow up on their intention to complete the notes, but 19 out of 22 also did not even read through their notes. While resources are available for improving note-taking skills,[3] the passive structure of lecture does not encourage teamwork or lifelong learning skills, and some students leave lecture-oriented courses confident that they can solve the inclass examples and little else. A number of group-learning approaches have been suggested to augment lecture courses. These include smalland large-group student-led discussions and in-class assignments. A nice review of what to expect is given by Felder and Brent.[4] These strategies can improve a student's ability to handle ambiguity and complexity, to recognize assumptions, to improve their communication skills, and to help them feel connected to a topic.[5] Additionally, shifting material from a lecture to a student-led discussion format increases student confidence that they can learn on their own, a prerequisite for lifelong learning. Discussion-format classes have to be carefully structured if they are to cover the same amount of material as a lectureformat course. This paper will describe the use of creative group-learning structures in an experimental methods course. Specifically, these structures were employed during the summer of 2000 offering of the course Experimental Methods in Chemical Engineering According to the University of Dayton Bulletin the objective of this course serves as an "Introduction to experimental methods, instrumentation, digital data acquisition, data analysis, and report writing. Use of digital computer is emphasized." The course is taught to secondsemester sophomores who are majoring in chemical engineering. It is their second course in the major. While having a stated objective of introducing the students to the engineering way of experimentation and to engineering instrumentation, it also serves the objective of maintaining student involvement in the department until they have completed the necessary mathematical background for the more advanced topics. Historically, this course, when taught in a standard classroom using a conventional lecture format, has received poor student reviews. The course themehow to conduct experiments as a chemical engineerleads to many varied topics, from uncertainty analysis and probability to instrumentation principles of operation to computer programming for data Copyright ChE Division of ASEE 2005 ChEclassroom Bob Wilkens is Assistant Professor of Chemical Engineering at the University of Dayton. He received his BChE and MS from the University of Dayton and his PhD from Ohio University, all in chemical engineering. He worked as a postdoctoral research engineer at Shell W esthollow Technology Center in Houston, T exas. His primary research areas include multiphase fluid flow and agitation. Amy Ciric is Associate Professor of Chemical Engineering at the University of Dayton. She received BS degrees in chemical engineering and in physics from Carnegie Mellon University and her PhD in chemical engineering from Princeton University. Her research interests are in process engineering, with a particular emphasis on synthesis, simulation, and optimization.

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Spring 2005 165acquisition. Students had difficulty seeing the common theme and tended to experience the course as a hodgepodge of information with no common thread. Bligh[6] reviewed and summarized hundreds of studies regarding the effectiveness of a straight lecture to alternative methods. He found that the lecture is statistically equivalent to other methods when the purpose is to transmit information, but if the purpose is to promote thought (necessary for problem-solving skills) or inspire interest (much needed for this course), then discussion is significantly more effective than a lecture. If the goal is to teach a skill (the computer programming portion of the course), then practice of the skill is superior to a lecture. A special offering of the course was taught in an ideal classroom for group workthe Studio in the Ryan C. Harris Learning Teaching Center at the University of Dayton. As part of an innovative approach to encourage faculty members to explore new pedagogical styles, the University of Dayton established the Ryan C. Harris Learning Teaching Center. In the Learning Teaching Center, a classroom called the "Studio" was erected that incorporates classroom flexibility and the latest technology. University faculty members use this top-notch teaching facility for pedagogical exploration and to test new technology on a small scale before implementing it in larger settings. The Studio, custom designed to foster classroom discussion and groupwork, was the best place to develop an improved pedagogical style for this course.THE CLASSROOMThe classroom is designed to handle up to 24 students. The room and the desks evoke memories of a kindergarten classroomonly with bigger seats. The floor is carpeted, and instead of desks, the students sit at specially designed tables that can be moved around as necessary. An open closet runs along one wall where coats and excess baggage can be placed. Portable whiteboards and corkboards can be placed along any wall or can be hung in the middle of the room by what can best be described as a tic-tac-toe railing system overhead. In one corner closet there is a combination TV/VCR along with a standard overhead projection unit, and in the other corner closet there is a notebook computer with wireless connection to the Internet and a computer data projection unit. This system is coupled with a SMART Board, which is much like a giant touch screen for the computer. Notebook computers are available for the classroom upon request. These also have wireless connections to the Internet along with standard network ports. Other unique aspects of this classroom involve its physical settingappointments both inside and outside of the Studio are exquisite. Just outside of the room is a coffee bar. In addition, one of the most promising aspects is that the Learning T eaching Center is in the basement of the library. Studio Evaluation Notes about the Studio and its technology were collected from the instructor, the students, and communications with other instructors who were using the classroom. These notes have been summarized in Table 1. Although certain aspects of the Studio could be improved upon, most were considered to be a step in the right direction.GROUP-DISCUSSION STRUCTURESBrookfield and Preskill,[5] McKeachie,[7] and Aronson and Patnoe,[8] among others, have discussed ways to promote classroom discussion. Five are particularly useful for engineering education Small-group discussion followed by large-group discussion, then a lecture Lecture with individual in-class practice (with instructor's help) Snowball followed by lecture Modified jigsaw with no lecture Straight lecture but open to questions As previously mentioned, this was an off term (summer) Interaction room (sufficient space to get in among the students) Extremely helpful LTC staff Availability of multimedia Wireless network Portability of whiteboards (they could be physically moved) SMART Board use excites students Students began showing up progressively earlier Tables don't move as easily as designed Whiteboards hanging on a track allows them to swing when writing (requires additional hand) Whiteboards should be able to cross tracks (they cannot cross intersecting support tracks) Whiteboards should be able to rotate Needed to arrive early to set up seating SMART Board screen must be calibrated to use as a touch screena slight bump during the lecture gets it out of calibrationT ABLE 1Summary of Comments About the LTC Studio Keep Change Discussion-format classes have to be carefully structured if they are to cover the same amount of material as a lecture-format course. This paper will describe the use of creative grouplearning structures in an experimental methods course.

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166 Chemical Engineering Education T ABLE 2Summary of End-of-Term Anonymous Student Evaluations of Modified Course(Select Questions)QuestionAgreeNeutralDisagreeN/A Y ou like the required text03110 The book was a useful reference3920 The instructor is boring3830 Y ou would recommend instructor to a friend11210 The course objective was clear13100 The course met the stated objective13100 As experienced co-ops, you feel that you've learned tools that will be useful to your future13100 The instructor is clear about the subject area9100 The instructor understands the material14000 The instructor is well prepared for class14000 T ABLE 3Summary of End-of-Term Anonymous Student Evaluations for Previous Term (Select Questions)StronglyStronglyNot QuestionAgreeAgreeNeutralDisagreeDisagreeApplicable The textbook was an asset to the course16810100 Instructor enthusiasm inspired interest09121410 Y ou would recommend this instructor to another student4915530 The instructor clearly communicated the course objectives3255300 Y ou learned a great deal from this course3209120 Class discussion contributed to your understanding11012445 Instructor encouraged classroom participation21115521 with 14 students. Thus, observations may be tainted by the small class size or by the fact that all of the students had just returned from their first cooperative education experience. All techniques were either immediately followed or immediately preceded by an appropriate homework assignment. Also, each technique was followed by a large-group discussion (entire class) to evaluate the style's effectiveness. Small Groups For the small-group discussion technique, the students were first asked to read selected sections from the text about a new topic prior to the next meeting. At the next meeting, the students were asked to reflect on aspects of the reading that they understood well and aspects that they found to be confusing. The students were then divided into groups of three or four and asked to create a group list. Finally, all of the lists were summarized on a board in the front of the room and a largegroup discussion ensued. What the students found was that, in general, they were all confused about the same things. This was followed by a lecture where additional focus and example problems were applied to the difficult material. All material was still covered for completeness. Knowledge of their limitations helped the students to focus on these parts of the notes. As an added benefit, topics that were not well understood by the minority were often cleared through the initial discussion. As with all techniques, when finished the approach was discussed in a large group to judge the effectiveness. In-class Practice While presenting aspects of computer programming, it was decided that it was best to program live along with lecture. The Studio provided a notebook PC to each student and one for the instructor, which projected onto a SMART Board. The programming had some lecture, a handout, and plenty of inclass practice where the instructor and the teaching assistant went from student to student to help them over the simpler hurdles that so often stop programming in its tracks. This structure was employed over a period of several weeks. Snowball Snowballing is much like the small-group discussion as applied to this course. After reading, students progressively get into larger groups until eventually the entire class is involved in the discussion. Lecture still follows the discussion, with focus on the areas of concern. What distinguished Snowball from Small Group was the addition of more group layers, much like a growing snowball. Jigsaw A jigsaw is an approach where groups are formed to discuss one topic. Then they form new groups with one topic expert in each (works best with a squared number of students 22 = 4, 32 = 9, 16, 25, 36, etc .). For this implementation, all students were first asked to read the entire chapter (temperature instrumentation). Next, four groups were created and each assigned to establish an area of topical expertise: thermal expansion techniques, thermocouple techniques, electrical resistance techniques, or radiation techniques. They met for one period in-class and then had until the next class period to create a set of notes. They were also provided with references to additional resources. At the following class, four new groups were formed that included a topical expert from each area. The students then gave lectures and examples to each other using the portable whiteboards. This only took one class period (1.5 hours) to present the information.

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Spring 2005 167 T ABLE 4Rank of Techniques Used in ClassroomT echniqueTopicPoints 1.Lecture with individual in-classcomputers66 practice (with instructor's help) 2.Small-group discussion followed byintroduction, basic concepts57 large-group discussion, then lecturedata analysis 3.Straight lecture but open to questionselectrical measurement, flow measurement, data acquisition33 4.Snowball followed by lecturepressure measurement32 5.Modified jigsaw with no lecturetemperature measurement16 6.Other6 Despite requests from the students, no lecture from the instructor accompanied the jigsaw notes (as a way to help assess the improvement). A specialized homework assignment was created to test how deep of an understanding was formed in each area. The homework was assigned to each of the new teams ( i.e. not to individuals) to be turned in collectively. Lecture and Other Other teaching styles were used as necessary, but they were not evaluated. The straight (traditional) lecture style was used, primarily as a basis for comparison. All lectures included examples, and students were encouraged to ask questions when they needed clarification. Another teaching format that was used but not evaluated involved meeting in the chemical engineering laboratory and collecting data. This was used at the end of the term to bring all of the aspects of the course together with a case study.STUDENT EVALUATIONFormal university evaluations are not required for courses taught in the Studio, but the instructor created a special evaluation form to help determine the success of the course. Table 2 summarizes the statements and responses. For comparison, related questions from two previous sections are reported in T able 3 (same instructor). The responses to most of the questions reflected well on the course. This is in stark contrast to evaluations received for the previous instruction of this course. The response to the question about the book is the same as previous; the students did not like the text. It is also apparent that the instructor is not too exciting (before and after). The most pertinent questions to the course modifications are the next four. For these questions, 90% of the student responses are at the highest level and 98% of the responses are favorable. This marked a significant improvement to whether or not the students would recommend the instructor to someone else. The other areas marked a slight increase. In the evaluation, the students were also asked to rank the techniques used in the classroom. Five points are given for the technique that the stud ent liked best, four points for the second, etc. with zero points given for the least-favorite method. The total points received by all students are summarized in Table 4. The top-ranked technique was the one applied to computer programming where the lecture was followed with in-class practice such as examples or homework. The second-ranked technique was small-group discussion followed by largegroup discussion and then lecture. The lowest-rated technique was the modified jigsaw with no lecture. The evaluation also contained several open-ended questions. One question asked the students to summarize topics covered in the course about which they felt confident and topics about which they felt confused. The topics about which the most students indicated confusion were electrical measurement, temperature measurement, and data acquisition (straight lecture and jigsaw). The topics about which the most students indicated confidence were computers, data analysis, pressure measurement, and flow measurement (each a different technique). Ironically, the students did best on the jigsaw-taught topics as judged by homework and test scores. The students were also asked to list the positive and negative aspects about the homework. Most agreed that while it was difficult, it was quite relevant. During the course, assignments were alternated between being due before the topic was covered in class and afterward. When asked which was better, 1 preferred before, 8 preferred after, and 5 indicated that they would like to alternate between the two scenarios. Adjusting the timing of notes and homework can lead to an increased student interest. When asked what modified methods they might propose, they responded with the following ideas: Emphasize important topics to be covered in jigsaw Add 1 lecture to the jigsaw V ariety Lecture followed by working on problems in groups Conduct class as a meeting These ideas are certainly worth future exploration. Another is to take the structure used for computer programming and apply it to problem solving with the other material.INSTRUCTOR COMMENTSThroughout the semester, notes were made about the progress of the class in a journal fashion. Notes were made prior to, during, and immediately following each class period. Notes prior to each class included a summary of announcements along with a proposed list of topics and objectives for

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168 Chemical Engineering EducationT ABLE 5General Interest Notes (Roughly Chronological Order) Students were slow to use whiteboards in the room T erm started quietly Small-group discussion Covered comparable material Students happy to know that others were confused Maybe assign review questions prior to reading assignment Nice to have peers explain topics Some students are already beginning to dominate conversation U-shape of desk arrangement works well for large group discussion and for lecture It would be nice to set aside discussion time for such topics as the impostor phenomenon[9] Students requested more practice problems Could try an e-mail discussion to kick off the topic Students are less likely to be shy in small-group discussion In the future, let small groups solve example problems Midway through the course, students speak out; still reluctant about moving desks During snowball approach, the four board writers were the students who tended to dominate large-group discussion Students enjoyed working through computer assignment in class (independently, but with instructor help) The jigsaw I should have videotaped this Approach would not work well without seat mobility Having students discussing same topics simultaneously makes instructor's evaluation job easier The students did additional research, but they did not make it apparent in presentations Students recommend that I do this (jigsaw) "to" the next class also In future, try role reversal (student professor) Attendance is exceptional the day. Occasionally, the objectives were written on a side whiteboard in the classroom for the students to consider for the entire period. As a way to ensure equal participation among the students, a list of students to "pick on" was also created prior to the class. The instructor first called upon two of these students to attempt to answer each question, for the entire period, before asking the other students to answer. During the course of the term, all of the students had their opportunity to be "picked on." Note that the term "pick on" was harsher than the implementation. Notes made during each class included how the lecture notes could be improved, who was late or missing from class, observations of the students, and summaries of student comments about the course topics and formats (including a summary of large-group discussions). Notes generated after the class period included an evaluation of the period, what was covered (or not covered), and ideas for future classes. T able 5 summarizes the notes that are of general interest; course-specific notes were deleted. This information establishes timelines and reinforces key concepts for the term. It also helped to keep track of smaller observations such as best seating arrangement (U-shape) for lecture or large-group discussion.CONCLUSIONSA classroom designed for group work with notebook PC's for each student, a SMART Board, and movable tables, whiteboards, and corkboards made an excellent location for exploring different cooperative-learning methods. The classroom was used as a setting to evaluate (a) the effectiveness of small-group discussions, in-class practices, snowballing, and jigsaw discussions, (b) how these techniques were received by students, and (c) the effect these techniques had on student confidence. Small-group discussions and in-class practices were well received by the students. Small-group discussions were well suited to the subject matter, and in-class practices gave the students the most confidence about their abilities. Although students developed the deepest understanding of the material covered by the jigsaw method, they did not enjoy it and, paradoxically, did not feel confident of their understanding of the material. This matches the observations of Felder and Brent,[4] ". . cooperatively taught students tend to exhibit higher academic achievement . [with] deeper understanding of learned material." If increased student confidence is desired then it would benefit the instructor to follow with a brief lecture. Overall, a well-designed classroom can facilitate cooperative learning methods, but preparing students for group work remains essential. Part II of this work[10] will compare these results to those in a traditional classroom setting.REFERENCES1.Wankat P.C., and F.S. Oreovicz, Te aching Engineering, McGraw-Hill, New York, NY(1993) 2.Hartley, J., and A. Cameron, "Some Observations on the Efficiency of Lecturing," Educational Rev. 20 30 (1967) 3.Hartley, J., and I.K. Davies, "Note-Taking: A Critical Review," Programmed Learning and Ed. Tech. 15 207 (1978) 4. Felder, R.M., and R. Brent, "Cooperative Learning in Technical Courses: Procedures, Pitfalls, and Payoffs," ERIC Document Reproduction Service, ED 377038 (1994) 5.Brookfield, S.D., and S. Preskill, Discussion as a Way of Teaching Jossey-Bass, San Francisco, CA (1999) 6.Bligh, D.A., What's the Use of Lectures? Jossey-Bass, San Francisco, CA (2000) 7.McKeachie, W.J., T eaching Tips 8th ed., D.C. Heath, Lexington, MA (1986) 8.Aronson, E., and S. Patnoe, The Jigsaw Classroom: Building Cooperation in the Classroom 2nd ed., Longman, New York, NY (1997) 9. Felder, R.M., "Imposters Everywhere," Chem. Eng. Ed. 22 168 (1988) 10.Ciric, A.R., and R.J. Wilkens, "Making Room for Group Work II: T eaching Engineering in a Traditional Classroom Setting," to be submitted to Chemical Engineering Education 2005