• TABLE OF CONTENTS
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 Front Cover
 Table of Contents
 Illinois Institute of Technolo...
 R. Russell Rhinehart of Oklahoma...
 Reduction of dissolved oxygen at...
 Positions available
 An open-ended mass balance...
 Death by Powerpoint
 Energy balances on the human body:...
 A project to design and build compact...
 A method for determining self-similarity:...
 Process security in ChE educat...
 Kinetics of hydrolysis of acetic...
 VCM process design: An ABET 2000...
 ASPEN plus in the ChE curriculum:...
 Environmental impact assessment:...
 Back Cover
































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Table of Contents
    Front Cover
        Front Cover 1
        Front Cover 2
    Table of Contents
        Page 1
    Illinois Institute of Technology
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
    R. Russell Rhinehart of Oklahoma State University
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
    Reduction of dissolved oxygen at a copper rotating-disc electrode
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
    Positions available
        Page 21
    An open-ended mass balance problem
        Page 22
        Page 23
        Page 24
        Page 25
        Page 26
        Page 27
    Death by Powerpoint
        Page 28
        Page 29
    Energy balances on the human body: A hands-on exploration of heat, work, and power
        Page 30
        Page 31
        Page 32
        Page 33
        Page 34
        Page 35
        Page 36
        Page 37
    A project to design and build compact heat exchangers
        Page 38
        Page 39
        Page 40
        Page 41
    A method for determining self-similarity: Transient heat transfer with constant flux
        Page 42
        Page 43
        Page 44
        Page 45
        Page 46
        Page 47
    Process security in ChE education
        Page 48
        Page 49
        Page 50
        Page 51
        Page 52
        Page 53
        Page 54
        Page 55
    Kinetics of hydrolysis of acetic anhydride by in-situ FTIR spectroscopy: An experiment for the undergraduate laboratory
        Page 56
        Page 57
        Page 58
        Page 59
        Page 60
        Page 61
    VCM process design: An ABET 2000 fully compliant project
        Page 62
        Page 63
        Page 64
        Page 65
        Page 66
        Page 67
    ASPEN plus in the ChE curriculum: Suitable course content and teaching methodology
        Page 68
        Page 69
        Page 70
        Page 71
        Page 72
        Page 73
        Page 74
        Page 75
    Environmental impact assessment: Teaching the principles and practices
        Page 76
        Page 77
        Page 78
        Page 79
        Page 80
    Back Cover
        Back Cover 1
        Back Cover 2
Full Text




CEE

VOLUMF 39 NUMM'R I SPRIt 2005




Feature Articles ... Ak at-A

-4 4. IW:









wid ChE (it ...
















Invitation for

Editorial Contributions


Chemical Engineering Education publishes editorials in this space that concern subjects
of current relevance to the community of chemical engineers.

The topic is normally controversial
and the author is encouraged to clearly state his or her opinion
on the issue and the rationale for the stated opinion.

The editorial should not exceed one journal page (approximately 400 words) in length
and should be submitted electronically to



cee@che.ufl.edu



Although submissions are not sent out for review,
the editors provide feedback when they feel it is appropriate
and reserve the right to make editorial changes or to refuse to publish material
that the they consider inappropriate.



The deadlines for inclusion in each issue are


Winter Issue
Spring Issue
Summer Issue
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October 15th
January 15th
April 15th
July 15th











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
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PROBLEM EDITOR
James 0. Wilkes, U. Michigan

LEARNING IN INDUSTRY EDITOR
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-PUBLICATIONS BOARD

CHAIRMAN *
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Colorado School of Mines

MEMBERS
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Georgia Institute of Technology
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Georgia Institute of Technology
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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 1


Winter 2005


> DEPARTMENT
2 Illinois Institute of Technology
HamidArastoopour Darsh T Wasan, Margaret M. Murphy

> EDUCATOR
8 R. Russell Rhinehart of Oklahoma State University

> CLASSROOM
14 Reduction of Disolved Oxygen at a Copper Rotating-Disc Electrode,
Gareth Kear Carlos Ponce-de-Leon Albarran, Frank C. Walsh
30 Energy Balances on the Human Body: A Hands-On Exploration of Heat,
Work, and Power
Stephanie Farrell, Mariano J. Savelski, Robert Hesketh
38 A Project to Design and Build Compact Heat Exchangers,
Richard A. Davis
42 A Method for Determining Self-Similarity: Transient Heat Transfer with
Constant Flux,
Charles Monroe, John Newman
76 Environmental Impact Assessment: Teaching the Principles and Practices
by Means of a Role-Playing Case Study,
Barry D. Crittenden, Richard England

> CLASS AND HOME PROBLEMS
22 An Open-Ended Mass Balance Problem,
Joaquin Ruiz

> RANDOM THOUGHTS
28 Death by Powerpoint, Richard M. Felder, Rebecca Brent

> CURRICULUM
48 Process Security in ChE Education,
Cristina Piluso, Korkut Uygun, Yinlun Huang, Helen H. Lou
62 VCM Process Design: An ABET 2000 Fully Compliant Project,
Farid Benyahia
68 ASPEN Plus in the ChE Curriculum: Suitable Course Content and
Teaching Methodology,
David A. Rockstraw

> LABORATORY
56 Kinetics of Hydrolysis of Acetic Anhydride by In-Situ FTIR Spectros-
copy: An Experiment for the Undergraduate Laboratory,
Shaker Haji, Can Erkey

21 Positions Available


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 andfor 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.


Winter 2005









" department



ChE at...


Illinois Institute of Technology

"A Century ofExcellence in

Chemical Engineering Research and Education"



HAMID ARASTOOPOUR, DARSH T. WASAN, MARGARET M. MURPHY
Illinois Institute of Technology Chicago, Illinois
In 2001, Illinois Institute of Technology (IIT) celebrated a century of excellence in
chemical engineering education and research. Among the very oldest programs in the
country, IIT's program has closely tracked the origin and evolution of the chemical
engineering discipline itself. This paper highlights the unique combination of visionary
administrators and talented faculty who piloted a once-fledgling program through more
than 100 years of rapid scientific and technological change, while at the same time main-
taining its continuous excellence and relevance to the needs of society and industry.

PROGRAM ORIGIN/EARLY HISTORY
Armour Intitute The very earliest record of chemical engineering studies at the then Armour Institute
Main Building surfaced in the year 1894 in the joint Department of Chemistry and Chemical Engineering.
Under the directorship of Dr. James C. Foye, PhD, LL.D, and professor of chemistry, a
four-year curriculum leading to the BS degree in chemical engineering was developed and
implemented. According to Dr. Foye, the instruction in chemical engineering was intended
"to meet the wants of students who wish to acquire a knowledge of chemistry, as applied to
the engineering profession, which will enable them to engage in industries demanding the
attainments of both the engineer and the chemist."'1M This educational initiative came only
six years after George Davis provided the blueprint for a new profession in a series of
twelve lectures on chemical engineering in England and, simultaneously, MIT began
"Course X (ten)," the first four-year chemical engineering program in the United
States. By 1895, the newly named Armour Institute of Technology had established a
stand-alone Department of Chemical Engineering as part of the Technical College to
be directed by Professor Foye.[2]

A CENTURY OF CHEMICAL ENGINEERING EXCELLENCE
The chemical engineering momentum begun at Armour by Dr. Foye was temporarily
halted by his sudden death on July 3, 1897. By the beginning of the fall semester, all
references to chemical engineering were dropped and the official name became the De-
Chairman apartment of Chemistry, headed by Thomas Allen, professor of chemistry.'31 One year later,
Willam T. McClemen William T. McClement was appointed director of the department and was promoted, at the
same time, to professor of chemical engineering. In September 1901, a degree-granting
Copyright ChE Division of ASEE 2005


Chemical Engineering Education









Department of Chemical Engineering was established with Professor McClement serv-
ing as director. All work in chemistry was also placed under his supervision as he became
responsible for the administration of what were basically two departments in one.
Under Professor McClement's direction, the Armour student chapter of the American
Chemical Society was formed and, on June 19, 1901, the department granted its first BS
degree in chemical engineering to Charles W. Pierce. Based on preliminary research, it
would appear that Mr. Pierce was one of the first-if not the first-African-American
chemical engineers in the nation. After leaving Armour, Mr. Pierce was named chief
engineer at Normal College (now Tuskegee Institute) in Tuskegee, Alabama, later be-
coming head of the Mechanical Department at the State Agriculture and Mechanical
College (now North Carolina A&T) in Greensboro, North Carolina.[41 According to Armour
ledgers, Mr. Pierce would have paid $75.00/yr in tuition fees, with an additional annual
lab deposit fee of $5.00!
In addition to the undergraduate curriculum, chemical engineering students could com-
plete one year of resident post-graduate study and investigation or two years of actual
engineering work to complete the "degree of chemical engineer." Professor McClement
directed the department until 1906. For the next two years, Associate Professor Oscar
Rochlitz would direct chemical engineering studies at Armour, which, by May 1907, had
conferred a total of 25 BS degrees in chemical engineering.

PROGRAM EVOLUTION
With the department foundation in place, the next nine decades would see brilliant
leadership and program evolution that not only kept pace with rapid industrial change,
but also prepared its chemical engineers to lead this dynamic revolution. Since the early
tenures of Professors McClement and Rochlitz, the department has been served by seven
chairmen to date: H. McCormack (1908-1946), J.H. Rushton (1946-1953), R.E. Peck
(1953-1967), B.S. Swanson (1967-1971), D.T. Wasan (1971-1987), H. Arastoopour (1989-
2003), and E Teymour (2003-present).
Significant development of the educational programs began under the leadership of
Professor McCormack. Interestingly, the American Institute of Chemical Engineers
(AIChE) was established in 1908, the same year that Professor McCormack became de-
partment chair. History shows that Professor McCormack was an exceptionally active
member of the society and, in 1924, served as a co-founder of the AIChE Chicago Sec-
tion-the society's first local chapter. In honoring his contributions to the society, the
Chicago AIChE local chapter offers the "Harry McCormack Outstanding Senior" award
to each of the top students in three chemical engineering departments in the Chicago
area. During the tenure of Professor Rushton, the department would reach another criti-
cal milestone when Miss Lois Bey became the first co-ed to receive a bachelor's degree
in chemical engineering from IIT. The department was also moved from Main Building
to its present location in Perlstein Hall.151
In commemoration of Professor Peck's dynamic teaching style and his famous "ten-
minute quiz," the Ralph Peck Lecture Series was established in the late 1970s, and was
endowed in the 1990s with funding by department alumni.
During the last two decades, the department has undergone extensive reorganization
and program revision. In 1985, under Dr. Wasan's leadership, the Gas Engineering edu-
cation and research activities moved from the Institute of Gas Technology (now Gas
Technology Institute) to the Chemical Engineering Department, under the name of the
Energy Technology Program. The scope of this program continued to grow and expand
to become the IIT Energy + Power Center. Today, this activity provides the focal point of
the Energy and Sustainability Institute, newly established under the leadership of Profes-
sors Henry Linden and Hamid Arastoopour.
In 1995, the Pritzker Department of Environmental Engineering merged with the Chemi-


Winter 2005











Undergraduate Prgfogra
Milestones

1908
Harry McCormack establishes first
Unit Operations .aboraory in the
nation
1930s
Chemical engineering- crriculum
begins t shift-fom ekemisrwyo
chemical engineering oriemarion

1936

d-on

Program recivnusftIcsreta- .
tJo :- . .-.. -, -- : .... .




Aotetre ,mcer c
1937 '. -_. ..-..-_-- :


1938
ProfsirsoratJakob, ajhaoity on
heat transfer join -t "
1940
Meerer of Armour rstitute of.
Technology with-Lewi rInstinaeof
Arts andScienceriojf[ f Htllnois -
Institute of Technology
1940s
Specializations developed in
chemlsry, food techabtogy,
instrumentation and control
management and metallurgy
1958
Professor Octave Levenspiel brings
chemical reaction engineering to
undergraduate curriculum
1980s
Specializations in biomedical and
biochemical engineering
Gas engineering acrivtiues
incorporated through energy
technology specialization
Unit operations expanded to include
transport phenomena
1990s
Specialized courses developed in
particle technology, fliidizanion
pharmaceutical engineering and
statistics
1995
Merger of chemical and
environmental engineering
programs

2000
Chemical engineering begin to
reflect growing trend toward
biological engineering


cal Engineering Department, marking the origin of the Department of Chemical and Envi-
ronmental Engineering (ChEE).

The following sections trace the history[61 and evolution of the department's research and
education programs and describe the contributions to the profession by its illustrious faculty
and dedicated alumni.


UNDERGRADUATE PROGRAM

In 1908, four years after joining the Department of Chemical Engineering, Professor Harry
McCormack assumed the chairmanship of the department-a position he would hold until
his retirement from IIT in 1946. Under his direction, the department would make great
strides in the advancement of its education programs and maintain a top ranking among all
fully accredited chemical engineering departments.
The Unit Operations Laboratory, established at Armour in 1908 by Professor McCormack,
provided the first real laboratory instruction in chemical engineering. The Unit Operations
outlook was immediately accepted by other schools and soon came to be recognized as an
essential part of student training. Students worked in teams of two or three to complete 24
independently developed and continuously modified experiments over a span of three
semesters. The result was a chemical engineering graduate who could devise a practi-
cal way to evaluate the results of industrial processes and determine the best method to
develop these processes.
In 1936, the chemical engineering program received accreditation by the Accreditation
Board for Engineering and Technology (ABET) under its first accreditation program. At the
same time, a cooperative education program was implemented to enhance the Institute's
interaction with industry.
During this time, the development of both undergraduate and graduate education pro-
grams received significant impetus from a number of events: the sabbatical visit in 1937 of
Professor Olaf A. Hougen, nationally prominent for his work on unit processes in chemical
engineering; the arrival in 1938 on the HT campus of Max Jakob, an internationally recog-
nized authority on heat transfer; and the merger in 1940 of Armour Institute of Technology
with the Lewis Institute of Arts and Sciences to form Illinois Institute of Technology.
In addition to core undergraduate courses, IIT faculty began to develop several elective
courses. This allowed undergraduate students to specialize in various branches of engineer-
ing and science, or in economics, management, and allied fields. The arrival to IIT in 1958
of Octave Levenspiel led to the introduction of chemical reaction engineering in the under-
graduate chemical engineering curriculum.
During the 1980s, under the leadership of Professor Wasan, specializations in energy
technology, polymer, electrochemical, biochemical and biomedical engineering were
added. In 1985, the unit operations course was revised by Hamid Arastoopour to in-
clude three courses: fluid dynamics and heat transfer, mass transfer operations, and
transport phenomena.
During the 1990s, under the leadership of Professor Arastoopour, several required courses
were also introduced in the curriculum, such as process thermodynamics, numerical and
data analysis, and process modeling and system theory. In addition, several elective courses
and specializations in the areas of particle technology and fluidization, bioengineering, en-
ergy, pharmaceutical engineering, and statistics were developed. In 1995, after the merger
of the environmental and chemical engineering programs, a series of undergraduate elective
courses in environmental engineering was also introduced.
Beginning in 2000, in response to the shift in industrial emphasis on biology applications,
the department began to increase its activities in biological engineering by hiring new fac-
ulty and expanding elective course offerings in this area.


Chemical Engineering Education









GRADUATE PROGRAM
IIT's graduate program in chemical engineering was established in the early 1930s, with
the first MS and PhD degree being awarded in 1933 and 1939, respectively. Integration of
the chemical engineering faculty of other universities through their visits to IIT campus,
interaction with distinguished colleagues in other departments such as Professor Max Jakob,
and initiation of research activities at the Armour Research Foundation, contributed to the
development of a successful graduate program.

At this same time, research activities on the development of processes for making petro-
chemicals from fossil and non-fossil fuels were expanding. The graduate curriculum re-
flected this expansion as courses were developed in applied chemical engineering thermo-
dynamics, catalysis, fuels and combustion, petroleum refining and chemistry of petroleum
hydrocarbons. In the 1950s, fundamental courses including chemical engineering process
kinetics, non-Newtonian fluid behavior, chemical reaction engineering, and fluidization,
were added. Around 1960, several courses were added to the graduate curriculum including
application of mathematics to chemical engineering, unit operations, computational tech-
niques, and transport phenomena.

Industrial short courses have been offered in specific areas of chemical engineering since
the 1960s when Professor Peck first taught courses in drying theory and technology. Addi-
tionally, in the 1970s and 1980s, many advanced courses in conventional and emerging
areas of chemical engineering were developed. These included advanced reaction engi-
neering, process optimization, computer-aided design, topics in biomedical and biochemi-
cal engineering, separation processes, particle technology, polymer engineering courses,
and interfacial and colloidal phenomena. In addition, inclusion of gas engineering research
and education and establishment of energy activities resulted in the gradual addition of
several new courses, such as flow through porous media, fluidization and fluid particle
systems, and energy/environment/economics. During the mid-1970s, through the generos-
ity of chemical engineering alum William Finkl, the interactive instructional television net-
work (IITV) was established that ultimately enable IIT to broadcast its programs and courses
to thousands of IIT students and employed professionals.
In the 1990s, the merger of the chemical and environmental engineering programs brought
more than 30 graduate elective courses in environmental engineering as electives for chemical
engineering students. In addition, formation of the Center of Excellence in Polymer Sci-
ence and Engineering and the Center for Electrochemical Science and Engineering, along
with pharmaceutical specializations resulted in the development of several elective courses,
such as electrochemical engineering, polymer rheology, drug delivery systems, pharma-
ceutical engineering, and particle processing and characterization. Process modeling, sta-
tistical quality, and process control were also among the elective courses developed and
offered. The establishment of the Master of Food Process Engineering with the collabora-
tion of the National Center for Food Safety and Technology at IIT enabled the department
to provide a series of food safety and processing courses for graduate students. Addition-
ally, the joint Master of Science in Environmental Management program was developed in
cooperation with the IIT Stuart Graduate School of Business.
The new millennium brought added program changes and the addition of new courses
and faculty in the bioengineering area as the department continued to work to meet the
needs of the engineering professional. Fall 2003 saw the introduction of the totally internet-
based Master of Gas Engineering program, developed in collaboration with the Gas Tech-
nology Institute. A double master of chemical engineering/master of science in computer
science program was jointly developed between the ChEE and Computer Science Depart-
ments to effectively train the new generation of process engineers.

RESEARCH PROGRAM
In January 1936, Universal Oil Products (UOP), largely through the efforts of Mr. John J.


Graduate Program
Milestones


1930s
Graduate education program in
chemical engineer ring
established



1940s
Graduate curriculum expanded
to reflect research in
petrochemucal processing



1950s
Curriculum shiftedfocus from
process design toward engineering
fundamentals



1960s
Short courses added to curriculum
to ensure continued relevance of
program to industrial needs



1970s-1980s
Advanced courser added in
emerging areas: advanced reaction
engmeering, computer-aided
design, polymer engineering,
biomedical and biochemical
engineering, gas engineering



1990s
Merger with environmental
engineering program adds more
than 30 electives to curriculum.
Graduate specializations
expanded through added ChEE
research centers and
collaborative programs



2000-
New millenniurmbrings expanded
programs in bioengineering and
delivery modes designed to meet
the changing needs of the
engineering professional


Winter 2005


















Chairman J. Henry Rushton
Renowned researcher in
mixing technology.


Chairman Bernet Swanson and
students snudv refiner model


Chairman Darsh Wasan (above)
and Ma McGraw Professor
Henry Linden (betow
NationalAcademy of Engineering
S members.


Excellence in Teaching Award
established in honor of
Chairman HamidAra toopour


Mitchell, established a research professorship affiliated with the Department of Chemical
Engineering. Dr. Vasili Komarewsky was appointed the first UOP Research Professor.
His field of research was catalysis in organic chemistry, especially its application to
the chemistry of petroleum.
The Armour Research Foundation (ARF, now known as IIT Research Institute), estab-
lished April 3, 1936, was the first not-for-profit research institute formed in the United
States. Research areas that were being conducted in the Department of Chemical Engineer-
ing in the late '30s that were compatible with the ARF research activities included catalysis,
chemical filtration, chemistry of oils, oil combustion, and heat transfer. In the areas of com-
bustion and heat transfer, significant interaction occurred among researchers between IIT's
chemical engineering and mechanical engineering departments and the Institute of Gas Tech-
nology (IGT), including Professors Peck and Jakob.
The research interests of the chemical engineering faculty in the 1940s were cataltytic
reactors, distillation, drying, liquid-liquid extraction, mixing, process control, and
hydrogenolysis of coal, oil shale, and petroleum fractions. During this period, Professor
Rushton developed a world-renowned research program in the chemical engineering as-
pects of mixing.
During the next 50 years, the research interests of the chemical engineering faculty were
substantially broadened. In the 1950s, the faculty pursued research in fluid dynamics, fluid-
ized bed systems, heterogeneous catalysis, mass transfer, partial combustion, and thermo-
dynamics, and, in the 1960s, research emphasized dispersed phase systems, interfacial phe-
nomena, and reactor engineering. In the 1970s, the research activities of newly recruited
faculty were concentrated in the areas of transport phenomena and electrochemical engi-
neering. Research areas pursued in the 1980s included analysis of energy conversion pro-
cesses, biochemical engineering, colloidal and interfacial phenomena, combustion, enhanced
gas and oil recovery, fluidization and gas/solid flow systems, multi-variable control, pro-
cess dynamics, and biomedical engineering.
In the 1990s, three research centers that exist today at the university were initiated and led
by chemical engineering faculty. They include: the Energy + Power Center, the Center of
Excellence in Polymer Science and Engineering, and the Center for Electrochemical Sci-
ence and Engineering. In addition, in 1995, environmental engineering research became a
major part of the department's research activity as a result of the merger of the environmen-
tal engineering program with chemical engineering. Since 2000, the department has added
two new research centers to its areas of expertise: the Particle Technology and Crystallization
Center and the Center for Complex Systems and Dynamics. Additionally, in 2004, the Institute
for Energy and Sustainability was established as an offshoot of ChEE faculty activities.

OUTSTANDING FACULTY EDUCATORS AND RESEARCHERS
IIT has been fortunate in its history to have had numerous outstanding educators. Profes-
sors Swanson, Peck, Wasan, Arastoopour, and Aderangi were honored as recipients of the
IIT Excellence in Teaching Award. Professors Peck, Swanson and Wasan were also recipi-
ents of the American Society for Engineering Education's (ASEE) Western Electric Fund
award for excellence in teaching.
In the '60s and '70s, the department was privileged to have the services of another out-
standing teacher, Professor William Langdon. In appreciation for his dedication to teaching,
the department's award for teaching excellence was named after him until 2001. At that
time, the teaching award was renamed for Hamid Arastoopour, recipient of both the IIT and
the department's excellence in teaching awards.
Throughout the department's history, the research and teaching contributions of the chemical
engineering faculty have been widely recognized by the American Association of Chemical
Engineers (AIChE) and numerous other professional societies and scientific organizations
S(see sidebar on next page).

Chemical Engineering Education










DYNAMIC AND LOYAL ALUMNI
Many of the department's alumni have achieved success and received widespread recog-
nition for their leadership roles in the chemical enterprise. A number of alumni have served
as the chief executive officers of major corporations and organizations, some of which
include: Martin Marietta (Bernard Gamson), A. Finkl & Sons (William Finkl), Great Lakes
Chemical (John Sachs), Energy Research Corporation (Bernard Baker), UOP (Maynard
"Pete" Venema), Institute of Gas Technology and Gas Research Institute (Henry Linden),
ARCO Chemical (Alan Hirsig), Pabst Brewing Company (Harris Perlstein), and Hyosung
Industries (S.R. Cho).
Several ChE alumni have held national office in the American Institute of Chemical
Engineers (AIChE), including past presidents Dr. James Oldshue and Dr. John Sachs. The
late Professor W. Robert Marshall served as past president of AIChE and was a member of
the National Academy of Engineering. Joining him in the Academy are ChE alumni Henry
Linden, Kenneth Bischoff, David Edwards, and James Oldshue.
Although a majority of our alumni have pursued professional careers in industry, over
the years, a significant number have joined the faculties at IIT and other institutions. IIT
chemical engineering faculty currently include alumni Henry Linden (chemical engineer-
ing) and Hamid Arastoopour, Dimitri Gidaspow, and Javad Abbasian (gas engineering/
gas technology). Today, more than 30 IIT department alumni hold academic positions
in the United States and abroad, with several of them occupying positions of aca-
demic leadership.
IIT alumni have historically been loyal supporters of the endeavors of their alma mater.
The most notable fundraising round to date began on November 21, 1996, when longtime
trustees Robert A. Pritzker and Robert W. Galvin provided a challenge grant to IIT of $125
million. This gift, at the time, represented the largest charitable gift ever promised to an
institution of higher education in Illinois, launched a five-year $250 million fundraising
campaign. In 1997, in response to the Pritzker/Galvin Challenge, the ChEE Department
launched its own highly successful capital campaign. These funds continue to be used to
establish endowed graduate and undergraduate scholarships, endow chaired professorships,
and to enhance departmental educational and research facilities. At the end of the cam-
paign, the market value of all endowments and pledges, including matching funds, stood at
more than $12 million.


WITH GRATITUDE
On the occasion of the Centennial of its founding, the IIT Department of Chemical and
Environmental Engineering acknowledges with thanks the visionary administrators, tal-
ented faculty and exemplary alumni for their contributions to the advancement of the chemi-
cal engineering profession since its very origin.

REFERENCES
1. Annour Institute Yearbook, 1894-95
2. Macauley, Irene, The Heritage of Illinois Institute of Technology
3. Peebles, James Clinton, "A History of Armour Institute of Technology," a manuscript prepared beginning
in 1948
4. Davis, Kevin, "Charles W. Pierce, African-American Pioneer in Chemical Engineering," IIT Magazine,
p. 28 (2004)
5. Kinter, R.C., and D. T. Wasan, "Illinois Tech: Chemical Engineering Department," Chem. Eng. Ed., 5,
p. 108 (1971)
6. Parulekar, Satish, and Darsh Wasan, "The History of Chemical Engineering at Illinois Institute of Technol-
ogy (IIT)," chapter in One Hundred Years of Chemical Engineering. N.A. Peppas (ed.), Kluwer Academic
Publishers, The Netherlands, p. 363 (1989)
*Photographs have been provided with permission of University Archives, Paul V Galvin Library, Illinois
Institute of Technology, Chicago. h


Renowned Faculty Educators
and Researchers

[ Hamid Arasloopour
AIChE Fluor Daniel Lectureship
Award in Fluidization,
Donald Q. Kern Award,
Fludi:ed Processes
Recognition Award.
Ernest W Thiele Aard

l All Cinar
AIChE Thiele Award

[O Dimitri Gidaspow
AIChE Donald Q. Kern A.ward,
Fluor Daniel Lectureship
Award in Fluidizanon,
NSF Special Creativity Award

0I Octave Levensplel
AIChE R. H. Rilhelm Award,
ASEE Chemical Engineering
Dwtision Lecture ship Award

[ Henry Linden
Member of the National
Academy of Engineerng.
Energy Award of the
U.S. Energy Association,
ACS Henry Storch Award,
AIChE Thiele Award.
Lowry Award of the U.S.
Department of Energy

[E Demetrios Moschandreas
Lifetime Achievement Award of
the Internanonal Soceiy for
Exposure Analvsis

[ Kenneth Noll
Ripperton Award of the Nanonal
Air and Waste Management
Association

1 J. Henry Rushton
AlChE William Walker Award

0N J. Robert Selman
Research Award of the Energy
Technology) Division of The
Electrochemical Society

N Darsh Wasan
Member of the National Academ
of Engineering,
ASEE Restern Electric Teaching
and Lectureship Awards,
ACS Colloid or Surface
Chemistry and Langmuir -
Lectureship Awards,
AIChE Thomas Baron and Thiele
Awards.
NSF Special Creativity Award


Winter 2005









S1educator


R. Russell Rhinehart

of Oklahoma State University


message written by the federal government at Fort McHenry has

more than ordinary meaning for Russ Rhinehart. In the War of
1812, when the British Navy attempted to capture the Fort and to
control the Baltimore harbor, Francis Scott Key was aboard a U.S. flag-of-
truce ship as a negotiator for the States. As the 25-hour siege ended, he saw
that "in the dawn's early light, our flag was still there," and, inspired by his
countrymen's bravery, he wrote a poem-the Star-Spangled Banner. Conse-
quently, Fort McHenry is a National Historic Shrine. When the government
posts a sign that says "Stay off [the] Wall" at such a memorial, Russ feels that
people should respect the request. He describes himself as an obedient re-
specter of authority.

We were implementing Internal Model Control on a heat exchanger.
Suddenly Russ asked whether we were ready for a disturbance, ran to
the restroom, and rapidly flushed several toilets, which created a cool-
ing water flowrate disturbance. Fortunately, the controller worked, be-
cause the last thing we wanted to include in the manual was a line which
said, "Please do not flush toilets during experiment."
Hoshang Subawalla, PhD, (MS ChE 1993)
GE Infrastructure
Water and Process Technologies
The Woodlands, TX

Russ was raised in Baltimore, Maryland, and whenever he visited his farm
cousins in Bucks County, Pennsylvania, or his coastal cousins in Point Pleas-
ant Beach, New Jersey, they labeled him as a "Southerner" because he had a
different accent. So although he was raised in an industrial town with Union
allegiance and Yankee heritage, he was perceived as a Southerner within the
family confines. But language and customs were never barriers to his playing
with his Yankee friends, and some of his favorite childhood memories include
making forts from bales of hay in the barn loft, saving a breached calf in birth
one memorable day, crabbing in the coastal rivers, building castles in the At-
lantic sand, and savoring the best submarine sandwiches on earth.
After college, Celanese hired Russ to work in the Carolinas, and without
any overt or intentional changes in accent or style, he suddenly became a
Yankee! The company promoted him through several engineering levels to
supervise engineers, and during his years there he enjoyed teaching gymnas-
tics to children at the YMCA and teaching values to them in Youth Fellow-
ship. The Yankee persona, it seems, did not make him ineffective.
Copyright ChE Division of ASEE 2005


Chemical Engineering Education









The 2-D photo of this 3-D object mimics an isometric drawing: from the front-left view, its projection is a
triangle; from the top view, its projection is a circle; from the front-right view, its projection is
a square. Russ hand-made this peg that fits into square, round, and triangular holes,
as a metaphor for human possibility.


Russ is fond of meta-
phors; he insists a square
peg can fit in a round
hole, and he proceeded
to prove it. Consider a
right circular cylinder
with height equal to di-
ameter. Along the cylin-
der axis, the "peg" will
fit perfectly into a round
hole-and perpendicular
to that axis, it fits perfectly
into a square hole. Shapes, how-
ever, have three orthogonal axes, and
if the projection on the third is a triangle, the unusual appear-
ing "peg" will fit perfectly into a round, a square, and a trian-
gular "whole." He enjoys woodworking and made a multi-
functional peg that sits on the office mantle, with the legend
"You can be effective, even if you are not the expected solu-
tion." He teaches this view of flexibility to his students.

Dr. Rhinehart has a way of making engineering a
philosophical art, and challenges students to look
beyond the numbers and equations for a deeper mean-
ing. His special ability to relate engineering to life,
metaphorically, gives students a fresh and creative
outlook on problem solving, one that better prepares
them for industry and research.
Cassie S. Mitchell, BS ChE 2004
Graduate Student
Georgia Tech

Russ's first summer job after high school taught him a valu-
able life lesson. He was a helper for carpet installers and
quickly learned how to sew invisible seams and cut the re-
verse wall pattern on the back of a folded carpet edge so it
unfolds nicely against a wall. Proud of the technical ability
he had learned, at summer's end he asked his boss for a letter
of recommendation, expecting to be acknowledged for his
expertise and productivity. But instead, he got a very disap-
pointing (to him) three-sentence letter describing him with
phrases that included "loyal," "dependable," and "good with
customers." His Dad saw his disappointment and explained
that quite often, those who are in charge think soft skills are
more important than technical skills.
After years of managing people in both industry and aca-
deme, Russ now concurs with that viewpoint. Technical skill
is important, and he stresses that to his students. But he also
tells them that working in a manner that makes the enterprise


successful is of even greater importance. Team effectiveness
and understanding the context of the engineering work are
really the critical attributes of success.

He made it clear to pursue an all-around devel-
opment, not just focus on school.
Mahesh Iver Ph.D. ChE 1997
Shell Global Solutions (US) Inc.

Russ graduated from Baltimore Polytechnic High School-
due, in part, (he says) to the kindness of three teachers. When
he showed no initiative to progress to the next step, however,
his Dad took matters in hand and gave him an alternative: if
he paid room and board, he could continue to live at home, or
he could go to college and the family would continue to sup-
port him. He chose college. State legislation required the Uni-
versity of Maryland to accept all in-State high school gradu-
ates, so that was his next destination. When asked to choose
a major, however, he was at a loss to pick a subject area, and
since he liked math and science, they eventually categorized
him as "A&S Undecided." Shortly after that, however, he
learned that engineering majors did not have to take a for-
eign language, so he switched to chemical engineering (be-
cause it paid the highest). He made the Dean's list in the first
semester, and now claims that he graduated in the upper 99%
of his class.
Russ ponders an analogy with nature when meeting new
students-he hopes to see larva become butterflies as the year
progresses. Unfortunately, he also sees the opposite, where
the most promising of matriculates do not survive in a col-
lege environment. So his annual welcome letter to new chemi-
cal engineering matriculates warns them that the college en-
vironment and cognitive expectations level the playing field,
and that the "best" from high school should come ready to
play harder than they ever expected, because the dark horses
have a strong chance of overtaking them.
Just as Russ learned that academic credentials from high
school do not predict college performance, he later learned
that academic credentials from college do not predict indus-
try performance. The academic and industrial environments
are so different that fitness in one has little relevance to fit-
ness in the other. This observation is the root of Russ's teach-
ing philosophy that past academic credentials should never
be used to judge the future-what appears as a root in one
environment may provide wonderful fruit in another season.
Life, passion, and a willingness to grow should be the traits
we look for in others.

Dr Rhinehart is graceful and humble, and in spite of


Winter 2005










being the school Head, he was always available to me. He listens hard,
provides support and encouragement, and respects and encourages intel-
lectual independence.
Jing Ou, PhD ChE 2001
Senior Control Engineer
PlugPower


He has been the greatest coach that I have met.
Vikas Shukla, MS ChE 1996
Senior Control Engineer
B. D. Payne Co.

Early in his junior year at college, Russ was actively progressing in gym-
nastic skills, but was beginning to be afraid of physical injury. The fear
made him hold back on the skill. If the "trick" is performed with proper
timing, body position, and use of momentum, it is both safe and awesome
to watch...and to feel. But when protecting yourself from injury, the flip
isn't as high in the air above the bars...it's kept lower, which means there is
less time and space to reach for the bars properly, which, conversely, in-
creases the chance of hurting yourself. Russ found that the fear was causing
him to cut back on the level of difficulty in his routines. By the end of his
junior year, however, he wanted to regain a sense of pride and excitement in
his routines, so made the conscious decision to concentrate on technique
and to ignore fear. The lesson learned: gymnastics is like life, as is every
sport. Understanding and working with the laws of nature, and focusing on
the details of performance, not failure, can be a successful approach to life. He
likes the logo "No Fear," and teaches it, along with the other fundamentals.


He has a talent for using analogies and stories in lectures. One memo-
rable example included showing us a picture of himself doing a hand-
stand on a stack of chairs to illustrate risk management.
Jennie Weber-Fine, BS ChE, 2003


As Editor-in-Chief of ISA Transactions, Russ quickly redefined the aim
and scope, recruited a talented pool of associate editors, established a
strong editorial advisory board, and set forth to recruit the best experts in
the world as article contributors. His success in building the strength of
the journal is reflected by an almost 100% growth in
subscriptions over his tenure. Russ fulfills his obliga-
tions unflaggingly and with verve.
T S. "Chip" Lee, Director
ISA
The Instrumentation, Systems, and Automation
Society

Removing fear requires partially eliminating the
power relationship that separates a professor from his
students. When students feel safe in personally extend-
ing their ideas, if imperfection does not automatically
mean failure, they can be free to do amazing "tricks."


I say, Good morning Dr Rhinehart. He responds,
"Good morning Ms. Krueger." He always wanted to


Russ participated on an exhibition gymnastics
troupe at the U. of MD, 1963-1969, and was
president in 1967. Gymkana shows
traveled throughout the region to
support High School fundraising.


Chemical Engineering Education











1946 January, 19, born, Neptune,
NJ
1963 Graduated, Baltimore
Polytechnic Institute,
Baltimore, MD
1968 BS ChE, University of
Maryland, College Park, MD
1969 MS Nuclear Engr, University
of Maryland, College Park,
MD
1969-73 Process Development
Engineer, Celanese Fibers
Co., Rock Hill, SC
1973-80 Senior Product Development
Engineer, Celanese Fibers
Co., Charlotte, NC
1980-82 Area Supervisor, Technical
Department, Celanese Fibers
Co., Rock Hill, SC
1985 PhD ChE, North Carolina
State University, Raleigh, NC
1985-89 Assistant Professor, Texas
Tech University, Lubbock,
TX
1988 President's Award for
Teaching Excellence, Texas
Tech University
1989-94 Associate Professor, Texas
Tech University, Lubbock,
TX
1991-94 Director, ISAAutomatic
Control Systems Division
1992-.... Member, Editorial Advisory
Board, Control magazine
1994-97 Professor, Texas Tech
University, Lubbock, TX
1995 ISAAutomatic Control
Systems Division, Man-of-
the-Year
1996-97 Graduate Administrator,
Texas Tech University,
Lubbock, TX
1997-.... Bartlett Chair & School
Head, Oklahoma State
University, Stillwater, OK
1998-.... Editor-in-Chief, ISA
Transactions
1999 Established the MS Control
Systems Engineering
program at OSU
2001 Inducted as Fellow to ISA -
the Instrument, Systems, and
Automation society
2002 General Chair, American
Control Conference
2004 Listed in InTECH's 50 most
influential industry
innovators in the past 50
years
2004-.... Treasurer, American
Automatic Control Council


the teacher-student level, and encouraged us to call him Russ or coach.
Katie Krueger BS ChE
December, 2004

Russ feels strongly that lifelong learning is fundamentally important for achieving
success in life. His first industrial assignment was on a fully-automated pilot plant, but
since he had not had any process control courses, he had to learn feedback control and
statistical process control through industrial practice, short courses, and product bulle-
tins. Modeling and decision making are important tools for process management, but he
had not had a course in statistics or optimization, so he learned them as he went along.
Effectively working on teams and managing others is critical in a competitive environ-
ment (whether in business or coaching at the "Y"), so he read self-help books on coach-
ing winning teams and took training courses on personal understanding and interper-
sonal effectiveness. He had to learn the sciences of adhesion, adsorption, and polymers,
and the technologies of pneumatic conveying, drying, and milling. He says that while
nearly everything that he learned in school was useful, perhaps 90% of what he actually
needed had to be learned out of school.
With that thought in mind, Russ strives to prepare students to direct their own educa-
tion and to be able to self-validate what they think they learned. He teaches a computer
programming class where 20% of the credit for each exercise requires the students to
demonstrate validation of their program. Russ says that if the professor always struc-
tures the course, prescribes assignments and tests, and grades the student, then school is
not imparting the critical ability that will enable students to manage their own learning.
Engineers should not be trained to submit work and hope that it is right.

He always tries to create a comfortable learning environmentfor his stu-
dents. Whenever he explains something to a student he makes them feel as if
they already knew what they came to ask about, and the students come out
feeling confident about themselves.
SamirAlam, MS ChE, 2004

Russ supervised a group of engineers in the technical support department of a manu-
facturing plant that hired eight fresh graduates to fill engineering positions. While these
new hires had the intelligence and fundamental base to learn the specific science and
technology for the job, they retained some student-oriented perspectives that prevented
them from being true business participants. So he decided to hold Friday afternoon
"industrialization" sessions to help accelerate their path toward team productivity. Ses-
sion topics included "Doing, bringing to fruition, is valued-not the learning," "People
effectiveness is more important than technical or economic proficiency," "Sufficiency
is a greater value than excellence," and "Work in a parallel, not sequential manner."
Russ says that if a school's intention is to take the high school students and prepare
them to be engineers, then the school needs to teach the aspects that will help them
realize their objective, but then adds that the word "teach" is the wrong word-teaching
is a professor's activity. A school should provide experiences from which students com-
prehend and integrate those viewpoints as their own. Engineering is a "way," an ap-
proach to working, not simply a collection of technical skills or a memorized set of
adages. The "way" must be internalized, not memorized.


In his graduate-level Fluid Dynamics class, he included a personal story from his
first job. They had a "sticky fiber" problem. Russ was keen to impress everybody with
his technical abilities, went off to his office, developed models and analysis, and came
back with a solution a week or two later Meanwhile, the operator solved the problem
by turning the temperature up a notch to dry out the solvent from the polymer fiber This
story, this one nugget that he gave me, has been vital to my success as an engineer and


Winter 2005









a technology leader.
Soundar Ramchandran, PhD ChE, 1994
Group Leader, Solutia.

Russ feels that industrial experience need not be a required
qualification of a professor. He sees no difference in the teach-
ing, research, or service effectiveness of professors who have
had, or have not had, industrial experience, and strongly feels
that success is not predicated on employment history. Ac-
knowledging that the environment and values of industry are
substantially different from those in academe, he says the
difference is not about technical substance and is not related
to the use of profitability indices in making decisions. It is a
difference in the work environment that makes the "way" of
success in one career inappropriate to fitness in the other.
Unless professors understand the difference and include an
industrial perspective in their curriculum, a school's program
cannot fully prepare graduates for fitness of use.
Roughly 5000 BS chemical engineering students graduate
every year in the US, and eventually about 100 of them end
up in academe. Russ feels that it is most important that the
undergraduate experience should focus on preparing the 98%
for successful futures.

Every year Dr. Rhinehart invites professionals from in-
dustry to evaluate our curriculum. Changes are made ac-
cordingly to ensure that we learn the viable tools to be
successful in industry and life.
Myszka (Karina) Paprocki, BE ChE 2003
Graduate Student U of IL

Russ enjoyed his years in industry, but it was not a perfect
fit. He had always been fascinated by the "why" of things
and spent hours at home secretly deriving equations as a way
to understand processes. At home in the late '70s, playing
with his TRS80 color computer (a 32k RAM, no hard drive,
computer connected to the TV), he realized that the games he
was programming in BASIC for his children were more ad-
vanced than the control algorithms that were being used in
industry. That revelation made him decide to explore the pos-
sibility of better methods of automating process management.
Since in his spare time he had also always enjoyed coach-
ing gymnasts, leading youth ministry, and developing engi-
neers from fresh graduates, he felt that the job of being a
professor might be a good place to pursue both human re-
source development and discovery in process management
automation. He returned to school to get his PhD, choosing
North Carolina State University for that endeavor.

When Russ came to N. C. State for his doctorate he joined
a large research group working on a coal gasification pi-
lot plant. We quickly recognized and admired his matu-
rity, wisdom, common sense, and invariable warmth and
cheerfulness, and he may still have been in his first year


when we asked him to take the position of plant supervi-
sor, a position he held until he finished his graduate pro-
gram. His skill as a leader in the deepest sense of the word
was transparently clear Russ also had a strong interest in
teaching then. At his request we put him in charge of a
recitation section of the material and energy balance
course, and almost immediately he became recognized as
one of the strongest teachers in the department. I was
pleased but not surprised at his post-graduation successes
on the faculty at Texas Tech and as department head at
Oklahoma State. Even when I was his doctoral advisor at
N. C. State I viewed him as more of a colleague and friend
than an advisee, and he remains one of my very favorite
people in our profession.
Richard M. Felder, Emeritus
North Carolina State University


"Take your passion, and make it happen" is a line from a
popular song of the '70s that has special meaning for Russ.
He enjoyed working in industry, but has always been glad
that he had the nerve to make his passion a reality and to start
a second career, although it was a difficult decision. Several
co-workers have expressed envy at his flexibility and deter-
mination in breaking out of the situational entrapment of a
comfortable life.

Dr Rhinehart's animated teaching style incorporates
humorous anecdotes that integrate the course material.
Jerimiah Cox, BS ChE 2000
Staff Product Support Engineer
National Instruments

His approach has the students grasp the fundamental
concepts and the more delicate intricacies. In addition,
his enthusiasm engenders students to the material.
Jacob Dearmon, BS ChE, 2000
PhD Candidate, Economics
University of Oklahoma

Russ has retained the industrial values of practicality, which
means that he is not exactly the round peg one expects to find
in academe. While accepting that theoretical analysis and
proofs are important to reveal understanding and limits of a
technique, and while he values the insight and direction they
provide, he feels their idealized nature makes them insuffi-
cient for establishing credibility of a technique in the real
world. Credibility requires experimental demonstration, and
experimental work reveals the problems that need solutions.
So his research program (both synthesis and analysis) has
always been, and continues to be, driven by its experimental
component and "the possible."
Russ enjoyed growing up in the mid-Atlantic of the '50s
and '60s, and in the next two decades he equally enjoyed the
contrasting culture, climate, style, and food that the South
presented to the "Yankee" among them. He also learned from
the contrast and discovered that there are many ways to


Chemical Engineering Education




























achieve an end. For instance, engineers and business leaders
of the South were just as creative, productive, and focused
on winning as their counterparts in the North, but in a hu-
manly gracious style. He was pleasantly surprised to have
unknown perceptions identified and challenged, and to dis-
cover that gentleness could be an essential part of the "Ameri-
can way." Accordingly, upon completion of his PhD, he con-
sidered that another region might provide additional personal
joy and insight, and moved to Lubbock and Texas Tech Uni-
versity. He subsequently enjoyed the many levels of experi-
ences he had there-Tex-Mex food, rodeos, the incredible sun,
and Texas-Friendly.
While he was in Lubbock, Russ married Donna, a Texan
with three sons (so once again, he was the one with the ac-
cent). Planning on staying there forever, they built their ulti-
mate dream house. Russ designed it and Donna decorated it,
and while this is not a recommended exercise for spouses, it
worked for them. Later, the family moved to Stillwater and
placed all their equity into an even grander ultimate house,
which they once again designed and decorated. When a new
family came to town and told their builder about the sort of
house they wanted to build, the contractor responded, "I al-
ready built that house, and the owners just might sell it to
you." The bottom line is that Russ and Donna have now built
four houses in their fifteen years of married life. They have
lived in the present home for over a year now, and friends are
asking, "When's the next one?"

I'm sure that other people will also mention Russ' an-
nual Christmas letter, his creativity always surprises and
delights me.
Lisa Bullard, PhD
Lecturer and Director ofNCSU
Undergraduate Studies

When Oklahoma State University was seeking a new School
of Chemical Engineering Head, Russ was looking for an op-
portunity to contribute on a broader level. The former Heads,


Bob Maddox, Billy Crynes, and Rob Robinson, had created
a very strong program legacy, and he felt honored to be cho-
sen to oversee its continued development.
Russ says it is easy to brag about the program at Okla-
homa State. Some of the accomplishments he is especially
proud of are
For three of the past ten years, a team of OSU
chemical engineering seniors won First Place
overall in the AIChE National Process Design
Contest.
For six years in a row the OSUAIChE Student
Chapter has been honored with an "Outstanding"
rating (top 10%) by the AIChE.
Last year an OSU senior who placedfirst in the
regional paper competition, placed second overall
in the nation.
This year the OSUjuniors won the regional
ChemE-Car contest, and will compete nationally,
as did three OSU teams in the past four years.
For the past ten years OSU chemical engineering
students have sustained a first-time pass rate of
97% on the FE Exam.
Last year two undergraduates were recipients of
Goldwater scholarships, and last year one of the
seniors was selected by USA Today to their All-
USA Academic First Team.
Russ believes that being a professor allows one to make a
substantial contribution to the quality of life through devel-
oping human resources, through developing the knowledge
and tools that can be used throughout a lifetime, and through
developing the infrastructure to support those efforts. He thor-
oughly enjoys helping chemical engineering make that kind
of a contribution in society. O


Winter 2005










SOclassroom


REDUCTION OF DISOLVED OXYGEN

AT A COPPER


ROTATING-DISC ELECTRODE




GARETH KEAR,1 CARLOS PONCE-DE-LEON ALBARRAN, FRANK C. WALSH
University of Southampton, Highfield, Southampton SO17 1BJ, U.K.


Industrial electrochemistry, which concerns the controlled
interconversion of electrical and chemical energy, has a
wide scope. The applications of electrochemistry include
batteries and fuel cells, materials extraction and synthesis,
chemical sensors, pollution control, corrosion monitoring and
the surface finishing of metals."' The discipline of electro-
chemical engineering has been defined as "the understand-
ing and development of practical materials and processes
which involve charge transfer at electrode surfaces.""'2 Elec-
trochemical engineering is the branch of engineering that
embraces electrochemical processes, the means of process-
ing, the resulting products, and the industrial/commercial/
social use of the products.[2,3'
In contrast to the well-established field of chemical engi-
neering, the specialist discipline of electrochemical engineer-
ing is much younger, having evolved over the last forty years
or so, as evidenced by the progressive appearance of texts
and monographs.[4-'10 It is important that undergraduate engi-
neers have a working knowledge of electrochemical engi-
neering principles in order to appreciate the scale and scope
of electrochemistry and its industrial and technological rel-
evance. Electrochemical engineering has all the challenges
of chemical engineering with the added challenge of elec-
trode potential as a controlling influence and current distri-
bution as an essential reaction parameter. A number of edu-
cators have realized the importance of the discipline of elec-
trochemical engineering and have described its introduction
into chemical engineering process laboratory courses."
The literature in the field of chemical sciences education
contains many papers on electrochemistry experiments; for

' University of Queensland, Brisbane, Queensland 4072, Australia


example, some 159 articles have been published in the Jour-
nal of Chemical Education since 1995, with the emphasis
often being on the demonstration of physical aspects of chem-
istry to the early stages of undergraduate courses and to sci-
ence courses in schools. Examples include a slide projector
corrosion cellI121 and the determination of Avogadro's num-
ber by electroplating.II31 There are still, however, relatively
few articles that have been devised for undergraduate engi-
neers in order to demonstrate the principles and practice of
electrochemical engineering in a clear, quantitative fashion.
Examples of education papers in electrochemical technology
include the topics of aluminium-air cells,[l41 proton exchange
membrane fuel cells,"15 reduction of ferricyanide ion at a ro-
tating disc electrode,"161 electrodeposition of copper at a ro-


Gareth Kear obtained both his bachelor degree with honors in Applied
Chemistry (1998) and his PhD in Applied Electrochemistry (2001) at the
University of Portsmouth in the United Kingdom. Gareth is currently a
Materials Scientist at the Building Research Association (BRANZ) Limited
in Wellington, New Zealand. His work directly concerns the continued
development of New Zealand's engineering and construction industries
through research, consulting and technology transfer.
Carlos Ponce de Leon Albarran has a BSc and an MSc in Chemistry
from the Autonomous Metropolitan University, Mexico, and a PhD in Elec-
trochemistry/Electrochemical Engineering from the University of
Southampton (1995). His research interests include electrochemical tech-
niques, metal ion removal, characterization of novel electrode materials,
electrochemical strategies for pollution control, redox flow cells for energy
conversion and electrochemical reactor design.
Frank Walsh holds the degrees of BSc in Applied Chemistry from Ports-
mouth Polytechnic (1975), MSc in Materials Protection following periods
of study at UMIST/Loughborough University (1976), and a PhD on elec-
trodeposition in rotating cylinder electrode reactors from Loughborough
University (1981). He is the author of over 200 papers and three books in
the areas of electrochemistry and electrochemical engineering. Currently,
he is Professor in Electrochemical Engineering at the University of
Southampton and takes a particular interest in the training of students
and industrial engineers in the areas of energy conversion and surface
engineering.


Copyright ChE Division of ASEE 2005


Chemical Engineering Education










We believe that this paper will prove useful to electrochemical engineering and
electrochemistry courses involving the study of corrosion processes, materials science, and
environmental electrochemistry. The level of teaching is relevant to second- or
final-year undergraduates, master degree students, and to the first
year of postgraduate MPhil/PhD research programs.


tating disc electrode,"71 and environmental recycling of ma-
terials.E'81
In the case of metal corrosion, one of the authors has over
25 years experience in dealing with industrial corrosion prob-
lems, many of them being attributable to a poor appreciation
of the principles of metallic corrosion by practicing engineers.
The field of corrosion and protection of metals is well estab-
lished, as evidenced by many texts."9-21] The subject areas of
fluid flow and mass transport, however, are often covered
superficially. The reduction of dissolved oxygen is a key ca-
thodic reaction and hence a major contributor to many cases
of industrial corrosion, and it is essential to consider the ef-
fects of fluid flow and mass transport of dissolved oxygen to
the electrode surface in a systematic and quantitative man-
ner. The chemical education literature contains relatively few
articles on the electrochemistry of oxygen although topics
covered include correlations to describe oxygen transfer from
air to waterl221 and an oxygen sensor for automotive gas
streams.[231
This paper describes a training tool in electrochemical en-
gineering, electrochemical technology, and corrosion. The ap-
proach is in line with the desire for students to "learn by do-
ing"'24' and has been used as part of a "consultant-in-the-class-
room" approach.'25' We believe that the paper will prove use-
ful to electrochemical engineering and electrochemistry
courses involving the study of corrosion processes, materials
science, and environmental electrochemistry. The level of
teaching is relevant to second- or final-year undergraduates,
master degree students, and to the first year of postgraduate
MPhil/PhD research programs. Delegates on short courses
in electrochemical engineering and corrosion have found the
experiment to be informative and successful in explaining
the role of cathodic kinetics in (and mass transport contribu-
tions to) corrosion reactions. Students have appreciated that
a (typically) 90-minute set of experiments can provide quan-
titative data on mass transport rates under controlled fluid-
flow conditions.
The experiment has been used as part of a training pro-
gram for first-year PhD students in electrochemical engineer-
ing and applied electrochemistry at the Universities of Bath,
Portsmouth, Queensland, and Southampton. The material has
been used as a laboratory exercise leading to BSc degrees in
applied chemistry and BSc in environmental sciences (Uni-


versity of Portsmouth) together with BEng and MEng in
chemical engineering and short courses on electrochemical
techniques, pure and applied, for industry (University of
Bath). The technique has also contributed to the study of flow-
enhanced materials degradation via MEng and PhD mechani-
cal engineering research projects at the University of
Queensland. The early training of PhD students in electro-
chemical engineering at the University of Southampton has
also benefited from studies described in this paper.
The reduction of oxygen at a cathode surface'26' is impor-
tant in several areas of technology, including the positive elec-
trode of metal-air batteries,t"4 fuel cells,[27' batteries,t281 and
gas sensors,'291 a competitive reaction during metal ion re-
moval130' and a common cathodic process enabling the corro-
sion of metals."9-21]
In neutral or alkaline electrolytes (as in the present studies
in seawater, at approximately pH 8), oxygen reduction can
be stated as

02 +2H20+4 e- 4 OH- (1)
The electrochemistry of oxygen reduction can be studied us-
ing linear sweep voltammetry at a disc electrode. In this tech-
nique, the electrode potential, E, is controlled (volts, V vs. a
reference electrode) by a potentiostat and swept at a constant
rate between fixed potentials. The current is continuously
monitored during this process and steady-state current vs. po-
tential curves can be recorded on a microcomputer (or an x-y
chart recorder).

DETAILS OF THE EXPERIMENT
The instrumentation and experimental arrangement are
shown in Figure 1 and Figure 2 (next page). All measure-
ments were made at 25 0.2C in air-saturated, filtered sea-
water. (The electrolyte used in this study can readily be re-
placed by the simpler 3.5% NaC1.) An Eco Chemie, Autolab
was used with a PGSTAT20 computer-controlled potentiostat
system with GPES (General Purpose Electrochemical Soft-
ware) version 4.5 coupled to the Pine Instruments Company
(model AFMSRX) analytical rotator. The rotator mechanism
provided better than 1% accuracy over a 50- to 10,000-rpm
speed range. A standard, RDE, three-compartment, electro-
chemical cell was used with a platinum gauze counter elec-
trode, and a Radiometer Analytical A/S, REF 401, saturated


Winter 2005









calomel electrode (SCE) was used in conjunction with a
Luggin-Haber capillary. The cell was fitted with a ther-
mostatically controlled water jacket.
The counter-electrode and working-electrode sections
of the electrochemical cell were separated from each other
with a Nafion" 423 ion-exchange membrane. The inter-
nal, wetted dimensions of the RDE cell were 5.5-cm di-
ameter and 6.0-cm height. From these values, a mean
electrolyte volume of approximately 140 cm3 was used.
Electrolytes were aerated for at least five minutes prior
to the commencement of measurement with a gas dif-
fuser connected to an air pump. In order to establish the
background current, de-aeration was achieved by sparg-
ing with standard oxygen-free nitrogen (supplied by Brit-
ish Oxygen Company) for at least 10 minutes prior to
measurement. Salinity was measured directly with a Profi-
Line LF 197, WTW Measurement Systems, Inc., sali-
nometer and indirectly via conductivity measurements
with the Metler-Toledo MPC 227 conductivity/pH meter.
Kinematic viscosity was measured directly with a B-type
Ostwald U-tube viscometer, and oxygen concentrations
were estimated with a Jenway 3420 dissolved oxygen
meter. All potentials are quoted relative to the saturated
calomel electrode (SCE).
The electrode surfaces were first degreased in ethanol
then wet polished, with a 0.3 itm alumina slurry, on mi-
cro-polishing cloth, followed by three series of 1-minute
polishings on double-distilled water soaked polishing
cloth.
From a health and safety perspective, the electrolyte
has been chosen to provide an inherently safe, low-cost,
aqueous, and room-temperature solution. The use of ro-
tating parts requires appropriate care, and demonstrators
point this out to the student. A low-power rotator is used
and the rotating parts are shielded from the students when
in use.

THE OXYGEN REDUCTION REACTION

A simplified relationship for the complete reduction of
oxygen involves an overall exchange of four electrons,
resulting in the production of hydroxyl ions (or water
molecules at low pH). The complete, four-electron re-
duction of oxygen may occur directly, as in Eq. (1) above,
or indirectly, via two steps each involving two electrons


02 +2 H20 + 2 e- HO +OH


HO +H20 +2e- -- 3 OH- (3)

Hydroxyl ions or water molecules can be products of a
single four-electron step or the result of cumulative two-
electron reduction steps where oxygen is reduced to per-
oxide, which in turn is reduced to hydroxyl ions. The


general scheme describing the reduction mechanism of the reduc-
tion of oxygen is shown in Figure 3.[26,291
Figure 3 shows the steps involved during the reduction of oxy-
gen. First, oxygen has to be transported to the electrode surface-
this process depends on the convection or mass transport, i.e., fluid
velocity or electrode rotation. Once on the electrode surface, the
oxygen molecule reacts to produce hydrogen peroxide and hydroxyl
ions, a step that is controlled by the electron transfer rate. The ki-
netics of oxygen reduction are expected to be very specific to the
''


Figure 1. Arrangement of instrumentation to obtain current vs.
potential (voltammetry) curves at controlled rotation speed of a
disc electrode. WE-working electrode (copper rotating disc elec-
trode: CE-counter electrode (platinum mesh); RE-reference
electrode (saturated calomel electrode).

r


Figure 2. Three-electrode electrochemical cell: (a) saturated
calomel electrode (SCE) reference electrode; (b) air gas blanket
outlet; (c) Pine Instruments MSRX arbor, ACMDII 906C rotator
arm; (d) thermostatic water jacket; (e) copper rotating disc work-
ing electrode; (f) Luggin-Haber capillary; (g) air diffuser; (h) plati-
num gauze counter electode; (i) perpex cell lid; (j) glass flange
containing cation exchange membrane (Nafion 423).


Chemical Engineering Education











system under study, where the character of the substrate, surface
condition, temperature, and electrolyte conditions all have an in-
fluence over each step in the reduction mechanism.126.3'-33 Once
the product is formed, its removal from the electrode surface de-
pends again on mass transport. Delahay performed an early study
dealing with the reduction of dissolved oxygen at copper in chlo-
ride media in 1950.1341 Over the whole range of negative
overpotentials studied in this case, it was determined from polar-
ization curves and oxygen-consumption data that the number of



Bulk solution Electrolyte Cathode

Mass transport
02 (bulk) of reactant 02 (surface)

Charge
transfer of
electrons 4e
from
surface
reactants to
products

Mass transport 40H
40H- ^uik) ut- 40H-l,,c)
of reactant

Electrode surface

Figure 3. The stages of oxygen reduction consisting of mass trans-
port to and from the electrode surface and electron transfer reac-
tion.


electrons consumed was predominantly four. Although
hydrogen peroxide was always formed, catalytic decom-
position of hydrogen peroxide was found to prevent the
build up of the intermediate reduction product.

RESULTS AND DISCUSSION
The experiments described in this paper have a num-
ber of learning outcomes, which are summarized in Table
1. The impact of the experiment on parts of a BEng/MEng
chemical engineering curriculum can be illustrated by the
following examples: (a) mass transport rates and dimen-
sionless group correlations (year 1 or 2), (b) process in-
tensification due to agitation (year 3), (c) fluid flow
around rotating systems (year 1), (d) corrosion and ma-
terials degradation (years 1 to 3), (e) electrochemical
engineering techniques (a year 2 option), and (h) physi-
cal transport phenomena (year 1).
Application of the rotating disc electrode, RDE, to elec-
trochemical systems is a well-established'31-33'361 method
of quantitatively controlling the fluid flow and mass trans-
port conditions. The use of ferricyanide ion reduction or
copper deposition have been well rehearsed in the litera-
ture but we have preferred in teaching experiments to
use the reduction of dissolved oxygen, which (a) is rel-
evant to corrosion and a wide range of other electrochemi-
cal technologies, (b) involves no significant phase
changes on the electrode surface, (c) provides a simple
reactant at a controlled level, (d) facilitates the use of an
inexpensive RDE material, and (e) shows regions of po-
tential where the reaction is under charge-, mixed- or
mass-transport control.


TABLE 1
Learning Outcomes of the Experiments


TOPIC


Instrumentation for electrochemistry


LEARNING OUTCOME
Appreciate the typical equipment used to obtain current vs.
potential curves at a controlled rotation speed of the disc electrode.


EVIDENCED BY...
Student's ability to describe the properties of the
instruments and electrochemical cell (in Figure 1).


Three-electrode electrochemical cells Understand the need for three electrodes. Student's ability to define the three electrodes used in
the study (i.e., working reference and counter
electrodes in Figure 2).
Fluid flow and its control Appreciate that the rotating disc electrode provides effective Student's knowledge that the fluid flow is laminar as
control of fluid flow. long as the disc surface is hydrodynamically smooth
and the rotation speed is within appropriate limits.
Mechanism of oxygen reduction Know the steps involved in transport of oxygen to the electrode Appreciation of the charge transfer and mass transport
surface followed by its reduction, steps involved (Figure 3).
Electrochemical voltammetry Understand the equipment needs for electrochemical voltammetry. Obtaining correct current vs. potential curves (Fig. 4).
Types of rate control Appreciate the different types of rate control, namely, charge The shape of the current vs. potential curves at a fixed
transfer, mass transport, and mixed control, rotation speed indicates the potential regions for
various types of rate control (Figure 4).


The rotating disc electrode


Understand the relationship between fluid flow and mass transport
rates.


Measurement of limiting current vs. potential for a
series of rotation speeds and the application of the
Levich equation (Figure 5).


Winter 2005










Figure 4 shows a family of current vs. potential curves
for oxygen reduction at the copper RDE. The potential
has been linearly increased, with time, from the open-
circuit potential to a value of approximately -1.4 V vs.
SCE, at a rate of 0.5 mV s-', while the current is con-
tinuously monitored. The linear sweep voltammetry in
Figure 4 shows a single wave for oxygen reduction,
which indicates an overall 4-electron exchange for this
system. The curves can be divided into the following
regions:
(a) At low overpotentials, the current rises exponen-
tially with potential and the reaction is under "com-
plete charge transfer control," i.e., the reaction rate is
governed by the speed of electron transfer from the
cathode to the oxygen adsorbed at the electrode sur-
face.
(b) At more negative potentials, the current increases
with potential; the current is affected both by potential
and by the speed of the rotating disc electrode. This is
the "mixed control" region.
(c) Further increase of potential reaches a region
where the current is approximately constant. This is the
limiting current (I1) plateau where the oxygen reduc-
tion is under "complete mass-transport control." The
rate-determining factor is the speed at which the reac-
tant (dissolved oxygen) can reach the cathode surface.
Under complete mass-transport control, the reaction is
very flow-dependent. Increasing the relative velocity
between the cathode and the electrolyte (i.e., agitation
of the solution) will increase the rate of mass transport
and, hence, IL will increase. (Students are encouraged
to consider alternative methods of agitation, such as
impeller stirring, pumped flow and the use of jets or
turbulence promoters together with their practicality).
(d) When the potential is made more negative, a sec-
ondary cathode reaction, hydrogen evolution takes place
in addition to the oxygen reduction

2H20+2e-- H2+20H- (4)

The entire oxygen-reduction curve can be analyzed
(considering charge-, mixed- and mass-transport con-
trol) using a Koutecky-Levich approach.131-33] Here, we
focus complete mass-transport control on the limiting-
current region. The limiting current depends on several
factors, including the bulk concentration of dissolved
oxygen, cb, the active area of the electrode A, and the
averaged mass transport coefficient km

IL = kmAzFcb (5)

where z is the number of electrons transferred per oxy-
gen molecule (= 4) and F is the Faraday constant (96 485
C mol '). The mass transport coefficient can be consid-


0.1
-- Mean background
0.0 0





-2
S( (a)



-0.3
4 1. -3 -

-0.4
I -4 0

-0.5 (d)

-5
-0.6
-1.6 -1.4 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2
Potential vs. SCE /V


Figure 4. Cathodic polarization curves for oxygen reduction at a
copper RDE in aerated seawater at 25C. Potential sweep rate-0.5
mV s- ; increasing order of rotation rates-21,42, 84, 126, 188, 251,
366, 503, 681, and 995 rad s-'. (a) electron transfer control, (b) mixed
control, (c) mass transport control, and (d) secondary reaction (hy-
drogen evolution). The broken lines show the region of mass trans-
port and the vertical lines show the points at which the limiting
current was measured in each current-potential curve. The mean
background current was measured in de-aerated electrolytes.


0.30
2.5

0.25
2.0 E

E 0.20 E

1.5
S0.15 c

C 1.0
S0.10
0

0.05 0.5
/
/
/
0.00 0.0
0 5 10 15 20 25 30 35
(Rotation rate, (o / rad s'1)05

Figure 5. Limiting current vs. angular rotation velocity (Levich) plot
for oxygen reduction at a copper RDE in seawater at 25 C. Limiting
current values were taken from the cross of the vertical lines and
the current potential curves in the plateaux of Figure 4.


Chemical Engineering Education









ered as a rate constant that is normalized with respect to dis-
solved oxygen concentration and cathode area. (Students are
encouraged to consider appropriate ways of measuring the
disc area and the accuracies involved; e.g., the assumption of
a circular area versus direct measurement using an optical
microscope.)
In this experiment, the electrode area is kept constant by
using the polished, flat surface of a fixed radius, r (0.19 cm)
rotating disc (A = rrr2 = 0.113 cm2) of pure copper. The bulk
concentration of oxygen is held constant by continuous sur-
face aeration of the seawater electrolyte to achieve a satu-
rated concentration (cb = 2.63 x 107 mol cm-3) at 250C.1351 In
other cases of electrode reactions, the bulk concentration of
reactant may be varied by volumetric preparation.
For a fixed electrode geometry and constant electrolyte
conditions, the mass transport coefficient is dependent on the
relative velocity, U, between the electrode and the electro-
lytellt0ol

km aUx (6)

The rotating disc electrode (RDE) enables the electrolyte
velocity towards the electrode to be carefully controlled un-
der conditions of highly reproducible laminar fluid flow. For
a polished RDE, the velocity exponent is very consistent be-
tween experimental systems, where x = 0.5. In this case, Eqs.
(5) and (6) can be combined to give

IL -c 00.5 (7)
Here, the rotation speed, o is in units of radians per second.
Conversion of rotation rate of the RDE in rpm to angular
velocity in rad s-' can be achieved by

rad s- rev min-1)(2 rad rev-1)
60 s min-1 (8)

The influence of the physical properties of the fluid on mass
transport were established by Levich,[361 who confirmed that,
for the smooth RDE, the limiting current, IL will vary to the
square root of the rotation rate

IL = 0.62 zFAD0-666v-0166Cb 00.5 (9)
where v is the kinematic viscosity of the electrolyte and D is
the diffusion coefficient of oxygen (sometimes called the dif-
fusivity, in the older literature). Under conditions of com-
plete mass transport control and for constant z, A, v and cb,
the Levich equation simplifies to

IL = Ko0.5 (10)
and a Levich plot of the limiting current vs. the square root of
rotation rate of the RDE should be linear and through the
origin with a gradient, K, where
K = 0.62 zFAD0.666v-0.166 Cb (11)


Electrochemical engineering
has all the challenges of chemical
engineering with the added challenge of
electrode potential as a controlling
influence and current distribution
as an essential reaction
parameter.


From the slope K, the diffusion coefficient D, can be calcu-
lated via a rearrangement of Eq. (11) to give

DO.666 IKI (12)
0.62 z F Av .166 Cb

From Eq. (12), the diffusion coefficient of dissolved oxygen
is given by

K K3
D= IK (13)
0.62 z F Av -0.166 Cb

The experimental program had three objectives
To characterize the oxygen reduction reaction and to
define the electrode potential ranges for kinetic
(charge transfer) control, mixed control, mass-
transport control and the side reaction.
> To show the relationship betweenflow conditions
and mass transport and, hence, the dependence of
reaction rate on rotation speed of the disc electrode.
To determine the diffusion coefficient for dissolved
0, under controlled conditions of temperature and
saturated concentration of dissolved 02.
As predicted by the Levich equation (Eq. 9), the limiting
current of each member of the family of current vs. potential
curves showed in Figure 4 depends on the mass transport
conditions, i.e., the rate of rotation of the electrode. The lim-
iting current at each rotation rate can be obtained by subtrac-
tion of the background current (dotted line), i.e., the current
of the electrolyte with no oxygen dissolved. Figure 5 shows
the plot of the limiting current vs. the square root of angular
velocity of the rotation disc electrode, according to Eqs. (9)
and (10). The linear plot passed through the origin according
to the theory and demonstrated that the reduction of oxygen
at the limiting current is proportional to the square root of the
angular velocity. Limiting current densities of approximately
-0.32 to -2.38 mA cm2 were measured for square root angu-
lar velocities of 4.6 to 31.6 rads0 s-05. The mean diffusion
coefficient was calculated as (1.5 0.2) x 105 cm2 s-'. The
data indicates that, under full mass transport control, the ex-
change of four electrons controls the rate of oxygen reduc-
tion (the reduction of a hydrogen peroxide intermediate was
not observed during oxygen reduction in these experiments).


Winter 2005









SPECIMEN CALCULATION OF D0 USING EQ. (13)


3
9.399 x 10-6 A rad0.5 s.5

)(4)(96485 C mol-' )(0.113 cm3 )(9.33 x 10-3 cm 2s- 0.1662.625 x 10- mol cm-3


Do = (6.08ox -4)3 =(1.5 0.2)x10-5 cm2s-1 at 25+0.1C


Using an experimentally derived value of K, the experi-
mentally determined diffusion coefficient for oxygen in fil-
tered seawater compares favorably with literature values ob-
tained at copper of 1.4 x 10-5 cm2 s-1 at 200C in 0.5 mol dm-3
NaC1,134] 1.7 x 10-5 cm2 s-1 at 230C in 1 mol dm3 NaC1,137' and
1.8 x 10-5 cm2 s- at 23C in 1 mol dm-3 NaCl.'3839' The experi-
ments can be extended to rationalize the rate of corrosion of
copper in chloride electrolytes under mass-transport controlled
conditions, the analysis of the mixed control region of cur-
rent vs. potential curves using a Koutecky-Levich approach,
and the use of a rotating cylinder electrode to study oxygen
reduction under turbulent flow conditions.1401

CONCLUSIONS
Technical achievements

1. The experimental current potential curves in Figure
4 showed various zones: (a) the charge transfer
zone between -0.3 and -0.5 V vs. SCE where the
current is independent of the rotation rate, (b) the
mixed zone where the rotation rate partially
influences the current values, (c) the mass transport
zone where the current depends completely on the
rotation rate and the charge transfer was fast, and
(d) the secondary reaction zone where hydrogen
evolution occurs together with the desired reaction.
2. Linear sweep voltammetry was used to obtain
qualitative data, such as the limiting current for the
reduction of oxygen on a copper electrode surface
as a function of rotation speed and the diffusion
coefficient of oxygen. A single, 4-electron wave for
the reduction of oxygen on a rotating disc copper
electrode was observed and under full mass
transport control.
3. The rotating disc electrode (RDE) technique
allowed the reduction of oxygen to be studied under
controlled conditions of laminar fluid flow.
4. The mass transport coefficient, k, was proportional
to the square root of the rotation rate of the disc
electrode, w)", under the experimental conditions
5. A linear, Levich plot oflL vs. ow1 allowed the


diffusion coefficient, D, of oxygen, in air saturated
seawater to be calculated as 1.5 x 10' cm2 s-1 at 25
"C in good agreement with literature values.

Educational experience
The specific learning outcomes of the experiments together
with their relevant subject areas are summarized in Table I.
The subject areas concerned include instrumentation and cells
for voltammetric techniques in electrochemistry, fluid flow
and its control, the mechanism of oxygen reduction, types of
rate control, and appreciation of mass transport control using
a rotating electrode.

ACKNOWLEDGMENTS
Early tutorial studies on oxygen reduction at rotating disc
electrodes were carried out in the Applied Electrochemistry
Group at the University of Portsmouth, UK. G. Kear and EC.
Walsh are grateful to Dr B. Des Barker (University of Ports-
mouth) for early tutoring in electrochemical corrosion.

NOMENCLATURE
Meaning [UnitsI
A active RDE area (A = 0.113 cm2) [cm2]
c, bulk oxygen concentration (c = 2.63 x 107 mol cm3) [mol
cm-3]
d electrode diameter [cm]
D diffusion coefficient of dissolved oxygen [cm2 s ]
F Faraday constant (F = 96 485)[A s mol']
IL limiting current [A]
j current density [A cm-2]
km mass transport coefficient [cm s']
K proportionality constant in Levich equation
(K = 9.40 x 10-6) [A rad-o's05]
r radius of rotating disc electrode [cm]
U velocity of rotating disc electrode [cm s']
z number of electrons transferred (z = 4) dimensionlesss]
v cinematic viscosity of electrolyte
(v...waer = 9.33 x 10-3cm2s- at 25'C and a salinity of
3.5% wt[371) [cm's-']
t angular velocity of the rotating disc electrode [rad s-']


Chemical Engineering Education











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153 79 (1983)
30. Reade, G.W., and F.C. Walsh, in Environmentally Oriented Elec-
trochemistry, C.A.C. Sequeira, (ed.), Elsevier, 3

Winter 2005


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Faculty Openings: Tenure-Track and Lecturer
Department of Chemical and Biomolecular Engineering
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lecular Engineering seeks outstanding applicants for both tenure-track
faculty and lecturer positions at all levels. Candidates who hold a doc-
torate in chemical engineering or a related field should apply.
Tenure-track positions: Applicants in all areas of chemical and biomo-
lecular engineering including colloids and surface sciences, bioengi-
neering, nanotechnology, and materials will be considered. Applicants
should send (preferred) or e-mail a resume, statement of research plan,
and names of at least three references to the Chair at the address listed
below.
Lecturer positions: Several non-tenure track Lecturer positions will be
available for candidates interested in teaching undergraduates. Appli-
cants should send a resume, statement of teaching plan, and three refer-
ences to the Chair at the address listed below.
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Department of Chemical and Biomolecular Engineering
Johns Hopkins University
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Baltimore MD 21218.
Telephone: (410) 516-7170; e-mail: mclancy2@ihu.edu.
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31. Pletcher. D., A First Course in Electrode Processes, Romsey,
The Electrochemical Consultancy, Romsey (1991)
32. Bard, A.J.. and L.R. Faulker, Electrochemical Methods, 2nd ed.,
John Wiley & Sons, New York, NY (2000)
33. Greef, R., R. Peat, L.M. Peter, D. Pletcher, and M.J. Robinson,
Instrumental Methods in Electrochemistry, Ellis Horwood Ltd.,
Chichester, England (1985)
34. Delahay, P., J. Electrochem. Soc., 97, 205 (1950)
35. Whitfield, M., and D. Jagner, (Eds), Marine Electrochemistry: A
Practical Introduction, J. Wiley and Sons, New York, NY (1982)
36. Levich, V.G., Physicochemical Hydrodynamics, Prentice-Hall:
Englewood Cliffs, NJ (1962)
37. Radford. G.W.J., F.C. Walsh, J.R. Smith, C.D.S. Tuck, and S.A.
Campbell, "Electrochemical and Atomic Force Microscopy Stud-
ies of a Copper Nickel Alloy in Sulphide-Contaminated Sodium
Chloride Solutions," in: S.A. Campbell, N. Campbell and F.C.
Walsh, (Eds), Developments in Marine Corrosion, The Royal
Society of Chemistry, Cambridge, U.K., 41 (1998)
38. King, F., C.D. Litke, M.J. Quin and D.M. LeNeveu, Corrosion
Sci., 37, 833 (1995)
39. King, F., M.J. Quin, and C.D. Litke, J. Electroanal. Chem., 385,
45 (1995)
40. Kear, G., B.D. Barker and F.C. Walsh, Corrosion Sci., 46, 109
(2004) 0









[ W -class and home problems


AN OPEN-ENDED

MASS BALANCE PROBLEM


JOAQUIN RUIZ
University of Zaragoza E50009 Zaragoza SPAIN
Mass balances, together with energy and momen-
tum balances, are the basis for understanding al-
most any problem in chemical engineering. When
undergraduate students have a clear understanding of these
kinds of problems, they are halfway to success in attaining
their chemical engineering degree.
A logical way to teach mass balances is to start with the
simplest situation (steady state, few streams, no chemical re-
action) and to gradually increase the difficulty of the situa-
tions, giving examples and asking the students to solve them.
Most of these problems are closed, with just one possible
solution, so getting the right answer is often mechanical.
In my first year, I noticed that when I was giving a lecture,
many students spent the time simply copying information
from the blackboard, instead of thinking about the strategy
for solving the problem. I also found that some students had
difficulty with unsteady-state situations. As a result, I became
interested in making my lessons more practical and closer to
reality, as well as more user-friendly. To answer this need for
practicality, I devised the following open-ended problem as
an additional task that could be useful not only for encour-
aging students to analyze a real-life situation, but also for
discussing different approaches suggested by the students
themselves.

BACKGROUND
Fresh water is a key factor for progress and a valuable re-
source in arid or semi-arid regions, which is the case in most
parts of Spain. To address this situation, in July 2001, a hy-


drological plan for national water management was approved
by the Spanish government. One of the most controversial
parts of this plan was to take water from the Ebro river in the
north of Spain and redirect it to the Mediterranean regions in
the south and east (up to 1050 Hm3 each year). The water
would be used to promote development in those areas by cre-
ating new agricultural land and developing tourism on the
Mediterranean coast (hotels, aquatic parks, golf courses, etc.).
Everyone in the country has an opinion about this plan.
Most people in the receiving region are in favor of it because
it signals progress and economic development. Ecologists,
however, feel that it will contribute to destruction of the coastal
areas through unlimited building of hotels and apartments.
They also fear that the expectation of vast quantities of water
will encourage the cultivation and resulting destruction of
virgin land.
People from donor regions in the north do not generally
agree with redirecting water to other areas, arguing that they


Copyright ChE Division of ASEE 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.
<__________________________________________


Joaquin Ruiz received his PhD in 1997at the
University of Zaragoza, where he is currently
an Assistant Professor teaching chemical en-
gineering fundamentals. He has worked in en-
vironmental protection in regional administra-
tion. His research is focused on soil remedia-
tion and renewable energy resources.









need the water for their own industrial and agricultural de-
velopment. In addition to these economic concerns, ecolo-
gists point out that taking away such a vast amount of water
from the Ebro river could have a disastrous ecological effect
on the mouth of the river. To compound the problem, some
farmers agree with the plan because it would involve con-
struction of new reservoirs that would solve their watering
needs during the summer dry period-but people living in
the mountains, where the reservoirs would
be constructed, are not happy with the plan.
So, there are many different points of view,
often diametrically opposed. The media This pap
often fuels the controversy, criticizing or an open-ei
supporting the hydrological plan depend- that cai
ing on regional interests. adapted
local coj
PROBLEM STATEMENT The p
The University of Zaragoza is located in beneficial
a donor region. In February, 2001, a local in ma
newspaper began publishing articles with it can
dramatic headlines such as "drought men- balance
ace set to create critical situation for agri- realis
culture," "reservoirs at their lowest level for facil.
ten years," "serious concern about the situ- assim
ation," etc. Similar news stories have ap- conceal
peared in the past, but they appeared dur- instead
ing the summer, not the winter. it can h
I read the articles and analyzed the num- careful
bers given to support this "critical limit situ- informant
ation." Reservoirs that were at 82% capac- by daij
ity last year were only at 58% this year in rad
the same month. The article went on to say
that the situation would be even worse (only newspaj
38% capacity) if two of the reservoirs were
taken out of the calculation (curiously, the
two largest).
To emphasize this situation, the newspaper pointed out that
the Yesa reservoir (470 Hm3 total capacity) contained only
73 Hm3 of water, i.e., 17% of its capacity. This reservoir is in
a secondary river of the Ebro and is one of the most contro-
versial parts of the hydrological plan. The proposal is to in-
crease its capacity from 470 Hm3 to 1000 Hm3 in order to
guarantee the agricultural water requirements within its area
of influence. Some people fear, however, that such a large
amount of water will simply guarantee diversion of the water
to the south and east regions of Spain. The plan would also
mean flooding some villages. One journalist stated that 700
Hm3 of water was required to meet agricultural demands, but
there were only 80 Hm3 available, of which a mere 30 Hm3
was available for agricultural use, because 10 Hm3 was re-
quired for domestic water supply and 40 Hm3 (10% of the
total capacity) was considered "dead water" that could not
be used (presumably for ecological reasons, to preserve
Winter 2005


er [
nde
n e
d t
ndii
rob
l to
ny
nak
class
tic,
itat
ilat
its s
y st
elp
lyC
ion
tel
io,
per


fauna). The newspaper also argued that depending on water
from early-spring thawing was not a solution since that source
is not reliable.
I showed this information to my students, stressing the need
to carefully evaluate numerical data, especially when pre-
sented by nontechnical people. Often the media will misun-
derstand or erroneously report such data, i.e., the journalist
in this case who confused cubic meters and cubic hectome-
ters. I went on to explain that the problem
was not how much water currently existed
resents] in the reservoirs, but how much we would
Spree ] need in the future. In February, a 58% ca-
d problem pacity did not seem so bad since additional
isily be water would likely come from spring rains.
o many Although there could be shortages in some
tions . reservoirs, such as Yesa, it was likely that
lem is the spring rain and melting snow would
students provide enough additional water.
ways: We cannot simply compare one year with
:e mass another and conclude that there is a prob-
;ses more lem. The prior year, for example, could
it can have been an exceptionally rainy year. Even
e the in a dry year, alternatives can be designed
ion of to reduce water consumption that will help
uch as prevent problems.
ate, and I asked students if they thought this situ-
students ation was as critical as the media wanted
analyze us to believe. I posed this concept as the
pro d statement of the problem, but provided no
provided .additional information. It would be their job
vision to analyze the problem, to find sources of
and information, and to make assumptions.
reports. While their solutions could, depending on
the results, be used to support or reject the
hydrological plan or the construction of
new reservoirs, this was not the main goal of the exercise.

PROPOSED SOLUTIONS TO THE PROBLEM
The problem statement was challenging to the students, who
were a bit confused-they did not know how to start. They
had not quite grasped the meaning of the problem. I provided
some help by stating that a way to solve the problem could
be to
First, define a "critical situation "-for example,
reaching 10% water capacity, which would mean a
"dead" reservoir, or 0% water capacity, or would
there be enough water to supply the population for a
limited period of time or would there be enough
water for agricultural, etc. ?
Second, predict if this "critical situation" could be
reached in the future.
In the first part, the point selected is a result of personal









choice and reasons for or against it can be given. The second
part, however, is a quantitative prediction which may or not
be valid, depending on how the prediction is made.
There are two approaches to the problem

Consider a general case of total water reserves
Consider the evolution of a particular reservoir such
as Yesa, since the first approach does not consider
the water levels of a reservoir that are far below the
average of the whole river.
The problem can be solved by an unsteady-state mass bal-
ance, i.e.
Accumulation = Final water Initial water
= Inputs-Outputs
or
A=V(t)-Vo =I- (1)

Water accumulation in reservoirs is the difference between
inputs and outputs. Outputs are defined as water designated
for agriculture, industry, and domestic use as well as water
that is returned to the river (thus guaranteeing ecological flow).
As long as we can quantify initial water reserves, ( V ), in-
puts (I*), and outputs (O*), over a future period of time, we
can predict the final water reserves at the end of that period,
V*(t), by applying Eq. (1) (in which the asterisk refers to fu-
ture values).


INSTRUCTOR'S SOLUTION #1

All Reservoirs in the Ebro
Data pertaining to the current situation, i.e., water accu-
mulated in reservoirs, allows us to control or regulate out-
puts so we can manage water for different needs. We cannot,
however, control global inputs, i.e., water that comes from
rain and snow. How we quantify the inputs and outputs of
accumulated water will be predicted differently in the future.
The whole system of the reservoirs, the main river, and the
secondary rivers are represented in Figure 1.
One of the main sources of data about the Ebro river is the
official organization "Confederaci6n Hidrografica del Ebro"
(CHE). Historical data can be found at the organization's web
site . Information such as average
consumption, current relation to the river as a whole, and
specifics about each reservoir can be found here.
Part of the site information involves the evolution of water
reserves, which is presented by comparing the current year's
evolution with that of the previous year, along with average
evolution over the past five years. A prediction of final water
at the end of a period of time (t) could be made (considering
the initial situation, with reservoirs at 58% capacity, and know-
ing inputs and outputs) by simply applying Eq. (1). Although
there is no data for individual inputs and outputs, we can
assume that inputs (I*) and outputs (O*) in the future will be
the average of those of previous years (I and O). This simpli-


fies the problem since all we need to know is the difference
between the two-that is, the difference between the final
and the initial accumulated water over several weeks. This
can be expressed mathematically by


Mass balance in the future (Eq. 1):
Mass balance in the past during
the equivalent period of time
(average last five years) (Eq. 1):
Assumption:


V*(t) V0 = I* *


I-O = V(t)-V,
I*=I and O*=0


Combining mass balances with our assumptions, we get

V (t)=V0 +[V(t)-Vo] (2)

The average difference can be used to calculate the final
water situation every week over a whole year by using Eq.
(2), i.e. the evolution of water reserves. Such results can pre-
dict if a critical situation, for instance 10% of total capacity,
will be reached. The results are shown in Figure 2.

SECONDARY SECONDARY
RIVER RIVER


Reserve" Reservor



SReservoir sea









Figure 1. Schematic representation ofEbro's basin.
EBROOD





6000




Hm53000
Figure 2. Predicted and real evolution of water
Real eolutioesevesn 2002 the year 2002 as
4000t -A-'


H,, ,A 3
Predston to, yea, 2002 o n glderig A *
the verge of last 5 yea, s
2000


1000


12-25-01 02.13-02 04-402 05-24-02 07-13-02 09-1-02 10-21-02 12-10-02


Figure 2. Predicted and real evolution of water
reserves in the year 2002.


Chemical Engineering Education










The water accumulated in the reservoirs is far from drop-
ping to 650 Hm3, which would be 10% of the total capacity
(6504 Hm3). The minimum capacity, during February through
October, was approximately 2500 Hm3 (38% of total ca-
pacity.) We can therefore conclude that the situation is
not really critical, or at least, not as much as the media
want us to believe.

In order to accurately support this prediction, real quanti-
ties of water, collected during 2002, are presented in Figure
2, but show a better situation than predicted. This strengthens
the argument that the situation, in February 2002, is not critical.

A more conservative approach is shown in Eq. (3) which
illustrates modification by including a coefficient (ac
V*(t)= V + a[V(t)-Vo] (3)


300







Real evolution of 2002 *
150 A


100 ,
Ao '
100


Prediction wth same inputs and
outputs of year 2001

12/25/01 02/13/02 04/4/02 05/24/02 07/13/02 09/1/02 10/21/02

Figure 3. Predicted and real evolution of water reserves
for Yesa reservoir in the year 2002 without
regulation of outputs.


500
450
400
Prediction ath
m ,'100% of inputs of 2001
350'
300 /
3 Prediction with only 80 %.0
: 250 of the inputs of year 2001
HmO 250
200
,I A Real evolution of 2002



50

12/25/01 02/13/02 0/4/02 05/24/02 07/13/02 09/1/02 10/21/02 121/02

Figure 4. Predicted and real evolution of water
reserves for Yesa reservoir in the year 2002
with regulation of outputs.

Winter 2005


INSTRUCTOR'S SOLUTION #2

Yesa Reservoir Only

A main criticism of the first approach is the lack of consid-
eration for specific situations of reservoirs where the water
levels are far below the 58% average of the whole river. To
increase the accuracy of this approach, it is necessary to ana-
lyze individual cases such as the Yesa reservoir which was
only at 17% capacity (82 Hm3).

The same approach can be made (considering inputs and
outputs) to predict the evolution of accumulated water in the
future. Data from the previous five years was difficult to ob-
tain, so we substituted it with data from 2001. By applying
Eq. (2) to this data we get the result shown in Figure 3, where
the real evolution of water reserves has been plotted.

At the beginning of 2001, the Yesa reservoir was almost
full. Considering that it was a rainy year and that no water
was accumulated during the following winter and spring (of
2002), we see that the outputs almost equal the inputs, giving
the results shown in Figure 3. This result is unrealistic be-
cause it does not take into consideration the regulation of
outputs, which is the only option that can be taken when ex-
tremely low water reserves (as they were at the beginning of
2002) verge on becoming dead reservoirs.

A different approach to consider involves the regulation of
outputs. First, we can assume that 2001 and 2002 inputs will
be the same. Second, we can also assume that outputs will
remain at 5 Hm3/week, the minimum, until April when agri-
cultural demand for water increases. We arrive at the 5 Hm3/
week minimum by deducing that outputs rarely drop lower
according to historical data. Third, we assume that outputs
from the current year and the previous year are the same from
April

Assumptions: I* = I
O* = 5 Hm3/week until April
O* = O from April

Taking all these assumptions into account, the results ob-
tained through Eq. (1) are shown in Figure 4, as well as the
real evolution of water reserves. The main inconvenience of
using input data from 2001 is that it was a rainy year and the
inputs could be overestimated. A more reliable prediction
could be made by reducing inputs-for example, only 80%
of the inputs from 2001 will be achieved in the year 2002.
The choice of 80% is arbitrary; any other amount could be
chosen. These results can also be seen in Figure 4.
The predicted evolution is quite different depending on the
assumed inputs (100% or 80% of the year 2001.) In the first
case, accumulated water levels do not fall below the initial
17% level (73 Hm3); it always exceeds 100 Hm3 (21%) even
at the end of the summer dry period, which is well over the
critical minimum of 47 Hm3 (10%). In the second case, how-
ever, accumulated water descends to the 10% level by the










end of August, and reaches zero in September. A minimum
decline in water inputs, with respect to the previous year, can
therefore lead to a critical situation if outputs are not regu-
lated and restricted.
The fact is, 2002 was not as rainy as 2001. Inputs were
down, which led to water restrictions and tighter regulation
of water outputs for agriculture. This resulted in a more ra-
tional usage of the limited water resources by implementing
better efficiency of watering techniques or lowering the de-
mand for growth. No indications have been reported by local
media about catastrophic damage to agriculture or signifi-
cantly lowered production as compared to previous years.
We can thus conclude that a largely available resource can be
used up inefficiently, even if it is as valuable as fresh water.


STUDENTS' SOLUTIONS

The proposed solutions here represent just one approach to
the problem; there are several different approaches that could
be made. Apart from merely qualitative solutions or simple
compilations of past data without predictions, various solu-
tions were proposed by the students, which are summarized
as follows:


Final Amount
of Water in
Reservoirs:


A = 7073 10885 = -3812 Hm3/year


4486 + (-3812) = 674 Hm3/year


Despite a negative accumulation term, at the end of the year there
was water in the reservoirs. In conclusion, with 58.8% capacity,
there was no critical limit situation.

Instructor's Comments The assumption that the flow in the
mainstream of the Ebro river is the average of the average
flows measured at different points in the mainstream involves
at least two mistakes. If the average is made upstream and
downstream of a reservoir, we are failing to take into account
water that is taken out of the river for consumption, as can be
seen in Figure 5.
Measured average flow is (1000 + 100) / 2 = 550 Hm3/
year, while in fact it is 1000 Hm3/year.
In addition to this effect, not all the water from secondary
rivers goes into the main river (Ebro), since part of it could
be used for consumption, as can be seen in Figure 6.
The calculated average flow is (200 + 300) / 2 = 250
Hm3/year, while the real available amount of water is 1200
Hm3/year.


Solution 1
Data Source: CHE
Estimations: Current amount of water
accumulated in reservoirs is
58.8% of total capacity of


domestic drinking water
agriculture
livestock
industry
water transfer to other areas
ecological flow
TOTAL CONSUMPTION


4486 Hm3
7630 Hm3

313 Hm3/year
6310 Hm3/year
66 Hm3/year
414 Hm3/year
246 Hm3/year
3536 Hm3/year
10885 Hm3/year


no water in reservoirs
Flow in the mainstream of the Ebro river is the
average of the average flows measured at
different points in the mainstream, since all the
secondary streams go into this mainstream.


average flow


7073 Hm'/year


Conclusion: Variation of accumulated water at the end of the
year will be


Output to channels
for consumption
900
Input from the river Output to the river
1000 -- Reservoir 100


Figure 5. Schematic representation of a reservoir


Solution 2
Data Source: local newspapers
Estimations: current amount of water
accumulated in reservoirs is
(60% of total capacity of
Water
Accumulated
one year ago:


Critical
Situation:


in reservoirs, less than
(for emergency situations
(5% of total capacity that cannot
be used because of its low purity


3950 Hm3
6583 Hm3)



5394 Hm3


1029 Hm3
700 Hm3)

329 Hm3)


Assumptions: Since we are in a dry period, there will be no pre-

SECONDARY RIVER
1000


MAIN RIVER (EBRO)
Figure 6. Schematic representation of a secondary river

Chemical Engineering Education


Local Water
Consumption:







Critical
Situation:
Assumptions:


900









cipitation at all in the future. The only inputs of
water to the Ebro will come from melting of cur-
rent snow into three secondary rivers: the Arag6n,
Gallego, and Cinca estimated as a total
amount of 202 Hm3
Outputs or consumption in one year are the dif-
ference between water one year ago and accumu-
lated water now
5394 3950 = 1444 Hm3/year
Conclusion: Since accumulation (A) = Inputs (I) Outputs
(0), then time to reach a critical situation
A = final water initial water
= 1029 3950 = -2921 Hm3
I = water from rain (=0) + water from
melted snow = 202 Hm3
O = consumption in one year x time
1444 Hm3/year x time (years)
time is therefore 2921 / 1444 = 2.02 years to
reach a critical situation, so the current
situation is not critical.

Instructor's Comments The assumption of no water pre-
cipitation in the future is highly improbable, and the assump-
tion that inputs to the system will come exclusively from snow
via three secondary rivers is unrealistic. These assumptions
represent, at best, a conservative scenario. The assumption
that water consumption in years is the difference between
water accumulated now and one year ago is invalid, how-
ever. Consumption is not 1444 Hm3/year; actually it is esti-
mated at 7500 Hm3/year plus 3400 Hm3/year ecological flow
at the mouth of the Ebro. To know the water consumption
figures, inputs and outputs during this period need to be
known. According to this incorrect assumption, if this year is
like the past year, the water accumulated in reservoirs would
have been the same and we would not have consumed any
water, and if this year had been more rainy that the past year,
instead of consuming water, we would have produced water,
showing negative consumption. This makes no sense.

Solution 3


Data Source: CHE
Estimations: current amount of water
accumulated in reservoirs is
62% of total capacity of


human consumption
ecological flow
TOTAL CONSUMPTION


4033 Hm3
6504 Hm3

7405 Hm3/year
3154 Hm3/year
10559 Hm3/year


REAL TOTAL CONSUMPTION 20035 Hm3


human consumption
measured at Ebro's mouth
average precipitation


7405 Hm3
12630 Hm3


Critical
Situation:


whole basin
average historical
precipitations (1940-199:
with a mimum of

no water in reservoirs


658 mm of water/m2


682 mm/m2
526 mm/m2


Assumptions: since we are in a dry period, there will be no
precipitations at all in the future.
Conclusion: since accumulation (A) = Inputs (I) Outputs
(0), then time to reach a critical situation
A = final water initial water
= 0 4033 = 4033 Hm3
I = water from precipitations 0 Hm3
O = consumption in one year x time
10559 Hm3/year x time (years)
time is therefore 0.382 years
i.e., 4 months and 17 days is the time to reach a
critical situation, so the current situation could
be critical but this is unlikely to occur because it
would require annual precipitations of
10559 / 20035 x 658 = 397 mm water/m2
which is well below the average annual
precipitations of 682 mm/m2 during the period
1940-1995, and less than the minimum in this
period of 526 mm/m2.

Instructor's Comments The implicit assumption is that wa-
ter demands will be distributed homogeneously throughout
the year, but this is not true. Water demand increases in spring
and summer, due mainly to agricultural needs. Thus in Feb-
ruary we are close to reaching the highest point of water con-
sumption that begins in spring and 4 months and 17 days to
consume all the water is very optimistic. In addition to this
problem, water reserves are not equal in every reservoir and
62% total capacity could mean that some reservoirs are full
and others are almost empty. A "case by case" study should
therefore be carried out.


CONCLUSION

This paper has presented an open-ended problem that can
easily be adapted to many local conditions, since use of a
limited and valuable resource such as fresh water is a prob-
lem almost everywhere. The problem is beneficial to students
in many ways: it can make mass balance classes more realis-
tic, it can facilitate the assimilation of concepts such as un-
steady state, and it can help students carefully analyze infor-
mation provided by daily television, radio, and newspaper
reports. It can also be helpful for finding possible solutions
as well as encouraging class discussions on the validity of
assumptions made by different solutions proposed by the stu-
dents themselves. 0


Local Water
consumption:



Oct. 2000 -
Oct. 2001


Winter 2005










Random Thoughts...







DEATH BY POWERPOINT






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


It's a rare professor who hasn't been tempted in recent
years to put his or her lecture notes on transparencies or
PowerPoint. It takes some effort to create the slides, but
once they're done, teaching is easy. The course material is
nicely organized, attractively formatted, and easy to present,
and revising and updating the notes each year is trivial. You
can put handouts of the slides on the Web so the students
have convenient access to them, and if the students bring
copies to class and so don't have to take notes, you can cover
the material efficiently and effectively and maybe even get
to some of that vitally important stuff that's always omitted
because the semester runs out.
Or so the theory goes.
The reality is somewhat different. At lunch the other day,
George Roberts-a faculty colleague and an outstanding
teacher-talked about his experience with this teaching
model. We asked him to write it down so we could pass it on
to you, which he kindly did.


"About five years ago, I co-taught the senior
reaction engineering course with another faculty
member That professor used transparencies exten-
sively, about 15 per class. He also handed out hard
copies of the transparencies before class so that the
students could use them to take notes.
"Up to that point, my own approach to teaching
had been very different. I used transparencies very
rarely (only for very complicated pictures that might
be difficult to capture with freehand drawing on a
chalkboard). I also interacted extensively with the
class, since I didn'tfeel the need to cover a certain
number of transparencies. However, in an effort to be
consistent, I decided to try out the approach of the
other faculty member Therefore, from Day 1, I used


transparencies (usually about 8 -10 per class), and I
handed out hard copies of the transparencies that I
planned to use, before class.
"After a few weeks, I noticed something that I
had not seen previously (or since)-attendance at my
class sessions was down, to perhaps as low as 50% of
the class. (I don't take attendance, but a significant
portion of the class was not coming.) I also noticed
that my interaction with the class was down. I still
posed questions to the class and used them to start
discussions, and I still introduced short problems to
be solved in class. I was reluctant to let discussions
run, however since I wanted to cover the transparen-
cies that I had planned to cover
"After a few more weeks of this approach, two
students approached me after class and said, in
effect, 'Dr Roberts, this class is boring. All we do is
go over the transparencies, which you have already

Richard M. Felder is Hoechst Celanese Pro-
fessor 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 El-
ementary Principles of Chemical Processes
(Wiley, 2000) and codirector of the ASEE Na-
tional Effective Teaching Institute



Rebecca Brent is an education consultant spe-
cializing in faculty development for effective
university teaching, classroom and computer-
based simulations in teacher education, and K-
12 staff development in language arts and class-
room management. She co-directs the ASEE
National Effective Teaching Institute and has
published articles on a variety of topics includ-
ing writing in undergraduate courses, coopera-
tive learning, public school reform, and effec-
tive university teaching.


Copyright ChE Division of ASEE 2004


Chemical Engineering Education









handed out. It's really easy to just tune out. 'After my
ego recovered, I asked whether they thought they
would get more out of the class and be more engaged
if I scrapped the transparencies and used the chalk-
board instead. Both said 'yes. 'For the rest of the
semester I went back to the chalkboard (no transpar-
encies in or before class), attendance went back up to
traditional levels, the class became more interactive,
and my teaching evaluations at the end of the
semester were consistent with the ones that I had
received previously. Ever since that experience, I
have never been tempted to structure my teaching
around transparencies or PowerPoint."


The point of this column is not to trash transparencies and
PowerPoint. We use PowerPoint all the time-in conference
presentations and invited seminars, short courses, and teach-
ing workshops. We rarely use pre-prepared visuals for teach-
ing, however-well, hardly ever-and strongly advise against
relying on them as your main method of instruction.
Most classes we've seen that were little more than 50- or
75-minute slide shows seemed ineffective. The instructors
flashed rapid and (if it was PowerPoint) colorful sequences
of equations and text and tables and charts, sometimes asked
if the students had questions (they usually didn't), and some-
times asked questions themselves and got either no response
or responses from the same two or three students. We saw
few signs of any learning taking place, but did see things
similar to what George saw. If the students didn't have cop-
ies of the slides in front of them, some would frantically take
notes in a futile effort to keep up with the slides, and the
others would just sit passively and not even try. It was worse
if they had copies or if they knew that the slides would be
posted on the Web, in which case most of the students who
even bothered to show up would glance sporadically at the
screen, read other things, or doze. We've heard the term
"Death by PowerPoint" used to describe classes like that. The
numerous students who stay away from them reason (usually
correctly) that they have better things to do than watch some-
one drone through material they could just as easily read for
themselves at a more convenient time and at their own pace.
This is not to say that PowerPoint slides, transparencies,
video clips, and computer animations and simulations can't
add value to a course. They can and they do, but they should
only be used for things that can't be done better in other ways.
Here are some suggested dos and don't.
Do show slides containing text outlines or (better) graphic
organizers that preview material to be covered in class and/
or summarize what was covered and put it in a broader con-


text. It's also fine to show main points on a slide and amplify
them at the board, in discussion, and with in-class activities,
although it may be just as easy and effective to put the main
points on the board too.
Do show pictures and schematics of things too difficult
or complex to conveniently draw on the board (e.g., large
flow charts, pictures of process equipment, or three-dimen-
sional surface plots). Don't show simple diagrams that you
could just as easily draw on the board and explain as you
draw them.
0 Do show real or simulated experiments and video clips,
but only if they help illustrate or clarify important course
concepts and only if they are readily available. It takes a huge
amount of expertise and time to produce high-quality videos
and animations, but it's becoming increasingly easy to find
good materials at Web sites such as SMETE, NEEDS, Merlot,
Global Campus, and World Lecture Hall. (You can find them
all with Google.)
Don't show complete sentences and paragraphs, large
tables, and equation after equation. There is no way most
students can absorb such dense material from brief visual
exposures on slides. Instead, present the text and tables in
handouts and work out the derivations on the board or-more
effectively-put partial derivations on the handouts as well,
showing the routine parts and leaving gaps where the diffi-
cult or tricky parts go to be filled in by the students working
in small groups.l~21
If there's an overriding message here, it is that doing too
much of anything in a class is probably a mistake, whether
it's non-stop lectures, non-stop slide shows, non-stop activi-
ties, or anything else that falls into a predictable pattern. If a
teacher lectures for ten minutes, does a two-minute pair ac-
tivity, lectures another ten minutes and does another two-
minute pair activity, and so on for the entire semester, the
class is likely to become almost as boring as a straight lec-
ture class. The key is to mix things up: do some board work,
conduct some activities of varying lengths and formats at
varying intervals, and when appropriate, show transparen-
cies or PowerPoint slides or video clips or whatever else
you've got that addresses your learning objectives. If the stu-
dents never know what's coming next, it will probably be an
effective course.
References
1. Felder, R.M., and R. Brent, "Learning by Doing," Chem. Engr Ed.,
37(4), 282 (2003). On-line at umns/Active.pdf>
2. Felder, R.M., and R. Brent, "FAQs. II. Active Learning vs. Covering
the Syllabus, and Dealing with Large Classes," Chem. Engr Ed, 33
(4), 276 (1999). On-line at umns/FAQs-2.html> J


Winter 2005


All of the Random Thoughts columns are now available on the World Wide Web at
http://www.ncsu.edu/effective_teaching and at http://che.ufl.edu/-cee/










classroomI


ENERGY BALANCES


ON THE HUMAN BODY


A Hands-On Exploration of Heat, Work, and Power





STEPHANIE FARRELL, MARIANO J. SAVELSKI, ROBERT HESKETH
Rowan University Glassboro, NJ 08028


Rowan's two-semester Freshman Clinic sequence is a
multidisciplinary course that introduces all freshmen
engineering students to engineering principles in a
hands-on, active learning environment. Engineering measure-
ments and reverse engineering methods are common threads
that tie together the different engineering disciplines in the
fall and spring semesters, respectively. One of the reverse
engineering projects is a semester-long investigation of the
interacting systems of the human body. Students discover the
function, interaction, and response to changing demands of
various systems in the human body: the respiratory, meta-
bolic, cardiovascular, electrical, and musculoskeletal systems.
The project introduces a wide range of multidisciplinary en-
gineering principles and reinforces scientific principles
learned in chemistry, physics, and biology.
The module described in this paper uses the respiration sys-
tem to introduce concepts related to energy balances, heat
transfer, and chemical reactions. In a hands-on experiment,
students measure physiologic variables such as breathing rate
and respiratory gas compositions at rest and during exercise
on a bicycle ergometer. We have previously described how a
similar experiment is used to teach mass balances and re-
lated concepts through the determination of the rates of oxy-
gen consumption, carbon dioxide production, and water
loss."',2 The module is appropriate for an introductory fresh-
man engineering course or for a sophomore-level course on
material and energy balances. These concepts can be explored
in greater detail in upper level core and elective courses.
The learning objectives of this hands-on experiment are to
Perform energy balances on the body
Determine the total rate of energy expenditure and


human mechanical efficiency
Determine the composition offood (%fat and %
carbohydrate) oxidized for energy
Use a process simulator to perform mass and energy
balances on the breathing process
Analyze the role of breathing in thermal regulation


Stephanie Farrell is Associate Professor of
Chemical Engineering at Rowan University. She
received her PhD (1996) from NJIT She has
developed innovative classroom and laboratory
materials in biomedical, food, andpharmaceu-
tical engineering areas. She is the recipient of
the 2000 Dow Outstanding Young Faculty
Award, the 2001 Joseph J. Martin Award, the
2002 Ray W FahienAward, and the 2004ASEE
Outstanding Teaching Medal.


Robert Hesketh is Professor of Chemical En-
gineering at Rowan University. He received his
PhD from the University of Delaware in 1987.
He has made significant contributions to the
development of inductive teaching methods
and innovative experiments in chemical engi-
neering. He is the recipient of the 2002 Quinn
Award, 1999Ray W. FahienAward, 1998 Dow
Outstanding New Faculty Award, and the 1999
and 1998 Joseph J. Martin Award.


Mariano Savelski is Associate Professor of
Chemical Engineering at Rowan University. He
received his PhD in 1999 from the University of
Oklahoma. His research is in the area of pro-
cess design and optimization, and he has over
seven years of industrial experience. His prior
academic experience includes two years as As-
sistant Professor in the Mathematics Depart-
ment at the University of Buenos Aires.


Copyright ChE Division ofASEE 2005


Chemical Engineering Education









Use HYSYS131 process simulator to
explore respiratory heat transfer
under different conditions.
semeste
The engineering concepts introduced through of th
this module are summarized in Table 1.
in

BACKGROUND
The air we inspire (inhale) is approximately
21% O2 and 79% N2 on a dry basis. After
rapid gas exchange in the lungs, the expired
(exhaled) gas contains approximately 75%
N2, 16% 0,, 4% CO, and 5% H20.[4.5] The
inspired air is at ambient pressure, temperature, and humid-
ity, while the expired air is saturated with water vapor at body
temperature and ambient pressure, and respiration accord-
ingly plays a role in temperature regulation. Oxygen con-
sumed during respiration is transported by blood to cells for
energy production through the oxidation of carbohydrates and
fats from food. The reaction stoichiometry and thermody-
namics are well known, and the rate of energy production
can be calculated from the rates of 0, and CO, exchange."'
This energy is used to maintain the function of the body (basal
metabolism, typically about 60-70% of total energy expendi-
ture) and to do external work (exercise, typically about 30-
40% of total).
Energy expended internally (e.g., for pumping blood, main-
taining organs, etc.) must ultimately be released as heat, and
it has been observed that the energy metabolism at rest is
related to the surface area (SA) of the body. This ratio of
basal metabolic rate (BMR) to the surface area (SA), [(BMR)/
(SA), kcal/h], is a function of age (Y, in years) and gender:16'
For males:

(BMR) 5479 kcal(1.303 kcal *Y+
=SA -154.79- 11303 2
(SA) m2h m2h yr)

0.0294 kca Yy 0.0001228 kl Y3
Sm2hyr2) i m'hyr3)


One of the reverse engineering projects is a
r-long investigation of the interacting systems
e human body. Students discover the function,
teraction, and response to changing demands
of various systems in the human body: the
respiratory, metabolic, cardiovascular,
electrical, and musculoskeletal
systems.


13.3558 *10-6 ca Y4 +
1112h yr4


2.903 10


-8 kcal Y5
m2h yr5


For females:


(BMR) (5573 kcal 1 ( kcal
(SA) mh) 757 m hyr)*

0.0414 kcal y2+5.21610-6 kcal
m2hyr ) m 2hyr3


m-hyr4

7.979*108 kcal *y5 (2)
1m2hyr5



Surface area can be found from the following correlation
that relates surface area to body mass and height:['7

SA= 0 1.275
SA= 0.202 M75 0.425 h0.725 (3)
kgo.425 )


TABLE 1
Summary of the Science and Engineering Concepts Introduced in this Module


Application


Reaction stoichiometry
Heat of reaction
Energy balance (First Law of Thermodynamics) on an open system
Heat transfer-relation to surface area; correlations


Food oxidation reactions -
Energy production from food oxidation reactions
Calculation of energy stored in one day
Determination of energy expenditure


Mechanical efficiency: work, frictional losses, heat Students performing mechanical work (cycling)
Simultaneous material and energy balance-heat capacity, enthalpy, sensible heat, latent heat, Heat transfer during respiration; HYSYS simulation
reference state; psychrometric chart


Unit-operations (heatng, humidification)


HYSYS simulation


Engineering Concept


Winter 2005









where SA is in units of (m2), m is mass in kg and h is
height in meters.
The energy needed to maintain the body during rest and
during physical activity is derived from the breakdown,
synthesis, and utilization of fats, carbohydrates, and pro-
tein. Protein is thought to be used primarily in building
tissue (anabolic processes), and most of our body's en-
ergy needs are met through the intake of carbohydrates
and fats. Glucose (a sugar) is a typical carbohydrate, and
is oxidized according to the reaction


C6H1206 +602->6CO2 +6H20


673kcal/mol (4)


Note that the heat of reaction at STP (-673 kcal/mol) is
provided in addition to the reaction stoichiometry. Fats
are another class of macronutrient that the body uses to
obtain energy. Triolein, a fat, is burned according to the
reaction

C57H3202+8002--57CO2+52H20 -7900kcal/mol (5)

The reactions shown in Eqs. (4) and (5) are for a spe-
cific carbohydrate (glucose) and a specific fat trioleinn),
and the heats of reaction were evaluated at STP.[81 Dietary
carbohydrates are a mixture of molecules with the approxi-
mate formula [C(H20)],; similarly, dietary fats are a mix-
ture of esters of various fatty acids. These two macronu-
trients are therefore commonly represented as typical mix-
tures (representing typical dietary intake). In the oxida-
tion of a mixture of carbohydrates, the ratio of CO2 pro-
duction to 02 consumption is 1:1, and approximately 113
kcal/mol 02 (STP) is released. The oxidation of a mixture
of fats results in a 0.707:1 ratio of CO2 production to 02
consumption, and releases about 104.9 kcal/mol 02
(STP).141 Measurement of the rates of 02 consumption and
CO2 production (Vo2 andVco2) allows determination of
the rates of energy derived from fats and carbohydrates
using these heats of reaction and stoichiometric relation-
ships.
The Respiratory Exchange Ratio (RER) is the ratio of
02 consumption and CO2 production and is a convenient
expression for use in metabolic calculations

RER #molesCO2 produced VCO2 (6)
RER=- (6)
#molesO2 consumed V02

Table 2 shows RER values for fats and for carbohydrates,
the energy released per LO2, and the mass of each macro-
nutrient oxidized per LO2 consumed.[41 When a mixture of
carbohydrates and fats is oxidized, the RER will lie be-
tween 0.707 and 1.0. The RER is a convenient indicator
for the proportion of each macronutrient being oxidized
and is related to the total energy expenditure. This is illus-
trated graphically in Figure 1. The equations of the lines
provide relationships between EE and RER, and between


the composition of the energy source and RER.
Nearly everyone is familiar with the concept of reducing caloric
intake and increasing exercise to lose weight. This is simply an
application of the First Law of Thermodynamics, which reveals
that if the energy equivalent of consumed food exceeds the energy
expended, the result is a net storage of energy. This excess energy
would be stored primarily as fat.

Q- Ws nairAair food Ar = Est (7)

Q is the rate of heat transferred to the body from the surroundings,
Ws is the rate of work done by the body on the surroundings,
ilairAH air is the rate of enthalpy change between the inspired and
expired air streams due to a change in temperature, nffoodAHr is the
rate of enthalpy change due to reaction, and Est is the rate of en-
ergy storage in the body. Several simplifying assumptions were
made to make the analysis appropriate for freshmen: 1) the effect
of composition on the molar enthalpy of the inspired and expired
air is neglected, 2) the difference in number of moles of inspired air
vs. expired air is neglected, and 3) the enthalpy change of the food
due to change in temperature is neglected.
The human body doing exercise can be analyzed as a machine



TABLE 2
RER and Energy Expenditure for Carbohydrates and Fats
(At Standard Temperature and Pressure, 0C and 760 mm Hg)
Values taken from Reference 4.

Carbohydrate Fat
~ ~- --
Energy released per mole of oxygen used (kcal/mol) 113.0 104.9

Grams of macronutrient oxidized per liter oxygen used (g/L) 1.231 0.496


S114 120


1041 0. I,
0.7 075 0.8 0.85 0.9 0.95 1 1.05
RER


- -Linear (carbohydrate) - Linear (fat)


- Linear (EE)


Figure 1. Fuel composition and energy expenditure as a
function of RER (0.707 < RER < 1.0).


Chemical Engineering Education


%carb = 341.38x -240.34




%fat = -341.38x 340.34










In a hands-on experiment, students measure physiologic variables such as
breathing rate and respiratory gas compositions at rest
and during exercise on a bicycle ergometer.


doing mechanical work. To do mechanical work such as bi-
cycling or running, the body expends energy. The efficiency,
Tq, of this human machine or a human is expressed by
mechanical work done 10
o= o100 (8)
energy consumed
Energy not used to perform external work is ultimately re-
leased as heat. Since this module focuses on respiration, of
interest is the total rate of heat transfer associated with respi-
ration. Under normal conditions, about 14%-20% of the
body's total cooling is accomplished through respiration, and
this percentage can change with exercise and ambient condi-
tions.171
During respiration, inspired air is warmed from ambient
temperature to body temperature prior to being exhaled. In
addition, water evaporates from the moist lung tissue to satu-
rate the air in the lungs prior to expiration. The humid ex-
haled air removes heat from the body in the form of latent
heat of vaporization. The rate of heat transfer (q kcal/min)
achieved through the process of respiration is
T T AH in out
q=nairCpair(Tin Tut )+AHvap(nw i w) (9)

where n is the molar flowrate (mol/min), C is the molar
heat capacity (kcal/mol K) of the inhaled humid air, T is tem-
perature (K) and AHyap is the latent heat of vaporization of
water (kcal/mol). Subscripts represent components air or
water, and superscripts represent inlet or outlet air.

EQUIPMENT
The equipment used for all cardiorespiratory measurements
was a respiratory gas-exchange system coupled with a cycle
ergometer. The MedGraphics (St. Paul, MN) CPX/D cardio-
respiratory gas-exchange system includes capability for di-
rect oxygen and carbon dioxide measurement and ventila-
tion (flow rate). The system interfaces with a cycle ergom-
eter (Lode Corvial) for exercise testing. Many universities
have such equipment available in a physiology or exercise
science laboratory, and several companies offer human physi-
ology teaching kits in the $3,000 range (e.g., Biopac Sys-
tems, Santa Barbara, CA; ADInstruments, Colorado Springs,
CO; Iworx, Dover, NH).

EXPERIMENT
A detailed experimental procedure was described previously
by Farrell, et al.,121 and a summary is provided here.


Students work in teams of three, and the team can com-
plete the experiment in approximately 20-30 minutes. One
student per team is selected as the test subject for the experi-
ment. Using the MedGraphics CPX/D cardiorespiratory test
system coupled with the Corvial Cycle ergometer, measure-
ments are taken for four minutes resting and for four minutes
during exercise. During exercise the subject pedals at a rate
of 70-80 rpm with a constant braking power set to 30W.
(Braking power is product of the tension on the flywheel
and the distance covered by the perimeter of the flywheel
per unit time).
The following quantities are measured directly and dis-
played using Med-Graphics Breeze Suite software: Volumet-
ric flowrate of exhaled air and component mole fractions

(Vout in out in out
n Yo uto z cozY co2)
Y 02' Y02' YCO2' 7CO2
and braking power. The gas exchange data are reported at
BTPS (Body Temperature and Pressure, Saturated) conditions.
In addition, the software provides calculated values of

VO2, VCO2, EE, and RER.

ASSIGNMENTS
The first assignment based on this experiment is a labora-
tory report that focuses on the food oxidation reactions in-
volved in energy production, determination of energy expen-
diture at rest and during exercise, and the application of the
First Law of Thermodynamics. From their experimental data,
students calculate the BMR, RER, EE, and mechanical effi-
ciency. Using RER values, students determine the percent-
age of energy expenditure derived from carbohydrates and
from fats, as well as the number of grams of carbohydrates
and grams of fat used as fuel. In addition to the data obtained
from the experiment described above, students record every-
thing they eat for an entire day and calculate the energy equiva-
lent of this diet using published nutrition tables. They also
keep track of their activities during the day and estimate the
total amount of energy expended required for this work. This
information is used to determine the total net chemical en-
ergy storage using the First Law energy balance.
The second assignment is a calculation-based homework
that focuses on a thermal energy balance on the respiration
process. This energy balance is simplified (for hand calcula-
tions) by using a constant heat capacity independent of com-
position. Only the energy changes associated with heating
and humidifying an air stream are considered. Students cal-


Winter 2005











culate the rates of latent heat exchange, sensible heat
exchange, and total heat exchange associated with
respiration. After performing the hand calculations
using tabulated values of C and A yap, students also
use a psychrometric chart to determine the rate of heat
exchange during respiration.

A subsequent laboratory period is used for a HYSYS
process simulation workshop in which students use
HYSYS to simulate the respiration process. Students
input their own experimental data, use HYSYS to
perform material and energy balances on the respira-
tion process, and compare the results of the simula-
tion to their hand calculations. Several simulations
are run to explore the effect of ambient conditions on
the relative contributions of sensible and latent heat
during respiration. Students explore a range of tem-
peratures and relative humidities that correspond to a
range of weather conditions (for instance, a dry win-
ter day, a rainy winter day, a hot desert, and a hot
steamy swamp).
As shown in the HYSYS flow diagram in Figure 2,
the respiration process can be represented by two unit
operations: a heater that heats the inhaled air to body
temperature (sensible heat effect), and a humidifier
that saturates the inhaled air with water (latent heat
effect). Students enter the ambient conditions of tem-
perature, pressure, and relative humidity into the
weather station. Because HYSYS requires a water va-
por mole fraction rather than relative humidity to be
provided, students use a spreadsheet to calculate the
mole fraction of water in the inhaled air using the
Antoine equation. The "inhaled humid air" stream
represents inspired air at ambient temperature, pres-
sure, and relative humidity. The stream called "ex-
haled warm saturated air" represents the exhaled air
at body temperature and pressure, saturated with wa-
ter vapor; students supply temperature, pressure, flow
rate, and composition of this stream using their ex-
perimental data. Temperature and pressure values
for the intermediate streams called "warm humid
air" and "moisture from lung tissue" are also sup-
plied by students.


RESULTS

Nearly everyone is aware of the body's physiologic
responses to exercise-the body's increased demand
for energy is met with an increased breathing rate and
heart rate. By comparing the resting and exercise gas
exchange measurements, students quantify this physi-
ologic response. Table 3 shows gas exchange mea-
surements and calculated values for the respiration
experiment for a 19-year-old female student (125 Ib,
66 in). According to Eqs. (2) and (3), the student has


TABLE 3
Gas Exchange Measurements and Calculations at Rest and During
Cycling Exercise
Vout1 y' y1 Yo l and y o are measured experimentally
at BTPS conditions.
Vq, and VCO, are calculated at STP.
(Ambient Conditions: T=200C, P=759 nmm Hg, RH=47%.)


Power Vout y tO VO VCO2 EE RER
(W) (L/min) (L/min) (L/min) (kcal/min)

0 13.08 0.185 0.023 0.25 0.23 1.38 0.87
30 20.50 0.175 0.031 0.62 0.52 3.07 0.85



TABLE 4
Energy Value of Consumed Foods and Activity Performed on a
Given Day for the Female Subject


Energy
Value
(kcal)


Carnation Instant Breakfast, 10 oz
Meatballs, 3 x 1 oz
Spaghetti, 1 cup
Tomato sauce, 1/4 cup
Kielbasa, 4 oz
Soft pretzel
Cinnamon toast crunch bar
Brownie
Milk, 1 cup whole
Hawaiian Punch, 12 oz

Pizza. 2 slices plain


Total


Activity


Energy
Value
(kcal/h)


200 Sleep, 7.5 h
234 Shower, 0.25 h
159 Dressing. 0.25 h
35 Walking, I h
320 Driving, 0.5 h
95 Class, 4 h
180 Homework, 4 h
160 Talk on phone, 1 h
150 Grocery shopping, 0.5 h
180 Talking with friends
standing, 2 hr
480 Eating, 1.5 h
Watching TV 1.5 h
2193 Total


Weather
Station

Relative
Humidity




Inhaled
Dry
Air


Sensible
Heat


W---------------P
F Exhaled
Warm


Inhaled
Humid
Air


Heater


I cxclang e S;
Ai
----rr-u
Warm Humidifier
Humid Moisture Hude
Air from
Lung
Tissue
Evaporative
Heat
Exchange


aturatec
r


Figure 2. The HYSYS respiration process flow diagram.


Chemical Engineering Education













30
25 *
20
1- 15 --Total, T=oC
10 --Total, T=20C
10 ---Total, T=30C
o --Total, T=37C
-J
g 0 -*-Total, T=45C
-5
I- 10-
-15
0 20 40 60 80 100 120
Relative Humidity (%)

Figure 3. The effect of ambient temperature and relative humidity
on the total heat transfer rate during respiration.


Figure 4. The effect of ambient temperature and relative humid-
ity on the sensible heat transfer rate during respiration.



25

20


S10 -e--Latent, T=0C
-4--Latent, T=20C
5 --Latent, T=30C
o0 -4 *-Latent, T=37C
S 5 .- Latent, T=45C


-15
0 20 40 60 80 100 120
Relative Humidity (%)

Figure 5. The effect of ambient temperature and relative humidity
on the latent heat transfer rate during respiration.


a surface area of about 1.59 m2 and an expected basal
metabolic rate of 57.5 kcal/h. The basal metabolic rate
is the minimum energy required for maintenance of the
body's vital functions and is about 70% of the body's
actual measured energy expenditure at rest (resting en-
ergy expenditure, REE). The resting energy expendi-
ture is therefore expected to be 82.2 kcal/h.

Comparison of exercise data to resting data reveals
that the breathing rate is substantially faster during ex-
ercise, and the oxygen concentration of expired air is
slightly lower than its resting value. This translates into
higher rates of oxygen consumption and carbon diox-
ide production during exercise. The energy expenditure
is calculated using the equation of the line in Figure 1,
which provides a relationship between EE and RER.
These results are summarized in Table 3. The mechani-
cal efficiency, calculated using Eq. (8), is only 23.4%,
because a significant amount of energy is required to
overcome internal friction in moving joints and ineffi-
ciencies of muscle contraction.'14 (Cycling is, in fact,
one of the most efficient exercises!)

The energy equivalent of the food consumed by this
student in one day was 2193 kcal, as shown Table 4.
From the basal metabolic rate of 57.5 kcal/h, this
student's minimum resting metabolic requirements are
1380 kcal per day. Since no external mechanical work
is done by the body at rest, all of this energy is assumed
to be transferred to the surroundings in the form of heat.
The energy expended on daily activities (external work)
is also shown in Table 4. These values represent the
energy required in excess of the basal metabolic rate
and are gathered from widely available published and
Internet sources (such as ).
This student estimated an energy expenditure of 839
kcal per day for her activities. The result of the First
Law energy balance indicates that this student expended
26 kcal more than her intake for the day, which would
result in a (very small) weight loss! It should be noted
that the published values of energy expenditure during
activity are estimated values based on averages for many
test subjects performing. In addition, BMR is deter-
mined using correlations based on age, height, mass and
gender. These correlations were developed using data
of many test subjects, and thus represent physiologic
estimates. This provides an ideal opportunity to ex-
plore the uncertainties related to the use of estimated
values as well as those associated with experimen-
tal measurements.

Using the HYSYS process simulator to simulate the
sensible heat and latent heat changes during respira-
tion, the role of respiration in thermal regulation of the
body is investigated. Figures 3, 4, and 5 show the total,
sensible, and latent heat transfer rates (respectively)


Winter 2005


7 -0
6
5
4
3 13 E3 E
3. O ----- B -B --- B ---
2

o G E 0 0 G E)
-1
-2
-3


-- Sensible, T=0C
-B-Sensible, T=20C
- Sensible, T=30C
---Sensible, T=37C
-- Sensible, T=45C


100 120


0 20 40 60 80
Relative Humidity (%)










In using traditional classroom
surveys, the students responded that
the module contributed to their
enthusiasm for engineering-
as evidenced with a score
of 4.75 out of 5.0.

under varying ambient temperature and relative humidity. The
data in these figures is obtained using HYSYS, but essen-
tially represents Eq. (9). Graphical representation of the equa-
tion is a useful visual tool that helps students grasp the ef-
fects of ambient temperature and humidity on the sensible
and latent heat exchange rates. Using the resting data above,
the overall rate of heat transfer through respiration at rest
(and at ambient conditions of the experiment) is about 19
kcal/h, or 23% of the total resting energy expenditure. By
performing HYSYS simulations at different combinations of
ambient temperature and relative humidity, students can make
the following important observations about heat transfer dur-
ing respiration:

1. The total rate of heat loss via respiration decreases
with increasing relative humidity (RH) and with
increasing temperature. Heat loss is positive except
under the most extreme conditions of high T and
RH when the heat loss is negative and heat is
transferred to the body via respiration. Heat loss
occurs via evaporative cooling in dry conditions,
and this effects a net cooling effect even when the
ambient temperature is higher than body tempera-
ture.
2. The sensible heat transfer contribution becomes
more significant when ambient temperatures are


farther from body temperature (at cold and hot
extremes). Sensible heat losses are greater at cool
temperatures and show little dependence on
relative humidity. When the ambient temperature
exceeds body temperature (37C), sensible heat
losses are negative.
3. The latent heat loss rate decreases with increasing
RH and with increasing temperature. When the
ambient air is at 370C and 100% RH, the total
sensible and latent heat losses are exactly zero. In
very hot and dry conditions, an overall cooling
effect is achieved by a high rate of evaporative
cooling (note that at 45 C and dry conditions the
total heat loss and the latent heat loss are both
positive, while the sensible heat loss is negative).

ASSESSMENT
An assessment plan based on the rubrics developed by
Newell, et al., 91 was developed to map student work directly
to the individual learning outcomes of these freshmen. The
learning outcomes specifically address ABET criteria, AIChE,
and program-specific goals. This assessment was based on
reasonable expectations for freshmen students who have had
their first introductory exposure to engineering principles.
Four instruments were chosen for the evaluation: a team
laboratory report, an individual in-class quiz, a formal oral
presentation, and an interactive poster presentation. These
were evaluated for three consecutive years.
Table 5 shows the stated objectives/outcomes that were
evaluated on a four-point ordinal scale to describe student
performance, using detailed rubrics as discussed previously
in the paper by Newell.[91 In these rubrics, levels of student
performance are assigned values of 1 to 4 on an ordinal scale.
A score of 4 represents an expert who has mastered the given


Chemical Engineering Education


TABLE 5
Desired Educational Objectives for this Project

Objective/Outcome (to demonstrate...) Mapped to Goal...
A working knowledge of chemical engineering pnnciples (energy balances., work, efficiency, psychrometnc
chart, unit operations AIChE Professional Component
A working knowledge of chemistry (reaction stoichiometry, heat of reaction) AIChE Professional Component
An ability to fuincon on multdisciplinary and/or diverse leams ABET d
An ability to approach tasks involving experimental results in a logical and systematic fashion
(measurements, recording, analysis, and interpretation) Program
An understanding of contemporary issues relevant to the field current technical material, find relevant
current information, and use in curricular assignments ABET -
An ability to use techniques, skills, and modem engineering tools necessary for engineering practice
(spreadsheets, word processors, and process simulators) to assist in problem solving ABET k
Effective oral and written communication skills ABET g










objective; a score of 3 represents a skilled problem solver; a
score of 2 represents a student who has some skills but lacks
competence; a score of 1 represents a complete novice. The
complete rubrics are available on a website at
< http://engineering.rowan.edu/~newell/rubrics>
Students were also surveyed regarding their perceived abil-
ity to demonstrate the same skills. The results of the assess-
ment by faculty are shown in Figure 6, and the results of
student self-assessment are shown in Figure 7. Both student
self-assessment and faculty assessment scores were consis-
tent and highly satisfactory; the percentage of students receiv-
ing a rating of 3 or 4 was above 89% for each objective.
We believe that the scores indicate that we were successful in
achieving our stated learning objectives. In using traditional
classroom surveys, the students responded that the module con-


Figure 6. Results of faculty assessment for this project.



90
son
80
S70O
70
.n 60
S60 Expert
W 50 Competent
7_ 40 E Inexperienced
Z 3 Novice
o 30
20
10
0L




q,?


Figure 7. Results of student assessment of this project.


tribute to their enthusiasm for engineering-as evidenced with
a score of 4.75 out of 5.0.

CONCLUSIONS

This paper describes a module with a hands-on experiment
and associated follow-up activities in which principles of en-
ergy balances are introduced through application to the pro-
cess of respiration. Basic physiologic responses are already
familiar to students through "common knowledge" and sen-
sory experiences, and most students have a natural curiosity
to learn how their own bodies work. This hands-on experi-
ment and the associated assignments focus on quantifying
and analyzing the physiologic system. This establishes a
framework within which new engineering concepts are in-
troduced. Students learn concepts related to energy balances,
chemical reaction stoichiometry and heats
of reaction, work, power, and mechanical
efficiency and are exposed to the use of
thermodynamic property tables, psychro-
metric charts, and process simulation soft-
ware.


ACKNOWLEDGMENTS

Funding for this project was obtained
from the National Science Foundation
Course, Curriculum, and Laboratory Im-
provement Program (NSF DUE
#0088437).

REFERENCES
1. Farrell, S., R.P. Hesketh, K.Hollar, M.J.
Savelski, R.Specht, "Don't Waste Your
Breath!", Proceedings of the 2002 Annual Con-
ference of the American Society for Engineer-
ing Education, Session 1613 (2002)
2. Farrell, S., R.P. Hesketh, and M.J. Savelski, "A
Respiration Experiment to Introduce Chemi-
cal Engineering Principles,"Chem. Eng. Ed.,
38(3) (2004)
3. HYSYS, version 2.4.1, Hyprotech Ltd. (2001)
4. McArdle, W.D., F.I. Katch, and V.L. Katch, Ex-
ercise Physiology: Energy, Nutrition, and Hu-
man Performance, 4th ed., Lea and Febiger,
Philadelphia, PA (1996)
5. Adams, Gene, Exercise Physiology Laboratory
Manual, W.C.B. McGraw Hill, NY (1998)
6. Wasserman, K., J.E. Hansen, D.Y. Sue, B.J.
Whipp, Principles of Exercise Testing and In-
terpretation, Lea and Febiger, Philadelphia, PA
(1987)
7 Cameron, J., J. Skofronick, and R. Grant, Phys-
ics of the Body, Medical Physics Publishing,
Madison, WI (1992)
8. Cooney, David O., Biomedical Engineering
Principles, Marcel Dekker (1976)
9. Newell, J.A., K.D. Dahm, and H.L. Newell,
"Rubric Development and Inter-Rater Reliabil-
ity Issues In Assessing Learning," Chem. Eng.
Ed., 36(3) (2002) 0


Winter 2005


90
80
70
a)
S 60
S50
S40
o 30
20
10


/


O Expert (4)
* Competent (3)
0 Inexperienced (2)
* Novice (1)


.1 ls









M% -classroom


A Project To

DESIGN AND BUILD

COMPACT HEAT EXCHANGERS


RICHARD A. DAVIS
University of Minnesota Duluth Duluth, MN 55812


ur department initiated a project for students to de-
sign and build a compact shell-and-tube heat ex-
changer in order to address needs defined by our
educational goals, by industrial advisors, and by our students
and alumni. The needs that fit neatly within the scope of this
project include putting theory into practice, developing engi-
neering judgment, and gaining hands-on experience. For our
purposes, engineering judgment is defined as the aspect of
problem solving and design that balances theory with prac-
tice, creativity, and common sense.11
Recently, members of our department's industrial advisory
board provided us with feedback on their experiences with
young chemical engineers in the work place. One theme that
emerged was that the modern student has a general lack of
practical, hands-on, mechanical skills with basic tools and
building materials. One company reported on a workshop they
started that offers intern and co-op students (as well as new
engineers) instruction on topics such as the use of small tools,
fittings, piping, filters, valves, automation and instrumenta-
tion, pump basics, heat exchanger knowledge, and basic
troubleshooting skills. Our experience, along with that of our
industrial partners, echoes Finlayson's observation121 that
We see students who have very little hands-on experience
in anything and their practical education begins when
they get into our laboratory. These people are more
susceptible to accepting whatever comes out of the
computer Now, instead of teaching people how to write
programs, we are teaching them how to check the results,
to use their heads and evaluate the information. We teach
them to be skeptical and some specific steps to use in
checking their work.
The project for students to design and build a compact shell-
and-tube heat exchanger was structured to meet several im-
portant objectives. First, it was designed to help students be-
come comfortable in industrial environments through expo-
sure to basic hand tools and construction materials; second,
it would provide students with an open-ended design prob-


lem where they could develop confidence in engineering prin-
ciples through application; and third, it was meant to develop
our students' sense of engineering judgment.

PROJECT DESCRIPTION
The heat-exchanger project was incorporated into a core
course on heat transfer, typically taken during the spring se-
mester of the junior year of our program, that covers topics
on transport phenomena and unit operations of heat transfer.
The assignment was to design and build a compact shell-and-
tube heat exchanger for water streams such that the tempera-
ture of the tube-side fluid changes by a magnitude of at least
20 C at the operating conditions listed in Table 1. The de-
sign objectives were to minimize cost and size. For this
project, the cost was assumed to be directly proportional to
weight. The size was taken as the largest dimension (e.g.,
length of exchanger).
A simple double-pipe heat exchanger was constructed as a
prototype for the purpose of demonstrating the concept of
the project to the students and to provide them with ideas of
materials and construction methods. The shell and tube were
made from four feet of one-inch schedule 40 PVC pipe and
1/4-inch copper tubing, respectively.
By intentional design, the prototype exchanger did not per-
form to the required specifications of the project. The stu-
dents formed teams of two or three students and were told to

Richard A Davis is Professor of Chemical En-
gineering at the University of Minnesota Duluth,
where he teaches transport phenomena, unit
operations, separations, biochemical engineer-
ing, and computational methods. He received
his BS and PhD degrees in chemical engineer-
ing from Brigham Young University and the Uni-
versity of California Santa Barbara, respectively.
His current research activities include process
optimization, modeling, and simulation.


Copyright ChE Division of ASEE 2005


Chemical Engineering Education









improve the design of the example exchanger to meet or ex-
ceed the project performance and design specifications. In
order to avoid proposals that simply lengthened the tube, the
teams were challenged to consider compact designs that mini-
mized the size and weight of the device. Individual students
were required to report their results in a memo report to the
instructor. Each team presented its findings to the class.
Materials of Construction The first objective was to
give students hands-on experience with tools and construc-
tion materials. The project also served as a learning vehicle
to acquaint students with pipe schedules and fittings (such as
caps, elbows, unions, re-
ducers, tees, and connec-
TABLE 1
tors). Students were lim-
Heat Exchanger Operating to mate s avail-
Specifications ited to materials avail-
Specifications
able in typical hardware
Feed Temperature Approximate stores or home building
Streams C Flow Rate centers, including stan-
(Umin) dard schedule 40 or
Cold Water <15 0.500.05 schedule 80 PVC pipe
Hot Water >55 0.20+0.05 and fittings, 1/4-inch
Room Air 202 copper tubing, compres-


TABLE 2
Tools Provided for Building Heat Exchangers


Hand Tools


* 8- and 10-inch adjustable
wrenches and locking pliers
* 1/2- to 9/16-in open end and
socket wrenches
* Cutting shears
* Tube cutter and bender
* Miscellaneous files and clamps
* Tap threading tools and drills
* Measuring tape and caliper


Power Tools


* Skil variable speed 3/8-in drill
* Craftsman 9-in drill press
* Delta 10-in compound miter saw
* Craftsman 9-in band saw
* Craftsman 42-in belt. 6-in disk
sander/grinder
* Dremel rotary tool, attachments
* Skil variable-speed jig saw


Figure 1. Experimental station to measure hot- and cold-
stream flow rates and temperatures in student-
manufactured heat exchangers.


sion fittings, and common insulation materials. Compression
fittings, PVC cement, and Teflon tape were used to seal the
connections. An allocation from the university laboratory fee
was used to purchase the materials. The average cost of a
heat exchanger was less than $20, and the department main-
tained ownership of the materials in order to recycle copper
tubing and compression fittings when possible.
Tools and Safety The project also provided students with
experience in using a variety of common hand tools and small
power tools-a complete list of tools for the project is given
in Table 2. While a few students already had significant prac-
tice with many of the tools, several indicated that they had
little or no experience. This provided an opportunity for in-
struction in basic safe practice using tools and materials.
Students were given training on the proper and safe use of
each hand and power tool, with the safety guidelines sup-
plied by the manufacturer of each power tool being used as
the basis for the training. The university's environmental
health and safety officer visited the laboratory to make a pre-
sentation and to measure the noise level in the vicinity of the
power tools-the conclusion was made that hearing protec-
tion was necessary around the power saws. Students were
issued leather gloves when using sharp hand tools and latex
gloves when using PVC pipe cement. Eye protection and
closed-toe shoes were required at all times during the con-
struction phase of the project. Students were not permitted to
use tools until they had completed the safety training.
Experimental Station The student-built heat exchangers
were tested on the experimental station shown in Figure 1.
The hot-water stream was generated in a constant-tempera-
ture circulating bath. Consistently cold tap water (straight from
the Minnesota shore of Lake Superior!) was used for the cold-
fluid stream. The flow rates were controlled with small ball-
and-pinch valves in the flow lines. Flow rates were measured
with McMillan 112 electronic flow meters. The temperatures
of the inlet and outlet streams were measured with type-K
thermocouples mounted in 1/4-inch brass tees placed in line
with the fluid streams, located near the points of entry and
exit. The temperatures and flow rates were monitored to de-
termine steady-state operating conditions, which were typi-
cally achieved in less than twenty minutes. By requiring 1/4-
inch connections for the feed and effluent tubes, the same
experimental setup was used to test all student-built heat ex-
changers without significant rearrangement.

DESIGN AND ANALYSIS
The second objective of this project was to enhance stu-
dent confidence in engineering design principles. They learned
the basic principles of heat exchanger design, including mass
and energy conservation, overall heat transfer coefficients,
and the log-mean temperature difference and effectiveness
number of transfer units (e-NTU) methods. They also par-
ticipated in discussions of nonideal behavior of heat exchang-


Winter 2005


I --









ers (such as the potential for heat exchange with the surround-
ings), orientation and fluid mixing, entrance and transition ef-
fects, and temperature dependent properties. Armed with these
skills, the teams were capable of designing a compact shell-
and-tube heat exchanger subject to the project constraints.
Each team was required to document its design calcula-
tions before it was allowed to begin construction. The teams
could not change or modify their basic designs once con-
struction began, to avoid a scenario of empirical design by
trial-and-error. The teams were also required to set up and
solve their design equations in computer spreadsheet appli-
cations, such as Excel, or general-purpose mathematics soft-
ware such as Mathcad, Polymath, or Matlab. An example of
student design calculations for a multipass heat exchanger
using Mathcad is available for download at www.d.umn.edu/~rdavis/htxr>.
Computer software tools allow students to quickly and ef-
ficiently perform a sensitivity analysis on their design equa-
tions and to investigate potential effects of uncertainty in
parameters such as operating conditions, material properties,
and heat transfer coefficients. For example, an analysis of
the overall heat transfer coefficient revealed that the conduc-
tion resistance through the wall of the copper tube was insig-
nificant for this project. It was also determined that heat ex-
change with the surroundings was negligible. The "design
first, build later" feature of the project was important for stu-
dents to develop their sense of engineering judgment and
transformed their skill set from the academic "learning by
doing" to the competitive edge of "learning before doing."[3]
Arange of creative designs emerged from the various teams.
The most common designs, illustrated in Figure 2, were varia-
tions on multipass heat exchangers imitating industrial con-
figurations. Students quickly discovered that correlations for
heat transfer coefficients specific to their design concepts were
not readily available in the literature, so they adapted gen-
eral-purpose correlations to
their geometries and flow con-
ditions. For example, one
team decided to coil the tube
in the shell and used a heat
transfer coefficient correlation
for cross flow over a cylinder (a)
for the fluid in the shell.
All of the groups designed
their exchangers for operation
with the hot stream on the tube
side and the cold stream on the
shell side, to minimize heat
(c)
transfer to the surroundings. F 2 S
SFigure 2. Schematics of co
They also noted from rations: (a) single shell-an
manufacturer's recommenda- flow pattern; (b) single shi
tions that PVC pipe is not suit- pattern; (c) single shell, m
able for hot-water plumbing pass with multiple-tube pa


mmI
d-tu
ell wv
ultil
ss.


service for temperatures exceeding 100F. Other design con-
siderations were tube spacing to allow the fluid to flow over
the available surface area for heat transfer and allowances
for tube length to include the designed heat transfer area re-
quirement plus accommodating the additional length required
by the pipe connections and tube fittings.

RESULTS AND DISCUSSION

A selection of student-built heat exchangers is shown in
Figure 3. In two cases, the shells were cut away to reveal the
interior tube configurations. The exchangers in Figure 3 are
representative of the construction materials used for the
project. PVC pipe and end caps were used for the shell, and
brass pipe and compression fittings were used for the copper
tube connections. The locations of the feed and effluent ports
were determined by the student teams to adapt their perfor-
mance and design calculations.
Teams that came to the laboratory well prepared were able
to construct their devices in approximately one hour. Appro-
priate preparation included team-member assignments for an
equal division of labor, a simple schematic with dimensions,
and an idea of where to cut, drill, and tap. Thirty more min-
utes were needed on a following day to test the performance
of the device. A few teams arrived at the laboratory ill-pre-
pared to begin construction and found that a considerable
amount of additional time was required to implement the fab-
rication process when they had only a general idea of how
the final product might look. In the future, teams will be re-
quired to present specific plans and a schematic for manu-
facturing their device, in addition to the basic design calcula-
tions, to avoid unusual laboratory time commitments.
At the end of the course, each student team had success-
fully designed and built a compact shell-and-tube heat ex-
changer that met the required performance specifications and
size objectives relative to the
prototype. The most success-
ful exchanger in terms of mini-
mizing size and weight used a
single copper tube making
four passes through the length
(b) of a 2-inch pipe. The success
) of the designs promoted stu-
dent confidence in the prin-
ciples of engineering design.
The students also gained an
appreciation for the limitations
of common assumptions (such
(d)
n ht e r c u- as steady-state operation, con-
on heat exchanger configu-
be bundle, countercurrent stant temperature or heat flux,
rith coiled tube, cross-flow perfect mixing, and constant
le-tube pass; (d) two-shell properties) typically required
to solve textbook problems.


Chemical Engineering Education









Some interesting questions were posed by the teams dur-
ing the construction phase of the project. For example, where
should the fluid inlets and outlets be located on the shell to
preserve the heat transfer area determined by the design cal-
culations? Students realized that their choice of feed and ef-
fluent port locations might have an effect on the fluid resi-
dence time in contact with the working heat transfer area.
Some other questions were posed regarding issues of fluid
mixing, stagnation, and entrance effects, as well as insula-
tion requirements and containing leaks. The best start-up pro-
cedure to eliminate pockets of air in the exchanger was also
considered. One team was particularly less careful than oth-
ers when assembling its exchanger. This team built a single-
pass shell-and-tube heat exchanger and found they could not
achieve steady-state operation. The team made the following
observations: the circulating bath reservoir was slowly drain-
ing, while the outside surface temperature of the shell was
increasing. They correctly deduced that the hot water was
leaking from the header into the shell side. This experience
fostered class discussions about how to improve the design
and further developed the students' troubleshooting skills.
Students reported that they enjoyed the project and appre-
ciated the opportunity to apply principles of heat transfer.
The teams were proud of their devices, gave them names,
and took them home to show friends and family. Much of the
learning came from interactions between the different teams.
Students were curious about the various designs that emerged
from the project and freely shared ideas for design and manu-
facturing tips during the construction phase. A friendly at-
mosphere of competition existed throughout the project and
lasted through the oral presentations. All of this combined to
generate enthusiasm for the subject matter of the course.
An informal discussion with several students revealed that
the project advanced their understanding of film theory, heat
transfer coefficients, and heat exchanger performance and
design methods. The students were also given a heat-ex-


Figure 3. Examples of student-built heat exchangers and
construction materials. At the left are examples with the
shell cut away to reveal a multipass and coiled-tube de-
sign. At the right are double-pipe and shell-and-tube heat
exchangers.

Winter 2005


changer design problem on the final exam in order to assess
the effectiveness of the project on student learning. The stu-
dents involved in the heat exchanger design project outper-
formed the classes from the previous three semesters on a
similar exam question, indicating that this project enhanced
their understanding of the material.
A few students claimed extensive experience with com-
mon hand tools from summer work experience, living on a
farm, or tinkering with engines. We worried that they might
find this project trivial and become disinterested, but were
pleased to find that they were equally enthusiastic about the
project and willingly shared their skills with the other stu-
dents. The mixture of students with a range of previous expe-
rience enhanced the overall learning experience for all stu-
dents in the class.
One drawback of this project was the additional time re-
quired of the students to be in a laboratory outside of lecture
periods. Reducing the lectures or including this project in the
unit operations laboratory may minimize the impact on stu-
dents' time demands. Another disadvantage was limited ac-
cess to tools. Currently, our department has only one set of
power tools, but there are plans to increase the availability of
tools to permit multiple teams working simultaneously.

CONCLUSIONS
A simple, inexpensive, hands-on learning project for stu-
dents to design and build compact shell-and-tube heat ex-
changers was assigned as part of a course on heat transfer.
Students worked in small teams of two or three, using the
basic principles of engineering design to propose a heat ex-
changer that would perform according to predetermined speci-
fications. The teams were required to manufacture their heat
exchangers according to their basic design calculations as an
integral part of the learning experience to encourage confi-
dence in the engineering principles and to develop their sense
of engineering judgment. The students gained mechanical
experience with basic tools and common building materials,
as well as lessons in safety. They were pleased with the out-
come of this exercise and recommended the project to stu-
dents that followed them.

ACKNOWLEDGMENT
This project was sponsored by a UMD Chancellor's Faculty Small
Grant.

REFERENCES
1. Peters, M.S., K.D. Timmerhaus, and R.E. West, Plant Design and
Economics for Chemical Engineers, 5th ed., McGraw Hill, New York,
NY, p. 12 (2003)
2. AIChE, The Global Environmentfor Chemical Engineering, New York,
NY, p. A-8 (2001)
3. Mancini, S., "Chemical Engineering in Process Development and
Manufacturing of Pharmaceuticals," ASEE Summer School of Chemi-
cal Engineering Faculty, Panel, "Industrial Needs from ChE Gradu-
ates," Boulder, CO (2002) J










re, classroom


A METHOD FOR


DETERMINING SELF-SIMILARITY


Transient Heat Transfer with Constant Flux



CHARLES MONROE, JOHN NEWMAN
University of California Berkeley, CA 94720-1462


When similarity solutions to partial differential equa-
tions are introduced in the classroom, the intro-
duction of similarity variables and the approach
to self-similar problems often appears to be something of a
"dark art." This paper provides an example to show how
proper dimensional analysis can be used to demonstrate the
existence of self-similar behavior. The procedure is as fol-
lows:
1. State the governing equations and boundary condi-
tions.
2. Rearrange any variables that can be combined in
additive or multiplicative groups to simplify the
governing equations and boundary conditions.
Simplifications that should always be performed if
possible include: rearranging the governing equa-
tions so one term has no coefficients, translating the
independent variables so inner boundary conditions
are at zero, setting all but one of the boundary and
initial conditions to zero by translation of the
dependent variable, and cross-multiplying the
boundary conditions so that they equal dimension-
less constants (e.g., 0, 1, or +).*L]
3. Write the dimensional-variable space of the problem
as a system of inequalities. Include dimensional
independent variables, dependent variables, and
system parameters that remain after performing step
two. State all lower and upper bounds of these
quantities. This bookkeeping measure concisely

In linear Dirichlet problems, the dependent variable should sometimes
be made dimensionless at this point in the procedure. An example is the
solution to the Navier-Stokes equation for impulsive motion of a flat
plate in a semi-infinite medium (also known as Stokes'first problem,
posed in Reference 1).


summarizes all variables and their possible values.
In addition, it clearly shows variables that can be
removed, or bounds that can be relaxed, during
asymptotic analysis.
4. Compose a dimensional matrix for the dimensional-
variable space. Determine the rank of this matrix.
Subtract the rank from the total number of variable
groups. If dimensionless groups arose during
rearrangement in step two, add one for each. The
result is the number of dimensionless degrees of
freedom involved in the problem.
5. If the number of dimensionless degrees of freedom
is two, a similarity solution exists. If the degrees of
freedom can be reduced to two by taking upper (or
lower) bounds of the independent variables to


John Newman joined the Chemical Engineer-
ing faculty at the University of California, Ber-
keley, in 1963, and has been a faculty senior
scientist at Lawrence Berkeley National Labo-
ratory since 1978. His research involves mod-
eling of electrochemical systems, including in-
dustrial reactors, fuel cells and batteries, and
investigation of transport phenomena through
simulation and experiment.


Charles Monroe recently completed his gradu-
ate study at the University of California, where
he investigated dendrite formation in lithium/poly-
mer batteries with Dr. Newman. He earned a
BS from Princeton University in 1999, received
the 2002 Dow Award for Excellence in Teach-
ing, and was granted a doctoral fellowship for
2003 by the Shell Foundation. Recently, he
joined the Department of Chemistry at Imperial
College, London, as a Research Associate.


@ Copyright ChE Division of ASEE 2005


Chemical Engineering Education











This paper provides an example to show how proper
dimensional analysis can be used to demonstrate the existence
of self-similar behavior.


infinity (or negative infinity), a similarity solution
describes this asymptotic regime.
We illustrate these steps below with the classic problem of
transient constant-flux heat transfer to a stagnant one-dimen-
sional medium between a conductive inner wall and an insu-
lated outer wall.
The earliest experiment under the conditions analyzed here
is credited to F E. Neumann, who performed experiments to
measure the thermal conductivity of solids. In 1862 he lec-
tured in Paris, proposing mathematics to describe bars heated
electrically at one end."2 He used the heat equation (with a
superfluous generation term) to obtain an expression for ther-
mal conductivity under conditions of constant flux; for cubic
bodies of low conductivity, he derived another expression to
show that temperature rises with the square root of time.
Preston's Theory of Heat references similar experiments by
0. J. Lodge (1879), and gives another incorrect mathemati-
cal treatment.?34] The finite problem was developed accurately
by Carslaw,1S5 and several avenues for solution of finite and


Conductive wall
qx = -k aT/ax


Insulating wall
q, =0


Figure 1. Experimental geometry for the heat-transfer
problem.

* To imagine a more concrete experiment, think of the wall atx = 0 as a
metal block, which has high thermal conductivity, and the wall atx = L
as a piece of low-density foam, both of which are impermeable to and
insoluble in the thermally conductive medium between. Assume the me-
dium is water, which is isotropic, has low viscosity, and is of intermedi-
ate conductivity. An electric heater supplies constant power to the metal.
The system can be oriented with respect to gravity to suppress the effect
offree convection.


semi-infinite cases were proposed by Carslaw and Jaeger,[6]
who were the first of these authors to mention a possible so-
lution by integrated error function complement. The similar-
ity solution was introduced as an exercise in the textbook by
Bird, Stewart, and Lightfoot.71'
Figure 1 shows a one-dimensional rectilinear region with
spatially uniform initial temperature To and walls at x = 0
and L. At time t = 0, a uniform and constant heat flux qx
(which may be positive or negative) is applied in the positive
x-direction at the conductive boundary x = 0; the boundary at
x = L is well-insulated.* We assume experimental conditions
with adiabatic walls parallel to the heat flux, effectively con-
stant and isotropic transport properties, and no homogeneous
heat generation.
Three solutions, valid at long times (Eq. 18), intermediate
times (Eq. 19), and short times (Eq. 20) are presented here.
Dimensional considerations are then used to realize a fourth
self-similar solution (Eq. 29), which describes asymptotic be-
havior in a semi-infinite medium or a medium observed at
very short times.

STATEMENT OF GOVERNING EQUATIONS:
INITIAL AND BOUNDARY CONDITIONS

We begin by writing the governing equations and bound-
ary conditions. The transient one-dimensional rectilinear heat
equation applies in this case

^ aT k a2T
pC at (1)

where p is density of the medium, Cp is its specific heat ca-
pacity at constant pressure, and k is its thermal conductivity.
Appropriate initial and boundary conditions are


T(0, x)= To

-k a
ax (t_>0,0)

(aT =0
X (t,L)


We seek mathematical solutions to Eq. (1) satisfying condi-
tions 2 through 4 that are easily calculated at all experimen-
tal time scales.
As a first approach to simplification, we apply the second


Winter 2005









step of our procedure, which results in this restatement:


a(T-To) k a2(T-T))
(5)
at pC ax2

T(0, x)- To = 0 (6)

k a(T-To) =-1 (7)
qx ax (t>o,o)

a(T -T) 0 (8)
ax (t,L)


The initial condition is now zero, and the governing equation
and boundary condition 3 have been rearranged. It is appar-
ent here that T0 appears only in an additive combination with
T, and that Cp and q. occur only in multiplicative combina-
tion with k.

STEADY STATE
FOURIER-SERIES SOLUTION:
LARGE-S LAPLACE-TRANSFORM SOLUTION
We now implement step three of the procedure. The di-
mensional-variable space of a problem summarizes the do-
mains of remaining dimensional independent variables, the
ranges of dimensional dependent variables and system pa-
rameters, and all known bounds of these quantities. While
not essential, this step is a useful tool to help clarify one's
thinking before approaching the differential equation. The
dimensional-variable space of the problem stated in Eqs. (5)
through (8) is


independent variables

dependent variable



parameters


00t<00




Ok- pm
PCp
k
-oo <-- <
qx


Inequalities 9 reflect that physical values of the properties
pCp and k are positive. The flux qx and temperature differ-
ence T To may take positive or negative values, because
heat can be added to or taken from the system, resulting in an
increase or decrease of temperature. The distance L between
walls has been included as the upper bound of x.
Step four is to apply the "Buckingham pi theorem" (the
rigorous development of which may be more appropriately


attributed to Bridgman, and the linear algebraic formulation
of which owes to Langhaar) to these groups of variables.89'"011,m
The dimensional matrix is

t x T-T,, k/pC, k/q, L
S 1 0 0 -1 0 0
m 0 1 0 2 1 1 (10)
K 0 0 1 0 -1 0

Matrix 10 is created by putting relevant fundamental SI units
to the left of the rows and elements of the dimensional-vari-
able space above the columns. The powers to which units are
raised in each variable determine the values of the matrix
elements.
There are 6 groups of variables, and the rank of the di-
mensional matrix is 3; therefore, by the pi theorem, the prob-
lem can be phrased in a dimensionless-variable space with
three degrees of freedom. If a two-dimensional boundary-
value problem with three dimensionless degrees of freedom
is separable and has a closed domain in one independent vari-
able, it can usually be reduced to a Sturm-Liouville system
in the closed domain if asymptotic behavior is subtracted from
the initial condition. Although our goal here is to illustrate
self-similarity, the Fourier-series solution and a Laplace-trans-

r


0.0 0.2 0.4 0.6 0.8 1.0



Figure 2. Plot of the long-time solution given by Eq. 18 and
the transient Fourier-series solution given by Eq. 19.


Chemical Engineering Education









form solution more useful at short times are shown now. The
Fourier series results from the standard approach to separable
partial differential equations; the next section will reveal that
the Laplace-transform solution relates fundamentally to the
result by similarity transformation.
At this point, the three dimensionless variables can be se-
lected by trial and error, with two dimensionless degrees of
freedom allotted to the independent variables and one to the
dependent variable. A more physically sound route to a natu-
ral set of dimensionless variables is provided by an overall
energy balance around the slab,

-tj. dS= pCp(T-To)dV (11)
s v
Upon simplification of the integrals, multiplication of both
sides by k, and some rearrangement, this energy balance re-
duces to the simple form


Od
0


In Eq. (12)


kt
SpCpL2


x -k(T T)
L qxL


which assigns the appropriate number of degrees of freedom
to the independent variables and the dependent variable. Sub-
stituting these variables into the governing equation and
boundary conditions, we find


ao a20


0(0, = 0


- (',>00)

JO0 =0
( ~1)


constant flux of heat, and therefore a constant increase or
decrease in system energy, the time derivative of the dimen-
sionless temperature approaches a nonzero value at long times.
To obtain long-time behavior when a system accumulates or
loses energy, the condition


T--f

should be employed. The solution that satisfies conditions
16 and 17 when t 0 is then

0,(,)=+ 2- 1 (18)
2 3
where the factor of 1/3 is included so that O, satisfies the
dimensionless energy balance given in Eq. (12). The Fou-
rier-series solution valid at all times is


(,)= + 12 ~ ~3 2 2 exp(-j2 2r)cos(ilOS )
2 3 n2 j=1
(19)

Equations (18) and (19) are plotted in Figure 2.
The rate of convergence of the Fourier series in Eq. (19)
slows as T -> 0. A series that converges much more rapidly is
obtained as follows. Take the Laplace transform of the prob-
lem with respect to time. A large-s expansion of this result
can be obtained by Maclaurin expansion of the transformed
problem with respect to exp(-,-). Term-by-term inversion
of this series by comparison with a table of Laplace trans-
forms"t21 gives an alternative to Eq. (19)

EO(, ) = 2 [ie fc" 2 + ierfc( 2+ 2 -- ] (20)
2-Fr2ief2j+


which converges rapidly at small values of T and is plotted
(16) in Figure 3 (next page). The integrated error function comple-
ments included in Eq. (20) are defined as the functions which
solve the differential equation


d2y +2zd 2ny=0
dz2 dz


n=-1,0,1,2,...


(21a)


Note that is always positive because the heat flux no longer
appears as a parameter.
A first step in the analysis of a transient partial differential
equation is to obtain a solution valid at long times.* Usually,
long-time solutions are obtained by discarding the terms con-
taining time derivatives, but because this problem involves


when n is equal to unity.
Ordinary differential Eq. (21a) is satisfied by functions of
the form"131
y = Ai"erfc(z)+ Bi"erfc(-z)


where


Winter 2005


* Taking the long-time form ofa transient equation to obtain an ordinary equation exemplifies a basic type ofastymptotic analysis: an independent variable
(t) can be removed from the variable space by assuming it takes a large value ( t -- 0 ). The governing equations and boundary conditions must then be
rephrased to reflect insensitivity to this variable (accumulation becomes a function ofx only). We applied this type ofasymptotic simplification implicitly
when reducing the problem to one spatial dimension.










i-lerfc(z) = 2 exp(-z2)


ierfc(z) = -f exp(-z2)dz = erfc(z)


i"erfc(z)= in-lerfc(z)+ in-2erfc(z) (21b)
n 2n


Solutions to Eqs. (14) through (17) given by Eqs. (19) and
(20) are identical. Fewer terms of Eq. (19) are required for
accuracy at long times, and fewer of Eq. (20) are needed at
short times.

SELF-SIMILARITY IN AN
ASYMPTOTIC REGIME
Previously, we used L to scale position x and time t. Step
5 of the procedure outlined in the first section of this paper
yields an asymptotic result for small T. Physically, the condi-
tion that << 1 corresponds to systems where the length scale
or volumetric heat capacity is large, or the thermal conduc-
tivity or time is small; the dimensionless energy balance given


by Eq. (12) further shows that when 7 is small, the di-
mensionless energy put into the system is also.
Under any circumstances where 7 << 1, L may be
considered to approach infinity, the domain of x be-
comes open, the number of columns in the dimensional
matrix reduces by one, and the degrees of freedom re-
duce to two. Parabolic problems that afford two dimen-
sionless degrees of freedom can be solved by grouping
the independent variables together in a single similar-
ity variable. This condition is called complete similar-
ity, or self-similarity of the first kind.1141
We choose two dimensionless variables, making sure
both independent variables are contained in one of them
and the dependent variable is in the other:


= 3ix kt


T-TO EkpC
e=B-q, Y---


(22)


Here, the similarity variable -q and dependent vari-
able 0 have been chosen because they are relatively
simple forms. To put x in the numerator of simplifies
back-substitution, because second derivatives of q with
respect to position are then zero. There is only one de-
rivative with respect to time in the governing equations
and boundary conditions and there are two with respect
to x, which suggests choosing a 0 that omits x, if pos-
sible. It should be noted that an ordinary differential
equation will result for any choice of dimensionless
similarity variable, as long as it excludes the depen-
dent variable and contains both independent variables.


We introduced constants 3, and P2 into relations (22); par-
ticular values for them can be selected later to simplify solu-
tion of the resultant ordinary differential equation and put
results in a standard form.
Taking L oo in Eqs. (5) through (8) and then inserting
relations (22) give


d20 1 dO 1

(oo0) 0

=o 1
dr = 0 P2
de =0
dj y-


Boundary condition (26) limits the asymptotic behavior of
the solution at large x, and is not as strict as Eq. (8), which
restricts the solution at a particular x. Substitution of rj into
Eqs. (5) through (8) as L approaches infinity to yield Eqs.
(23) to (26) represents a similarity transformation.


0.0 L-
0.0


0.2 0.4 0.6 0.8 1.0


Figure 3. Graph of the integrated error-function-complement
series solution, Eq. (20).


Chemical Engineering Education









Note that introduction of the similarity variable has re-
duced governing Eq. (5) to an equation of second order. In
problems that are amenable to similarity transformation, two
of the boundary conditions should collapse to a single condi-
tion. Either boundary condition (24) or (26) can be discarded
on the basis that it is superfluous-a solution that satisfies
governing Eq. (23) and one of Eqs. (24) or (26) must satisfy
the other.
If p, is chosen to be 1/2, then Eq. (23) matches Eq. (21a)
with n = 1. Boundary condition (25) takes its simplest form
when

I3132 =1 (27)
To satisfy Eq. (27), we choose P3 = 2. The dimensionless
similarity variables are


x ICp
2 V kt


and 0(1)-= 2(T-To) kpC
qx


A solution to Eqs. (5) through (8) when L oo is given by

(rI) = ierfc(ri) (29)
Equation 29 is plotted in Figure 4. Because

0 -
24r
this solution matches the first term of series 20 when reflec-
tions from the far wall are neglected. As an exercise, the stu-
dent can take the limit of series (20) when dimensionless time
approaches zero to retrieve the similarity solution.


0.6


0.5


0.4


a 0.3


0.2


0.1


0.0
0.0


0.5 1.0 1.5 2.0 2.5
11


CONCLUSION
A methodology has been proposed that allows stepwise
determination of self-similar solutions of the first kind by
dimensional and asymptotic analysis. The five-step proce-
dure is given in section 1, and is illustrated by the problem of
transient constant-flux heat transfer to a stagnant medium with
an insulated far wall in the remaining sections. Our approach
illustrates how simplifying governing equations and bound-
ary conditions according to certain rules and writing a di-
mensional matrix at the outset of a problem can effectively
guide its solution.
A procedure to obtain self-similar solutions of the second
kind, where the similarity variable can be used but more than
two dimensionless degrees of freedom are present, will be
addressed in future work. An example of a self-similar prob-
lem of the second kind is the transient mass transfer of a sol-
ute from a sphere at constant concentration into a stagnant
medium in which the solute is homogeneously consumed with
first-order kinetics.

ACKNOWLEDGMENTS

This work was supported by the Shell Foundation, and by
the Assistant Secretary for Energy Efficiency and Renew-
able Energy, Office of FreedomCAR and Vehicle Technolo-
gies of the U. S. Department of Energy, under contract DE-
AC03-76SF0098.

REFERENCES


1. Stokes, Sir G.G., Mathematical and Physical Papers, Vol. 1,
Cambridge University Press, Cambridge, U.K., 21 (1880)
2. Dorn, E., et al., Eds., Franz Neumanns Gesammelte Werke, 2nd
Ed., Vol. 2, Kraus reprint, Liechtenstein, 144 (1979)
3. Lodge, O.J., Phil. Mag., 251, 198 (1879)
4. Preston, T.. Theory of Heat, 41h Ed., Macmillan and Co., Lon-
don, U.K., 600 (1929)
5. Carslaw, H.S. Introduction to the Mathematical Theory of the
Conduction of Heat in Solids, 2nd Ed., Dover Publications, New
York, NY, 74 (1945)
6. Carslaw, H.S., and J.C. Jaeger, Conduction of Heat in Solids,
2"d Ed., Oxford University Press, Oxford, U.K., 52 (1959)
7. Bird, R.B., W.E. Stewart, and E.N. Lightfoot, Transport Phe-
nomena, 1" Ed., Wiley and Sons, New York, NY, 372 (problem
l.F) (1960)
8. Buckingham, E., Phys. Rev., 4(4), 345 (1914)
9. Bridgman, P.W., Dimensional Analysis, Yale University Press,
43(1922)
10. Van Driest, E.R., J. Applied Mechanics, 13(1), A34 (1946)
11. Langhaar, H.L., Dimensional Analysis and Theory ofModels,
Wiley and Sons, New York, NY, 31 (1951)
12. Churchill, R.V., Operational Mathematics, 2nd Ed., McGraw-
Hill, New York, NY, 464 (1958)
13. Abramowitz, M., and I.A. Stegun, Handbook of Mathematical
Functions with Formulas, Graphs, and Mathematical Tables,
4' Printing, National Bureau of Standards Applied Mathemat-
ics Series No. 55. Washington, D.C., 299 (1965)
14. Barenblatt. G.I., Scaling, Self-Similarity, and Intermediate
Asymptotics, Cambridge University Press, Cambridge, U.K.,
95(1996) 0


Winter 2005


Figure 4. The similarity solution yielded by Eq. (29).









curriculum


PROCESS SECURITY

IN ChE EDUCATION




CRISTINA PILUSO, KORKUT UYGUN, YINLUN HUANG, HELEN H. Lou*
Wayne State University Detroit, MI 48202


he tragedy of September 11, 2001, and subsequent
terrorist attacks have alerted the chemical pro-
cess industries to the need for plant security assur-
ance at all levels: infrastructure-improvement physical secu-
rity, information-protection cyber security, and design-and-
operation-improvement process security. Process security
is possibly the most difficult task due to the level of so-
phistication involved in integrating security with the pro-
duction process.
Security as a whole is an extremely complex subject due to
its unpredictable and improbable nature. Physical security
protects against attacks (such as bombings, theft, or sabo-
tage) by armed terrorists, disgruntled employees, political ac-
tivists, etc."' Lemley, et al.,"' discuss an approach to enhance
the process hazard analysis (PHA) by including a relative
risk assessment in order to establish physical security infra-
structure and programs. They also discuss physical security
countermeasures, including communication with local law
enforcement agencies, vehicle barriers that prevent driving
through fencing, alarms, access control, security cameras, and
double-gate entries.
Cyber security is defined by Baybutt[2] as the protection of
manufacturing and process control computer systems, along
with their support systems, from adversaries interested in
obtaining, corrupting, immobilizing, destroying, or prohibit-
ing access to important information. Baybutt also describes
asset-based methods for including cyber security vulnerabili-
ties in the assessment of a security vulnerability analysis
(SVA). Examples of cyber resources include computers, serv-
ers, operating systems, e-mail, user names and passwords,
process control data, and business plans, etc.
Despite these countermeasures being outside the realm of


* Lamar University, Beaumont, TX 77710


typical chemical engineering practice, the significance of
physical and cyber security should not be ignored.
Traditional process safety measures alone are no longer
sufficient for total plant security.[3' Process security is an ex-
tended concept and practice of process safety, but while the
typical scientific tools for safety assessment are based on
probabilistic analysis, security incidents are intentional rather
than accidental. In the chemical process security arena, a major
concern is the potential for an event that results in a cata-
strophic outcome, such as an explosion, a toxic release, and/
or loss of life.[41 If such an event is possible, even with a low
probability, it must be addressed and solutions must be found.
Process security cannot take probability into account-
the adverse events by terrorists or saboteurs do not follow
likelihood; they are completely unexpected. In this context,
attacks are due to harmful manipulations by saboteurs who
have sufficient technical knowledge rather than the brute force
that traditional security methods address. While no funda-

Cristina Piluso received her BS degree in chemical engineering at Wayne
State University in 2003. She is currently an NSF-IGERT fellow and a PhD
student working with Professor Yinlun Huang on process security assess-
ment and decision making using advanced computing methods.
Korkut Uygun received his BS and MS in chemical engineering from
Bogazici University (Turkey) and his PhD from Wayne State University. He
is currently a post-doc with Professor Yinlun Huang on the development of
dynamic optimization tools for IPD&C and has recently introduced a fast
security assessment theory for chemical processes.
Yinlun Huang is Professor of Chemical Engineering at Wayne State Uni-
versity He received his BS from Zhejiang University (China) and his MS
and PhD from Kansas State University all in chemical engineering. His
research interests are in process systems science and engineering, infor-
mation processing and decision making, computational biology, and sus-
tainable engineering.
Helen H. Lou is Assistant Professor of Chemical Engineering at Lamar
University. She received her BS from Zhejiang University (China), and her
MS and PhD (all in chemical engineering) and her MA (in computer sci-
ence) from Wayne State University. Her research and teaching interests
are mainly in the areas of process synthesis, modeling, control, and optimi-
zation, information technology, and industrial sustainability.


Copyright ChE Division of ASEE 2005


Chemical Engineering Education








mental method can hope to prevent the consequences of a
bomb being dropped on a facility, developing better-designed
processes can reduce the inherent vulnerability of a process.
Traditional process safety techniques that rely on steady-state
information, likelihood, and preset alarm systems may not
be sufficient for addressing process security problems.
With the first work describing process security, Lou, et al.,131
suggested that process security should be a
separate subject of interest, under a broader
umbrella of safety methodologies, and that Jn the
the objective in process security studies pr
should be the design of secure processes
through use of rigorous and deterministic -Oe ,j
simulation-oriented methods. Note that COBe6
while the objective is parallel with inherent potent
safety studies,151 the suggested method of so- evet 1
lution is quite different.
In this article, we discuss the value and in -at
necessity of a process-security concept in OUtCOm
undergraduate chemical engineering cur- an eXr
riculum, as an addition to or extension of tOXiC "8l
the existing process safety material. We will
also introduce a process-security analysis OT loS
tool, developed for educational use, that en- If such
ables a seamless and easy integration of the is pOSS
process-security concept to the process
safety and process design materials. W
probably
PROCESS SAFETY AND be addr
SECURITY IN EDUCATION soluti
Since process safety is of primary impor- j
tance to the chemical process industry and
is second nature for chemical engineers,16t
it should be systematically integrated into
chemical engineering education. The Center for Chemical
Process Safety (CCPS), under AIChE, has developed much
information in the area of safety and has disseminated it to
industry and to universities.1791 For more than a decade, the
Safety and Chemical Engineering Education (SACHE) Com-
mittee of the CCPS has generated various educational prod-
ucts for undergraduate curricula.'E10 These products have been
used, at different levels of details and comprehensiveness, in
a number of universities, including Texas A&M University,
Wayne State University, and Michigan Technological Uni-
versity. Courses on process-safety fundamentals and risk as-
sessment are very popular at those universities in their chemi-
cal engineering programs at both the undergraduate and gradu-
ate levels.111
Wayne State University has also developed several course
modules and used them in senior process-design courses, un-
der a grant from NSF's Course, Curriculum, and Laboratory
Improvement (CCLI) Program. The process safety materials


S SE
a.
rn
Ial

iat
tas1

e,s
fOS
ea
Fos




fty


ess


Winter 2005


and the teaching experience accumulated by the partici-
pating universities should be valuable as a model for other
chemical engineering programs to integrate process safety
into their curriculums.
Today, process safety education has become more impor-
tant than ever before, especially due to the need of homeland
security assurance. The nature of chemical industries, whether
due to the toxicity and hazardousness of in-
gredients used, the highly exothermic nature
"lCual of many reactions involved, or simply be-
rnurlvy cause of their importance as an essential
component of the infrastructure, presents a
mIIJO possible security target.
is-the The chief responsibility of handling these
for an issues naturally falls on the shoulders of
teSultS chemical engineers who have the most in-
sight into the process. As such, the concept
. f/l:ic of process security becomes a critical ele-
uch .as ment in chemical engineering education.
ion, a Chemical engineers must be made aware of
se, and/ their responsibilities and roles with regard
to process safety and security, and must be
f -hf. educated about the existence of process se-
1 event curity analysis methods and tools. While this
e n type of education represents a long-term ef-
fort, it needs to be addressed immediately.1121
lOW In chemical engineering, the available edu-
, it must national materials on process safety are truly
id and valuable for this purpose. The concepts,
scope, and underlying principles and meth-
SuIst odologies of process safety, however, should
id. be extended to meet the need for process
security.113-14'

PROCESS SECURITY EVALUATION
METHODOLOGY
The methodology used in this work is based on a Fast Se-
curity Assessment Theory introduced by Uygun, et al.5-
16] A deterministic, model-based, process-security concept
is a new subject with few related works."' Updating the
instructional materials will be necessary as progress takes
place in this area.
A security threat is defined as an incident that will result in
disaster if no effective countermeasure is taken, typically
occurring over a span of minutes or seconds.15' Under this
theory, a process is considered "secure" if the time needed to
detect and eliminate the threat (denoted as Minimum Time to
Disaster-MTD) is less than the time it takes for the system
to move from a nominal operation to a disaster condition,
assuming the worst conditions possible. It is quite apparent
that these time limits are dependent on the reaction type and
conditions present in the process in question.









Uygun, et al.,115-16] have developed two fundamental defi-
nitions in process security studies
Definition 1.[161 In most chemical systems, a plant
model consists of more than one system variable; yet
only afew of these need to be used directly to define
disaster boundaries, such as pressure. These variables
are referred to as critical variables.
Definition 2." A process is secure if

TT 2r (1)
where 7 (MTD, the Minimum Time to Disaster) is the
minimum time required by the process to move from
the nominal operation point to the disaster border; rr
(the resolution time) is the minimum time needed for
detecting the threat, making decisions, and taking
necessary countermeasures to eliminate the threat.
While an exact determination of the resolution time is
difficult, a large value (e.g., more than 15 minutes)for
MTD is generally a mild vulnerability; beyond an
hour should be considered secure, as this allows
ample time to prevent a disaster
Accordingly, the process security problem is mathemati-
cally given as

r= minjdt (2)
d(t) 0


s.t. dy = f(y,d,p) (3)
dt
Yc() = Yc,d (4)
yc(0)= yc.o (5)
dmin < d(t) < dmax (6)

where y is the vector of system variables and d is the vector
of disturbances. The reference points for defining the mini-
mum time to disaster (T) are the nominal operation point, yco,
and the disaster border, yc,d for the critical variable. Vector p
is a constant vector of design parameters. Process security
models (Eq. 3) have various requirements different from nor-
mal process models. They should be able to describe the sys-
tem to the limit of disaster. It should also be noted that in a
security-threatening situation, both manipulated variables and
disturbances can be the causes of security threat; hence
they are both included as disturbances. Uygun, et al.,[16]
further point out that some state variables are also directly
vulnerable to security threats and hence should be treated
as disturbances.

y -ANALYSIS
The process security problem in Eqs. (2-6) can be solved
in various ways, including the calculus of variations and con-


ventional numerical schemes employed for similar problems,
such as model predictive control. The convergence proper-
ties of existing dynamic optimization algorithms, however,
are generally poor if the models are nonlinear-this limits
the reliability of the results. This problem is caused by the
complexity introduced by time-dependence, which may cause
the optimization algorithm to be trapped in local optima.
Uygun, et al.,i51 have devised a novel approach to simplify
the solution process. The principal idea in the y-analysis is to
investigate the time derivatives of the system dynamic equa-
tions directly. The method involves discretizing the differen-
tial equations along the critical variable to create a number of
much simpler static-optimization problems. This simplifies
the problem significantly and drastically reduces the com-
plexity of the individual optimization problems (as compared
to conventional dynamic optimization schemes) so that the
results are far more reliable and can be obtained within sec-
onds. The method generates a "confidence interval" where
the MTD can fall in, rather than an estimate of the exact value.
This allows a fast security assessment for the process either
off-line or on-line; hence it is a justifiable engineering solu-
tion to the rather difficult problem of predicting how a
saboteur's mind works.
In addition to providing a confidence interval for MTD,
the y-analysis method facilitates further process analysis and
hence a more thorough process security assessment. This as-
sessment is performed through calculating the importance of
each variable on the overall system security and the time to
disaster; Uygun, et al.,~'61 define the importance as each
variable's "significance." Essentially, this is a sensitivity
analysis algorithm using the y-analysis method, and a calcu-
lated significance value is the relative change that would be
observed in MTD if the particular variable were under con-
trol. A large significance value implies that the variable is
critical for a disaster situation to occur. On the other hand, a
value of zero significance suggests that the variable in ques-
tion is not important from a process security point-of-view.
Significance analysis is a key function for design/retrofit stud-
ies using the y-analysis method.

INTEGRATION OF PROCESS SECURITY
INTO SENIOR DESIGN
The differences in the scope of the problem and implicit
assumptions about the nature of the safety and security threats
have already been summarized in the preceding sections, but
another important difference is the methodology employed.
Process safety is typically experience-based and is employed
through checklists and other managerial tools that may not
be sufficiently adequate for integration into an engineering
curriculum except specific safety courses. The vision in pro-
cess security, however, is to construct first-principles-based
deterministic models and use them (for instance with simula-
tions) to gain knowledge about the vulnerabilities of the pro-


Chemical Engineering Education









cess, and if possible, to eliminate the vulnerabilities through
modifying existing processes. As such, process-security prob-
lems feature a combination of control, design, and modeling
aspects, and thus require the students to be able to combine
and apply the skills and information gained in core chemical
engineering courses, such as mass and heat transfer, kinetics,
unit operations, process control, and design.
The major difficulty in integrating process security into
the undergraduate cur-
riculum lies in this very
multi-subject nature of
the problem. It is only in Prcess scy As
the senior year of an un- Versi
dergraduate curriculum op.ord w.
Laboratorylor Compute, Aided Proc
that the students can be DepientofChemticEng
expected to have suffi-
cient understanding of
the basics and to be able
to fully combine them
and analyze and synthe-
size process flowsheets.
Note that this is in con-
trast to process safety
that can be integrated
earlier. To avoid any I
RunDemo EnteSsn
problems in this regard,
we recommend that pro-
cess security be inte-
grated primarily into the Figure 1. Process secu
senior process design wi
and process safety
courses, so as to maxi-
mize the impact per time ratio on the students. Short demon-
strations about process security that rely on the software tool
introduced in this work, however, can be carried out at any
phase of the curriculum since it allows carrying out a basic
analysis without much insight into the details of modeling
and optimization.
Note that the same difficulties make process security an
excellent open-ended project for design and safety courses.
The analysis and solution require an understanding of dy-
namic modeling and conceptual design, a basic understand-
ing of optimization, and beyond that, analytical reasoning by
the students.
Sample module. The objective of a process security mod-
ule in a senior design course is to teach students how to ana-
lyze process performance under both normal and abnormal
conditions and to create retrofit solutions to compensate for
the security vulnerabilities by altering the design of existing
units, or adding supplementary units. The scope of a retrofit
problem can be adjusted to conceptual idea generation for
small projects, or completely integrated into a full-scale de-
sign project where process security is added as a third objec-


ity a
ndoi


sessrm
on 1.0
iyne SSl
ess Syst
ineenng


Winter 2005


tive in addition to economic and technical feasibility. The
first case will be exemplified in the case study section.

THE SOFTWARE
To aid in the instruction of process security, we have de-
veloped a MATLAB-based tool for educational use. This tool
enables application of the process security assessment theory
introduced by Uygun, et al.,[161 with a graphical interface and
various reporting tools.
The tool enables focusing
on the conceptual security
ent Software problem rather than on de-
tailed modeling, if that is
i .We.nive the objective of the course.
ems Science nd Engineering
end Maenrn Science Another important feature
is that the software per-
forms an optimization pro-
cedure, which is necessary
in the specific method em-
Sployed, "behind the
scenes," such that a knowl-
edge of optimization is not
necessary for security
analysis. This renders the
software ideal for under-
graduate education, where
optimization is usually of-
fered as an optional course
assessment tool-main by most chemical engi-
w. neering programs.
For educational use, the
software is envisioned as a tool that can perform the security
analysis for some typical example cases, where the system
parameters can be customized so that different problems can
be accommodated. These problems can be used as educa-
tional modules in related courses. The software can be used
for either simple demonstrations of security vulnerabili-
ties in an existing process or for an in-depth process se-
curity analysis project where students are asked to ana-
lyze a process and to create retrofit solutions to reduce or
remove vulnerabilities.
Upon entering the security evaluation program, the user
has the option to follow a walk-through demonstration, which
is a default example for demonstration purposes (see Figure
1). Another option is to enter a simulation environment where
the user can model a specific reaction process. Though fu-
ture work will involve expanding the capabilities of the se-
curity software, the current program is functional only for
a nonisothermal CSTR example that will be discussed in
the next section.
The software interface is simple and user friendly. If the
user runs into some confusion, help boxes are implemented
throughout the program, allowing the user to right click on










any item for a brief explanation of the button func-
tionality. Ample information on the theory, a step-
by-step walkthrough, and other documentation are
provided in the information menu (see Figure 2). The
case study being analyzed is fully customizable by
simply modifying the feed, outlet, and reactor pa-
rameters, including properties such as activation
energy, overall heat transfer coefficient, and re-
actor area (see Figure 3).

The software has two main functions: process se-
curity assessment and significance analysis. The
former is to evaluate a confidence interval on the
minimum time to disaster, and the latter enables prac-
tical evaluation of the significance for the param-
eters of the system with regard to their effect on mini-
mum time to disaster. The software is also capable
of producing graphical representations of the sys-
tem temperature profile as it escalates toward the
disaster boundary.

Instead of presenting a more detailed explanation
of the functions, an example problem is analyzed
using the software.

SAMPLE STUDY PROBLEM

* Problem Statement

Uygun, et al., 151 present the following differential
equations describing a nonisothermal CSTR, based
on modification of an example by Luyben117] (see
Figure 4)


dV
S= F0 -F (7)
dt

dV- = FN FOUT (8)
dt
dCA dV
Vd + CA d = FoCAO FCA VkCA (9)
dt dt
dT dV FVkCA UAH(T-
V -+T- = FoTo FT A H (T -Tj)
dt dt pCp pCp

(10)

Vj dTJ +T dV FINTJ -FTT, + UA (T-Tj)
dt dt pCjJ

(11)


where


k = Ae-E/RT (12

The system parameters and variable ranges are
listed in Table 1. In this example of a security threat,
the current control system is assumed not operational


and therefore characterizes manipulated variables as disturbances. The
reactor temperature (T) should be considered as a critical variable, since
temperature is the main variable of concern when there is a possibility
of a runaway reaction. It should be noted that the volumetric holdups in
the reactor and the jacket, reactant concentration and jacket tempera-
ture are also assumed to be "vulnerable" (i.e., they can be modified
instantly in a security threat condition) so are treated as disturbances. In
fact, only the reactor temperature is assumed to fully follow the govern-
ing differential model.

There are two obvious threat situations that would drive the critical
variable, and hence the exothermic reaction in this example, to disaster
conditions. First, redirection or shutdown of the cooling water will re-


I E


Non-lsothermal CSTR


Jewt Pmperte, |


JsckstOulput
Rae r-aoe1 i


~-ls


I M t w It s-.I |


ose


Figure 2. Process security assessment tool-
nonisothermal CSTR example.


pm-,~n Ier~


Pa.l..IM
Aea.aq Einae [El


Ana Md .M He. I.AHa
GeCa.iU [RI
PenaWi ui Facle. [lah


Hat Capaly cl LUquid m JRadd

Dmut oC Liquid I J ikL Idhe
Heal l Reic ..bn (Lddlc
Lame. Bomd Reaimo Vahm IV
uop aund Resl V-me IV
Up.e land Re Vca. IV


Reaaoor Properltes
Valu


(UI 1 3066.3
2 23.23

JI I 7.08B+01
tl C) 3 4
hl i 8OO195
I |11 419
J| 1 997795
S-69780
0l [ 001 98

I F I
ub| F ~


U.mn


,a:,mol
. ..,
4 i r, rr I
m^2 .
kJ/kmolK
1/h
k/kg K
kg/m^3
kJ/kgK
kg/m^3
kJ/lkol
m*3
m.3
m^3


Cancl LondD falt


Help Box
S a r .r .



I i i


Figure 3. Nonisothermal CSTR example-the reactor
properties window.


Chemical Engineering Education


~d~


.Icuiaia m





































































A --- B T


A Figure 4. Nonisothermal CSTR with a
cooling jacket.


Figure 5. Minimum time to disaster (MTD)
calculations for the nonisothermal
CSTR problem. >


TABLE 1
Variable Ranges and Parameters

Variable Name Minimum Nominal Maximum
Reactor Feed Flowrate (F,)(m3/h) 0 1.13 1.98
Reactor Output Flowrate (F)(m3/h) 0 1.13 1.98
Jacket Feed Flowrate (F,'")(mV/h) 0 1.41 2.83
Jacket Output Flowrate (F,""')(m/h) 0 1.41 2.83
Reactor Feed Temperature (T0)(K) 222.22 294.44 555.56
Temperature in Reactor (T)(K) 222.22 333.33 555.56
Temperature in Jacket (T,)(K) 222.22 330.33 555.56
Inlet Concentration (CA,)(kmol/m3) 0 8.01 16.02
Concentration (CA)(kmol/m3) 0 3.92 16.02
Volume of Liquid in Reactor (V)(m3) 0.02 1.26 1.98
Coolant Volume in Jacket (V,)(m3) 0.002 0.11 0.198

Parameters

Jacket Feed Temperature (Tj0) = 294.44K
E = 69,780 kJ/kmol
U = 3,066.3 kJ/h m2 K
A = 23.23 m2
R =8.314 kJ/kmol K
a = 7.08 1010 h
Cp = 3.14 kJ/kg K
p = 800.95 kg/m3
C, =4.19 kJ/kg K
p, = 997.98 kg/m3
h = -69,780 kJ/kmol


Security Assessment


1.5 < MinimumlTimetoOisMer < 67.4


Lowe Bound Ti Lt Uppe Bound Time ULi
IThis te s th telst time, coiderin the wot cae .cena.i (1 he tru dieow.e h Me consdeing the ~ l case seea.
that it would take fthe system ioe to diameter tr)h I o o laed k to the *sptem I o to o asaitm

SLoad Previous Results Close


PltAssct to Dbate F Loe Bnd Time


Po Ascen to Disadr F UWp Bound T. I


Process is NOTSECURE.


suit in a decrease in heat removal from the system, ultimately
leading to a runaway reaction. Second, an increase in the re-
actant concentration could provide similar effects as in the
first situation, granted higher concentrations of the reactant
are available at the plant.

* Tasks
Perform a process security assessment study using the soft-
ware. Specific questions to answer are
Q1 Is the process secure?
Q2 At what temperature does the temperature runaway
begin?
Q3 Which variables have a large impact on the mini-
mum time to disaster (MTD)?
Q4 Suggest multiple retrofit scenarios for the reactor to
reduce vulnerability, outline your reasoning, and
discuss the effect of your proposed change.

* Solution
The example stated above corresponds to the demo case in
the software, and is also the default value in the simula-
tion environment. As such, modification of parameters is
not necessary.
As specified earlier, the software comprises two main func-
tions. The first, "Security Assessment," enables evaluation
of a confidence interval for the minimum time to disaster.
Again, this interval represents the time it would take during a
security threat situation to proceed from the nominal opera-
tion to a disaster condition, considering the worst-case sce-
nario. This time range will give the user an understanding of
the overall security of their reactor. Choosing this function
opens the "Security Assessment" window, which, upon click-
ing the start button, makes the necessary calculations for
evaluation of the confidence interval (Figure 5).


Winter 2005


1~11111 1~1









Answer to Q1. The confidence interval of the
MTD is between 1.5 seconds and 67.4
seconds. Obviously, this time is too short for
any mitigation. The process clearly presents a
security vulnerability. The upper bound time
limit would have to be more along the line of
minutes or even hours, rather than seconds, in
order for the security threat to be reasonably
eliminated.

It is also possible to graphically depict the system as
it moves from the nominal operation to disaster. Two
figures are generated: the first representing the transi-
tion that yields the lower bound in the confidence in-
terval, and the latter corresponding to the upper bound.

Answer to Q2: The transition to disaster is
displayed in Figures 6 and 7. The exponential
behavior starts around 360 Kfor the upper
bound and 450 Kfor the lower bound. The
actual response will be somewhere between
these two curves. Choosing the lower bound
time, it can be stated that runaway reaction
begins at 360 K.

Answer to Q3: The second facet of the security
evaluation process consists of the generation
and analysis of the priority list, which gives
the significance and percent significance of
each reactor variable (see Figure 8). For the
given nonisothermal CSTR example, it is
shown that the two variables with the highest
percent significance, and hence the highest
effect in sending the process to disaster
during a security threat, are the jacket
temperature at just over 70% and the volume
of liquid in the reactor at about 25%. Signifi-
cance analysis is quite important in that it
illustrates the variables that need to be
monitored closely at all times. If a given
variable has a low percent significance, it
therefore has a low effect on the temperature
runaway.

Answer to Q4: The significance values hint at the
first clue by pointing out high significance
values for jacket temperature and reactor
volume: the heat from the jacket is instrumen-
tal in kick-starting the runaway reaction,
whereas a low volumetric content in the
reactor significantly increases the heating
rate. Consider changing the coolant and
jacket design such that it would start evapo-
rating at 400 K (Figure 9) and yet would not


create a significant pressure buildup in the jacket. This new
analysis yields the MTD between 6.4 seconds and 72
seconds. Now consider diluting the reactantfeed stock by
50% such that the maximum feed concentration is halved to
8.01 kmol/m3. A new analysis yields the MTD between 9.2
seconds and 150.4 seconds. Although we have easily
doubled the MTD, this is not sufficient to render the system
secure. Other modifications are possible but similarly have
limited effect. As such, the system displays an inherent
vulnerability that cannot be eliminated by a simple retrofit
of the reactor

CONCLUDING REMARKS
Process security addresses the most critical issues in pro-



1 I. A /,/ A. A'


figure o. temperature projle for me lower oouna
time to disaster.


Figure 7. Temperature profile for the upper bound
time to disaster.


Chemical Engineering Education


Ylullllllm~j~?/mll~~~i~l.mnrml~mn~lEln aeji~m~n










cess safety, as it concerns completely unexpected occurrences and the ex-
treme severity of process safety problems. As an integrated part of home-
land security, process security must be completely assured. To fully pre-
pare engineers with security knowledge, the authors propose to vertically
integrate the undergraduate curricula upon the theme of process security.

This paper has introduced a tool that can be implemented in under-
graduate process design and/or process safety courses to aid in the incor-
poration of simple but illustrative examples of the essential nature of pro-
cess security in a chemical engineering curriculum. This development is a
quantitative tool based on the dynamics of a system, which arise when the
process experiences various disturbances that may be set by saboteurs who
may have sufficient technical background. The software will be made avail-
able for instructors of the relevant chemical engineering courses upon writ-
ten request to Professor Yinlun Huang.


ACKNOWLEDGMENTS

This work is in part supported by the National Science Foundation un-
der grants CCLI-0127307, CTS-0211163, DGE-9987598, and CTS-
0407494.




SPriority Ust Calculation


15 < uiMWi ime to Dite < 67.4


Vaiable Name
Reactor Feed Flow Rate
Output Feed Flow Rate
Jacket Fee F Flo Rate
Jaket Outpt Flow Rate
Reslew Feed Temperate
Jacket Feed Temperalhe
Jacket Te pesaa.
Feed Concenratiem
Reactant Cfceneetreie
Voume o Liquid i Reacto
Coolaen Vaome Jacket


Signicance Pe.ant Sigrificane
n 02 0 04


I Ca ela Priort List Load Pe s- ReIis CloIse

Figure 8. Process security assessment-priority list.


REFERENCES
1. Lemley, J.R., V.M. Fthenakis, and P.D. Moskowitz,
"Security Risk Analysis for Chemical Process Facili-
ties," Process Safety Progress, 22(3), 153 (2003)
2. Baybutt, P., "Cyber Security Vulnerability Analysis:
An Asset-Based Approach," Process Safety Progress,
22(4), 220 (2003)
3. Lou, H.H., R. Muthusamy, and Y.L. Huang, "Process
Security Assessment: Operational Space Classifica-
tion and Process Security Index," Trans. IChemE. Part
B. Process Safety and Environmental Protection, 81(6),
418 (2003)
4. Center for Chemical Process Safety, Guidelines for
Analyzing and Managing the Security Vulnerabilities
of Fixed Chemical Sites, AIChE, New York, NY (2002)
5. Hendershot, D.C., "Designing for Safety in the Chemi-
cal Process Industry: Inherently Safer Design." Acci-
dent Precursors Workshop: Linking Risk Assessment
With Risk Management, July 17-18, 2003, Washing-
ton, DC, Washington, DC: National Academy of En-
gineering (2003)
6. Crowl, D.A. and J.F. Louvar, Chemical Process Safety:
Fundamentals with Applications, 2"d ed., Prentice-Hall,
Upper Saddle River, NJ (2002)
7. Center for Chemical Process Safety, Inherently Safer
Chemical Processes-A Life Cycle Approach, AIChE,
New York, NY (1996)
8. Center for Chemical Process Safety, Guidelines for
Chemical Process Quantitative RiskAnalysis, 2nd Ed.,
AIChE, New York, NY (2000)
9. Center for Chemical Process Safety, Layer of Protec-
tion Analysis, Simplified Process Risk Assessment,
AIChE, New York, NY (2001)
10. Dimitriadis, V.D., J. Hackenberg, N. Shah, and C.C.
Pantelides, "A Case Study in Hybrid Process Safety
Verification," Computers Chem. Engng., 20, Suppl.,
s503 (1996)
11. Mannan, M.S., A. Akgerman, R.G. Anthony, R. Dabby,
P.T. Eubank, and K.R. Hall, "Integrating Process
Safety into ChE Education and Research," Chem. Eng.
Ed., 33(3), 198 (1999)
12. Cunningham, S., "What Can the Industrial Chemical
Community Contribute to the Nation's Security," pre-
sented at the Workshop on National Security & Home-
land Defense: Challenge for the Chemical Science in
the 21" Century, National Academies of Sciences and
Engineering, Irvine, CA, Jan. 14-16 (2002)
13. Margiloff, I.B., "Geopolitics and Chemical Engineer-
ing," Chem. Eng. Prog., 97(12), 7 (2001)
14. Ragan, P. T., M.E. Kibum, S.H. Roberts, and N.A.
Kimmerle, "Chemical Plant Safety: Applying the Tools
of the Trade to a New Risk," Chem. Eng. Prog., 98(2),
62 (2002)
15. Uygun, K., Y.L. Huang, and H.H. Lou, "Process Se-
curity Analysis: y-Analysis and i-maps," AIChE J.,
49(9), 2445 (2003)
16. Uygun, K., Y.L. Huang, and H.H. Lou, "Fast Process
Security Assessment Theory," AIChE J., 50(9), 2187
(2004)
17. Luyben, W., Process Modeling, Simulation and Con-
trol for Chemical Engineers, 2"d ed., McGraw Hill,
New York, NY (1990) 0


Winter 2005


Load Defal I Cancel Save


Figure 9. Altered coolant properties.









S laboratory


KINETICS OF

HYDROLYSIS OF ACETIC ANHYDRIDE

BY IN-SITU FTIR SPECTROSCOPY

An Experiment for the Undergraduate Laboratory


SHAKER HAJI, CAN ERKEY
University of Connecticut Storrs, CT 06269-3222


he senior-level chemical engineering undergraduate
laboratory course at the University of Connecticut con-
sists of two four-hour labs per week, during which
groups of three to four students typically perform five ex-
periments during the course of the semester. Each experi-
ment is studied for either one or two weeks, depending on its
complexity and the scale of the equipment. The students are
given only the general goals for each experiment and are re-
quired to define their own objectives, to develop an experi-
mental plan, to prepare a pre-lab report (including a discus-
sion of safety measures), to perform the experiments and ana-
lyze the data, and to prepare group or individual written and/
or oral reports.
One or two of the experiments in this course involve reac-
tion kinetics. Over the years, we have encountered some chal-
lenges with reaction kinetics experiments, including inaccu-
rate, tedious, and/or outdated methods for measuring con-
centrations of reactants or products, and very long or very
short reaction times that make it difficult to monitor concen-
trations with current conventional methods.
We developed a reaction engineering experiment that em-
ploys in-situ Fourier Transfer Infrared (FTIR) spectroscopy
for monitoring concentrations. The FTIR is a nondestructive
technique that is increasingly employed by chemists and
chemical engineers to obtain real-time data by in-situ moni-
toring. Since no sampling is required, this analytical tech-
nique allows the reaction kinetics to be observed under ex-
perimental conditions without disturbing the reaction mix-
ture. The FTIR provides an effective but expensive analyti-
cal capability.
The hydrolysis of acetic anhydride (Ac20) to acetic acid
(AcOH) was selected as the model reaction.


0 0
II II
H3cC o 0 CcH3


+ H20 2


0
II
HjC/ ^oH


Quite a few studies have been reported in the literature on the
kinetics of hydrolysis of acetic anhydride.[l1,24,51 Eldridge and
Pirett41 obtained the pseudo-first-order reaction rate constant
using a batch reactor. To determine the acetic anhydride con-
centration, samples from the reactor were withdrawn into tared
flasks containing 15-20 times the quantity of saturated aniline-
water required to react with the sample. Since the anhydride
rapidly acetylates the aniline, producing acetanilide and ace-
tic acid, the samples were then titrated to determine the con-
centration of acetic acid. In another study, Shatyski and
Hanesian15' determined the kinetics of the above reaction by
using temperature-vs-time data obtained under adiabatic con-
ditions in a batch reactor.

Shaker Haji received his BSc in chemical en-
gineering from King Abdul Aziz University in
Jeddah (SaudiArabia) in 1999. He is currently
a full-time PhD student in the Department of
Chemical Engineering at the University of Con-
necticut. His research focuses on removal of
organosulfur compounds from diesel for fuel-
cell applications.



Can Erkey received his BS degree from
Bogazici University (Turkey), his MS from Uni-
versity of Bradford (England), and his PhD from
Texas A&M University. He is currently an asso-
ciate professor in the Chemical Engineering
Department at the University of Connecticut and
teaches chemical reaction engineering and ca-
talysis courses, both at the graduate and un-
dergraduate levels. His main research interests
are in catalysis and nanostructured materials.


Copyright ChE Division of ASEE 2005


Chemical Engineering Education









For this laboratory, the reaction is carried out in a batch
reactor at a minimum of three different temperatures. The
concentration of acetic anhydride is measured as a function
of time using in-situ FTIR spectroscopy. The data are then
analyzed to determine the reaction order and the rate con-
stant for this reaction. The resulting rate equation is used to
predict the performance of a semibatch reactor, which is then
compared to experimental data. This experiment requires three
laboratory periods if the students construct the calibration
curve themselves-otherwise, the teaching assistant can do
the calibrations and it requires only two laboratory periods.
The hydrolysis of acetic anhydride reaction is a suitable
reaction for many reasons. The final reaction product is a
harmless acetic acid solution with concentrations in water
ranging from 8 to 20 vol %. As with most chemicals, how-
ever, acetic anhydride and acetic acid should be handled in
the hood. Safety glasses are needed when handling concen-
trated or moderately concentrated acid solutions. Butyl rub-


2000 1800 1600 1400
Wavenumber, cm-


1200 1000


Figure 1. IR spectra of pure water, acetic anhydride, and
acetic acid.


Figure 2. Schematic diagram of the experiment setup.


ber or neoprene gloves should be used when handling con-
centrated solutions of acetic acid. Contact with eyes or skin
should be avoided. Furthermore, both the reactant (acetic
anhydride) and the product (acetic acid) can be monitored.
The IR spectra of the reactants and the product (see Figure 1)
indicate that each species has its own distinctive absorption
peaks that are not obscured by those of the other two species.
In addition, the rate of the reaction is such that a few experi-
ments can be carried out in a four-hour laboratory period.

THE EXPERIMENT SETUP

A schematic diagram of the laboratory apparatus is shown
in Figure 2. The reactor used in the experiment is a three-
necked, 500-mL jacketed flask equipped with a magnetic stir-
rer. Water is circulated through the jacket to keep the reac-
tion mixture at a constant temperature. A thermometer is fit-
ted into one of the side necks of the flask and immersed in
the reaction mixture. A mid-IR probe consisting of a zinc
selenide ATR (attenuated total reflectance) crystal is fitted
into the middle neck of the flask and submerged into the re-
action mixture. The probe is connected to a Remspec mid-IR
fiber-optic system comprising a bundle of 19 optical fibers,
which transmits in the mid-IR range, 5000-900 cm-'. Seven
of these fibers are attached to a signal-launch module attached
to the collimated external beam port of a Bruker Vector 22
FTIR spectrometer; twelve fibers are attached to an external
liquid-nitrogen-cooled MCT detector fitted with specialized
optics to optimize capture of the mid-IR signal from the end
of the fiber bundle. The data are processed using computer
software to obtain the IR absorption spectra.
For batch operation, the reactant (acetic anhydride) is in-
troduced at initial time through a glass stopper that is fitted
into the open neck of the reaction flask. For semibatch op-
eration, a graduated addition funnel is fitted to the neck that
can be calibrated to add acetic anhydride to the flask at a
desired rate. The reactor is initially filled with a known quan-
tity of water at the beginning of each experiment.

PROCEDURE

Before acquiring IR spectra during the reaction, a back-
ground spectrum of the empty reactor with optical fibers at-
tached is acquired. For each experiment, 150 ml of distilled
water is placed in the reactor. After heating or cooling the
reactor to the desired temperature, a background spectrum is
acquired again with the probe immersed in water.
For the batch mode, 10 ml of acetic anhydride is added to
the stirred reactor, and the reactor is sealed with a glass stop-
per. The spectra are acquired using the repeated measure-
ments option enabled by the software controlling the FTIR.
The settings are adjusted for the acquisition of a spectrum
every 50 seconds for 35 minutes. Spectral scans are taken at
4 cm-' resolution and signal averaged over 32 scans. The ab-


Winter 2005









sorbances of the selected peaks are measured from the indi-
vidual spectra. It takes around 30 seconds for the 32 scans to
be acquired.
Care should be exercised in selecting the operating condi-
tions or the scan number to make sure that the concentration
does not change significantly during the acquisition of each
spectrum. For example, at the beginning of the reaction at 350C,
the concentration of acetic anhydride changes by 11% during
the acquisition of the second spectrum (50-80 s).
For the semibatch reactor operation, an addition funnel is
placed in the unoccupied neck. The acetic anhydride addi-
tion rate can be set between 2 to 5 ml/min. Once the first
drop hits the water, the repeated measurements function is
activated so that a spectrum is acquired every 50 seconds for
one hour. The level in the addition flask is read at various
times to determine the rate of addition as a function of time.
The reaction mixture's temperature is recorded manually with
each IR spectra acquired or as needed.


THEORY

For a constant-volume batch reactor, the rate of appear-
ance of reactant A (acetic anhydride), rA, is given by

dA (1)
dt
where rA can be expressed as

-rA = kCnAC (2)

where k is the reaction rate constant, n and m are the reaction
orders with respect to species A (acetic anhydride) and B
(water), respectively. Since water is in excess, CB remains
essentially unchanged during the course of the reaction, and

-rA = k'C (3)

where k' is a pseudo rate constant

k'= kC = kCmo (4)

The specific reaction rate, k, is a function of reaction tem-
perature and is given by the Arrhenius equation

k = Ae-E/RT (5)

where A is a pre-exponential factor, E is the activation en-
ergy for the reaction, and T is the absolute temperature.
The reaction order and rate constant can be determined by
the integral method of analysis.131 In this method, the rate
expression is guessed and the differential equation used to
model the batch system is integrated. If the assumed order is
correct, the appropriate plot (determined from the integra-
tion) of concentration-time data should be linear. For a zero
order reaction with -rA = k, integration of Eq. (1) yields

CA =CAo-kt (6)


For the first-order case where -rA = kCA, integration of Eq.
(1) yields

n CA = kt (7)
CA

For the case where -rA = kCA2, integration of Eq. (1) yields

1 1
CA -kt (8)
CA CAO
The differential method can also be used to analyze the
rate data.13J In this method, the reaction rate at each concen-
tration is determined by differentiating concentration-versus-
time data. By combining the mole balance (Eq. 1) with the
rate law (Eq. 3), we obtain

dCA = kCA (9)
dt A
Taking the natural logarithm of both sides of Eq. (9) gives



5 0.6

2 X 0.5 a
4 [Ac20]= 2.931*X
R2= 0.9979
0.4
a3
a [AcOH] =13.414*X 0.3
R2 0.9997
2 '
P 0.2

o1 a
Acetic Anhydride
0 0.0
0.0 0.1 0.2 0.3
Absorption intensity

Figure 3. Calibration curves of acetic anhydride and
acetic acid.


0.12

0.10

a 0.08

e 0.06
o
< 0.04

0.02

0.00


1800 1600 1400 1200
Wavenumber, cm-

Figure 4. The hydrolysis of acetic anhydride at different times
[the acetic anhydride concentration is decreasing (1107 cm-')
and that of acetic acid is increasing (1287 cm-1)].


Chemical Engineering Education










n -CA = in(k)+ en iCA (10)

The slope of a plot of (n(-dC /dt) vs. (n CA) is the reac-
tion order.
For the semibatch reactor where species A is being added
to the system with a concentration of CAO, the following rela-
tion can be derived from the mole balance relationship:

V AdC +CA d rAV+VoCAO (11)
dt dt
where vo is the volumetric flow rate into the system and V is
the volume of the reacting mixture and is a function of time.

LAB SESSIONS AND RESULTS
Laboratory Period 1: Calibration Curve
In this session, the students learn how to operate the FTIR
spectrometer and acquire data. Before they construct a cali-
bration curve, IR spectra of the pure reactants (water and acetic
anhydride) and the product (acetic acid) are acquired. The
three spectra are compared, and the compounds that would
be monitored along with their distinctive bands are selected
(see Figure 1). Since water is present in excess, its concen-
tration is not monitored. The concentration of acetic anhy-
dride is monitored via the band at 1107 cm-1 associated with
the stretching of C-O-C bond because it's the strongest peak
and also does not overlap with the other peaks. The peaks
due to carbonyl could also be monitored (1821 or 1750 cm-').
The concentration of acetic acid is monitored via its C-OH
absorption peak at 1287 cm-' even though other peaks can
also be used, e.g., the carbonyl peak at 1703 cm-', which is
the strongest peak in the acetic acid spectrum, or the peak at
1407 cm-'. The peak at 1287 cm-1 does not overlap with the
other peaks, however.
The calibration curve for the concentration of acetic acid
solution in water vs. its absorption intensity is obtained by
acquiring the spectra of solutions with known concentrations
(e.g., 0.6 M, 1.0 M, 2.0 M, and 4.0 M), as shown in Figure 3.
It is not trivial to obtain a similar calibration curve for acetic
anhydride, for it readily reacts with water. It is possible, how-
ever, to obtain a calibration curve for acetic anhydride using
the calibration curve for acetic acid. At room temperature, 12
ml of acetic anhydride is added to 150 ml of water. The spec-
tra are acquired every 2.5 minutes (see Figure 4). In each
spectrum, the concentration of acetic acid is determined by
measuring the absorbance of the designated peak and using
the calibration curve. Given the reaction stoichiometry and the
initial concentration, the acetic anhydride concentration can be
calculated. Accordingly, a calibration curve for concentration
of acetic anhydride vs. absorption intensity of the assigned band
is constructed, as shown in Figure 3. Students are expected to
determine the ranges in which the calibration curves for both
acetic anhydride and acetic acid should be obtained.


Winter 2005


Figure 5. Plots of the appropriate concentration function vs.
time (a) zero order, (b) first order, and (c) second order reac-
tion with respect to acetic anhydride (integral method). Data
acquired at 25 C.









The calibration curves are obtained at room temperature
and are assumed to be valid over the range of temperatures at
which the experiments were carried out. It is also assumed
that the calibration of acetic acid in water solution is not af-
fected by the presence of a third species (acetic anhydride) in
the solution. Furthermore, it is possible to base the calcula-
tions only on measurements of the AcOH concentration and
then back calculating the Ac,O concentration without the need
to obtain a calibration curve for the latter.

Laboratory Period 2: Isothermal Batch Reactor

Once the calibration curves are obtained, experiments are
carried out in a batch reactor to determine the rate expres-
sion. Specifically, the hydrolysis of acetic anhydride in the
presence of excess water (78.3:1 H,O/Ac20) mol ratio, or
15:1 vol ratio) is carried out isothermally at room tempera-
ture (250C). The concentrations of acetic anhydride and ace-
tic acid are measured as a function of time. The concentra-
tion of acetic anhydride through the course of the reaction is
shown in Figure 5(a). The data collected are analyzed using
the integral method. The plot of CA vs. time, as shown in
Figure 5(a), and that of (I/CA- /CA) vs. time, as shown in
Figure 5(c), are not linear, indicating that the reaction is nei-
ther zero nor second order with respect to acetic anhydride.
As Figure 5(b) illustrates, the plot of 1n(CAO /CA) as a func-
tion of time is linear, which suggests that the rate law is first
order with respect to acetic anhydride concentration under
given reaction conditions of excess water. The slope repre-
sents the rate constant, k. The rate constant is found to be
0.169 0.0047 min-' at 250C, which is 7% higher compared
to that reported in the literature,[4] which is 0.158 min-' at the
same temperature. The same reaction is repeated at tempera-
tures of 15, 20, and 35'C. The data show the reaction is first
order at all temperatures studied and the rate constants are
found to be 0.0631, 0.0924,0.2752 min- 'at 15, 20, and 35'C,
respectively.
According to the Arrhenius equation (Eq. 5), a plot of
fn(k) vs. 1/ T should be a straight line and the slope is pro-
portional to the activation energy. Thus, knowing the reac-
tion rate constant at four different temperatures, the students
determine the activation energy and the pre-exponential fac-
tor. Once these values are known, k at any temperature could
be determined using the Arrhenius equation. The pre-expo-
nential factor is found to be 3.19*108 min and the activation
energy to be 53,408.3 J/mol (see Figure 6). The average
activation energy reported in the literature151 is 50,241.6
J/mol, which differs by -5.9% from the value reported by
the students.
The differential method can also be used to analyze the
data collected. For instance, the data collected for the reac-
tion at 150C are analyzed to obtain the reaction order and the
reaction rate constant. Only the data for conversion between
15% and 85% are used to increase the accuracy of the analy-


-1.0
-1.2
-1.4
-1.6
S-1.8
-2.0
S-2.2
-2.4
-2.6 Y =19.5809 6423.9*X
-2.8 R2 = 0.988
-3.0
3.2e-3 3.3e-3 3.3e-3 3.4e-3 3.4e-3 3.5e-3 3.5e-3

1/T, K-1

Figure 6. Determination of the activation energy and the
pre-exponential factor using the Arrhenius equation.


0 5 10 15 20 25 30


Time, min


Q


-2.5 -2.0 -1.5 -1.0 -0.5

ln(CA)


Figure 7. (a) Acetic anhydride concentration vs. time for
the batch reactor at 150C fitted to a polynomial. (b) Differ-
ential method used to determine the reaction rate constant
and order.


Chemical Engineering Education


CA=0.6332-0.03416*t+0.00056*t2
k R2 = 0.997


Y = -2.743 + 0.9996*X
2
R = 0.949


..S









sis. First, the concentration-time data are fitted to a polyno-
mial, as shown in Figure 7a. The polynomial is differentiated
to obtain the rate of reaction (dC /dt). As Eq. (10) illustrates,
a plot of en(-dCA /dt) vs. (n(CA) should give a slope equal
to the reaction order and an intercept of en(k). Figure 7b
represents a reaction with an order of one and a specific reac-
tion rate of 0.0644 min', which differs by 2% from the value
obtained by the integral method and -20% from that reported
in the literature,[41 which is 0.0806 min-'.

Laboratory Period 3: Isothermal Semibatch Reactor
In this part of the experiment, the students use the rate ex-
pression obtained in the previous laboratory period to predict
the concentration profile in an isothermal Semibatch reactor.
The software "Polymath" is used to solve the differential
equation given above (Eq. 11). In this experiment, the run is
divided into two periods. In the first period, the Ac,O is added
to water at a particular rate. Subsequently, the addition of
Ac20 is stopped and the reaction proceeds in batch mode until
all the Ac20 is consumed. The experiments can be varied for
different groups by changing the addition rate, the amount of
Ac20 added, or the reaction temperature. Figure 8 illustrates
the simulated and experimental concentration profiles for a
run carried out at 250C where a total of 29 ml of acetic anhy-
dride was added at an average rate of 3.55 ml/min. There is
close agreement between the predicted and the experimental
data, with a maximum difference of around 10% in the case
of acetic acid at the end of the run and around 20% in the
case of the acetic anhydride at the end of the addition. The
slight discrepancy may be due to errors in the measurement
of concentration of acetic acid, due to errors in the param-
eters of the rate expression, due to a slight deviation from
isothermal operation because of heat of mixing and exo-
thermic nature of the reaction, and/or due to errors in de-


0 Experimental [Ac,0]
Predicted [Ac,O]
-Predicted [AcOH] AAAA
A Expenmental [AcOH] / AAAA
/ A

/AA
/A





0 5 10 15 20 25


termination of the volumetric addition rate.

CONCLUSIONS
The use of in-situ FTIR spectroscopy for following the
hydrolysis of acetic anhydride reaction has been demon-
strated. The analysis of the batch reactor data showed that
the hydrolysis of acetic anhydride is a pseudo-first-order re-
action. The rate constants were calculated from the batch data
using both integral and differential methods of analysis and
were used to predict the performance of a semibatch reactor.
Predicted acetic anhydride and acetic acid concentrations were
in good agreement with the experimental concentrations. The
undergraduate students found this laboratory experience a
good opportunity to implement many of the concepts they
learned in their reaction engineering course.

NOMENCLATURE
A Arrhenius pre-exponential factor
C concentration
CA acetic anhydride concentration
CAO initial or entering acetic anhydride concentration
C, water concentration
CBS initial water concentration
E activation energy
k reaction rate constant
k' pseudo reaction rate constant
N number of moles
n,m reaction order
r reaction rate
R universal gas constant
t time
T temperature
V volume
v. volumetric flow rate

ACKNOWLEDGMENTS
We would like to thank the following students, whose data
are presented here: Joanna Domka, Sofia Simoulidis, Justin
McNeill, Allison Foss, Cliff Weed, and Jessica Zimberlin.
We are also grateful for the financial support of the School of
Engineering at the University of Connecticut for purchasing
this equipment.

REFERENCES
1. Wojciechowski, B.W., S.P. Asprey, N.M. Rice, and A. Dorcas, "Ap-
plications of Temperature Scanning in Kinetic Investigations: The
Hydrolysis of Acetic Anhydride," Chem. Eng. Sci., 51, 4681 (1996)
2. Glasser, D., and D.F. Williams, "The Study of Liquid-Phase Kinetics
Using Temperature as a Measured Variable," Ind. Eng. Chem. Fundam.,
10,516 (1971)
3. Fogler, H.C., Elements of Chemical Reaction Engineering, 3rd ed.,
Prentice Hall, New Jersey (1999)
4. Eldridge, J.W., and E.L. Piret, "Continuous-Flow Stirred-Tank Reac-
tor Systems. I. Design Equations for Homogeneous Liquid-Phase Re-
actions. Experimental Data," Chem. Eng. Prog., 46, 290 (1950)
5. Shatynski, J.J., and D. Hanesian, "Adiabatic Kinetic Studies of the
Cytidine/Acetic Anhydride Reaction by Utilizing Temperature versus
Time Data," bid. Eng. Chem. Res., 32, 594 (1993) O


Winter 2005


I Time, min

Figure 8. Comparison between the predicted and experi-
mental data obtained for an isothermal semibatch reactor
at room temperature.









W curriculum


VCM PROCESS DESIGN

An ABET 2000 Fully Compliant Project


FARID BENYAHIA
United Arab Emirates University Al Ain, United Arab Emirates


Process design projects constitute the ideal vehicle for
applying and acquiring chemical engineering knowl-
edge in all its forms. Indeed, accreditation bodies such
as ABET (USA) and IChemE (on behalf of the Engineering'
Council, UK) view the quality of senior design projects as a
sort of health check of the programs that lead to an under-
graduate degree. When properly researched by advising fac-
ulty members, senior design projects involving petrochemi-
cal processes can provide the complete ABET 2000 learning
outcomes from a to k. Indeed, when the overall chemical en-
gineering program learning outcomes show deficiencies in
certain areas, a design project is often the balancing mecha-
nism for bridging gaps in educational outcomes in the form
of "integrating learning umbrellas."
From the author's long experience in supervising a wide
range of senior design projects, the vinyl chloride monomer
(VCM) process can be considered one of the most diverse,
challenging, and complete design missions chemical engi-
neering undergraduate student groups can engage in. Indeed,
the VCM process history is well established, its safety and
environmental impact attributes are well documented, and
the diversity of process equipment associated with VCM plant
operations is second to none.
The VCM process is the subject of a case study in process
synthesis in the latest edition of the textbook written by Sieder,
et al."' In fact the VCM process is so "rich" in chemical engi-
neering principles and plant operations that it can be offered
to several groups of students in the same year with little or no
overlap-or it can be offered to single groups every year,
tweaking design objectives to make the successive years of
student design work experience complementary and cumu-
lative. This latter approach has been very powerful and gen-
erates useful educational data for faculty members interested
in surveying collaborative and cooperative learning in major
design assignments.
In this paper, the author shares his experience in supervis-
ing senior design projects in accredited chemical engineer-


ing departments (by the Institution of Chemical Engineers,
UK and ABET, UAE) by providing full details on the VCM
process, on the typical design tasks expected from groups of
students, and on the wider learning outcomes that make such
senior design projects fully compliant with ABET 2000. The
details of the process described in this paper are based on
extracts compiled from nonconfidential actual plant data sup-
plied by the European Vinyl Corporation to assist process
design at UK chemical engineering departments.

THE VCM PROCESS DESIGN BRIEF
Staged Learning Outcomes The design groups comprised
teams of 3 to 5 students. In the United Kingdom (Teesside
University) the groups had mixed-ability students, according
to GPA scores, and in the United Arab Emirates (UAE Uni-
versity), students were allowed to choose partners. The in-
structor acted as a client at the beginning of the project, but
thereafter acted as a consultant where "penalty points" were
incurred for excessive requests for help. The rule was clearly
explained to students at the outset and did not pose any par-
ticular concern. Such a rule is primarily aimed at showing
the degree of independence in the work achieved and is some-
what related to the final grade. This approach allows weaker
groups to make progress at a "cost," does not give unfair
disadvantage to more independent groups, and is considered
fair by students themselves.
The design project was presented to the students as a for-


Farid Benyahia is currently an associate pro-
fessor in chemical engineering at the United
Arab Emirates University. He was previously
senior lecturer in chemical engineering at
Teesside University (UK) and post-doctoral re-
search fellow at Leeds University (UK). He ob-
tained his BSc from the University of Aston in
Birmingham (UK) and his MSc and PhD from
the University of Newcastle (UK). His process
design experience, both industrial and academic
spans a period of over 20 years.


Copyright ChE Division of ASEE 2005


Chemical Engineering Education









mal "invitation for tender" from a "local" client in a suitably
phrased letter. A "standard starter pack" consisting of initial
references, essential design data or information not easily
available in the library was also distributed to the student
groups.[2-14] An extract of the content of this pack is presented
in the sections below.
The student groups were either allocated names of ficti-
tious contractor companies or allowed to name themselves
as such. They responded to the invitation for tender by sub-
mitting a design proposal that included details of the approach
to be adopted, milestones, and deliverables.
Students are exposed to a strong element of project man-
agement at the outset. The grading philosophy takes into ac-
count the following ABET learning outcomes that were staged
(denoted by the letters shown in parenthesis):
Literature study: market, available technologies, safety/
environment, societal impact, process route selection
(f h, j)
0 Acquisition or analysis of provided plant design data (b)
N PFD, material and energy balance of selectedprocess after
evaluating alternatives (a,c,d,e,k)
> PID and HAZOP study (d,e,f)
> Costing and project economic evaluation (h,k)
N Mechanical design of major items of equipment and
application of suitable standards (c,d,e,k)
> Final report, poster, presentation, web site (d,g,k)

DESCRIPTION OF THE PROCESS AGREED
TO BETWEEN CLIENT AND CONTRACTOR
The process agreed to (after a thorough literature review
and technical evaluation of alternatives) is based on the "bal-
anced" VCM process. It comprises 3 reaction sections, a pu-
rification section for the intermediate 1,2-Dichloroethane
(EDC), and a purification section for VCM. Process infor-
mation and data from real plants, compiled in a condensed
form,r21 are made available to students along with a list of
start-up references.13-"1 The substance and structure of infor-


TABLE 1
Extent of Side-Product Formation

FeClI in EDC Oxygen in feed Temperature B-tri formed
(g/m' as Fe) (% v/v in Cl) (C) (ppm w/w)
50 0.5 60 2000
2000 0.5 60 1500
50 2.5 60 500
2000 2.5 60 400
50 0.5 84 50000
2000 05 84 5000
50 2.5 84 10000
2000 2.5 84 2000


mation supplied to students were designed to encourage co-
operative work and critical thinking. This is presented in the
following sections and constitutes a sizeable amount of the
undergraduate design experience described in this paper.

DIRECT CHLORINATION SECTION
Process Chemistry The reaction between gaseous ethyl-
ene and gaseous chlorine to form EDC takes place readily in
a liquid EDC phase at moderate temperature and is strongly
exothermic. The further chlorination of EDC to beta-
tricholoroethane, or B-tri, (substitution reaction) takes place
to a limited extent. The substitution reaction is inhibited by
the presence of iron (in the form of FeCl3) and dissolved oxy-
gen. The effect of these inhibitors is additive. The degree of
substitution is also temperature-dependent. These relation-
ships (shown in Table 1) constitute a subject for discussion
among the students.
As can be deduced from Table 1, there are two possible
processes: 1) the "sub-cooled process" at 600C where EDC
is maintained below boiling temperature by circulation
through an external cooler, and 2) the "boiling process" where
the reactor contents are maintained at boiling by allowing
vapor to boil off and condense externally, with some of it
being returned to maintain the liquid inventory. The sub-
cooled process produces a purer organic product but is iron
contaminated, while the boiling process gives more B-tri but
can in principle be obtained iron free.
The material fed to the cracking furnace is
B-tri 500 ppm w/w
Fe 1 ppm w/w


Process Details The reaction of ethylene and chlorine
proceeds very rapidly. The rate-limiting factor is believed to
be the dissolution of ethylene in EDC. Therefore the reactor,
whether sub-cooled or boiling, should be designed to pro-
vide adequate residence time for the gas dissolution, to avoid
excessive liquid carry-over in the vapor stream leaving the
reactor, and for proper sparging of the feed gases into the
reactor. Actual production data suggests that a production of
500 kg/h EDC per m3 hold-up of liquid can be achieved. In
addition, sparging velocities of around 100 m/sec are appro-
priate.
To ensure complete reaction of the chlorine, it is normal to
work with a slight ethylene excess in the ratio of gases fed to
the reactor. The excess ethylene should be of the order 0.5 -
1.0 % by volume compared to chlorine. The presence of oxy-
gen in the chlorine feed, together with other flammables that
are present, gives rise to a potential flammability hazard in
the final vent from the direct chlorination reactor and must
be prepared for in some way.
If a sub-cooled reactor is chosen, the EDC product must be


Winter 2005










[The] VCM process can be considered one of the most diverse, challenging,
and complete design mission [for] chemical engineering undergraduate student. [The] process
history is well established, its safety and environmental impact attributes
are well documented, and the diversity of process equipment
associated with VCM plant operations is second to none.


washed to remove iron chloride. This is preferably done in
two stages-the first stage using water and the second stage
using dilute caustic soda. In each case, the volume of aque-
ous and organic phases continuously in contact should be ap-
proximately equal. The wet EDC must then be dried by azeo-
tropic distillation.
If a boiling reactor is chosen, there is no need to wash the
bulk of the product (providing precautions are taken against
liquid entrainment), and therefore no drying is required. There
will still be a need to periodically wash the purge stream,
however, when the solids content becomes too high. This is
normally done by pumping out the vessel contents batch-wise
to a wash system and replenishing it with a fresh catalyst
charge. This should be done when the ratio of EDC made to
vessel contents exceeds, say, 200. As stated before, boiling
reactor material will have to be processed through a distilla-
tion column to remove B-tri.
Vent gases can be released into the atmosphere providing
the total emission of chlorinated hydrocarbons is less than 10
kg/h, but precautions must be taken against a breakthrough
of chlorine due to loss of ethylene feed or any other reason. It
is normal to provide a large scrubbing tower that has a caus-
tic soda solution permanently recycled through it and is ca-
pable of neutralizing the full flowsheet rate of chlorine.
Feedstocks Ethylene is available at 100 psig (690 kPa)
pressure and ambient temperature. It will contain up to 400
ppm by volume of ethane.
Chlorine is available either as cell gas or as revaporized
liquid. Both can be made available at 30 psig (207 kPa). Cell
gas will contain the following impurities:


Oxygen
Nitrogen
Hydrogen
CO2


2% v/v
0.5% v/v
0.1% v/v
0.15% v/v


Revaporized liquid chlorine can be assumed 100% pure.

CRACKING SECTION
Process Chemistry EDC pyrolysis is an endothermic
reaction and is normally carried out as a homogeneous non-
catalytic gas-phase reaction at elevated temperature and pres-
sure in a direct-fired furnace. Free-radical chain reactions are
involved with chlorine atoms acting as the chain propaga-
tors. The product of the main reaction, vinyl chloride (VC),
is itself highly reactive towards free radicals. This gives rise
to a significant group of by-products that includes acetylene,


chloroprene, and dichlorobutenes.
The quantity of by-products formed per ton of VC made
increases rapidly as the fractional conversion of EDC per pass
("depth of cracking") increases (see Table 2).
Other factors such as the pressure, the level of impurities
(especially iron) in the EDC feed, the residence time of gases
in the cracking reactor, and the tube wall material used in
that reactor, all have some bearing on the by-product spec-
trum but it can be assumed that the depth of cracking is the
dominating parameter.
One by-product in the EDC feed, beta-trichloroethane, will
partially undergo pyrolysis to vinylidene chloride. Empirical
data indicates that the ratio of B-tri converted to EDC is
roughly 0.4.
As can be deduced from Table 2, a low depth of cracking is
desirable to minimize by-product formation. A low crack,
however, implies increased steam use in the distillation col-
umns used to separate the cracked gases and to further purify
the uncracked EDC before it can be recycled to the cracking
furnace. An optimum depth of crack is thus sought.
In addition to volatile by-products, tarry and carbonaceous
materials are formed in the cracker. They deposit inside the
reactor tubes and eventually cause reduced heat transfer and
increased pressure drop to such an extent that the reactor must
be shut down for decokingg." Real plant data shows that (not
surprising) the fouling is also a strong function of depth of
crack-this can be seen in Table 3.
Each decoke causes a shutdown of the reactor for about 72
hours. Fixed costs for the plant are $400/hour.
Process details Purified EDC is stored as a liquid at
ambient temperature in an atmospheric-pressure storage tank.
It has to be pumped up to pressure, vaporized, and passed
into the cracking furnace. The cracked gases are quenched
by a recirculation stream of liquid EDC to terminate the crack-
ing reaction, and then they pass through one or more con-

TABLE 2
Impurities Formed ppm w/w of VC Product

45% 50% 55% 60%
Crack Crack Crack Crack
Acetylene (C,H,) 1000 1600 2500 4000
Chloroprene (C4H,C1) 2000 3000 4500 7500
Dichlorobutenes (C4H6CI,) 3000 4500 7000 12000


Chemical Engineering Education









densers to partially condense the products.
The mixture is then separated into three constituents-HC1,
VC, and EDC. It is conventional to remove the HCI as the
overhead product from a first column and then to separate
the VC and EDC in a second column. The HCI overhead prod-
uct can be taken off as a vapor, but there is still the need of a
refrigerated condenser to provide reflux for the column. Eco-
nomics require that the VC column condenser avoid refrig-
eration.
A key parameter to select is the operating pressure. EDC
has to be vaporized at the front end of the process at one
pressure and HCI condensed at some lower pressure at the
back end, allowing for the pressure drop through the process
train. To help determine the appropriate pressure we need to
bear in mind that
1. The minimum pressure at the top of the HCI column should
be 100 psig (690 kPa) to enable HC1 to pass to the
oxychlorination section without compression.
2. The maximum temperature at which it is advisable to
vaporize EDC is about 220 C because
above this it tends to thermally degrade
and cause fouling of heat transfer surfaces.
TA
3. We must allow a reasonable pressure drop Depth of Cr
through the cracking furnace, especially
when fouled. Minimum values are Average Dep
typically 20 psig (138 kPa) clean, 35 psig of Crack(%
(241 kPa) fouled and we would allow 1/4" 45
(0.635 cm) coke layer formation inside the
cracker tube wall before decoking.
55
4. In the refrigeration machine for the HCI
condenser we would consider using an 60
environmentally friendly fluorocarbon
refrigerant as the working fluid, making
sure that we do not go much below
atmospheric pressure in the boiling Residence 1
refrigerant on the service side of the HC1 Exit '
condenser. This is to avoid having to
handle very large volumes of gas into the Mean Reside
Gases in Radi
suction of the refrigeration compressor and (aaed
calculateda
also to avoid air ingress into the machine, condition.
Other Design Parameters Maximum ra- 5
diant heat flux to cracker furnace tubes: 12000 9
Btu/hr.ft2 ( 37.85 kW/m2). Maximum inside 16
tube wall temperature for stainless steel grade
321: 570 C. Number of parallel tube passes
in furnace: 1 or 2 (more makes control diffi- TA
cult). Impurit
Table 4 shows the equivalence of residence Crac
time and cracker exit temperature to give the Cl lights
same VC output at same depth of crack.
C2 lights
Feedstocks and Products EDC fed to C4 lights
the cracker should have a minimum purity of C2 heavies
99% by weight. Specific impurity maxima are C4 heavies
shown in Table 5. ___


kBL
rack

th








,BL
rime
'emp

ce Tin
ant Sec
Ion ex
s) (sec)






LBL
y Ma
ing

2(
4(
1
1(


Definition of lights and heavies:
Cl lights: (CHC1, + CC1,)
C2 lights: (CH,Cl, C,H,C1,, C,HCl3, CH2)
C2 heavies: (CH3C13, CH,C4,, CC14)
C4 lights: (CH Cl)
C4 heavies: (CH Cl,)
The final vinyl chloride (VC) product produced should not
contain more than 100 ppm by weight total impurities.
HCI and EDC separated from the cracked gas mixture should
each not contain more than 200 ppm by weight of VC.

OXYCHLORINATION SECTION
Process Chemistry The oxychlorina-tion of ethylene by
HC1 and oxygen is catalyzed by copper chloride, normally
supported on alumina. In addition, a direct oxidation of eth-
ylene to CO2 occurs. Normally, oxychlorination is the domi-
nant mechanism and the oxidation reaction accounts for only
a few percent of the ethylene converted. Catalyst activity in-
creases with temperature but an increased
temperature favors oxidation at the expense
E 3 of oxychlorination. There is thus an opti-
ad Run Life mum temperature, and the acceptable oper-

verage Run Life ating temperature range in the reactor is
(days) small. This factor, combined with the high
300 exothermicity of the reaction, has led to the
250 use of fluidized-bed catalytic reactors for
large-scale operations. For fluidized-bed op-
180
erations, a mean catalyst particle size of
100 about 100 microns can be assumed. The
particle size distribution can also be as-
E 4 sumed if it is not available in the literature.
and Cracker In the absence of contact-time data for flu-
erature idized-bed operations, data for fixed-bed re-
actors can be used.
neof Exit Gas
Sof Exit Gas Some processes do employ multitubular
action (C)
it fixed beds, however. Comments on draw-
i backs of fixed-bed reactor technology for
525 highly exothermic systems are encouraged.
500 Experimental data obtained with a certain
475 catalyst formulation is shown in Table 6,
next page, (on a once-through, i.e., no-re-
cycle basis). In addition to the main
E 5 oxychlorination reaction to produce EDC,
ixima for there are other chlorinated hydrocarbons
Section formed. On analysis, an approximate com-

000 ppm w/w position of the dry organic product is found
to be
)00 ppm w/w
00 ppm w/w Cl lights (CHC1, + CC1,)
000 ppm w/w 8000 ppm w/w
C2 lights (CHC1, C2,HC1,, C2HC13)
50 ppm w/w 5000 ppm w/w


Winter 2005









C2 heavies (CH3CI3, C2H2C14, C2C14)
Balance EDC


12000 ppm w/w


It can be assumed that any acetylene and VC brought in with
the HCI is directly oxidized.
Process Details A major decision to be taken concerns
the construction material used for the reactor shell and cooler
bundle. Obviously, the gas mixture has to be kept above the
dew point or very rapid corrosion will ensue, but industrial
data shows that the onset of corrosion occurs at temperatures
well above the theoretically calculated dew point. This is due
to complex erosion/corrosion mechanisms that are not well
understood. There is also an upper temperature threshold
above which corrosion increases, but the effect is not so clear-
cut as the lower limit.
The key parameter to be studied in a metallurgical analysis
is the partial pressure of steam in the reactor product gas mix-
ture because this has a prime influence on the dew point. Table
7 shows recorded data.
The reactor must contain means of properly introducing
the main feeds, bearing in mind that ethylene and oxygen (or
air) should not be premixed outside the reactor. Facilities to
remove most of the catalyst particles entrained in the reactor
exit gases are also needed.
Upon leaving the reactor, the gases have to be quenched
and condensed, and residual HCI must be neutralized. The
organic and aqueous phases are separated, with the former
being sent to an azeotropic drying column and the latter to a
stripping column to recover dissolved EDC.
If an air fed process is chosen, the vent gasses leaving the
main oxy condenser must pass through equipment to recover
as much EDC as practical before being vented. If an oxygen
process is chosen, most of the gas will be recycled to the
reactor to achieve the desired gas partial pressures, and only
a small amount is vented to maintain pressure control.
Feedstocks and Products The compositions of ethylene
and HC1 were given earlier in this paper. Oxygen purity is
not critical and will normally be supplied as 99% by volume
at whatever pressure required. The EDC product purity was
also given. The aqueous effluent should be steam stripped to
give less than 5 ppm EDC by weight in the final effluent
discharge. Assume that the vent gas hydrocarbon content does
not exceed 10 kg/hour.
Plant Operation Data
> Plant attainment: 94%
> Annual production of VCM: 150 000 000 kg
Cost and Economic Data
Average market price for VCM (over period 2000-03):
$700/1000 kg
Average market prices for Ethylene, Oxygen ,and Chlorine
(over 2000-03) are 360, 45, and 150 US Dollars per metric
ton, respectively.


Expected plant life: 25 years
Capital: To be estimated from step-counting methods8" in
US dollars; prices must be adjusted for inflation using the
cost index in the United States. The total investment can be
distributed as follows:
Year I Design costs: 9% of capital cost
Year 2 Construction phase 1 costs: 45.45% of capital cost
Year 3 Construction phase 2 costs: 45.45% of capital cost
Year 4 Working capital: 13.60% of capital cost
Fixed operating costs were estimated to be
3.7% of the capital cost per year, up to year 10
4.6% of the capital cost per year after year 10, up to year 17
5% of the capital cost per year from year 17 onward
The variable operating costs were estimated to be
$15 per ton (1 ton = 1000 kg) of product up to year 17
$18 per ton of product from year 17

TYPICAL DESIGN TASKS
In the structured report, the student is instructed to
> Write a cover letter to your client when you hand in
your design report.


TABLE 6
Oxychlorination Kinetic Information


Conversions at contact
time of 15 sec


Operating temperature (C)


230 240 250 260
% HC1 converted 95 97 98.5 97.5
% CH4 to EDC 93 95 95 93
% C,H4 to CO, 2 2.5 3.5 5
% C,H4 converted 5 2.5 1.5 2

Conversions at operating
temperature of 250 C Contact time (sec)
10 15 20


% HCI converted
% total CH4 converted
% total 02 converted


96 98.5 97.5
95.5 98.5 98.5
90 96 98


Chemical Engineering Education


TABLE 7
Water Partial Pressures and Corresponding Acceptable
Temperature Ranges

Metal pp H, (bar abs) Acceptable Temp. Range (C)
Mild steel 1 200-260
1.5 None
Statnlis~srE 316- 1 190-300
1.5 210-300
2 None
Iconel 1 160-280
1.5 190-280
2 220-280
-Hastelloy I 160-300
1.5 170-300
2 180-300









> Write an introduction section that provides informa-
tion about VCM, its applications and safety issues, the
world market situation, and a balanced societal impact
(benefits and potential problems).
- Select a suitable site (in the country of residence of
students during their studies) to locate the VCM plant.
Justify your site selection and carry out an environ-
mental impact assessment, using accident or acciden-
tal spill/release scenarios.
Produce the complete PFD for the process described
above. Use a computer drawing tool.
- Carry out a complete material balance using the
spreadsheet presentation method. You may find it
convenient to divide the process into smaller sections
when reporting the material balance tables with
portions of the PFD in the spreadsheet.
Carry out a complete energy balance, stating clearly
any assumptions made. You may also employ HYSYS
for part of the energy balance calculations where there
is a justification for doing so.
> Produce a complete PID for the oxychlorination
section justifying all instruments implemented.
Carry out a detailed HAZOP analysis on 4 streams in
the oxychlorination section using keywords: NO,
LESS, MORE on deviation FLOW. You must refer to
the PID symbols produced before in the HAZOP
table. Adjust your PID in the light of recommenda-
tions from your HAZOP study.
> Carry out a detailed mechanical design of the
oxychlorination reactor and its ancillary equipment.
State and justify any assumptions made, and refer to
appropriate design standards.
Carry out the following economic analysis of the
process:
The net cash flow in each year of the project and plant
operation
The future worth of the project, NFW
The present worth, NPW, at a discount rate of 15%
The discounted cash flow rate of return, DCFRR.
Explore discount rates 25%, 35% and 40% to tabulate
values, but use Excel Solver for the final answer.
Produce a suitably labeled cash flow diagram too.
Estimate the pay back time.

ALTERNATIVE DESIGN TASKS
Different annual production rates may be given to differ-
ent groups or in successive years, according to situations in
departments (e.g., do students readily have access to past de-
sign reports? Are students monitored and quizzed periodi-
cally for original contribution? etc.). Mechanical design of
different major items (there are a few in the VCM process
and most are challenging) for each group or in successive
years (direct chlorination reactor, cracking furnace, distilla-
tion columns, etc). Depending on whether simulation tools


are allowed, the level of design complexity can be adjusted
accordingly. The process economic evaluation can be made
more complicated by assuming variable raw material costs
over the plant lifetime. HAZOP and operability studies can
also be made more challenging-that would be an ideal ex-
ercise for team cooperative work. The same approach can be
adopted for process instrumentation and control.

CONCLUSION

The VCM process design project has been offered to a
multitude of groups of international students in the UK and
UAE for a period spanning ten years and was found to be an
excellent vehicle for integrating scientific knowledge, chemi-
cal engineering principles, and a whole range of transferable
and interpersonal skills, thus making it a truly ABET 2000
compliant senior-design project. The way design informa-
tion has been provided to students enables them to engage in
critical thinking and to evaluate constrained alternatives. On
completion of the demanding design tasks, virtually all stu-
dents recognized the benefits of working on such projects.
The faculty member advising the students also benefited from
the experience of supervising such project and became in a
stronger position to revise curricula and propose relevant
changes where appropriate. Details of the VCM process pre-
sented in this paper are based on real plant data that are be-
lieved not to be available anywhere else, thus making this
article of major benefit to faculty members and students alike.

REFERENCES
1. Sieder W.D., J.D. Seader, and D.R. Lewin, Product and Process De-
sign Principles, Second Edition, John Wiley & Sons (2004)
2. Benyahia, F, "VCM Design Notes," Department of Chemical Engi-
neering, University of Teesside, UK (1995)
3. McPherson, R.W, C.M. Starks, and G.J. Fryar, "Vinyl Chloride
Monomer...What You Should Know," Hydrocarbon Processing, p.
75, March (1979)
4. Wong, E.W., C.P. Ambler, W.J. Baker, and J.C. Parks Jr., "Produce
High Purity VCM Product," Hydrocarbon Processing, p. 129, Au-
gust (1992)
5. Schillmoller, C.M., "Alloy Selection for VCM Plants," Hydrocar-
bon Processing, p. 89, March (1979)
6. Balasubramanian, S.N., D.N. Rihani, and L.K. Doraiswami, "Film
Model for Ethylene Dichloride Formation", Ind. & Eng. Chemistry
Fund., 5(2), 184, May (1966)
7. Encyclopedia of Chemical Technology, 23, p 865 (1990)
8. Coulson, J.M., J.F. Richardson, and R.K. Sinnott, Chemical Engi-
neering Design, Vol 6, Butterworth-Heinemann (2000)
9. Perry, R.H. and C.H. Chilton, Chemical Engineer's Handbook, 7'h
edition, McGraw-Hill (1998)
10. Treybal, R., Mass Transfer Operations, 3rd edition, McGraw-Hill
(1989)
11. Kern, D.Q., Process Heat Transfer, McGraw-Hill (1965)
12. Kletz, T., HAZOP and HAZAN: Identifying and Assessing Process
Industry Hazards, IChemE publication distributed by Hemisphere
Publishing Corporation (1992)
13. Kunii, D. and 0. Levenspiel, Fluidization Engineering, 2nd edition
(1989)
14. HYSYS 3.2 Process Simulation Package (physical properties, en-
ergy balance) O


Winter 2005









B, curriculum


ASPEN PLUS

IN THE ChE CURRICULUM


Suitable Course Content and Teaching Methodology



DAVID A. ROCKSTRAW
New Mexico State University Las Cruces, New Mexico 88003


ASPEN Plus software represents the standard in the
chemical process industries (CPI) for process simu-
lation. This software serves industries such as refin-
ing, oil and gas, chemicals and petrochemicals, polymers,
pharmaceuticals and specialty chemicals, power and utilities,
consumer goods, food and beverage, and engineering and con-
struction. It is used by forty-six of the world's fifty largest
chemical companies, twenty-three of the world's twenty-five
largest petroleum refiners, eighteen of the world's twenty larg-
est pharmaceutical companies, and seventeen out of the
world's twenty largest engineering and construction firms that
serve the CPI. This popularity is also evidenced in the aca-
demic community, where ASPEN Plus continues to be the
simulator of choice for studying process design and simula-
tion.15-'71 As such, providing undergraduates with a strong
background in ASPEN Plus is a desirable program trait for
many chemical engineering (ChE) departments, and is a re-
cruiting consideration to many employers of ChE graduates.
This paper does not attempt to teach the software, nor does
it contain teaching materials for use by instructors. Lecture
resources drawn from numerous sourcestl14 are available on-
line on the homepage of the author on the Chemical Engi-
neering Department's web server at New Mexico State Uni-
versity . Demonstration files can be
obtained from the author as well as from the Knowledge Base
of the ASPENTech website .

INCORPORATING ASPEN PLUS
INTO THE CURRICULUM
The topic of chemical process simulation is taught as a com-
puting laboratory integrated with a senior-level design course
at New Mexico State University. The ASPEN Plus simulator
is taught as a one-credit hour laboratory that is taken concur-
rently with a three-credit lecture on process design during
the first semester of the senior year. Students must demon-


state competency with the simulator in their last semester
by providing an independently worked solution to a chemi-
cal plant design problem.
It has been found that the fundamental ASPEN Plus educa-
tion is best taught through a watch-and-do method, using a
short discussion of a concept, followed by a live application.
Consequently, lectures become a forum for demonstration.
The homework assignments associated with each lecture are
then slightly modified, requiring the students to follow the
same keystrokes as they observed during the lecture. In do-
ing so, students learn to navigate the location of the major
features of the software, while interpreting the response
of the software.
The design projects) for the course (and subsequent
courses) are designed to compel the students to demonstrate
a more advanced level of understanding of these features than
the laboratory homework. Whenever possible, it is recom-
mended that previously built examples be used to demon-
strate new concepts. Homework should also be designed
around this principle.

DEFINING BASIC SKILL SETS
IN ASPEN PLUS
Because of the many levels of complexity associated with

David A. Rockstraw is Associate Professor of
Chemical Engineering at New Mexico State
University. He worked at DuPont, Conoco,
Ethyl, and Kraft prior to joining the NMSU fac-
ulty, and has been an active ASPEN Plus user
since 1990, applying the simulator to numer-
ous commercial syntheses. He was a coauthor
of the problem statement for the 1999 Ameri-
can Institute of Chemical Engineers' national
design contest and received the 2004
Aspen Tech Educational Innovation Award.


Copyright ChE Division of ASEE 2005


Chemical Engineering Education









ASPEN Plus, preparing to teach the tool in an undergraduate
curriculum can be as intimidating as preparing to learn the
software in that same environment. Preparation of a reason-
able curriculum that builds upon knowledge learned in pre-
vious lessons is critical in the training of students to begin
using the software independently. Such a program of study
must teach students to
Specify unit operations in rating and design modes
Manipulate physical property models and estimate
physical property parameters
Access variables to perform sensitivity analyses and
variable optimizations, or to specify design criteria
Insert user-specified code
Work with non-conventional materials, pseudocompo-
nents, electrolytes, and solids
Understand the interoperability of ASPEN Plus


Weekly computation laboratories permit f
a standard semester-based program (one
of the fifteen three-hour sessions is used
for student presentations). Each week
gives the opportunity to build up on the
concepts of the previous week.


HOMEWORK SUBMISSIONS

While the students should be aware
of the information that can be included
in an ASPEN Plus report file, and how
to modify such content, it is unneces-
sary (and a waste of paper) for students
to submit a lengthy report for grade
evaluation. Most of the simulations in
this semester course can be evaluated
from a three-page document that in-
cludes copies of the flowsheet, the
stream table, and the input file. Conse-
quently, it is worthwhile for the instruc-
tor to learn to interpret a simulation
from the input file. In addition, the in-
put summary generates a header that
contains time/date/user information that


ourteen topics for



TABL
Weekly Topic

Week Topic
1. Graphical User Inter
2. Distillation Models,
3. Distillation Models,
4. Stoichiometric Reac
5. Kinetic Reactor Mo
6. Physical Property M
7. Property Constant E
8. Accessing Variables
9. Accessing Variables
10. Accessing Variables
11. Electrolytes
12. Non-Conventional S
13. Optimization and PF
14. Interoperability


is unique for each user and file generated. This informa-
tion is useful in assuring that each student is submitting a
unique document.

SUBJECT TOPIC SCHEDULE
The basic schedule of topics discussed in this course (see
Table 1) can be categorized into five groups:
(1) Specifying unit operations
(2) Manipulating physical properties
(3) Accessing variables
(4) Specifying nonstandard components
(5) Applying advanced features


Specifying Unit Operations Early in the course, topics of
discussion center on specification of the most important unit
operations: the RADFRAC distillation column and the reac-
tor blocks. While these primary units are discussed, units of
lower complexity (such as the simple HEATER heat ex-
changer block) are included in demonstrated process flow
diagrams, and are thus also learned. The student becomes
comfortable with graphical user-interface (GUI) during
these discussions, and is prepared for the more difficult
concepts that follow.
Manipulating Physical Property Information Having es-
tablished students as "users" of the software, the next step is
to demonstrate the methods by which the software treats
physical property models and data. In two sessions, the stu-
dents are shown how ASPEN Plus obtains physical property
data, where the information is located within the GUI, and
how to generate parameters for components not present in
the database. Students initially make property comparisons
and generate parameters in the stand-
alone mode, then convert their files to
E 1 simulations.
Summary Accessing Variables Once students
have learned the basics of building a
face, Basic Unit Ops flowsheet, specifying unit operations,
and manipulating physical properties,
Rating Mode
ign Mode they are ready to begin learning to ac-
Desig e cess and manipulate variables within
tor Models the software. The ability to create man-
dels aged objects based on accessed vari-
ethods ables is a necessary skill for students
stimation System to derive from the program of study.
: Sensitivity Analysis Without an understanding of how to ac-
: Design Specs cess variables, one is unable to perform
:FORTRAN a sensitivity study, converge process
design specifications, or insert user-de-
fined code into a simulation. Thus, the
.olids and Substreams
ois an ustras fundamentals of accessing variables in
0D Customization ASPEN Plus is the most important con-
cept beyond flowsheet construction and
requires a minimum of three sessions
to complete. Tear stream convergence
is also considered during these sessions.

Nonstandard components By this point, students are ca-
pable of preparing a relatively sophisticated flowsheet of a
traditional chemical process in the sense that it contains only
conventional database components. Undoubtedly, students
have sought to perform simulations of processes that contain
aqueous salt systems, non-conventional components, or sol-
ids. While performing a simulation with such components is
not difficult, specifying such components differs from and is
slightly more difficult than simply selecting a species from
the database, as is done with standard conventional compo-
nents. Consequently, it is important that examples and prob-


Winter 2005









lems to this point in the course only include conventional
components.
The first feature covered in this section is the inclusion of
electrolytes in a simulation. The Electrolyte Wizard GUI
makes this the simplest of the concepts in this section to ap-
ply, yet greatly expands the students capabilities within AS-
PEN Plus.
In the second discussion, non-conventional solids and solid
substreams are introduced, affording the student the capabil-
ity of including heterogeneous solids in a simulation. This
discussion leads quickly to the ability to specify Solids sepa-
ration unit operations.
Advanced User Features Students have now become pro-
ficient in applying the simulator, and many have developed
the confidence to explore and apply some of the advanced
features on their own. The final two sessions supplement the
students' simulation capabilities by presenting them with op-
tions for fine tuning their programs, and enhancing the pre-
sentation of their works. In the first session, the optimization
and constraint capabilities are demonstrated. These features
are contained with the sensitivity analysis feature in the model
analysis tools folder, thus students already know of their ex-
istence, and some have likely used these attributes.
Customization of the PFD is also considered.
In the final session, students learn of the software
interoperability, with emphasis on integrating the numerical
results of the simulation with a spreadsheet. The spreadsheet
can be designed to perform subsequent equipment sizing and
economic calculations.
Advanced Elective Content The described fundamental
education in ASPEN Plus prepares the student for an elec-
tive course containing advanced simulator concepts, includ-
ing: specifying pseudocomponents; working with the
MULTIFRAC multiple column model; minimizing utilities
with MHeatX, rating exchangers with the HeatX block, writ-
ing ActiveX code to run the simulator in the background of a
spreadsheet, and ultimately, preparing a USER2 block based
on FORTRAN code and seamlessly integrating the block into
the software.


Bemonistration Lecture Details


E[ Week 1: Graphical User Interface, Basic Unit Ops
The introductory session should be informative, entertain-
ing, and, most importantly, not intimidating. The instructor
should open the software and build the first flowsheet from a
blank page, rather than start with the program opened to a
completed flowsheet. It is critical that the first example be
simplistic, with the emphasis of the first session more on be-
coming familiar with navigating the software than with the
details of the unit operations. A suggested protocol for this


session is
1. Discuss the need for chemical process simulation.
2. Explain the origin of ASPEN Plus (Advanced
Simulator for Process Engineering).
3. Discuss good flowsheeting practices (build large
flowsheets a few blocks at a time to facilitate
troubleshooting; check that units for input data match
values entered; ensure inputs are reasonable; check
that results are consistent and reasonable).
4. Navigate through the key features of the software,
including such items as the menu bar, tool bars,
process flowsheet window, model library, the "Next"
button, and the reporting functions.
5. Demonstrate common operations, such as switching
between the data browser and the process flowsheet
window. Perform these common operations by using
the toolbar and by using the menu, thereby allowing
each user to determine their individual preference,
rather than forcing them to use those of the presenter.
6. Establish the variety of unit operations available in
the software by scrolling through the items in the
module library. Comment on those that will be used
regularly, pointing out when each will be covered in
the curriculum.
7. Build and solve a simple material and energy balance
flowsheet employing only simple unit operations,
such as the Heater, Pump, and Flash2 blocks. Use the
"Next" button to fill in data upon completing
construction of the flowsheet.
8. Specify which property package to use without
justification, noting that later sessions will cover
physical properties in greater detail.
9. Prepare a report file and manipulate the content of
the report file.
10. Demonstrate to the students how to access the input
summary for purposes of preparing the submitted
documentation of their simulation.
11. Assign a flowsheet identical to the one prepared in
class, but request the material and energy balances be
performed for a different set of operating conditions
associated with the unit operations (i.e., the heat
exchanger and flash units operate at different
temperatures than used in class).

E[ Weeks 2 and 3: Distillation Models
The rigorous distillation model RADFRAC is the work-
horse of the separation models in ASPEN Plus. The number
of options and capabilities associated with the RADFRAC
block are tremendous. Consequently, it should be introduced
early in the course to give the student as much time as pos-
sible to become comfortable with using it. Each use of the
block should be directed toward specific goals to avoid over-


Chemical Engineering Education









whelming the student, however.
RADFRAC simulations can be per-
formed in design or rating modes. In
design mode, the simulation determines
the value of operating parameters to
achieve specified product criteria; while
in rating mode, the simulation provides
performance data (i.e., flowrates and
compositions of product streams) for a
column of specified geometry. The
modes of operation create a natural break
for two lectures.


Begin Week 2 with a one-column, two-component, rating
mode, RADFRAC simulation. Use a binary system for which
data is plentiful (methanol/water) and avoid systems that form
an azeotrope (ethanol/water). In rating mode, Design Speci-
fications and Vary statements are unnecessary since one only
seeks to understand the performance of a given column for a
specified feedstock. In the absence of these complications,
demonstration of Murphree efficiencies and the inclusion of
a pressure profile are simplified. Time should be dedicated
during this week to considering the wealth of results pro-
vided by RADFRAC, as well as to demonstrating the use of
the Plot Wizard to visualize results graphically.
Begin the discussion of the design mode in Week 3 by dem-
onstrating use of the DSTWU block (Winn-Underwood-
Gilliland method) to estimate the reflux ratio and number of
physical stages that are necessary to meet the design specifi-
cations of the product stream. Continue working with the same
chemical system that was used in demonstrating the rating
mode in Week 2. Reinforce to the student that DSTWU re-
sults are starting points, based on non-rigorous calculations.
Demonstrate replacing the DSTWU column with a
RADFRAC column once the needed design information has
been estimated with DSTWU, reconnecting the source and
destination streams to the new column. This simulation with
RADFRAC will employ the Design Specification and Vary
folders to complete the design calculation, which will also be
the first exposure to Object Managers in ASPEN Plus. Upon
completion of the basic material and energy balance calcula-
tions, the simulation can be enhanced with little additional
effort to perform tray-sizing calculations, another object man-
ager-based block.
Upon completing these two lectures, students will have been
introduced to the basic functions of the RADFRAC block.
In addition, the concept of an object manager will no
longer be foreign, allowing students to confidently ex-
plore similar folders.

[E Weeks 4 and 5:Stoichiometric and Kinetic Reactor
Models
The primary reactor models with which the student should


The design projects) for the course are
designed to compel the students to demonstrate a
more advanced level of understanding of these features
than the laboratory homework. Whenever possible, it
is recommended that previously built examples
be used to demonstrate new concepts.


become familiar can be categorized into three classes: bal-
ance-based (RStoich and RYield), equilibrium-based (REquil
and RGibbs), and kinetics-based (RBatch, RCSTR, and
RPLUG). The first class are the non-rigorous blocks that sim-
ply complete a material balance based on specified conver-
sion and yields. The equilibrium-based and kinetics-based
blocks use the rigor of equilibrium constants and kinetic rate
equations, respectively. As such, this natural distinction should
be used to divide the discussion of reactors into two parts.
In Week 4, the reactor blocks are introduced using the bal-
ance-based reactors. The object manager into which stoichio-
metric information is assembled can be demonstrated with-
out the need for a rate equation at this point. In addition, the
effect of using this non-rigorous method on the energy bal-
ance can be pointed out by performing the simulation by ig-
noring, specifying, and allowing the simulator to calculate
the heat of reaction based on heats of formation, then observ-
ing the effect on the duty of the reactor.
In the fifth week, the reactor block capabilities are extended
to include the equilibrium-based and kinetics-based blocks,
which share kinetic data from the Chemistry and Reactions
subfolders. Students are already familiar with the methods
for entering stoichiometry for each reaction at this point.
Emphasis can thus be afforded to assuring students under-
stand the reaction types (equilibrium, salt, dissociation, reac-
tion) and the power laws kinetic model (power law, Langmuir-
Hinshelwood-Hougen-Watson, reactive distillation, and user-
defined models based on FORTRAN code) at their disposal.


[E Week 6: Physical Property Methods
The selection of a property model package tends to be an
arduous task for students. To this point in the course, prop-
erty packages have been specified in demos and on home-
work assignments without justification, but there have un-
doubtedly been questions from the more inquisitive students
concerning how to select appropriate models.
To address this question, two tasks must be accomplished
first. A series of terms relevant to ASPEN Plus physical prop-
erties must be defined: property method, model, parameter,
and set. Secondly, management of Henry's Law components


Winter 2005









must be discussed. Point out that Henry's Law can only be
used with the Ideal & Activity Coefficient models.
Deliberating justifications for specifying a particular
method is usually a necessary aside at this point in the course.
It is helpful to summarize this discussion with a graphic de-
cision tree as that provided in Figure 1, providing a quick
mechanism for dividing the lengthy list of property methods
into two classes. Yet, this interchange does little to further
the students' knowledge of the simulator. The educational
endeavors associated with Week 6 should include: selecting
an appropriate method for a simulation based on the compo-
nents present; identifying and changing the model used for a
physical property calculation when a given method is ap-
plied; performing a stand-alone properties analysis; and
preparing an object manager containing a user-defined
property set for tabulation.


E Week 7: Property Constant Estimation System
While the ASPEN Plus Database of constituent chemicals
is quite large, there is often the need to work with a chemical
that is not in the database. The Property Constant Estimation
System (PCES) is used to estimate parameters required by
physical property models. It is used to estimate (i) pure com-
ponent physical property constants, (ii) temperature-depen-
dent property constants, (iii) binary interaction parameters,
and (iv) group parameters for UNIQUAC. Estimations are
based on "group contribution methods" and "corresponding
state correlations." Experimental data can be incorporated into
the estimation to improve accuracy of results.
The capabilities of the PCES are best demonstrated sequen-
tially. The connectivity of a component is first built in the
molecular structure folder, and its properties are generated
based strictly on atomic connectivity and molecu-
lar weight. The results are improved by then adding
some laboratory data for this pure component. In-
cluding vapor pressure data demonstrates the input An
of temperature-dependent data into the data pre
subfolder for a pure component. The estimations
are then further improved by including one or more
of the functional group contribution methods.
Are
Recommended exercises include nea
Estimate pure component parameters using
the general structure method
Define molecular structure using functional
group methods and approximate a structure
when ASPEN Plus is unable to completely sup
determine all functional groups from the
general structure
Incorporate experimental data into a
parameter estimation simulation Fig
Compare estimated property results versus


experimental values
Apply the PCES Compare function to identify
appropriate estimation methods when generating
parameters and properties for a component that is
similar to a component contained in the ASPEN Plus
database.


E Week 8: Accessing Variables: Sensitivity Analysis
The ability to access and manipulate the value of a variable
in ASPEN Plus represents a knowledge level at which the
student becomes capable of preparing simulations of a higher
degree of sophistication. The need to modify/record a vari-
able value occurs often in generating a process simulation,
particularly when one is attempting to define operating con-
ditions to meet a design specification. The concept of ac-
cessing a variable refers to references made to flowsheet
quantities. It is important to stress that the values of user-
entered variables may be manipulated directly; while ASPEN
Plus-calculated variables should not be overwritten, but should
be varied indirectly.
Emphasis on the introduction to this topic must be on the
process of accessing variables, and thus the first application
should be the least complicated. Introduction of the Sensitiv-
ity Analysis function provides a tool for applying the access-
ing variables technique, while providing a user-friendly pro-
cess evaluation tool that the students can begin using imme-
diately with their design projects, allowing students to study
the effect of changes in input variables on process outputs
and thus perform rudimentary optimizations. It should also
be noted that this method allows one to study the effect of
time varying variables using a quasi-steady-state approach.
The instructor should demonstrate displaying the results


re 1. Decision tree used in selecting an appropriate physical
property method in ASPEN Plus.


Chemical Engineering Education









graphically based on data in the Results form of the sensitiv-
ity block object manager, and should point out that changes
to flowsheet inputs made by the sensitivity analysis do not
affect the simulation as the base-case is run independently.
Homework developed to assess knowledge of the sensitiv-
ity analysis should be based on a simulation from a previous
homework assignment. A flowsheet with a recycle stream can
lead to some interesting results and can lead into a discussion
of manual selection and convergence of a tear stream (i.e., a
process in which effective convergence of the recycle loop
requires user intervention). Emphasis on this material is thus
dedicated to the application and interpretation of the access-
ing variables and sensitivity analysis tools, and expectations
of the workload related to these concepts can be increased.


E Week 9: Accessing Variables: Design Specifications
The Design Specification tool in the Flowsheeting Options
folder provides a type of feedback controller for setting the
value of a calculated flowsheet quantity to a particular value.
This objective is achieved by manipulating a specified input
variable. The specification portion of this tool provides a sec-
ond exercise with accessing variables.
It is important to note during this section that design spec
calculations are iterative; thus, providing a good estimate for
a manipulated variable will help convergence in fewer itera-
tions. This can be best learned by demonstrating a problem
that does not seem to work the first time the simulation is
run, allowing the students to contemplate the apparent dif-
ficulties. During the brainstorming to identify the con-
vergence problem, a checklist of things to investigate can
be generated:
See if manipulated variable is at one of the bounds
Verify that solution exists over range (hide the design spec
and perform a sensitivity analysis)
Confirm the manipulated variable affects the sampled
variables
Attempt to provide an improved initial guess
Change the convergence block characteristics (step-size,
number of iterations, algorithm, etc.)


E Week 10: Accessing Variables: In-Line FORTRAN
The last session covering accessing variables involves ma-
nipulating variables within ASPEN Plus through the use of
FORTRAN code executed during a simulation run. ASPEN
Plus can translate simple FORTRAN statements, with the
simulation engine; but complex code requires a FORTRAN
compiler. Many engineering degree programs no longer teach
FORTRAN, but this does not preclude teaching this tool as
the simple FORTRAN is understood by anyone with a struc-
tured language background.
When building the simulation that demonstrates the use of


inline FORTRAN code, indicate that one must provide ac-
cess to all flowsheet variables that are to be used within FOR-
TRAN statements, and that all read or written variables must
be declared. The execution sequence must also be specified.
Further remind students that, as with other accessing vari-
able techniques, only input to the flowsheet should be over-
written by the FORTRAN. When reviewing the simulation
output, show that the results of the execution of the FOR-
TRAN block must be viewed by directly examining the val-
ues of the variables modified by the FORTRAN block.


[E Week 11: Electrolytes
As noted earlier, the first feature covered in the non-stan-
dard materials section is electrolytes. The "Electrolyte Wiz-
ard" walks the user through the process of including electro-
lytes in a simulation. While the wizard makes specifying an
electrolyte system simple, there is some information and defi-
nitions that need to be provided during this demonstration.
Use of the Electrolyte Wizard
Generates new components (ions & solid salts)
Revises pure component databank search order so
that first databank searched is ASPENPCD
Generates reactions among components
Sets the property method to ELECNRTL
Creates a Henry's Component List
Retrieves parameters for reaction equilibrium
constant values, salt solubility parameters,
ELECNRTL interaction parameters, and Henry's
constant correlation parameters.
The student must ensure the simulated chemistry represents
the actual system, modifying the wizard-based process as
needed. Typical modifications may include
Adding to the list of Henry's components
Eliminating irrelevant salt precipitation reactions
Eliminating irrelevant species
Adding species and/or reactions that are not in the
electrolyte expert system database
Eliminating irrelevant equilibrium reactions.
The difference between the True Component Approach (re-
sults reported in terms of ions, salts, and molecular species
present after considering solution chemistry) and the Appar-
ent Component Approach (results reported in terms of base
components present before considering solution chemistry)
must be explained.
The limitations of the two approaches should be pointed
out. In particular, in the true component approach, liquid/liq-
uid equilibrium cannot be calculated and a number of mod-
els cannot be used (Equilibrium reactors: RGibbs, REquil;
Kinetic reactors: RPlug, RCSTR, RBatch; Shortcut distilla-
tion: Distl, DSTWU, SCFrac; Rigorous distillation:


Winter 2005









MultiFrac, PetroFrac). For the apparent component approach,
the chemistry may not contain any volatile species on the
right side of the reactions, the chemistry for liquid/liquid equi-
librium may not contain dissociation reactions, and the input
specification cannot be in terms of ions or solid salts.


E[ Week 12: Conventional-Inert solids, Non-conventional
solids & substreams
ASPEN Plus uses the concepts of component types, com-
ponent attributes, substreams, and stream classes to segre-
gate components that require separate equilibria calculations.
Conventional components are likely the only component type
used to this point in the course. Conventional components
participate in vapor/liquid, salt, and chemical equilibria, have
a defined molecular weight, and are located in the MIXED
substream. Demonstrations and homework to this point should
have used only the CONVEN stream class, the default for
simulations containing only a MIXED substream.
Understanding the need for multiple substreams, and thus
the other stream classes, requires an understanding of the two
other component types: Conventional Inert Solids (CI Sol-
ids) and Nonconventional Solids (NC Solids). At minimum,
it should be pointed out that CI Solids are solids that
Are inert to phase equilibrium and salt precipitation/
solubility
May undergo chemical equilibria and reaction with
conventional components
Have a molecular weight
Are located in a substream called CISOLID
while NC Solids are heterogeneous substances that
Are inert to phase, salt, and chemical equilibria
Are heterogeneous substances that do not have a
molecular weight (e.g., coal, ash, wood pulp, deposited
catalytic materials)
May react with conventional or CI Solid components
Are located in the NC substream
Although these materials are common to commercial chemi-
cal processes, they are not necessarily trivial to represent in
ASPEN Plus.


Component attributes are typically defined to represent the
composition of a component in terms of some set of identifi-
able constituents as illustrated in Table 2 for the major at-
tribute types. Students must be aware that component at-
tributes are assigned by the user, initialized in streams, and
can be modified by unit operation models. An example of a
fluidized bed reactor with catalyst regeneration unit is useful
to show all three of these concepts.
The number and types of substreams, together with their
attributes, define a stream class. A stream class can have any
number of substreams, but the first substream for each stream
class must be of type MIXED. Stream classes include
CONVEN, MIXNC, MIXCISLD, MIXNCPSD, MIXCIPSD,
MIXCINC, MCINCPSD; where the acronym contains some
combination of the substream acronyms MIXED, CISOLID,
and NC, and may end with PSD to specify that a particle size
distribution has been defined.
Solid properties calculated for conventional components
and conventional solids include enthalpy, entropy, free en-
ergy, and molar volume using property models in the prop-
erty method on the Properties/Specification/Global form. En-
thalpy and mass density are computed by property models
specified in the Properties/Advanced/NC-Props form.


EL Week 13: Optimization Function and Constraints / PFD
Customization
The last couple of sessions of the computation laboratory
are used to present subject matter beyond that of the casual
user. In the first of the final two sessions, the Optimization
function is demonstrated as a means to find extrema of an
objective function. The objective function is expressed in
terms of flowsheet variables and in-line FORTRAN using
variable accessing techniques. Constraints may be qualities
or inequalities. Equality constraints in an optimization are
similar to design specifications.
A simple demonstration simulation using both features
should be built by following the following steps, identifying
each step of the process as it is performed in the simulator:
Identify the measured (sampled) variables
Specify the objective function
Specify maximization or minimization of the objective


Chemical Engineering Education


TABLE 2
Details of Component Attributes

Attribute Type Elements Description
3 .-- niem ,fixed ca voatilo-man i .proximawlanalysis, weight % dry basis
ULTANAL Ash, C, H, N, Cl, S, O Ultimate analysis, weight % dry basis
SLFtANAL y- -ritic, stlfate, orgi -c- Forms of sulfur analysis, weight % of original coal, dry basis
GENANAL Up to 20 constituents General constituent analysis, weight or volume %









function
Specify constraints (optional)
Specify the manipulated variables
Specify the bounds for the manipulated variables
Like design specifications, the convergence of an optimi-
zation can be sensitive to the initial values of the manipu-
lated variables. It is best if the objective, constraints, and
manipulated variables are in the range of 1 to 100 (accom-
plished by normalizing the function). Furthermore, it should
be stressed that the optimization algorithm only finds local
minima and maxima in the objective function. With some
objective functions, it is possible to obtain different ex-
trema by starting at a different point in the solution space.
A visual demonstration to emphasize this effect will have
a lasting impact.
Presentation of the Optimization function tends to be com-
pleted quickly because the students have already been drilled
in the art of accessing variables. Consequently, this discus-
sion can be augmented with a demonstration of the numer-
ous PFD customizations that can be applied to the graphical
look of the flow diagram, including annotations and OLE
Objects. Use the PFD mode to change flowsheet connectiv-
ity by adding or deleting unit operation icons to the flow-
sheet for graphical purposes only. Since the PFD-style draw-
ing is completely separate from the graphical simulation flow-
sheet, students can improve the visual aesthetics of their flow
diagram for use in reports and presentations. One must re-
turn to simulation mode to change the simulation flowsheet.


El Week 14: Windows Interoperability
ASPEN Plus has been designed to achieve a high degree of
Windows interoperability. This includes the ability to copy
and paste simulation data into spreadsheets or reports, copy/
paste flowsheet graphics and plots into reports, create active
links between ASPEN Plus and other Windows applications,
embed OLE, and automate with ActiveX.
Students value the ability to perform Paste Links (live data
links that update applications as the process model is changed
automatically propagate results of changes). Most students
learn to perform a net present worth analysis in a spreadsheet
as a means of comparing project cash flows. Link an ASPEN
Plus sensitivity analysis to a spreadsheet that performs a com-
plete net present worth analysis by sizing equipment and es-
timating capital cost based on key simulation parameters, as
well as calculating direct costs based on material and energy
balance data. A worksheet based on each run of the sensitiv-
ity analysis can be used to graphically build a cost vs. operat-
ing parameter figure. If the appropriate operating parameter
is used in the sensitivity analysis, a minimum in total cost
will be observed in the figure. The direct and indirect costs
can be shown as separate additive functions, giving rise to
the minimum. Such a demonstration thus represents a strong


reinforcement of basic engineering economy concepts.

SUMMARY
ASPEN Plus is the most powerful chemical process simu-
lation tool available, but is not a typical Windows-based pro-
gram that can be learned by trial-and-error. The most effi-
cient manner to learn the software is through a thought-out
curriculum in which examples are introduced in an order that
builds on previously learned concepts, and all concepts are
reinforced with hands-on demonstrations. Students can com-
plete an undergraduate degree and enter the workforce of the
chemical industry with more than a working knowledge of
the ASPEN Plus. This can be accomplished without requir-
ing an overly demanding academic workload if the instructor
assembles an appropriate curriculum.

REFERENCES
1. ASPEN Plus software documentation
2. ASPENTech Process Simulation course materials
3. ASPENTech Physical Properties in ASPEN Plus course materials
4. ASPENTech Instructor Toolkit
5. Kim, J.K., and P.C. Wankat, "Quaternary Distillation Systems with
Less than N-l Columns," Ind. & Eng. Chem. Res., 43(14), 3838 (2004)
6. Van Hoof, V, L.Van den Abeele, A. Buekenhoudt, C. Dotremont, and
R. Leysen, "Economic Comparison Between Azeotropic Distillation
and Different Hybrid Systems Combining Distillation with
Pervaporation for the Dehydration of Isopropanol," Sep. and Purifi-
cation Tech.; 37(1), 33 (2004)
7. Bisowarno, B.H., Y.C. Tian, and M.O. Tade, "Interaction of Separa-
tion and Reactive Stages on ETBE Reactive Distillation Columns,"
AIChE J., 50(3), 646 (2004)
8. Kaantee, U, R. Zevenhoven, R. Backman, and M. Hupa, "Cement
Manufacturing Using Alternative Fuels and the Advantages of Pro-
cess Modeling," Fuel Proc. Tech., 85(4), 293 (2004)
9. Dirk-Faitakis, C.B, and K.T. Chuang, "Simulation Studies of Cata-
lytic Distillation for Removal of Water from Ethanol Using a Rate-
Based Kinetic Model," Ind. & Eng. Chem. Res., 43(3), 762 (2004)
10. Jayawardhana, K, and G.P. Van Walsum, "Modeling of Carbonic Acid
Pretreatment Process Using ASPEN-Plus (R)," Appl. Biochem. and
Biotech., 113-16, 1087 (2004)
11. Smejkal, Q., and M. Soos, "Comparison of Computer Simulation of
Reactive Distillation Using ASPEN Plus and HYSYS Software," Chem.
Eng. and Proc., 41(5), 413 (2002)
12. Pacheco, M, J. Sira, and J.Kopasz, "Reaction Kinetics and Reactor
Modeling for Fuel Processing of Liquid Hydrocarbons to Produce
Hydrogen: Isooctane Reforming," Appl. Catal. A-General, 250(1),
161 (2003)
13. De Simon, G.F. Parodi, M. Fermeglia, and R. Taccani, "Simulation of
Process for Electrical Energy Production Based on Molten Carbonate
Fuel Cells," J. of Power Sources, 115(2), 210 (2003)
14. Zheng, L.G. and E. Furimsky, "ASPEN Simulation of Cogeneration
Plants," Energy Conv. and Management, 44(11), 1845 (2003)
15. Lim, C.S, Z.A. Manan, and M.R. Sarmidi, "Simulation Modeling of
the Phase Behavior of Palm Oil-Supercritical Carbon Dioxide," J.of
the Amer Oil Chem. Soc., 80(11),1147 (2003)
16. Kuchonthara, P., S. Bhattacharya, and A. Tsutsumi, "Energy Recu-
peration in Solid Oxide Fuel Cell (SOFC) and Gas Turbine (GT) Com-
bined System," J. Power Sources, 117(1-2), 7 (2003)
17. Rivera, W., J. Cerezo, R. Rivero, J. Cervantes, and R. Best, "Single
Stage and Double Absorption Heat Transformers Used to Recover
Energy in a Distillation Column of Butane and Pentane," Inter J. of
Energy Res., 27(14), 1279 (2003) 0


Winter 2005









SOclassroom


ENVIRONMENTAL IMPACT

ASSESSMENT

Teaching the Principles and Practices by

Means of a Role-Playing Case Study


BARRY D CRITTENDEN AND RICHARD ENGLAND
University of Bath Bath, UK, BA2 7AY


Environmental impact assessment (EIA) is an impor-
tant technique to help ensure that all the likely envi-
ronmental effects of a new development are under-
stood and taken into account before permission to proceed
with a development is given. The governing legislation var-
ies from country to country. In the USA, the 1969 National
Environmental Policy Act (NEPA) requires that an EIA must
be carried out for federally funded projects likely to have an
impact on the environment. This policy set the precedent for
European legislation (EC Directive 85/337). In the UK, the
most recent regulations are Statutory Instrument 1999 No 293
(The Town and Country Planning [Environmental Impact
Assessment][England and Wales] Regulations 1999) avail-
able from the HMSO web site at si/si 999/19990293.htm>.
Since many developments in chemical engineering un-
doubtedly have the potential to create significant environ-
mental impacts, EIA should form a key component of the
undergraduate chemical engineering curriculum. Suitable
texts are Wathern,'1 Petts and Eduljee,[21 Kreske,[31 Marriott,[41
etc. Environmental Impact Statements (EISs) to illustrate
teaching are readily available in the public domain and for
the USA are listed on the EPA Office of Federal Activity's
web site index.html> by date of distribution. A keyword search for
environmental assessment information can be completed by
searching the Federal Registry at fedrgstr/index.html>.
Role playing provides an opportunity for students to un-
derstand in a practical way that there can often be opposing
views on the impacts arising from a particular development.
An ideal way of teaching the importance of understanding
all viewpoints is to create an adversarial situation in which


key issues of a proposed development can be researched and
debated. Clearly, the most meaningful debates not only cen-
ter around controversial issues, but also involve participants
from a wide variety of backgrounds with a wide range of
viewpoints. To facilitate this, a group of chemical engineer-
ing students (around 15) in the final year of their MEng pro-
gram at the University of Bath is joined by a similarly sized
group of students from an MS program in Environmental Sci-
ence, Policy, and Planning.
The MS students bring to the case study a broad range of
educational backgrounds that includes biology, chemistry,
business management, estate management, environmental sci-
ence, European studies, geography, geology, health educa-
tion, mathematics, physics, psychology, zoology, etc. They
strengthen the role-playing case study since they bring a much
broader range of personal opinions, as well as expertise, than
would come from chemical engineering students alone, who


Barry Crittenden is Professor of Chemical
Engineering at the University of Bath. He re-
ceived both his BS and PhD in chemical en-
gineering from the University of Birmingham.
all forms of environmental management and
nanoporous solids for selective separations.




Richard England is Senior Lecturer in Chemi-
cal Engineering. He received his BS, MS, and
PhD in chemical engineering from the Univer-
sity College Swansea, University of Wales. His
teaching and research interests are in waste
management and the application of mem-
branes.


Copyright ChE Division of ASEE 2005


Chemical Engineering Education









tend (quite naturally) to be in favour of any development be-
ing made within their own discipline. If the case study were
to be run with only ChE students, it would be necessary to
provide additional teaching and time to allow them to take
on roles that are outside the normal scope of chemical engi-
neering.
In view of the complexity of environmental regulations,
the role-playing case study would be strengthened further if
law school students could also be involved. The two instruc-
tors at Bath are both experienced in environmental legisla-
tion and in giving expert opinions. Indeed, one has an educa-
tional qualification in law and is a coauthor of three EISs,
including one on the regeneration of GAC. Both instructors
teach on a parallel Environmental Legislation module.

AIMS AND OBJECTIVES
The educational aim of the Environmental Impact Assess-
ment module (an elective) at Bath is to develop a deeper un-
derstanding of environmental, technical, and social issues as-
sociated with the preparation and defense of an environmen-
tal impact statement for a chemical (or bioprocess) develop-
ment. For the student, the learning objective is an ability to
critically analyze the content of an environmental impact state-
ment and to prepare the outline of an expert opinion. It is not
a learning objective for students to be able to actually pre-
pare an EIA.
Of the 167 hours involved in this double module, the ma-
jority (147) are assigned to private study, while 15 are given
to the role-playing exercise and 5 are devoted to tutorials and
seminar support by two senior members of the academic staff.
While at the final-year MEng and MS levels, students at Bath
are expected to work in a substantially independent manner;
their work on EIA is nevertheless supported beyond the re-
quired hours by almost unrestricted access to both the library
learning facilities and the two instructors.

THE CASE STUDY
The case study concerns a planning appeal for a proposed

TABLE 1
Six Environmental Issues

0 Emission of carbon monoxide, hydrogen chloride, oxides of
nitrogen, particulates, and dioxins
D The possibility of the GAC being contaminated by polychlori-
nated biphenyls
> The increase in traffic on a minor access road
0 Access to and from the site by large articulated trucks (carrying
the GAC) at a very busy junction with a main highway through a
residential district
Alternative sites for the regeneration plant, including the "do
nothing" option
> Visual impact


development to regenerate granular activated carbon (GAC),
which is used in packed beds to remove triazine pesticides
(such as atrazine and simazine) from drinking water. The re-
moval of pesticides is the duty of the regional, private water
companies. Once spent, the GAC must be regenerated be-
cause it is too expensive and environmentally unsatisfactory
to be disposed of in a landfill. Thermal regeneration is the
most commercially viable technology for removing organic
contaminants from GAC to a level where it can be safely
returned for reuse in water-treatment works. For economies
of scale, GAC regeneration plants are built in only a few lo-
cations strategic to a number of water-treatment works in
which the pesticides are removed. Thus, the spent and regen-
erated GAC must be transported as an aqueous slurry in tank-
ers to and from the regeneration plant. No one can dispute
the need to provide wholesome drinking water. On the other
hand, both the technology (involving combustion) and the
siting of the thermal regeneration plant is often controver-
sial. To many observers, a thermal regeneration plant with its
chimney is viewed as nothing other than an incinerator.
The case study involves an appeal by a GAC regeneration
company against an adverse planning decision made by a local
authority. The principal reason for using an appeal is that the
case study becomes adversarial since the local authority must
defend its original decision in the appeal. The appeal process
thereby demands that both sides of the argument must be de-
bated unless prior agreement can be reached by the two prin-
cipal sides (the developer and the defendant).
The original planning application was to build two 17.5
tonne/day thermal regeneration plants in a common building
on unused low-quality industrial land owned by the company.
The site is in close proximity (about 300 m) to a residential
housing area, an old but operational iron foundry, and a rela-
tively modern metal fabrication factory in a heavily popu-
lated region of the UK. The land was previously used for
effluent treatment and the sewerage connection to a modern
treatment facility remains in existence.
In the case study, the local authority refused planning per-
mission for the development because inadequate attention had
been paid in the original Environmental Impact Statement to
six environmental issues (shown in Table 1). Each of these
issues is debated in the appeal, and other aspects surrounding
the issues, such as industrial accidents, are naturally drawn
into the debate. The environmental and health risks center
around the six issues in Table 1. Thus, for example, the un-
certain, controversial, and emotional aspects associated
with the impact of dioxin releases on human health, ani-
mals, and the food processing factory are researched and
debated by the students.
The GAC thermal regeneration process is a waste disposal
and recycling process that is prescribed by the UK's Envi-
ronment Agency for Integrated Pollution Control (IPC, to be
superseded by Integrated Pollution and Prevention Control


Winter 2005









(IPPC)). While the agency's Guidance Note S2 5.031'5 de-
scribes matters relating to what must be done in order to ob-
tain an authorization (permit) to operate, the contents of this
21-page document provide substantial information on what
would constitute an acceptable design. Students are informed
that conformation with provisions in this document does not,
by itself, constitute sufficient grounds to win the appeal. This
is because an authorization (permit) to operate can only be
granted if permission to build the plant has been granted in
the planning process.

THE GAC
THERMAL-REGENERATION PROCESS
A simplified process-flow diagram is shown in Figure 1.
Students are provided with a more detailed diagram. GAC
granules are typically 0.5-1 mm in size and are probably
loaded to no more than 30% by weight with organic matter,
of which only a very small fraction is pesticide (about 10 Jig/
kg of GAC). Each of the two 17.5 tonne/day plants is planned
to operate continuously between periodic shut-downs for
maintenance. Between three and six purpose-built 38-tonne
road tankers would arrive at and leave the GAC regeneration
plant each working day, excluding weekends. The incoming
carbon slurry is pumped to a bulk water-carbon separator lo-
cated at the top of the regeneration furnace, which is of the
multiple-hearth type.
The cylindrical, refractory-lined steel shell of the furnace
carries a series of refractory hearths one above the other. A
revolving central shaft, with attached rabble arms, sweeps
the carbon from the inlet port on the outside of the top hearth
to the center, where it drops onto the hearth beneath. It is
then rabbled to the outside and falls to the next hearth, and so
on. The upper hearths form a heating zone where water and
volatiles are driven off. The carbon
regeneration and reactivation oc-
curs on the lower hearths under a
controlled range of temperature
and composition conditions. Steam R o Sp ,
and some air are added as required Tk," hopp r
so that the combustion conditions -"
are non-oxidizing and the atmo-
sphere contains significant concen-
trations of carbon monoxide. Red He
hot regenerated GAC falls from the
bottom hearth into a water-quench N,
tank, from which it is pumped as a
slurry into road tankers to return to
the water treatment facility.
Gases leaving the top of the re-
generation furnace pass directly Roa
into a separate afterburner that is Tnkers Hoppee
designed to operate with an outlet
temperature of 850C. The after- Figure 1. Scheme


burner contains natural gas burners and an excess of air to
create 6% by volume of oxygen at the outlet. The residence
time of gases in the afterburner is set to be two seconds,
conforming with information in the Environment Agency
Guidance Note.E51
The process is designed not only to generate all the steam,
which must be injected into the furnace, but also to put suffi-
cient energy into the gases entering the base of the stack in
order to ensure that the plume leaving the stack is invisible
except for the occasional appearance of water vapor in ex-
ceptional meteorological conditions. The gases leaving the
afterburner pass through a waste-heat boiler and then through
a heat exchanger in which air is heated prior to injection into
the stack. This air (which is not in contact with the GAC
being regenerated) is taken from the hot central shaft of the
multiple hearth furnace.
Gases leaving the energy recovery unit pass into a venturi
scrubber (to remove particulates) and then to a trayed scrub-
ber (to remove acid gases) before passing into a 20-m stack
via an induced draft fan. The fan provides for a pressure
slightly below atmospheric throughout the process and does
not allow carbon monoxide to escape from the multiple-hearth
furnace. Should the fan cease to operate for any reason, then
(after some predetermined time as the pressure increases) the
emergency by-pass stack would open, an alarm would be
sounded, and the plant would automatically go into shut-
down. During this period, of course, the contents of the mul-
tiple-hearth furnace would bur, thereby releasing gases into
the atmosphere that had not passed through the gas-cleaning
parts of the process. This aspect is inevitably one of the more
hotly debated aspects in the case study.
The benchmark release levels set by the Environment
Agency'5 are given in Table 2. They are not emission limits.


ztic of the granular activated carbon regeneration process.


Chemical Engineering Education









They are values that are subject to consideration of site-spe-
cific environmental issues by the Environment Agency when
framing conditions in an authorization (permit) to operate.
The Guidance Notes state that the emissions of polychlori-
nated dibenzo-p-dioxins (PCDDs) and polychlorinated
dibenzofurans (PCDFs) should be reduced as far as possible
by progressive techniques. The aim should be to achieve a
guide International Toxicity Equivalent (ITEQ) value of 0.1
ng/m3.,51 Controversy is introduced into the case study by in-
cluding some fictitious emission data from a similar plant
showing that some of the benchmark levels of carbon mon-
oxide and dioxins are periodically exceeded.

THE ROLES AND THE TIMETABLE
Typical roles for the students, together with the written (and
assessable) material each must produce, are shown in Table


TABLE 2
Environmental Agency Benchmark Release Levels to Air

Substance Achievable
Total particulate matter 20 mg/m3
Hydrogen chloride 30 mg/m3
Sulphur dioxide (as SO,) 50 mg/m'
Oxides of nitrogen (as NO,) 350 mg/m3
Carbon monoxide (after last injection of air) 50 mg/m3
Volatile organic compounds 20 mg/m3
Dioxins and furans (International Toxicity 1 ng/m3
Equivalent ITEQ
Smoke Free from smoke
during normal opera-
tion and within five
minutes of start- up



TABLE 3


3 for both the GAC Carbon Company (the appellant) and the
local authority (the defendant). The full range of environ-
mental issues is covered with matching experts on opposing
sides, thereby helping to ensure lively debate on all the is-
sues in Table 1. In addition, two students take the roles of
lawyers, two students act as journalists (one for a local
newspaper, the other for a national newspaper), and the
remaining students take third-party roles that include,
among others, the chairperson of a local environmental
pressure group, a professional chemist residing in the area,
an elderly resident, and a lawyer acting on behalf of a
local food-processing company.
The ChE and MS classes are divided more-or-less equally
between the three groups, so that each side can bring expert
opinions on the full range of subjects and facilitate the re-
quired debate. Thus, for example, a chemical engineering
expert for the appellant would provide an expert opinion on
the technology with which emissions will be abated on the
proposed GAC plant, while a technology expert for the de-
fendant would try to expose weaknesses in the appellant's
proposed technology. Quantitative work is required of many
experts. For example, either new calculations or checks on
the values in the Environmental Impact Statement (EIS) would
be carried out on the emission and dispersion of gases, par-
ticulates, and dioxins released through the emergency vent.
This is a very difficult area for debate, not only because the
frequency with which the vent opens is ill-defined but also
because rather uncertain estimates have to be made for the
quantity and duration of each emission. Working in this
way, in areas of uncertainty, is a thought-provoking exer-
cise for ChE students.
The appellant and defendant teams are provided with sepa-
rate offices to maintain confidentiality but the press officers
publish daily releases for
the benefit of the opposing
side, the journalists, and


Roles for the Appellant and Local Authority

Appellant Local Authority Material to be submitted
Lawyer #1 (barrister/advocate) Lawyer #2 (barrister/advocate) Opening and closing statements
GAC company project engineer Engineering consultant Statement on process technology
Engineering consultant #1 Engineering consultant #8 Statement on PCBs
Engineering consultant #2 Engineering consultant #9 Statement on dioxins
Engineering consultant #3 Engineering consultant #10 Statement on particulate
Engineering consultant #4 Engineering consultant #11 Statement on CO
Engineering consultant #5 Engneenng consultant #12 Stalement on HCI
Engineering consultant #6 Engineering consultant #13 Statement on Nox
Engineering consultant #7 Engineering consultant #14 Statement on water quality and pesticides
Planning consultant Deputy Chief Planning Officer Statement on land quality, planning, and transport
Press Officer #1 Press Officer #2 Series of press releases


the third-party group. The
journalists try to get inter-
views to help them prepare
their daily articles. Daily
press releases and news-
paper articles are posted
on a notice board for all
to read.
The case study runs over
a two-week (full-time) pe-
riod commencing on a
Monday morning when
students select their pre-
ferred roles. Students act-
ing as experts then have
one full week to research
their roles and to become


Winter 2005









experts. During this period, the two lawyers guide their teams
in preparing thorough and expert cases. At a set time during
the Monday of the second week, the expert statements are
exchanged. Between this exchange and early Wednesday
morning, each side needs to determine how to counter the
now-declared, opposing arguments and the lawyers need to
prepare their opening statements. The two instructors assist
the appellant and defendant groups in developing their re-
search and arguments, as well as advising what constitutes
good practice in an expert opinion.
The appeal is formally held on the Wednesday and Thurs-
day of the second week in a room that is laid out in the style
of a courtroom. Each expert, in turn, is led through his/her
expert opinion by his/her lawyer and then is cross-examined
by the opposition lawyer. If the expert has experienced a diffi-
cult cross-examination, another chance is given for re-exami-
nation. The two lawyers finally present their closing statements.
The two instructors sit in judgment over the appeal process
(and can ask questions of the experts to clarify points made),
but they do not make a final decision on the Thursday as to
whether or not the appeal should be upheld; this reflects
UK practice whereby further research might be required
before the final decision is made by the appropriate Gov-
ernment department.

MATERIALS SUPPLIED TO STUDENT
GROUPS
Several documents are provided in order to enable the stu-
dent groups to prepare their expert opinions and for the law-
yers to prepare their arguments. The principal document is
an adaptation of the original Environmental Impact State-
ment (EIS), an 85-page report containing a six-page nontech-
nical summary, together with descriptions of the proposed
development, measures proposed to abate pollution, residual
environmental impact, benefits to the local community, and
appendices comprising site plans, a survey of flora and fauna,
likely conditions to be imposed on discharges to sewer, air-
emission surveys from a similar plant already in operation,
dispersion calculations from the chimney and emergency vent,
drawings of the building elevations, and a noise survey. The
original EIS has been adapted firstly to avoid using refer-
ences to actual company and individual names, and secondly
to bring it up to date in terms of the new European IPPC
legislation. The EIS is supported by a 20-page document con-
taining maps, plans, and photographs of the area before de-
velopment. The scale of the maps ranges from 1:625,000
(showing the location of the site in the context of the UK and
its major highways) to 1:5000 (showing the proposed site
and its neighborhood in detail).
Other documents supplied include the IPC Guidance Note,E51
a practical guide to IPC,l61 a guide for incorporating environ-
mental assessments into chemical engineering projects,E71 a
guide for assessing releases to the environment,r8' and a guide


on discharge-stack heights for polluting emissions.191 Stu-
dents are also shown examples of written expert opinion
and provided with specialist references to aid research in
their roles as experts.

ASSESSMENT
Each student submits the written material required for each
role (some of which is listed in Table 3) as well as a 1000
word critique, which identifies the strengths and weaknesses
of both sides in the appeal. The overall assessment is divided
equally between the two. No attempt is made to assess oral
activities. Assessment of the role-playing material is subdi-
vided equally into quality of presentation, content, structure,
originality, and conclusion in the context of the role played.
The second submission is a critical evaluation of the strengths
and weaknesses of both sides to the appeal. This reflective
exercise is set to be the same for all students; its assessment
is subdivided equally into quality in setting out aims, degree
of impartiality in reflection, quality of arguments, quality of
conclusion, and quality of English and presentation.

CONCLUSION
A lively review and feedback session is held at the end of
the second Friday. Refreshments are provided and discus-
sion centers around both the quality of the technical argu-
ments and the emotional aspects of cross-examination. In-
formal and written feedback from the MEng and MS stu-
dents confirms that not only is the role-playing case study a
most enjoyable way of learning the subject, but it also pro-
vides a firm basis for the need to understand all sides to the
argument on environmental issues.

REFERENCES
I. Wathern, P., Environmental Impact Assessment Theory and Practice,
Unwin and Hyman, London (1989)
2. Petts, J., and G. Eduljee, Environmental ImpactAssessmentfor Waste
Treatment and Disposal Facilities, John Wiley and Sons, Chichester
(1994)
3. Kreske, D. L., Environmental Impact Statements: A Practical Guide
for Agencies, Citizens and Consultants, John Wiley and Sons, New
York (1996)
4. Marriott, B. B., Practical Guide to Environmental Impact Assessment,
McGraw-Hill, New York (1997)
5. Environment Agency. Processes Subject to Integrated Pollution Con-
trol, Cleaning and Regeneration of Carbon, IPC Guidance Note S2
5.03, HMSO, London (1996)
6. Department of the Environment. Integrated Pollution Control: A Prac-
tical Guide, HMSO, London, (1993)
7. Institution of Chemical Engineers. Don't Forget the Environment, A
Guide for Incorporating Environmental Assessment into Your Project,
Rugby (1999)
8. Institution of Chemical Engineers. Emissions and Your Licence to
Operate: A Guide for Assessing Releases to the Environment, Rugby
(1999)
9. Her Majesty's Inspectorate of Pollution, Guidelines on Discharge Stack
Heights for Polluting Emissions, Technical Guidance Note (Disper-
sion) Dl, The Stationery Office, London (1993) 7


Chemical Engineering Education














AUTHOR GUIDELINES


This guide is offered to aid authors in preparing manuscripts for Chemical Engineering Education (CEE), a quarterly journal
published by the Chemical Engineering Division of the American Society for Engineering Education (ASEE).
CEE publishes papers in the broad field of chemical engineering education. Papers generally describe a course, a laboratory, a
ChE curriculum, research program, machine computation, special instructional programs, or give views and opinions on various
topics of interest to the profession. (Note: Articles for the special series on outstanding ChE departments and ChE educators are
invited articles.)


SSpecific suggestions on preparing papers *

TITLE Use specific and informative titles. They should be as brief as possible, consistent with the need for defining the
subject area covered by the paper.

AUTHORSHIP Be consistent in authorship designation. Use first name, second initial, and surname. Give complete mailing
address of place where work was conducted. If current address is different, include it in a footnote on title page.

ABSTRACT: KEY WORDS Include an abstract of less than seventy-five words and a list (5 or less) of keywords

TEXT We request that manuscripts not exceed twelve double-spaced typewritten pages in length. Longer manuscripts may be
returned to the authors) for revision/shortening before being reviewed. Assume your reader is not a novice in the field. Include
only as much history as is needed to provide background for the particular material covered in your paper. Sectionalize the article
and insert brief appropriate headings.

TABLES Avoid tables and graphs that involve duplication or superfluous data. If you can use a graph, do not include a table.
If the reader needs the table, omit the graph. Substitute a few typical results for lengthy tables when practical. Avoid computer
printouts.

NOMENCLATURE Follow nomenclature style of Chemical Abstracts; avoid trivial names. If trade names are used, define at
point of first use. Trade names should carry an initial capital only, with no accompanying footnote. Use consistent units of mea-
surement and give dimensions for all terms. Write all equations and formulas clearly, and number important equations consecu-
tively.

ACKNOWLEDGMENT Include in acknowledgment only such credits as are essential.

LITERATURE CITED References should be numbered and listed on a separate sheet in the order occurring in the text.

COPY REQUIREMENTS Submit the manuscript electronically as a pdf, Word, or tif file that includes all graphical material
as well as tables and diagrams. Send an additional copy of the manuscript on standard letter-size paper through regular mail
channels and include original drawings (or clear prints) of graphs and diagrams on separate sheets of paper. Label ordinates and
abscissas of graphs along the axes and outside the graph proper. Figure captions and legends will be set in type and need not be
lettered on the drawings. Number all illustrations consecutively. Supply all captions and legends typed on a separate page. State in
cover letter if drawings or photographs are to be returned. Authors should also include brief biographical sketches and recent
photographs (preferably head shots) with the manuscript.


Send your electronic manuscript to
cee@che.ufl.edu
and your hard copy to
Chemical Engineering Education, c/o Chemical Engineering Department
University of Florida, Gainesville, FL 32611-6005







































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