Citation
Chemical engineering education

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Title:
Chemical engineering education
Alternate Title:
CEE
Abbreviated Title:
Chem. eng. educ.
Creator:
American Society for Engineering Education -- Chemical Engineering Division
Place of Publication:
Storrs, Conn
Publisher:
Chemical Engineering Division, American Society for Engineering Education
Publication Date:
Frequency:
Quarterly[1962-]
Annual[ FORMER 1960-1961]
quarterly
regular
Language:
English
Physical Description:
v. : ill. ; 22-28 cm.

Subjects

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

Notes

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

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Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
01151209 ( OCLC )
70013732 ( LCCN )
0009-2479 ( ISSN )
Classification:
TP165 .C18 ( lcc )
660/.2/071 ( ddc )

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Chemical Engineering Documents

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CHEMICAL ENGINEERING EDUCATION


with a donation of funds.











EDITORIAL AND BUSINESS ADDRESS:
Chemical Engineering Education
Department of Chemical Engineering
University of Florida
Gainesville, FL 32611

EDITOR: Ray W. Fahien (904) 392-0857
ASSOCIATE EDITOR: T. J. Anderson
CONSULTING EDITOR: Mack Tyner
MANAGING EDITOR: Carole Yocum (904) 392-0861

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*MEMBERS.

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Northeast
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Northwest
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Library Representative
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Chemical Engineering Education
VOLUME XXIII NUMBER 1 WINTER 1989


EDUCATOR

2 Warren E. Stewart of Wisconsin, R. Byron Bird

DEPARTMENT

6 Rensselaer Polytechnic Institute, Michael M. Abbott

VIEWS AND OPINIONS

12 Accreditation: Changes are Needed,
Charles A. Sleicher

CLASSROOM

16 Cheating Among Engineering Students: Reasons for
Concern,
William R. Todd-Mancillas, Edwin A. Sisson

18 A Course to Examine Contemporary Thermodynamics
William E. Lee, III

38 Experiencing Team Responsibility in Class,
R. Russell Rhinehart

50 Lubrication Flows, Tasos C. Papanastasiou

CURRICULUM

22 Design Education in Chemical Engineering:
Part 1 Deriving Conceptual Design Tools,
J. M. Douglas, R. L. Kirkwood

29 An Alternate Approach to the Undergraduate Thesis,
P. R. Amyotte, M. Fels

RANDOM THOUGHTS

26 Nobody Asked Me, But..., Richard M. Felder

LABORATORY

32 An Experiment in Autotrophic Fermentation:
Microbial Oxidation of Hydrogen Sulfide,
Kerry L. Sublette

44 Unsteady-State Heat Transfer Involving a Phase
Change: An Example of a 'Project-Oriented' Under-
graduate Laboratory,
D. C. Sundberg, A. V. Someshwar

10 LettertotheEditor
27 Positions Available
11,31,37 Book Reviews




CHEMICAL ENGINEERING EDUCATION (ISSN 0009-2479) is published quarterly by 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. Advertising mate-
rial may be sent directly to E. O. Painter Printing Co., P. O. Box 877, DeLeon Springs, FL 32028. Copyright
1989 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 with
120 days of publication. Write for information on subscription costs and for back copy cost and availability.
POSTMASTER: Send address changes to CEE, Chemical Engineering Department, University of Florida,
Gainesville, FL 3S611.


WINTER 1989









I educator



Warren E. Stewart

of Wisconsin



R. BYRON BIRD
University of Wisconsin
Madison, WI 53706-1691

Warren received his BS and MS in chemical en-
gineering at the University of Wisconsin in 1945 and
1947 respectively, and then he migrated eastward to
study at MIT, where he received his ScD in 1951. I
started graduate school at Wisconsin in 1947 and just
missed meeting Warren then. However I heard many
tales about him from the chemical engineering stu-
dents at the AXI house who had been classmates of
his. They uniformly sang his praises and mentioned
time and again what a brilliant student he was, how
they always got help from him on difficult homework
problems, and that he was the first person to go
through the undergraduate chemical engineering cur-
riculum with a straight-A average. Within a few
months he had become a legendary figure, and it was
with this mythical Warren Stewart that I became ac-
quainted in 1947.
In 1948 I took Joe Hirschfelder's course in quan-
tum mechanics. Joe assigned Pauling and Wilson as
the text for the course but said that we might find it
helpful to study some mimeographed materials that
he distributed to the class. These were Warren
Stewart's notes of Joe's lectures in 1946, and Joe said
they were much better than his own. So my next en-
counter with Warren was by studying quantum
mechanics from his careful transcriptions of Joe's lec-
tures.
After graduate work at MIT, where he did his
thesis on heat, mass, and momentum transfer, War-
ren became a Project Engineer at Sinclair Research,

S. in 1960 the hardback textbook Transport
Phenomena appeared. Warren was a superb
contributor to the project for a number of reasons:
he has exceptionally high standards for teaching
and writing; he has a photographic memory of
where things are in the literature;
he insists on accuracy.

C Copyright ChE Division ASEE 1989


1988



Inc., in Harvey, Illinois. There he participated in the
development of a catalytic reforming process and also
in early work on computerized process simulation.
In 1953 I joined the chemical engineering depart-
ment staff at UW. Here Warren's name came up often
in conversations when faculty members recalled how
scary it was to teach classes in which both Warren
Stewart and Ed Daub were present (Ed was another
legendary figure whose scholastic performance and
keen mind had dazzled both staff and students).
In 1956 I finally had the chance to meet Warren,
when he came to the department to interview for an
assistant professorship that had opened up; shortly
thereafter he joined our faculty. This was the begin-
ning of a long friendship which I have very much val-
ued through the years. Warren lived up to the legend,
and more. I found him to be a great scholar with an
awesome grasp of science and engineering, as well as
a compassionate teacher, a dedicated family man, and
a marvelous raconteur of jokes. Those who see only


CHEMICAL ENGINEERING EDUCATION









the serious side of Warren don't realize that his reper-
toire of jokes, puns, and conundrums is every bit as
impressive as his uncanny ability to solve complex sci-
entific problems.
By 1957 Warren Stewart, Ed Lightfoot, and I had
joined forces to prepare mimeographed material for a
new course on transport phenomena. This occupied
much of our time in the fall of 1957 and the spring of
1958; our green paperback book, Notes on Transport
Phenomena, was published by Wiley in the fall of 1958
as a "preliminary edition." Then we spent another two
years revising the "Notes," and in 1960 the hardback
textbook Transport Phenomena appeared. Warren
was a superb contributor to the project for a number
of reasons: he has exceptionally high standards for
teaching and writing; he has a photographic memory
of where things are in the literature; he insists on
accttracy; he is a meticulous proofreader (his ability to
detect the smallest of errors earned him the nickname
"Gimlet-Eye"); and-very important in book-writing
-he has a wonderful sense of humor. During the man-
uscript preparation I felt that I was continually learn-
ing about transport phenomena from Warren (just as
I had learned quantum mechanics from him a decade
earlier). He had had, after all, a lot of experience in
transport phenomena in boundary layers during his
thesis work at MIT as well as some five years of prac-
tice in solving industrial problems. That period of in-
tense work, 1957-1960, formed particularly strong
bonds within the triumvirate-bonds that have sur-
vived for many years.
A few years later Warren started studying
Spanish, an effort which has given him another "di-
mension." He has made Latin America his primary
overseas field of interest. He provided assistance to
the translator who prepared the Spanish Edition of
Transport Phenomena. He was a Visiting Professor
at the Universidad Nacional de la Plata (Argentina)
in 1962, and a Visiting Lecturer at the Instituto Tec-
nol6gico de Celaya (M6xico) in 1983 and at the Univer-
sidad Nacional Aut6noma de M6xico in 1985. He has
also given seminars (usually in Spanish) at a number
of other Latin American institutions. It is rare for
engineering professors to take the trouble to learn
another language well enough to be able to lecture in
it. Of course, this carries with it certain dangers. War-
ren attained instant fame in Mexico because of a lin-
guistic blunder he committed in a lecture at the In-
stituto Tecnol6gico de Monterrey. Someone in the au-
dience asked him a question to which he unfortunately
didn't know the answer. So he wanted to say to the
audience something like, "I'm very embarrassed that
I don't know the answer to that question." Now when


A few years later Warren started studying
Spanish, an effort which has given him another
"dimension." He provided assistance to the
translator who prepared the Spanish
Edition of Transport Phenomena.


---

Warren and Jean (bottom row) in 1982 at a family
gathering.
we speak foreign languages we often encounter words
that are not in our vocabulary and so we make a guess
and hope the listeners will understand. This works
pretty well for an English speaker talking Spanish.
Warren didn't know the word for "embarrassed" but
boldly produced the sentence "Estoy muy em-
barazado, que no se la respuesta a ese pregunta" (in-
stead of "Es embarazoso, que. ."). Well, it turns
out that "estoy muy embarazado" means "I am very
pregnant." Understandably the audience exploded
with laughter. (See what fun you miss out on if you
don't try learning a foreign language!) This story pop-
ped up in a limerick read at Warren's 60th birthday
party on July 2, 1984:
He tackles tough tasks with bravado
With the verve of a wild desperado-
But he's really quite droll
When he talks espaiiol
And says that he's "embarazado."
Anne Nonimus
Despite his occasional problems with Spanish, Warren
has for several decades administered the departmen-
tal PhD Spanish reading exam. He and his wife Jean,
(who for many years has been the "alderperson" for
Madison's 20th District), have often shared the hospi-
tality of their home with visitors from Latin America
(and from other parts of the globe as well). They and
their children have been gracious hosts on many occa-
sions, and countless visitors will long remember their
pleasant evenings at the Stewart home.
Warren's linguistic accomplishments are not re-
stricted to Spanish. He is also very fluent in "Alfalfa."


WINTER 1989











This is a pig-Latin-like way of speaking where you
insert "LF" in the middle of the predominant vowel
in each word; thus "seem" transforms into "seelfeem."
Since I also learned "Alfalfa" as a youngster, Warren
and I often carry on long conversations in our "secret
language" much to the astonishment of bystanders.
Warren can even speak Alfalfanized Spanish!
But, we digress. Let's get back to Warren and
chemical engineering. Warren is one of the most ver-
satile people that I know. I think he has taught almost
every course in the department. His list of research
publications is also characterized by great diversity.
How many chemical engineers could write significant
contributions on such widely varying topics as predic-
tion of vapor pressures; reciprocal variational princi-
ples; kinetics of benzene hydrogenation; multicompo-


nent diffusion; orthogonal collocation; measurement of
diffusivities; droplet vaporization; kinetic theory of
rigid-dumbbell suspensions; tokamak reactors; ther-
mal diffusion; catalysis; corrosion; parameter-estima-
tion; Bayesian statistics; viscoelastic fluid dynamics;
sensitivity analysis; and distillation column design?
Whereas most professors work in rather narrow
areas, Warren has been an impressive generalist.
When he was chairman of the chemical engineering
department (1973-1978), he was able to discuss details
of research projects being carried out by all of his
departmental colleagues; no other chairman before or
since has been able to do that. This was one of his
great strengths when he served the department so
ably as our chairman.
Warren's enormous breadth of interest has re-


STEWART'S TOP TEN


1. Forced Convection in Three-Dimensional Flows: I. Asymp-
totic Solutions for Fixed Interfaces, by W. E. Stewart, AIChE
Journal, 9 528-535 (1963). This deals with the prediction of heat
and mass transfer in thin boundary layers at rigid interfaces,
with given interfacial shape and velocity gradient. A prediction
of the Nusselt number for a packed bed is given. The importance
of this paper was not widely appreciated until the publication of
[6] eleven years later.

2. Matrix Calculation of Multicomponent Mass Transfer in
Isothermal Systems, by W. E. Stewart and R. Prober, Ind. Eng.
Chem. Funds., 3, 224-235 (1964). This paper (and another that
year by Herb Toor at CMU) showed how to solve a large class of
multicomponent mass-transfer problems realistically by
transforming the problem to a set of binary problems; this
method is used extensively in the current literature on distilla-
tion and absorption.

3. Solution of Boundary-Value Problems by Orthogonal Collo-
cation, by J. V. Villadsen and W. E. Stewart, Chem. Eng. Sci.,
22, 1483-1501 (1967); ibid., 23, 1515 (1968). This paper (which was
designated as a "Citation Classic" in Current Contents on
9/21/81) has been widely adopted by reactor designers for calcu-
lating radial profiles in reactor tubes and catalyst particles.
This method of computation combines the simplicity of colloca-
tion with the efficiency of orthogonal polynomial interpretation.

4. Forced Convection in Three-Dimensional Flows: IL Asymp-
totic Solutions for Mobile Interfaces, by W. E. Stewart, J. B.
Angelo, and E. N. Lightfoot, AIChE Journal, 16, 771-786 (1970).
Here single-phase transfer coefficients in fluid-fluid contractors
are related to the fluid properties and interfacial motion. This
theory should eventually supplant the penetration and surface-
renewal theories, and it includes time-dependent and turbulent
flows. Comparisons with experiment show good agreement.

5. Practical Models for Isothermal Diffusion and Flow in
Porous Media, by C. Feng and W. E. Stewart, Ind. Eng. Chem.
Funds., 12, 143-146 (1973). This paper gives extensive data on 3-
component diffusion in catalyst pellets and thereby tests several
diffusion models; it has been widely cited in works on realistic
modeling of catalyst particle performance.

6. Computation of Forced Convection in Slow Flow Through
Ducts and Packed Beds, by J. P. S0rensen and W. E. Stewart,


Chem. Eng. Sci., 29, 811-837 (1974). In this 4-part pioneering
study the fluid dynamics and mass-transfer processes in regu-
lar packed beds are studied. Impressive agreement with exper-
iments is found for the appropriate ranges of Reynolds and
Peclet numbers.

7. Computer-Aided Modelling of Reaction Networks, by W. E.
Stewart and Jan P. S0rensen, in Foundations of Computer-
Aided Process Design (R. S. H. Mah and W. D. Seider, Eds.),
Vol. II, Engineering Foundation, New York, 335-366 (1981).
This survey paper summarizes the work of Warren's group on
digital analysis of reaction models and on parameter estima-
tion from multiresponse reactor data. "Expert" programs are
provided for use by kinetics researchers. The programs auto-
matically evaluate reaction schemes for their fit of data and
then estimate the parameters that are determinable from the
data given.

8. Simulation of Fractionation by Orthogonal Collocation, by
W. E. Stewart, K. L. Levien, and M. Morari, Chem. Eng. Sci.,
40, 409-421 (1985). Whereas in [3] above Jacobi polynomials were
found to be optimal for continuous systems, here it is shown that
for discrete systems Hahn polynomials should be used. Hence,
stagewise processes can be analyzed and designed very
effectively.

9. Sensitivity Analysis of Initial-Value Problems with Mixed
ODEs and Algebraic Equations, by M. Caracotsios and W. E.
Stewart, Comput. Chem. Eng., 9, 359-365 (1985). This work gives
an efficient method for computing the sensitivity of a process
model to its parameters. The algorithm is implemented on a
modern differential-algebraic equation solver and is illus-
trated by a reaction modeling problem. Sensitivity calculations
are widely useful in modeling, control, and optimization.

10. Forced Convection: IV. Asymptotic Forms for Laminar and
Turbulent Transfer Rates, by W. E. Stewart, AIChE Journal, 33,
2008-2016 (1987); 34, 1030 (1988). Here "dominant-balance ar-
guments" are used to get information about heat and mass
transfer rates without integrating any differential equations.
New results are obtained for turbulent flows, and this work sup-
plements [1] and [4] above. The celebrated Chilton-Colburn j-
factors correspond to the leading term of the long-time
expansion.


CHEMICAL ENGINEERING EDUCATION









suited in the fact that he frequently functions as an
"in-house consultant" to colleagues and students in
chemical engineering as well as from other depart-
ments. It's not unusual to see him conferring in his
office with a professor of zoology on heat transfer
through fur, with a student from nuclear engineering
on a problem related to controlled nuclear fusion, or
with a chemical engineering graduate student on vis-
coelasticity. I've never heard of an undergraduate or
graduate student ever being turned away by Warren.
His door is always open for interruptions, and he has
always been very generous with his time and very
patient with his "customers." His willingness to help
others by sharing his talent is the subject of this bit
of doggerel:
A student came in to see Warren
And said in a voice quite forlorn
"I can't find a path
Through this quagmire of math;
These nablas are terribly foreign."
So Warren (who's also called Earl)
Proceeded to help this young girl.
Without using a book
He unflinchingly took
The Laplacian of grad div curl curl.
Anne 0. Nimes
Well now you know what the "E" stands for in Warren
E. Stewart.
All researchers have publications of which they
are especially proud. Warren feels that the box on
the opposite page lists his ten best research publica-
tions. He is currently working on the manuscript of a
book on computer-aided modeling of reacting systems
which promises to be a thorough, scholarly, and useful
work.
Warren is a quiet and modest person. He never
talks about the many awards that have come his way,
including honorary membership in Phi Beta Kappa,
the ASEE Chemical Engineering Lectureship Award,
the Alpha Chi Sigma Award and the Computing in
Chemical Engineering Award of AIChE, the Benja-
min Smith Reynolds Teaching Award at UW, and the
McFarland-Bascom Professorship at UW. In 1989 he
will receive the Murphree Award of ACS. He should
also receive a special award for being able to meet
deadlines in a photo-finish. At 10:59 am he can be seen
frantically xeroxing materials for an 11:00 am class.
At 11:59 pm on April 14th he can be seen speeding up
to the main post office in Madison with his income tax
return. And I recall the time when several of us de-
cided to see Warren and his family off at the airport
when they were headed for the Middle East where
Warren was to give some lectures. At 10 minutes be-
fore plane time, the Stewarts were still not at the


Warren takes time out of a typically busy day
to welcome a visitor.

airport; at -5 minutes still no sign of them; at -2 mi-
nutes they scrambled out of a taxi cab and they did
make the plane. Apparently Warren thrives on the
excitement of seeing how close he can come to not
quite missing a deadline.
One of Warren's most outstanding contributions
has been the development of the powerful technique
of orthogonall collocation," and according to Harmon
Ray it is probably one of the most significant original
contributions to numerical analysis ever made by a
chemical engineer. Here again, this activity has been
memorialized in a poem inflicted on the audience at
Warren's 60th birthday party:

He's often referred to as "WES".
He's known from Rangoon to Loch Ness
For fast collocation
In flash distillation-
And multicomponent, no less!
U. N. Bekannt

No doubt about it-Warren has had a distin-
guished career. And he is still going strong with a
very active research program, book-writing activities,
consulting, memberships on editorial boards, public
and community service activities, and music (he plays
the trombone!). He has certainly earned a place in the
"ChE Hall of Fame."

ACKNOWLEDGEMENT
Many thanks to ENL, EED, WHR, and REF for
constructive criticisms of the original manuscript. El


WINTER 1989









m[J^ departmentt


RENSSELAER




POL YTECHNIC


MICHAEL M. ABBOTT
Rensselaer Polytechnic Institute
Troy, NY 12180

Rensselaer Polytechnic Institute was founded as
the Rensselaer School in 1824, "for the purpose of in-
structing persons who may choose to apply themselves
in the application of science to the common purposes
of life." It has evolved into a university comprising
five schools, 400 faculty and full-time researchers, and
6400 students. Of the latter, approximately 1900 are
graduate students.
Chemical engineering at Rensselaer began seventy
years ago as a program in the Department of Chemis-
try. In 1943, it became a separate academic unit, with
Lewis S. Coonley as its first head. It is now one of the
eight departments and five centers which compose the
School of Engineering. Chemical engineering has eigh-
teen active faculty members; another three from other
departments hold joint appointments with us. Under-
graduate enrollment is approximately 175, and
graduate students number about 60, with 75% pursu-
ing the PhD.
We have a building largely to ourselves. Separated
by a comfortable 100 yards of football field from the
Engineering-School administration, the Ricketts
Building is our home. Ricketts contains offices, class-
rooms, a unit-operations laboratory, and about 14,000
square feet of research laboratories. An in-house elec-
tronics/machine shop is available for use by students
and staff.
The perceived heart of a contemporary
engineering department is the range and strength
of its research interests. In that respect, chemical
engineering at Rensselaer is fortunate
to have coverage in many areas .

Copyright ChE Division ASEE 1989


INSTITI



Our research labs are relatively new, the result of
an extensive renovation undertaken in 1978. Since
then, a central graduate-student office/study area has
been constructed and furnished. Most recently,
through the generosity of Howard Isermann (a
Rensselaer chemical engineering alumnus), we have
been able to renovate and outfit 3000 square feet of
new laboratory space for our biochemical engineers.
This facility will help us to compete successfully with
other first-class programs in biochemical engineering.

BREADTH AND DEPTH
The perceived heart of a contemporary engineering
department is the range and strength of its research
interests. In this respect, chemical engineering at
Rensselaer is fortunate to have coverage in many
areas: air resources, advanced materials, biochemical
engineering, control and design, fluid-particle sys-
tems, interfacial phenomena, kinetics and reactor de-
sign, polymer engineering, separation processes, ther-
modynamics, and transport processes. A special pride
is our biochemical engineering group, with a critical
mass of three (approaching four) specialists.
Interdisciplinary interactions are currently encour-
aged at Rensselaer, and chemical engineering benefits
from numerous collaborations. Belfort works with Don
Drew from mathematics, Gill with Marty Glicksman
from materials engineering, and Nauman with various
polymeric enthusiasts from chemistry and materials
engineering. Rensselaer's Center for Integrated Elec-
tronics provides one of several foci for those (e.g., Gill,
Wayner) with interests in advanced materials. Belfort,


CHEMICAL ENGINEERING EDUCATION































Home Sweet Home: The Ricketts Building. Local legend has it that Palmer C. Ricketts (a
former Rensselaer president) is interred behind his memorial plaque in the foyer. On
moonless nights, his shade perturbs unattended experiments.


Littman, Morgan, and Wayner are members of the
Center for Multiphase Flow; Belfort, Bungay, Cramer,
Gill, Morgan, and Nauman, of the Bioseparations Re-
search Center; and Cramer, of the Biophysics Re-
search Center. And the Department of Electrical,
Computer, and Systems Engineering harbors like-
minded souls with whom Bequette exchanges ideas on
process dynamics and control.
What makes academic research "go"? Money, of
course, and a dedicated and energetic faculty. We, like
others in this business, must scramble for the former.
The latter, fortunately, is a given. Our research envi-
ronment is healthy; we are better than competitive,
and yearly attract a strong group of graduate students.
Problems of student support are mitigated by fifteen
new Isermann Graduate Fellowships which are en-
dowed in perpetuity.
FACULTY SNAPSHOTS
R. H. Wentorf is Distinguished Research Professor
of Chemical Engineering. Bob is inventor or coinventor
of techniques for commercial production of very hard
materials (Borazon, diamond). He has many technical
interests, ranging from polymer-fiber fabrication to
semiconductor processing. After-hours, Bob is a
farmer and a glider pilot. P. C. Wayner, Jr. studies
transport phenomena in evaporating menisci and in
ultra-thin films. His arsenal of experimental tech-


niques includes scanning microphotometry and photo-
scanning ellipsometry. For analysis, he uses capillarity
concepts and London/van der Waals theory. Pete en-
joys tennis and skiing. H. C. Van Ness is Institute
Professor of Chemical Engineering. He specializes in
the measurement, reduction, and correlation of ther-
modynamic properties of liquid mixtures. Hank's
equipment designs have been widely adopted, and are
the source of many of the world's heat-of-mixing and
VLE data. Hank golfs and plays the piano.
J. L. Plawsky works with optical substances. He
seeks to understand how the various transport
phenomena affect the processing of wave-guide de-
vices. Related interests include developing novel ma-
terials based upon inorganic/organic copolymer sys-
tems and investigating complex mixing effects in flow-
ing glasses. Joel plays rock guitar and swims. E. B.
Nauman is director of the Industrial Liason Program
for chemical engineering. His principal research in-
terests are in polymer processing and polymer-reaction
engineering. Much of his current work relates to the
compositional-quenching process, which he invented.
Bruce characterizes his hobby as "pure and applied
flamboyance"; he is the only R.P.I. prof whose winter
car is a Jag XJS. C. Muckenfuss shepherds our seniors
through the final year of chemical engineering; he is
responsible for their advising and eventual clearance.
His research centers on first-principle studies of trans-


WINTER 1989




















Bruce Hook adjusts a data point. Behind him: Littman's
cat combustor, a.k.a. High-Temperature Gas-Phase
Spouted-Bed Catalytic Reactor.

port phenomena, i.e., on the application of kinetic
theory and irreversible thermodynamics to multicom-
ponent, reacting systems. Charlie is an avid bicyclist/
traveler.
M. H. -Morgan III works with fluid/particle sys-
tems. His current research focuses on the development
of reactor theories and of fluid-mechanical models for
spouted beds with draft tubes. Experimental and
theoretical studies abound. Morris is a serious competi-
tive runner: in 1988 he took a Submaster's gold medal
with a 2:03 half-mile in New York's Empire State
Games. H. Littman conducts basic research on gas/liq-
uid and fluid/particle systems. Ongoing efforts include
studies on the dynamics and control of spouted-bed
reactors, pneumatic transport of fine particles, and jet
stability and the transition to bubbling. Howard is a
1988 recipient of Rensselaer's Distinguished Faculty
Award. He hikes and runs for fun.


P. K. Lashmet is Executive Officer of chemical en-
gineering. His research concentrates on process en-
gineering and on the improvement of basic design pro-
cedures. Currently, he explores the effects of parame-
ter uncertainties and process variations on non-
dynamic equipment performance, employing Monte
Carlo simulation techniques. P.K. enjoys his family
and power-boating (in that order).
W. N. Gill is Head of chemical engineering; his
research is in the applied transport areas. Current
efforts include studies in membrane separation tech-
niques and the design and modeling of chemical vapor
deposition reactors. Of special interest are experimen-
tal and theoretical investigations of dendritic growth
of ice and of succinonitrile, and the non-linear dynamics
of pattern formation in crystal-growth systems. Bill
likes films (classic and foreign), music, plays, running,
and martinis. A. Fontijn studies combustion. The
major efforts of his group concern the high-tempera-
ture reaction kinetics of combustion intermediates. For
the experimental studies, Fontijn has developed spe-
cial fast-flow and pseudostatic thermal reactors. Ar-
thur hikes and travels for relaxation. S. M. Cramer
specializes in biochemical engineering. His interests



"As soon seek ice in
June": Bill Gill does. This
dendrite began life as a
smooth disk. Bill studies
its evolution with digital
image analysis, and pre-
dicts its development
with theory.


"Fringe benefits": Wayner's scanning ellip-
someter with interferometer and laser
light source. Mounted on a vibration-proof
table, it is immune to the shocks of Ric-
ketts's frequent renovations.


Nauman's compositional
quencher. Bruce probes the
depths of the spinodal re-
gion, seeking to produce rub-
ber-modified polymers with
controlled particle-size distri-
butions.


An unattended experiment? Not to worry.
This machine (Cramer's new Delta Prep
chromatographic unit) practically runs it-
self.

CHEMICAL ENGINEERING EDUCATION









center on the synthesis and separation of biomolecules.
Research efforts include experimental and theoretical
studies of preparative chromatographic techniques
(especially displacement chromatography), and enzy-
matic organic synthesis. Steve is an accomplished jazz
pianist who performs regularly with High Society, a
group of professional musicians.
H. R. Bungay III conducts research into microbial
growth and biomass refining. Capillary microelec-
trodes with tips a few microns in diameter are used
to study oxygen transfer in various microbial systems.
Intensive efforts are geared toward eventual commer-
cialization of processes for conversion of wood chips to
salable chemicals. Harry is a licensed pilot and a bridge
Life Master. W. D. Bradley is an essential contributor
to our undergraduate instructional program. He brings
to us forty years of experience as a practicing chemical
engineer. Bill's technical interests span the spectrum
of design topics and focus on the ultimate questions:
Will it work? Will it make money? His hobbies include
beekeeping and herb-gardening. B. W. Bequette seeks
to integrate the traditionally separate issues of model-
ing, design, optimization, and control into a consistent
methodology. Emphasis is on applications to the man-
ufacture of semiconductor devices. Nonlinear control
theory is a special enthusiasm. Wayne's outside in-
terests include collision theory and trajectory analysis
(softball) and high altitude inefficient conversion of po-
tential to kinetic energy (skiing with reckless aban-
don).
G. Belfort studies the fundamentals of synthetic
membrane processes and applications of these pro-
cesses to biotechnology. Fluid-mechanical concepts are
used to analyze membrane particulate fouling and to
develop rational design procedures. Flow cytometry
and NMR imaging are among the experimental tech-
niques employed in Belfort's work. Georges coaches
soccer and plays squash. E. R. Altwicker works in
selected areas of air pollution control and atmospheric
chemistry. Current efforts include studies of S(IV) oxi-
dation and of the heterogeneous combustion of waste
fuels. A falling-drop reactor allows controlled investi-
gation of scavenging and scrubbing operations, and
complements theoretical studies of mass transfer with
chemical reaction. Elmar skis and plays tennis and the
violin. M. M. Abbott does thermodynamics. Technical
interests include phase equilibria, solution ther-
modynamics, and the PVTx equation of state. His pro-
fessional passion is the classroom. Mike reads history,
poetry, and music.

DISTINGUISHED COLLEAGUES
Outside recognition by one's peers is an indicator


Is there professional life beyond the laboratory?
We hope so. Education is still our major business,
and service to the profession is a close second.
Van Ness, Cramer, Bungay, and Abbott have
all won major teaching awards: .


Fontijn's HTFFR (pronounced "aitch-tuffer'), with Clyde
Stanton at the controls. With this and other devices,
Arthur studies gas-phase kinetics over humongous tem-
perature ranges.
of the strength of a department, and we enjoy a share
of such honors. In 1985, Fontijn received the ACS
Award for Creative Advances in Environmental Sci-
ence and Technology. Bill Shuster (just retired from
Rensselaer) was a 1987 recipient of AIChE's Award
for Service to Society. And 1988 has been an especially
happy year for us, with Bungay obtaining the ACS
Marvin J. Johnson Award in Microbial and Biochemical
Technology and Van Ness receiving AIChE's Warren
K. Lewis Award.
Four Rensselaer faculty (Bungay, Nauman, Van
Ness, and Wayner) are AIChE Fellows. Wentorf is a
member of the National Academy of Engineering. Gill,
Littman, and Van Ness have done Fulbrights. Gill was
the first Glenn Murphy Distinguished Professor at
Iowa State University. In 1988, Belfort was Flint Scho-
lar at Yale University, and Van Ness was Phillips
Petroleum Company Lecturer at Oklahoma State Uni-
versity. And so it goes: we enjoy our share.

LAST, BUT NOT LAST
Is there professional life beyond the laboratory?
We hope so. Education is still our major business, and
service to the profession is a close second. Van Ness,
Cramer, Bungay, and Abbott have all won major teach-


WINTER 1989










ing awards; Abbott has just finished a two-year stint
as a Rensselaer Distinguished Teaching Fellow. We
currently have in print ten textbooks and mono-
graphs: Basic Engineering Thermodynamics, 2nd Ed.
(Zemansky, Abbott, and Van Ness); BASIC Environ-
mental Engineering (Bungay); Chemical Reactor De-
sign (Nauman); Classical Thermodynamics of
Nonelectrolyte Solutions (Van Ness and Abbott);
Computer Games and Simulation for Biochemical En-
gineering (Bungay); Energy: The Biomass Option
(Bungay); Introduction to Chemical Engineering
Thermodynamics, 4th Ed. (Smith and Van Ness); Mix-
ing in Continuous Flow Systems (Nauman and Buff-
ham); Schaum's Outline of Theory and Problems of
Thermodynamics (Abbott and Van Ness); and Under-
standing Thermodynamics (Van Ness).
Several of us serve on AIChE technical program-
ming committees. Most of us are members of one or
more editorial boards. And, of course, Rensselaer is
the home of Chemical Engineering Communications,
edited by Bill Gill. CEC receives about 400 manuscripts
each year, thus providing valuable interaction between
Rensselaer and the international chemical engineering
community.
Douglas R. Hofstadter asks if the soul of a collection
of individuals can be greater than the hum of its parts.
We believe so. With strong commitments to education,
to professional service, and to research and scholar-
ship, chemical engineering at Rensselaer is certainly
a humming place. A diversity of styles and interests,
a healthy dedication to the principle of lese majesty,
and a sense of collegiality combine to provide our de-
partment with a lively atmosphere in which to pursue
one's professional goals. It's a great place to work and
study. El


LtIR letters

LEVENSPIEL CLAIM DISPUTED

To the Editor:

We wish to reply to Dr. Octave Levenspiel's letter
published in your Summer 1988 issue which erroneously
compares Chemical Engineering Science with Chemical
Engineering Communications as to both cost and price.
Doctor Levenspiel's analysis is incorrect in just about
every respect imaginable. Unfortunately, the sorry busi-
ness could have been avoided had Dr. Levenspiel verified
his information with us prior to publication. I hope that in
view of the facts as outlined below, he will retract his let-
ter and save further embarrassment.
1. The subscription prices quoted by Dr. Levenspiel


for the present calendar year in his letter article are false.
He quotes a price of $296 for a volume. In fact the aca-
demic library rate is $184, substantially less that (sic] the
figure quoted in his letter. Furthermore, there is an
individual subscription rate at 50% of the library rate, or
$92 per volume.
2. In a comparison, these rates are further reduced by
the fact that our rates include airmail postage and
handling charges all over the world, while in other
publications, these costs may be added separately. So a
comparable library subscription rate with a publisher
who charged separately for these services, would be
about $25 lower or about $169.
3. We did study a recent front matter of an issue cho-
sen at random of Chemical Engineering Science. It was
volume 43, number 7 of that publication. In that issue the
1988 institutional subscription rate for a single year is
listed at 1400 DM. We telephoned a major subscription
agent who today [August 24, 1988] advised us that the
present price in dollars of an academic subscription was
$862.50, about twice as expensive as the rate of $435
quoted in Dr. Levenspiel's letter. Incidentally, having
chosen this particular article quite by chance, we were
surprised that the lead article was the Third P. V.
Danckwerts Memorial Lecture by 0. Levenspiel and that
the front matter included a photograph taken in May
1988 showing Dr. Levenspiel together with the Editorial
Director of Pergamon Press as well as the Executive
Editor of Chemical Engineering Science. We did not
verify the other columns of pages and words per page as
in Dr. Levenspiel's article but in view of the fact of the
other distortions of price and size, we have no reason to
accept these as being any less biased.
4. As to the change in format, there was a change in
format of Chemical Engineering Communications but the
amount of material offered subscribers per volume has
always been adjusted and remained the same. The num-
ber of pages per volume was increased to compensate for
the decreased amount of material per page for the
change from a double-column to a single-column format.
Dr. Levenspiel suggests that the change in format was
made to deceive readers; this is simply untrue.
We have always published on a flow basis in that we
estimate the number of pages and/or volumes for publi-
cation in the upcoming 12-month period. Rather than
delay publication of articles to conform to a fixed number
of pages, articles are published as ready for most rapid
publication. In prior years, as the number of pages billed
was reached earlier or later than anticipated renewals
were either advanced or delayed accordingly. In the last
two years, we have changed this policy so that issues are
published on a calendar-year basis. The number of pages
for the coming year is estimated and this determines the
subscription price for that year. Should the number of
pages be over or underestimated, the price is adjusted
accordingly in the subsequent renewal period. In the year
1987, we overestimated the number of pages which
would be supplied. Accordingly the subscription price for


CHEMICAL ENGINEERING EDUCATION









1988 was reduced by 38% in the present subscription
year. Each month, the number of pages ready for publi-
cation is published so that individual issues may vary
widely in size. Thus a 250 page issue may be followed by
a 1000 page issue in the next month, and so on. Any single
issue which Dr. Levenspiel uses in his comparison is
therefore likely to distort the results.
4. [sic] Furthermore, the comparison with CES is
further distorted by other erroneous information. I
cannot directly comment on the difference in subscriber
bases and cannot comment on the differences in
publication methods, except to say that unless a complete
analysis of the subscriber bases and international
markets are [sic] made, no cost comparison can be made.
For example, a society publication, say, may have other
sources of editorial funding such as page charges or
distribution methods such as bulk society purchase
would no doubt have other ways of generating revenue
which would supplement the subscription price. Some
publications accept advertising and are distributed on a
controlled circulation basis, while others are not. In any
event the scopes of the publication are quite different.
Chemical Engineering Communications provides "a
forum for the rapid publication of papers in all areas of
chemical engineering." A recent issue of CES states in its
scope "The object of the journal is to publish papers
dealing with the application to chemical engineering of
the basic sciences and mathematics...."
The other areas of distortion in a valid comparison
can include such factors as complexity of typesetting and
quality of materials. For example, CEC offers free publi-
cation of color photographs as well as other special ser-
vices. In addition libraries subscribing to CEC can, for an
additional nominal $5 per volume receive a photocopy
licence [sic] allowing them unlimited photocopying thus
providing a very low cost of dissemination.
The true current cost to subscribers of CEC is about
half of that quoted in Dr. Levenspiel's letter and com-
pares favorably with other commercial, international
journals. In a major pricing study recently prepared by a
major university library system our company was
ranked 18th.
In fact, we are quite concerned about the current li-
brary budget crisis. We have been trying for some time
now to find a way to defer or lessen the effect of inflation
and currency problems on our regular subscribers. We
are enclosing a press release of a program which we are
announcing to further reduce the costs to existing sub-
scribers. Our prices, after adjustment for changes in
numbers of pages, have increased only 10% in the last
three years despite a higher inflation rate and a falling
dollar. Unfortunately, damaging false analyses like Dr.
Levenspiel's serve only to raise prices by reducing units,
not to lower them.
We work in an intellectual area with intellectual prod-
uct and try to orient our services to the needs of the
community. Libelous attacks made without fact or


knowledge and without verification like those of Dr. Lev-
enspiel serve no useful purpose in this enterprise.

Martin B. Gordon
Gordon and Breach, Science
Publishers, Inc.

Editor's Note: The Press Releases enclosed with the
above letter describe a "Subscriber Incentive Plan" (SIP)
that would result in 10-20% discounts when certain con-
ditions are satisfied. A basic membership earns a 10%
discount which will be automatically granted for the
1988-89 period, with future discounts dependent on
membership in SIP; a 5% discount voucher "credit
memo" good on future renewals will be extended with
enrollment in the SIP; and an additional 5% discount is
offered to the subscriber if the order is placed through
their preferred agent, STBS. The offer will initially be
restricted to North American libraries.


MI. book reviews

DIRECT CONTACT HEAT TRANSFER
by Frank Kreith and R. F. Boehm
Hemisphere Publishing Corp., 1988

Reviewed by
Joseph J. Perona
The University of Tennessee: Knoxville

The term "direct-contact heat transfer" denotes the
physical contacting of media for heat exchange purposes
in the absence of a separating barrier, such as a tube wall.
Some applications are quite old, e.g., cooling towers and
barometric condensers. The concept is not mentioned by
such modern textbooks on heat transfer as those by
Lienhard and by Incropera and DeWitt. A chapter is de-
voted to it in Kern's book, published in 1950.
Direct contact operations are fundamental to chemi-
cal engineering. Nearly all mass transfer processes are
direct contact operations. From an analysis or modeling
standpoint, direct-contact heat transfer is not signifi-
cantly different from nonisothermal mass transfer, un-
less radiation is important. The state-of-the-art is the
same. For transfer between fluid phases, interfacial areas
are usually not known and experiments produce volu-
metric coefficients, in which the transfer coefficient and
interfacial area are lumped together. Similar contacting
devices are used. Since mass transfer inevitably accom-
panies direct-contacting, its extent must be evaluated in
any heat transfer application. It may or may not be
desirable for the objectives of the operation.
The primary advantages of direct-contact heat
transfer over surface exchangers are the elimination of
Continued on page 30.


WINTER 1989










n3views and opinions


ACCREDITATION

Changes Are Needed


CHARLES A. SLEICHER
University of Washington
Seattle, WA 98195


THE PRIMARY PURPOSE of accreditation of under-
graduate engineering programs is to protect stu-
dents by assuring a set of minimum academic stand-
ards. A secondary purpose is to protect the public,
companies, governments, and professional engineers
themselves from employment of ill-qualified individu-
als, which is to say anyone who graduates from a pro-
gram that is not accredited. This purpose will always
be secondary, for no program can guarantee the qual-
ifications of every graduate. That is the purpose of
licensing, whereas accreditation is simply the
academic equivalent of the Good Housekeeping Seal
of Approval.
There is a price to be paid for accreditation, and it
is therefore appropriate to ask if we gain as much as
we lose by the accreditation process and to examine
what can be done to overcome some of the negative
aspects of accreditation. The four principal benefits of
accreditation to a department are:

1. It is an asset to enrollment. Students seek to enroll in
accredited programs. (In some states one must be a
graduate of an accredited program in order to take the
E. L T. exam.)
2. Accreditation suppresses competition. Accreditation is
usually necessary for survival of the program, but de-
veloping the resources necessary for accreditation is ex-
pensive and, therefore, not easily undertaken.
3. Accreditation protects its graduates from quacks, char-
latans, and graduates of non-accredited programs who

. chemical engineering is a dynamic
profession. It is constantly changing chemical
engineering education must change too or
it will become irrelevant and die.

Copyright ChE Division ASEE 1989


Charles A. Sleicher is Chair of the Department of Chemical Engineer-
ing at the University of Washington, a position he has held since 1977.
He has a BS in chemistry from Brown University, and the MS and PhD
degrees in chemical engineering from M. I. T. and the University of
Michigan, respectively. He worked for the Shell Development Company
for four years before joining the faculty of the University of Washington
in 1960.

seek the same jobs. That is important. Most companies
that hire BS chemical engineers do not hire them from
non-accredited programs. On the other hand, most com-
panies do not need accreditation to tell them what pro-
grams are of high quality, so this consideration is of little
importance.
4. Accreditation affects the administration's view of the
department and, therefore, its budget. That is, of course,
important, but should be regarded as a necessary evil in
the sense that Program A needs accreditation only be-
cause it might otherwise be regarded, sometimes even by
the Dean, as inferior to accredited programs B, C, and
D. This argument cuts both ways; in some cases an ac-
creditation report that faults a department might result
in decreased support, while in other cases threatened loss
of accreditation might result in increased support to re-
medy deficiencies.

The sacrifices a department makes for accreditation
are these:

1. It is a modest direct expense. The current minimum
cost of accreditation is $1025, plus $1025 for each pro-


CHEMICAL ENGINEERING EDUCATION










Can accreditation requirements accommodate the range of changes discussed in the Amundson report .?
The answer is no. What will happen instead is that no department will wish to endanger its
accreditation, and the rigidity of the ABET requirements will severely restrict
the scope and implementation of those changes.


gram, plus $50-150 per year, plus other miscellaneous
charges.

2. It is a large indirect expense and a gigantic headache
for the department. Extensive documentation of every
aspect of the department as well as supporting facilities
and departments is required. Hundreds of hours of fac-
ulty and staff time go into the preparation of the required
reports.
3. Many faculty members spend much time on ABET
committee work or act as program evaluators. Through
a sense of obligation to the profession, they sacrifice val-
uable time to undertake these tasks (and they deserve
more credit and thanks than they usually get).
4. The fourth cost, and by far the most important, is that
accreditation requirements place constraints on cur-
ricula that unduly limit creative experimentation in cur-
riculum design and that severely limit the capacity of
departments to respond to changes in the profession.
Moreover, present requirements leave almost no time for
electives. This cost is borne not alone by departments but
by their students and the profession as well.

The remainder of this paper concerns certain nega-
tive effects of accreditation on chemical engineering
curricula and what might be done to make improve-
ments.
We all know that chemical engineering is a
dynamic profession. It is constantly changing, but the
rate of change, like that of evolution, is uneven.
Periods of slow change are punctuated by periods of
sudden change, such as the one we have gone through
in the past five years. Chemical engineering education
must change too or it will become irrelevant and die.
Indeed, signs of change in curricula are apparent.
Many departments have made, or are about to make,
changes in curricula in response to recent changes in
the profession, and the "Amundson Report" will cer-
tainly stimulate more.
The central theme in most of these revisions is
increased flexibility-more options for the students.
A thoughtful and provocative article on this theme
appeared in the spring 1987 issue of Chemical En-
gineering Education by Richard Felder and entitled,
"The Future Chemical Engineering Curriculum-
Must One Size Fit All?" Professor Felder argues per-
suasively for flexibility in the curriculum. He asks
why not "abandon the pretense that all of our students


have the same needs and can therefore be served by
the same curriculum, give or take a few electives?"
He then proposes some steps towards restructuring a
chemical engineering curriculum. Neither he nor ap-
parently anyone else, however, is proposing radical
changes. The basic chemical engineering material will
still be there, but there is obsolete material in our
curricula that should be removed. In fact, in the same
issue Phil Wankat has some suggestions as to what
should be removed to make room for new material.
No two chemical engineering faculties are alike,
and so if the curricula of many departments are re-
structured, there will inevitably be less uniformity
among departments than there is now, and therein
lies the rub with accreditation. Can accreditation re-
quirements accommodate the range of changes dis-
cussed in the Amundson report now being considered
by many departments? The answer is no. What will
happen instead is that no department will wish to en-
danger its accreditation, and the rigidity of the ABET
requirements will severely restrict the scope and im-
plementation of those changes.
For many departments the principal accreditation
problem centers on the ABET engineering science re-
quirement, which is one year or thirty-two semester
credits of a narrowly restrictive definition of engineer-
ing science. There are two subsets of problems here:
the distinction between engineering science and basic
science on one hand and between engineering science
and engineering design on the other. We will look at
each. First, the engineering science/basic science
problem.
One of the great strengths of chemical engineering
curricula is that their graduates are adaptable to a
wide range of technologies and, moreover, are able
relatively easily to change career directions in mid-
stream. They are able to do so because they are well-
grounded in basic science and fundamentals. Com-
pared with other engineering disciplines, chemical en-
gineering students take about the same amount of
math and physics but a vastly larger amount of
chemistry (typically twenty-six semester credits ver-
sus about four for other disciplines). But the heavy
dose of basic science takes a big chunk out of the cur-
riculum. In fact, basic science and engineering science
together take up almost exactly two years, or one-half
of the curriculum.
The reason that engineering science is a problem


WINTER 1989









lies in its ABET definition and the interpretation of
that definition by evaluators. The relevant words are:

The objective of the studies in basic science is to acquire
fundamental knowledge about nature and its phenomena, in-
cluding quantitative expression. The engineering sciences
have their roots in mathematics and basic science, but carry
knowledge further toward creative application. These studies
provide a bridge between mathematics/basic sciences and en-
gineering practice. While it is recognized that some subject
areas may be taught from the standpoint of either basic sci-
ence or engineering science, the ultimate determination of
engineering science content is based on the extent to which
there is extension of knowledge toward creative application."

Clearly, the foregoing definition requires judg-
ment, and opinions will differ. However, the guidelines
of the Engineering and Accreditation (E &A) Commit-
tee pf the AIChE state that: "Instruction in this cate-
gory (engineering science) will ordinarily be given both
by the chemical engineering faculty and the faculty of
other engineering departments." Therefore, although
the disclaimer "ordinarily" is in place, the practice of
some accrediting evaluators has been to define basic
science as science taught in basic science departments
and engineering science as science taught in engineer-
ing departments, and in practice it is rare that a course
taught outside of an engineering department is allowed
to count as engineering science.
The E&A Committe is, of course, aware of this
basic science/engineering science problem and has
taken four steps to alleviate it. The first and most
important step was taken some years ago when 1/5
year of advanced chemistry was allowed to count to-
ward the engineering science requirement, i.e., it could
be double counted as engineering science and advanced
chemistry. That simple idea was a great help to cur-
riculum planning and flexibility.
The next step was in December 1984 when Bryce
Andersen, then chair of the E&A Committee, wrote
a memo to all chemical engineering department chairs
on the subject, "A Possible Change in the Chemical
Engineering Program Criteria." The memo said that
the committee was considering a change in require-
ments and asked for comment. The proposed change
was to allow 1/4 year of advanced science, instead of
1/5 year of advanced chemistry, to count as engineering
science.
The proposed change was a step in the right direc-
tion but was too small to be significant. It meant that
and additional 1-1/2 semester credits, i.e., about 1/2
of a course, could be counted as engineering science.
A better choice would be to permit 1/3 to 1/2 year of


advanced science to count as engineering science.
There are two reasons for this suggestion. First, basic
science and engineering science are sometimes difficult
to distinguish. There are, of course, extremes of sci-
ence and applied or engineering science, but there is
also a huge range of grey in between that often makes
the distinction irrelevant. Today, many courses in such
disciplines as chemistry, physics, biochemistry, and
even genetics, microbiology, and applied mathematics,
are more applied, more engineering-oriented, than are
other courses in those departments, i.e., these courses
contain a substantial element of engineering science.
Second, chemical engineers pride themselves on their
flexibility and their ability to change the direction of
their careers in response to the vagaries of the job
market. This flexibility can only be provided if the
chemical engineer has a strong background in funda-
mentals. As new technologies develop, this flexibility
becomes ever more important.
The change of 1/5 to 1/4 year proposed by the com-
mittee was put into practice except that only advanced
chemistry, not advanced science, was allowed to count.
Strong letters of support from several department
chairmen urging a change to 1/3 year did not affect
the committee decision.
The final two changes to increase flexibility oc-
curred just last year. One was to combine the math
and basic science requirement. Instead of 1/2 year of
each, the requirement is now one year of both, pro-
vided the math includes differential equations. That is
an ABET requirement applicable to all engineering
disciplines. But since chemical engineering has so much
basic science, the new requirement amounts to allow-
ing a decrease in mathematics. That provides a little
flexibility, but not much. Most chemical engineering
departments probably will not reduce their math re-
quirement.
Finally, the latest change in requirements allows
certain courses to qualify as advanced chemistry. The
wording is: "If a course deals with changes in compo-
sition, structure, and properties of matter at an ad-
vanced level, then it may qualify as an advanced
chemistry course, regardless of the department in
which it is taught" (emphasis added).
Again, that is a step in the right direction, but only
a tiny one. What is needed is to replace the previously
quoted and misleading sentence, "Instruction in this
category. .," by a statement that would explicitly
allow a course to count toward the engineering science
requirement even if taught outside of engineering.
That would really help. E&A Committee guidelines
might go something like this: "Instruction in engineer-


CHEMICAL ENGINEERING EDUCATION









ing science will ordinarily be given by the faculty of
an engineering department, but up to six semester
credits of courses in other departments that extend
basic science toward creative application may also
count toward the engineering science requirement."
Now let us look at the engineering science/en-
gineering design problem. Like the distinction be-
tween basic and engineering science, the distinction
between engineering science and design is not always
clear. In fact, the ABET definition of design is quite
broad'; some topics straddle the line and whether
pigeonholed in one slot or the other might depend on
where or how they are taught or on the judgment or
prejudice of the teacher. Moreover, a new topic has
appeared, design science. Which pigeonhole will that
fit in? At present, every engineering course must be
assigned x credits of engineering science and y credits
of design. Then the credits for all courses are totaled
and the hope is that it sums to 1.0 year for engineering
science and 0.5 for design. If it does not, then the
figures are juggled a little, or course substitutions are
made, or a course is actually restructured until the
count comes out exactly right, 1.00 and 0.50. Those
minimum figures are seldom exceeded.
The E&A Committee is concerned about this prob-
lem also. In fact, there has been some discussion and
writing2 about discarding the rigid requirement of a
half a year of design and one year of engineering science
and replacing it with one and a half years of both with
certain restrictions, the principal one being a require-
ment for "a meaningful design experience." I think
that appropriate wording could be found for such a
change which would be a considerable help in obtaining
the sort of flexibility in our curricula that will be re-
quired to meet the challenge of new technologies. It
is my understanding that this change is now under
consideration by the committee.

WHAT CAN BE DONE?
Quality control of chemical engineering education,
accreditation, is in the hands of the profession itself.
It is a voluntary, peer-review process involving both


'The ABET definition of design has little to do with whether instruc-
tion is "practical" or not. Rather, the essence of the definition is
that instruction include design problems that are open-ended and
require innovative and creative intellectual activity to arrive at one
of many possible solutions. Consideration of competing constraints
such as economics, safety, reliability, aesthetics, ethics, and environ-
mental impact are inevitably and explicitly required.
2Memorandum from John W. Prados, Chairman, E&A Committee,
to Chemical Engineering Department Chairmen, 26 November 1986.


academic and industrial engineers who must develop
criteria that do not stifle innovation, yet provide
reasonable assurance of competent graduates. If we
do not do the job well, the government will do it for
us, and that threat ought to provoke at least some
readers to make their views known to the E&A Com-
mittee.
The members of the ABET and of the E&A Com-
mittee represent all of us. Many of their members,
however, apparently think that accreditation require-
ments are already flexible enough. ABET Curriculum
Policy #8 is:

To avoid rigid standards as a basis for accreditation in
order to prevent standardization or ossification of engineering
education, and to encourage well-planned experimentation.

The E&A Committee has a similar statement. The
job for those of us in the trenches is to convince ABET
and the E&A Committee that in order to abide faith-
fully by this policy statement, they must further
liberalize the curriculum requirements.
The wheels of ABET and the E&A Committee
grind so slowly that any changes made might be both
too little and too late. The profession will suffer as a
result. Therefore, the effort should be made to influ-
ence them now. As experience has shown, letters from
half a dozen chairmen have little effect. We need much
more support than that. What we must do is to express
our concerns vocally, in writing, and often to members
of the Committee and to the AIChE Council itself.
Letters can be addressed to committee members at
their addresses or to them through AIChE at 345 East
47 Street, New York, 10017.
The 1988-1989 members of the AIChE E&A Com-
mittee are John W. Prados (Chairman), Robert R.
Furgason (Vice Chairman), L. Bryce Andersen (Past
Chairman), Dan Luss (Council Liaison), Harold I. Ab-
ramson (Staff Liaison), Donald K. Anderson*, Edward
L. Cussler, John L. Hudson, Gilbert V. McGurl, Stan-
ley I. Proctor, Herman Bieber, Charles A. Eckert,
Larry A. Kaye, Francis S. Manning, T. W. Fraser
Russell, Warrren D. Seider, David T. Camp*, Robert
A. Greenkorn*, James G. Knudsen, William H. Man-
ogue*, Richard C. Seagrave.

ACKNOWLEDGMENT
The author acknowledges with thanks helpful dis-
cussion and correspondence with Prof. John W.
Prados. El

*AIChE representative on the ABET E&A Commission.


WINTER 1989










Classroom


CHEATING AMONG ENGINEERING STUDENTS

Reasons for Concern


WILLIAM R. TODD-MANCILLAS
California State University, Chico
Chico, CA 95929-0502
and
EDWIN A. SISSON
Goodyear Tire and Rubber Co.
Akron, OH

IN RECENT DECADES, our society has become in-
creasingly dependent upon engineers. As it be-
comes more technologically complex, engineers will
be called upon to make decisions of ever greater im-
portance to society. Recent events, however, cast
serious doubt upon the capability of some engineers
to make appropriate ethical decisions in their work.
There are several recent and catastrophic exam-
ples of unethical behavior among some engineers. In-
cluded among these is the decision of Ford Motor
Company to market the Pinto automobile, even
though testimony indicates that at least one high-
ranking engineer considered the design unsafe [1].
Another example concerns the B. F. Goodrich con-













William R. Todd-Mancillas received his PhD in Interpersonal and
Instructional Communication from Florida State University. He has con-
ducted interpersonal and instructional research at Rutgers and Pace
Universities, the University of Nebraska, Lincoln, and at Chico State
University. (L)
Edwin Sisson attended the University of Nebraska, Lincoln, and
has BS degrees in chemical engineering and communication. He is
currently enrolled in Case Western Reserve University's MBA program
and is employed by the Goodyear Tire and Rubber Company. He has
held jobs in production, development and marketing. (R)


tract to develop a 4-rotor brake. When tested, the
brake failed to meet specifications, but regardless of
the contradictory test data, the engineers involved
were instructed to draft a positive qualification re-
port. In order to do this, the engineers had to use
falsified data. One of them consulted an attorney and
was advised to inform the FBI, eventually exposing
the fraud, but only after-not before-his complicity
in the fraud.
A third example of unethical behavior concerns the
1974 Paris crash of a DC-10 airplane. One engineer
thought that the cargo door and passenger supports
should be redesigned, yet his supervisor decided
against modifications for fear that their firm would
have to pay for the redesign costs. Although they now
know that should have been the proper course of ac-
tion, they both admitted that at the time it posed "an
interesting legal and moral problem." Apparently not
interesting enough.
Of course, only a small percentage of engineers
engage in such behavior, and even those who do are
seldom responsible for consequences as serious as
those described above. Nonetheless, only a few such
occurrences are enough to make us consider how to
better help engineers avoid such situations.
To begin with, one might examine the extent and
quality of ethics instruction received by most en-
gineering students. Two observations are pertinent.
First, one notes that there are few, if any, courses in
engineering ethics offered in most engineering pro-
grams. Second, and perhaps more problematic, is the
inadequate action taken by most engineering faculty
and departments to prevent or respond to academic
dishonesty. Academic dishonesty is a serious problem:
if students learn to cheat with impunity in the class-
room, they might continue to cheat when gainfully
employed.
Inasmuch as cheating appears to be pervasive, on
the increase, and perceived by many students as
legitimate, there is need to be concerned about its
impact. One study, conducted by the Arizona State
University College of Engineering and Applied Sci-
ences, found that 56% of 364 students polled had
Copyright ChE Division ASEE 1988


CHEMICAL ENGINEERING EDUCATION










Despite the serious nature of the possible consequences of academic dishonesty, too few
instructors implement measures for prevention, controlling, or detecting the problem. Reasons for this may
be a lack of departmental or university support in prosecuting offenders, an attitude
that teachers ought not act as police officers .


cheated [5]. Sisson and Todd-Mancillas found that 56%
of the entire graduating class of engineers (287) had
in one way or another cheated [6].
Instructor complacency, pressure to win, and stu-
dent ignorance appear to be the main reasons why
cheating is widespread and increasing. Also, some re-
search has been done which helps us to better under-
stand how cheaters justify their behavior [8].
Dienstbier's findings lead him to conclude that stu-
dents are most likely to cheat when they feel sub-
jected to intense and seemingly unjustified pressure.
He further concludes that eventually cheaters learn
to perceive their academic dishonesty not as morally
unjustified or even as questionable, but rather as a
necessary and rational way of coping with the pres-
sure to get good grades. Having developed a perspec-
tive justifying and promoting academic dishonesty,
it is probable that the cheater goes on to apply this
self-serving perspective to a variety of other cir-
cumstances, which, like stressful academic environ-
ments, pose no assurance of success, yet great pres-
sure to succeed.
Thus, upon graduation and finding oneself in the
midst of a highly competitive work environment, an
engineer (one who formerly developed the ability to
rationalize academically dishonest behaviors) may
cheat on the job as well. This cheating may be man-
ifested in defrauding documents, such as those forged
by B. F. Goodrich engineers discussed earlier. Just as
students cheat in school as a means of coping with
academic pressure, these engineers cheated as a
means of coping with the professional demands of the
marketplace. Regretfully, these engineers will now
have to suffer the long-term psychic and financial cost
of their involvement in the fraud. There is, then,
reason to be concerned about the long-range conse-
quences of cheating on cheaters themselves. But what
of the consequences to other students? The non-cheat-
ing student suffers at least as much as the cheating
student does. Statistically, even a small percentage of
cheating students will create distorted grades, putting
an honest student at severe disadvantage. Further-
more, this distortion is exacerbated in engineering
courses where partial credit and curving are common
grading practices. For instance, by merely glancing
at another's paper, a dishonest student may learn how
to set up a problem. Later, that student may claim,
"At least I set up the problem correctly, and that


should be worth at least 60 percent."
While dishonesty in the classroom puts honest stu-
dents at a disadvantage, at least insofar as achieving
high grades is concerned, two other consequences are
even more serious. First, dishonest students obtain
an unfair advantage when seeking employment, as
employers prefer to hire applicants with better
academic records. Second, the dishonest student has
an unfair advantage when applying for scholarships
and admission to graduate school.
Presume, for instance, that a company hires an
engineering graduate of University X who had dishon-
estly obtained a high G.P.A. Subsequently, the com-
pany discovers that the engineer's job performance is
far below what had been anticipated, given the en-
gineer's impressive undergraduate record. In the fu-
ture, that company may be less likely to rely on the
academic records of other students graduating from
University X, or perhaps the company's experience
with this particular engineer will be so disappointing
that they will recruit from other universities in the
future. A similar predicament may occur when a stu-
dent is admitted to graduate school on the basis of a
dishonestly obtained (inflated) G.P.A. Conceivably,
the student might be unable to perform at the level of
competence expected of him, resulting in failure to
complete the program. Disappointment in this stu-
dent's performance may cause this graduate program
to exercise greater caution when selecting future ap-
plicants from University X. This would be unfair to
future applicants whose competencies may be very
real, but whose grade point averages are lower than
the one obtained dishonestly by the previously admit-
ted student.
Despite the serious nature of the possible conse-
quences of academic dishonesty, too few instructors
implement measures for prevention, controlling, or
detecting the problem. Reasons for this may be a lack
of departmental or university support in prosecuting
offenders, an attitude that teachers ought not act as
police officers, a disregard for either the high fre-
quency of cheating or its serious short- and long-term
consequences, or simple ignorance of how to prevent
and control cheating in engineering courses. Some of
the reasons listed above seem to account for inaction,
and it was for this reason that a detailed consideration
of the consequences of cheating has been presented in
Continued on page 56.


WINTER 1989










classroom


A COURSE TO EXAMINE


CONTEMPORARY THERMODYNAMICS*


WILLIAM E. LEE III
University of South Florida
Tampa, FL 33620

"OUR VISION OF nature is undergoing a radical
OJ change toward the multiple, the temporal, and
the complex." These are the opening words of the pre-
face to Order Out of Chaos by Ilya Prigogine and
Isabelle Stengers [1]. Many instructors of engineering
thermodynamics would probably agree that there is
little evidence of anything "radical" going on in re-
gards to the content of the typical undergraduate
courses in thermodynamics. Engineers are taught
basic thermodynamic principles with which they can
eventually enter the world of industry and enjoy
meaningful technical careers. These principles as pre-


William E. Lee III is currently an Assistant Professor of Chemical
Engineering at the University of South Florida. General research in-
terests involve the application of chemical engineering science, particu-
larly contemporary thermodynamics, to problems in the biological and
medical sciences. Current projects involve cancer research, chronobiol-
ogy, sensory perception, and biological aging. He also has an active
interest in the philosophy of thermodynamics and complex systems.

*This is based on a presentation made at the American Institute of
Chemical Engineers 1987 Annual Meeting, Nov. 15-17, in New
York City (Paper no. 146b).
0 Copyright ChE Division ASEE 1989


sented in the various textbooks on the subject have
undergone little change in the recent past. This in
itself is not necessarily bad, for many have recognized
that this thermodynamic "toolkit" with which we are
equipping our students (or, as H. G. Jones calls them,
thermodynamicc plumbers" [2]) is really a powerful
collection of ideas and methodologies. Keeping within
the narrow confines of chemical or mechanical en-
gineering, students often fail to realize just how pow-
erful their thermodynamic toolkitss" can be. For
example, anyone who is aware of recent developments

TABLE 1
Course Outline

I. An introduction to philosophy of science
A. Logic, reasoning processes, and logical fallacies
B. Scientific method
Inductivism
Falsification
Other methods
C. Theories, hypotheses, etc.
II. Entropy and its many forms
A. The second law and its historical and scientific basis
B. Forms of entropy
"Steam engine" entropy
Statistical entropy
Informational (Shannon) entropy
Others (e.g., "negentropy")
C. Irreversibility and its implications

III. Contemporary thermodynamic concepts and related
topics
A. Time and time's arrows
B. "Brussels school" concepts and theories
C. Bifurcation and catastrophe theory
D. Cybernetics, synergetics, systems theory, and
related theories
E. Fractals
F. Non-Western viewpoints

IV. Thermodynamic analysis in other disciplines
A. Biology
First law: Does it apply?
Second law: Does it apply?
B. Psychology, social sciences, etc.


CHEMICAL ENGINEERING EDUCATION










there have been many exciting developments in such diverse fields as psychiatry,
biology, and social science. Thermodynamicists are providing new insights into these fields-fields which
many scientists previously thought were not amenable to thermodynamic "intrusions."


in the application of thermodynamic concepts knows
that there have been many exciting developments in
such diverse fields as psychiatry, biology, and social
science. Thermodynamicists are providing new in-
sights into these fields-fields which many scientists
previously thought were not amenable to ther-
modynamic "intrusions." Most engineering students
are unaware of this. They think thermodynamics is
something confined to heat engines and not much
more.
Even when the discussion is confined to more tech-
nical matters of physical science, students are often
unaware of the recent advances in thermodynamics.
Most of them leave with their Bachelor of Science de-
grees, never having heard of such things as "dissipa-
tive structures" and having received only limited ex-
posure to the general field of irreversible ther-
modynamics. "Catastrophies" may be associated more
with test performance rather than with a powerful
analytical tool. In many ways, their knowledge of
thermodynamics may be more reflective of the closed
system close-to-equilibrium mentality of the past.
Finally, their understanding of very basic concepts
such as entropy and the second law is often poor. As
one person lamented, "One of the most highly de-
veloped skills in contemporary Western civilization is
dissection: the split-up of problems into their smallest
possible components we often forget to put the
pieces back together again" (A. Toffler in [1]). Indeed,
many professors have noted that engineering students
probably work harder than other students, but may
not possess sufficient critical analytical skills or
philosophical abilities. This is not all that surprising,
given the pragmatic or empirical nature of engineer-
ing "science." We teach students how to work prob-
lems, often resorting to "black box" strategies, but
rarely do they get to sit back and just "think," particu-
larly in a more qualitative philosophical sense.
With these things in mind, we developed a course
which would give students a chance to critically think
about and otherwise analyze the contents of their
thermodynamic toolkitss." In addition, the students
would be exposed to recent developments in ther-
modynamics and related topics, including attempted
applications to fields other than the physical sciences.
Finally, students were exposed to the general field of
philosophy of science in an attempt to stimulate
further development of their critical skills.


COURSE OBJECTIVES AND OUTLINE

The course was organized to achieve four broad
objectives:
To critically discuss and analyze fundamental ther-
modynamic concepts such as entropy
To expose the student to contemporary thermodynamic
concepts such as those put forth by the "Brussels group"
and to related topics such as bifurcation theory
To critically discuss attempted applications of the above
objectives to other fields, particularly to the life sciences
To introduce the student to the field of philosophy of sci-
ence, including logic and scientific method.
Table 1 presents the course outline. The course
was run in a seminar fashion to encourage student
discussions. During the first offering of the course,
the books presented in Table 2 were utilized, and




TABLE 2
Books Utilized in the Course

Required Texts

Time's Arrows, by R. Morris: Simon & Schuster, New York,
1985
Order Out of Chaos, by I. Prigogine, I. Stengers; Bantam
Books, Toronto, 1984
The Systems View of the World, by E. Laszlo; George
Braziller Inc., New York, 1972
An Introduction to Catastrophe Theory, by P. T. Saunders;
Cambridge University Press, New York, 1980
Referenced Texts (Texts which were referred to repeatedly
during the course.)
The Tao of Physics, by F. Capra; Shambhala, Berkeley,
1975
Entropy, by J. D. Fast; Gordon & Breach, New York, 1968
Against Method, by P. Feyerabend; Thetford Press Limited,
Thetford, 1978
The Structure of Scientific Revolutions, by T. S. Kuhn;
University of Chicago Press, Chicago, 1970
Conjectures and Refutations: The Growth of Scientific
Knowledge, by K. R. Popper; Harper & Row Publishers,
Inc., New York, 1965
Entropy:A New World View by J. Rifkin; Viking Press,
New York, 1980
The Tragicomical History of Thermodynamics 1822-1854,
by C. Turesdell; Springer-Verlag, New York, 1980
Catastrophe Theory, by A. Woodcock, M. Davis; E. P.
Dutton, New York, 1978


WINTER 1989









numerous journal articles were discussed. A list of
the more useful journal articles is presented in Table
3. While the course was basically run by myself, I
found that the presentation of scientific method by an
actual philosopher of science to be particularly effec-
tive.
The typical assignment was to read the assigned
materials and be prepared to discuss them but there
were also several assignments which required some
library work. For example, students were instructed
to find specific examples of the application of catas-
trophe theory and present them to the class. Overall
grading was based on a consideration of in-class par-
ticipation (reflecting preparation), the written assign-
ments, and performance on a comprehensive final
exam.


DISCUSSION
On the first day, I gave a simple quiz that consisted
of two parts: 1) define the words entropy, time, order,
and stability; 2) define hypothesis, law, and theory,
and outline how you would prove a given hypothesis.
The answers to the first part were rather poor. In
fact, blanks appeared with an alarming frequency. An-
swers to the second part were typically inductive in
nature-"go run experiments." Following the quiz,
students readily admitted their personal embarrass-
ment over their performances. But while a few egos
may have been bruised, students for the most part
had a clearer understanding of the importance of the
class objectives. A point had been made.
Further in-class discussion on the nature of en-
tropy revealed the usual associations with order and
chaos. Others have written on this superficial under-
standing as expressed by "naive" students (for exam-
ple, see [3]). All students challenged the idea that
movement further and further away from equilibrium
could possibly lead to the creation of stable structures.
Again, it was clear that the students' basic under-
standing of the thermodynamic fundamentals was nar-
row and shallow.
The typical class consisted of some initial lecturing,
usually outlining the basic ideas associated with the
assigned readings and sometimes presenting historical
perspectives. Most of the class time was devoted to
free-style discussions. A key to this sort of format is
to maintain several opinions for a while and not to
converge on a "right" answer (if there even is one) too
quickly. In fact, sometimes there may be several ten-
able explanations (for example, what is time?) and the
students are left to make up their own minds.
I found it was a good strategy to present the


TABLE 3
Selected Journal Articles Utilized in the Course

"Equilibrium, Entropy, and Homeostasis: A Multidisciplinary
Legacy," by K. D. Baily; Systems Res. 1,1984; 25-43
"The Theory of Open Systems in Physics and Biology," by L.
von Bertalanffy; Science, III, 1950; 23-29
"Life, Thermodynamics, and Cybernetics," by L. Brillouin; Am.
Scientist, 37,1949; 554-568
"Entropy and Disorder," by J. M. Burgers; Brit. J. Phil. Sci., 5,
1954; 70-71
"The Interdisciplinary Study of Time," byJ. T. Fraser; Ann. NY
Acad. Sci., 138 (art. 2), 1967; 822-847
"Entropic Models in Biology: The Next Scientific Revolution?"
by D. P. Jones; Persp. Biol. Med., 20,1977; 285-299
"Order and Irreversibility," by P. Kroes; Nature and System,
4,1982; 115-129
"Gibbs vs. Shannon Entropies," by R. L. Liboff; J. Stat. Phys., 11,
1974; 343-357
"Maxwell Demon and the Correspondence Between
Information and Entropy," by R. P. Poplavskii; Sov. Phys.
Usp., 22, 1979; 371-380
"Time's Arrow and Entropy," by K. Popper; Nature,207,1965;
233-234
"Can Thermodynamics Explain Biological Order?" by I
Prigogine; Impact Sci. Soc., 23, 1973; 151-179
"Should Irreversible Thermodynamics be Applied to
Metabolic Systems?" discussion forum; Trends Biochem.
Sci., 7, 1982; 275-279
"Entropy, Not Negentropy," by J. A. Wilson; Nature, 219, 1968;
535-536



philosophy of science topics first. It provided a
framework for later critical discussions. Questions
such as, "Is it a testable hypothesis?" or, "What logical
fallacy is being committed?" could be posed more intel-
ligently. The main scientific method lecture was pre-
sented by a philosopher of science. This proved to be
a good move since it gave the students a chance to see
that philosophers might actually have something of
value to offer engineering students. Also, students
found the discussion on various scientific methods
(e.g., inductivism, falsification, etc.) to be very
stimulating.
I also tried to present conflicting views whenever
appropriate. The article "Gibbs vs. Shannon En-
tropies" (see Table 3) is an example of this. The forum-
style article "Should Irreversible Thermodynamics be
Applied to Metabolic Systems?" (see Table 3) is
another example. In general, a fair presentation of
the strong points and the weak points of a given view-
point should always be made.
The books Time's Arrows and Order Out of Chaos
were excellent choices. I currently plan to use the
book What is This Thing Called Science [4] as the
third principle text the next time the course is offered.
It is a good overview of recent topics in scientific
method. However, there are probably other available


CHEMICAL ENGINEERING EDUCATION









books that could also serve this purpose. The remain-
ing topics in Table 1 can be handled with lecture notes
and relevant journal articles.
I judged this course to be effective based on sev-
eral observations. First, the same quiz previously
given on the first day was also given near the end of
the class, and needless to say, the answers were much
more satisfactory. In fact, students felt they did not
have enough time to respond completely. Second, the
students themselves seemed to feel more confident of
their understanding of thermodynamics. While there
may have been periods of confusion (probably a good
sign) during the semester, students generally
emerged on a firmer basis. Finally, several students
stated that they planned to continue their self-educa-
tion in the topics they were exposed to during the
course.


ACKNOWLEDGEMENTS
The author wishes to thank the Department of
Chemical Engineering for supporting the develop-
ment and offering of this course. Professor J. A. Bell
of the Department of Philosophy was also extremely
supportive.

REFERENCES
1. Prigogine, I., and I Stengers, Order Out of Chaos, Ban-
tam Books, Toronto, 1984
2. Jones, H. G., "Thermodynamics: A Practical Subject,"
Phys. Educ., 19 (1), 15-18, 1984
3. Johnstone, A. H., J. J. MacDonald, and G. Webb,
"Misconceptions in School Thermodynamics," Phys.
Educ., 12 (4), 248-251, 1977
4. Chalmers, A. F., What Is This Thing Called Science?,
University of Queensland Press, St. Lucia, Queensland,
1986 O


DISCUSSION: The reviewers of this paper presented some interesting comments of their own.
We feel their views deserve consideration and present
them here for our readers' information


Review #1:
Although I have serious reservations about the
course described by Lee, I am not inclined to recommend
rejection of his manuscript. Thus, while I may deplore his
poor taste (...applications of thermodynamics to problems
in psychiatry and social science? Why not throw in
psychohistory and social Darwinism as well? and...
[exposure to] philosophy of science in an attempt to stim-
ulate...critical skills. He apparently has had much better
experiences with philosophers of science than I), he has
taught the course and so does have something to report.
If there is a single "fault" to the plan, it is Lee's
strategy of bolstering students' admittedly inadequate
understanding of a well-defined subject (thermodyna-
mics) by exposing them to ideas about other topics,
namely, the philosophy of science (a discipline that is
itself disdained by many knowledgeable scientists and
scientific historians for whom I have great respect),
Prigogine's dissipative structures stuff, and the pseudo-
scientific applications of thermodynamic terminology to
psychiatry and social science. That last one really gets
me. These are interesting items, perfectly suitable for
dinner table conversation, but unlikely to advance the
understanding of thermodynamics. Still, I doubt that it
can hurt...and it is comforting to see that the "simple
quiz"...doesn't include the Mumbo Jumbo. If the course
enhances the students' understanding of these terms and
concepts, then it probably is worthwhile. I would opt for
more attention to these and less for the topics about
which I already have vented my spleen. Finally, a course
that attempts to cover so many complex topics surely
must be superficial: how do students discuss whether


irreversible thermodynamics should be applied to
metabolic systems...without a thorough grounding in
irreversible thermodynamics?
In summary, I recommend that the manuscript be
published so that others can judge for themselves
whether this or a related course should be included in
their own curricula.
John S. Dahler
University of Minnesota
Minneapolis, MN 55455
Review #2:
I agree with the author that many undergraduates
do not develop a good understanding of thermodynam-
ics, especially of the Second Law. There are several rea-
sons for this, including hasty exposure and emphasis on
routine and mechanized problem solving, overloading
with other courses, etc. The cure, in my opinion, is em-
phasis on critical understanding, more interesting prob-
lems and more substantial injection of statistical
thermodynamics.
As for irreversible thermodynamics of the Prigogine
fame, this reviewer believes that the subject is practically
useless to chemical engineering. The only contribution
that irreversible thermodynamics has made to our disci-
pline stems from the Onsager relations which provide a
framework for constitutive transport relations. Ap-
plications to social sciences or medicine are best tackled
by more experienced workers and not by the un-
dergraduates who struggle with basic physics and
chemistry.
G. R. Gavalas
California Institute of Technology
Pasadena, CA 91125


WINTER 1989









curriculum :


DESIGN EDUCATION

IN CHEMICAL ENGINEERING

PART 1: Deriving Conceptual Design Tools


J. M. DOUGLAS and R. L. KIRKWOOD*
University of Massachusetts
Amherst, MA 01003

MOST OF THE CHEMICAL engineering curriculum
is focused on the analysis of either engineering
science problems or single unit operations. That is,
very well-defined physical systems that normally in-
volve chemical (or biological) reactions and/or separa-
tions, are investigated in considerable detail. Students
usually do not encounter any synthesis problems until
their senior year design course, where one of the goals
is to integrate the complete curriculum by demon-
strating how the individual process units fit together
into a large system, i.e., a chemical process. However,
because of time constraints, usually only a narrow
range of design problems is considered.
The purpose of this paper is to describe the spec-
trum of process design problems and to suggest a
methodology for teaching the important concepts used
in design. The topics that will be considered are: the
types of processes considered and their designs, some
new tools that are useful in conceptual design, and a
strategy for developing conceptual designs.

CLASSIFICATION OF PROCESSES
We can classify processes in a variety of ways,
including the type of operation, what they produce,
and the types of products they make. There are two
main types of operations: continuous and batch. Con-
tinuous processes are designed to operate twenty-four
hours a day, seven days a week, for 300 to 350 days
a year, and hopefully, nothing changes with time. In
contrast, batch plants contain units that are deliber-
ately started and stopped according to some schedule.
They may operate twenty-four hours a day, or they
might be designed to operate for only a single shift.
*Current Address: E. I. Du Pont de Nemours & Company, Polymer
Products Department, Experimental Station, E262/314, Wil-
mington, Delaware 19898


Batch plants are more flexible, but they are usually
less efficient than continuous processes. In general,
continuous processes are associated with large pro-
duction capacities, whereas batch plants are as-
sociated with specialty chemicals.
Another way of classifying processes depends on
the number of products they produce. Some plants
produce only a single product stream, whereas others
might produce several products simultaneously. Still
others might produce different products in the same
equipment, but at different times of the year.
We can further define a process based on the
characteristics of the product. Sometimes we may
wish to produce pure chemical compounds (pet-
rochemical processes), while at other times the final
product is a mixture (there are hundreds of com-














J. M. Douglas is a professor of chemical engineering at the Univer-
sity of Massachusetts, Amherst. He received his BS in chemical en-
gineering from John Hopkins University and his PhD from the Univer-
sity of Delaware. He worked at ARCO and taught at the University of
Rochester before joining the faculty at the University of Massachusetts.
His research interests include conceptual design, control system synthe-
sis, and reaction engineering. (L)
Robert Kirkwood, a research engineer in the Polymer Products De-
partment of E. I. du Pont de Nemours & Co., has been involved with
process design and synthesis since 1982. He received his BS degree in
chemical engineering from Lehigh University in 1982 and his PhD
from the University of Massachusetts in 1987. (R)


0 Copyright ChE Division ASEE 1989


CHEMICAL ENGINEERING EDUCATION


IC-hE










Experience indicates that less than 1% of the ideas for new designs ever becomes commercialized.
In order to avoid expensive failures, it is common practice for process engineers to develop a heirarchy
of designs where the accuracy of the design calculations and the amount of detail
considered increases as the next level in the heirarchy is considered.


pounds in gasoline or furnace oil streams). In still
other instances we produce materials that are de-
scribed by distribution functions (solid products are
usually characterized by a particle size distribution,
and polymer products are normally characterized as a
function of their molecular weight distribution.
Since such a wide variety of processes exists, it is
not surprising that different design techniques and
criteria are applicable. Moreover, it should be appar-
ent that there is not enough time in an under-
graduate's program to discuss all of these types of
problems. Thus, it has been common practice to have
undergraduates consider the design of only one type
process (usually a petrochemical process that pro-
duces a single, pure product) in the design course.

A GENERAL STRATEGY FOR
APPROACHING DESIGN PROBLEMS
Experience indicates that less than 1% of the ideas
for new designs ever becomes commercialized. In order
to avoid expensive failures, it is common practice for
process engineers to develop a hierarchy of designs
where the accuracy of the design calculations and the
amount of detail considered increases as the next level
in the hierarchy is considered (see Table 1, from [2]).
The design course in chemical engineering looks at
Level 2 for a single process. That is, the students are
given a flowsheet, i.e., a description of the process
units and the interconnections between these units.
They calculate the process material and energy bal-
ances, the required equipment sizes, the utility flows,
the capital and operating costs, and the process prof-
itability. The design calculation routines used are
fairly rigorous so that obtaining a solution normally
requires extensive iteration, which often becomes
quite tedious.
Most design research has focused on Levels 2 and
3 in the hierarchy. The emphasis has been on the de-
velopment of improved algorithms for the rigorous de-
sign of a variety of types of equipment or complete
flowsheets. Similarly, improved optimization proce-
dures for various types of problems have received con-
siderable attention.
Level 1 in the hierarchy of Table 1, also known as
the conceptual design phase, is usually undertaken by
experienced engineers. They use numerous heuristics
and back-of-the-envelope calculations to develop the


TABLE 1
Types of Designs

1. Order of magnitude estimate (Error about 40%)
2. Factored estimate (Error about 25%)
3. Budget authorization estimate (Error about 12%)
4. Project control estimate (Errorabout6%)
5. Contractor's estimate (Error about 3%)

first design, i.e., the base-case design, and then to
screen the process alternatives. In some companies
an engineer is sent to a chemist's laboratory as soon
as the chemist has discovered a new reaction or a new
catalyst, and the engineer is expected to complete a
base-case design within a period of two days to one
week. The results of this design study are then used
to help guide the development of the project.

TEACHING CONCEPTUAL DESIGN
Conceptual design is a creative activity where the
goal is to find the best flowsheet from a large number
of process alternatives. If one were to blindly consider
all of the possible alternatives, it would be necessary
to consider something like 104 to 109 flowsheets. Ac-
cording to Westerberg [4], each flowsheet is described
by about 10,000 to 20,000 equations, and there are
usually ten to twenty optimization variables as-
sociated with each alternative. It is necessary to com-
pare these alternatives at close to the optimum design
conditions in order to determine the best flowsheet.
Typical of design problems in other disciplines, chem-
ical process design problems are characterized by the
combinatorially explosive nature of the possible solu-
tions.
The question then arises as to whether it is possi-
ble to teach undergraduates how to complete a first
design in a two-day to one-week period, and how to
determine the best flowsheet in another two-day to
one-week time frame. This requirement implies that
it will be necessary to teach them how to derive back-
of-the-envelope calculation procedures and how to de-
rive heuristics, since these are the tools used by ex-
perienced engineers. It will also be necessary to teach
the undergraduates a systems approach to synthesis
which emphasizes the interactions that may occur
when we put a complete process together. A discus-
sion of some new tools of this type follows.


WINTER 1989









DERIVING BACK-OF-THE-ENVELOPE DESIGN MODELS
Chemical engineers are used to having a hierarchy
of models, with increasing orders of complexity and
accuracy, available for solving various problems. For
example, the Navier-Stokes equations used in fluid
mechanics are sufficiently complex that it is necessary
to use order-of-magnitude (or scaling) arguments to
simplify them in order to obtain an answer. It is sur-
prising that no one seems to have attempted to use
this same approach to simplify models in other prob-
lem areas, such as equipment or process design.
One could use order-of-magnitude arguments to
derive a back-of-the-envelope model for an isothermal,
plate-type gas absorber used to recover solutes from
a dilute feed stream. For this special class of absorber
problems there is an analytical solution, called the
Kremser equation [1], which most undergraduates
have studied.
SL Y.- mX. 1
In 1 Yin m-mX + 1
N + 1= N G Yout i (1)
in L


We would like to develop a short-form of this equation
to further simplify our analysis. Since we do not need
great accuracy for conceptual design (see Level 1 in
Table 1) our criterion will be to drop any term that
does not affect the answer by more than 10%.
We first note that most gas absorbers encountered
in practice contain 10 to 20 trays, and therefore we
are interested in obtaining accurate solutions when N
is of the order of 10 to 20. When we examine Eq. (1)
we see that order-of-magnitude arguments yield

N+1=N (2)

For gas absorbers with pure solvent streams, Xm
= 0. From other arguments it can be shown that L/
mG = 1.4, approximately, and that Yin/Yout = 100,
or so. When we compare the orders-of-magnitude of
the terms in the numerator on the right-hand-side of
Eq. (1), we see that


In [L 1] [Y ]+ 1 = n [ L][ in- (3)
mG JYout J LmG YILt I

Since L/mG = 1.4, we could replace the de-
nominator in Eq. (1) by its Taylor series expansion
and write, approximately

n 1] = 0.4 (4)


Our result becomes, after replacing In by log

2.31og [ 1[m
N = (5)

If we are willing to sacrifice accuracy for simplicity,
the final form is

N+2=61og (6)
Yot

and we have achieved our goal of developing a back-of-
the-envelope model.
Of course, it is essential to check our simple model
against the more rigorous expression. For the case of
99% recoveries, where Yin/Yout = 100, Eq. (6) pre-
dicts 10 trays versus the rigorous value of 10.1, and
for 99.9% recoveries where Yin/Yout = 1000, Eq. (6)
gives N = 16 versus the correct value of 16.6. We
have used this same procedure to develop short-cut
models for process material and energy balances, a
variety of equipment design procedures, cost expres-
sions, etc.

DERIVING ERROR BOUNDS FOR DESIGN MODELS
The simple models used to describe process units
or other physical relationships normally have specific
limitations (i.e., the Kremser equation is valid for
isothermal, dilute systems and the ideal gas law is
valid only for low molecular weight, non-polar mate-
rials at low pressure). Of course, students need to
know when they can use these simplified models and
it is easy to quantify when these approximations are
valid simply by applying Taylor series expansions.
For example, in order to assess the validity of the
assumption of dilute, isothermal operation in a plate-
type gas absorber, we can use Taylor series expan-
sions around the condition of infinite dilution, along
with some back-of-the-envelope approximations (i.e.,
that high recoveries are equivalent to complete recov-
ery) to show that the value of the distribution coeffi-
cient will change by less than 10% if


Yin 1+ 2(A21- 2A 12)+ < 1 (7)


Thus, the dilute, isothermal assumption depends
on the heat of vaporization of the solvent, as well as
the inlet solute composition. We can develop a similar
expression for how this assumption affects the number
of plates required in the absorber by considering how


CHEMICAL ENGINEERING EDUCATION









changes in m affect N in Eq. (1). This approach is
simple to teach, and it provides a way of making deci-
sions that can be used instead of experience.

DERIVING DESIGN HEURISTICS
Design heuristics were originally proposed by ex-
perienced engineers who solved similar problems
many times, and then noticed common features of the
solution. At the present time, however, they are being
developed by graduate students who solve hundreds
of case studies on a computer and then attempt to
generalize the results (see Tedder and Rudd [3]). The
fact that heuristics exist implies that their solutions
must be insensitive to almost all of the design and cost
parameters. Therefore, by eliminating these insensi-
tive terms using order-of-magnitude arguments, it
should be possible to derive heuristics.
As an example of a derivation of a heuristic, we
again look at the design of the simple gas absorber
problem that we considered above. The number of
trays selected for the gas absorber depends on an
economic trade-off, i.e., as we increase the number of
trays we increase the cost of the absorber, but we
decrease the amount (and therefore the value) of the
material that is not recovered. If we express the cap-
ital cost of the absorber on an annualized basis and
assume that the total cost depends only on the number
of trays and the annual value of the lost solute, we
obtain


TAC=(C,)(G)(Yi) y- 8150hr/yr)+(C )(N) (8)


Now if we substitute Eq. (6) for N and find the op-
timum value of Yout/Yin, we obtain

Yout (6)(CN) (9)
Yin (C,)(G)(Y. )(8150hr/yr)

and by substituting some reasonable values for the
parameters, we find


Y"out (6)(850) =0.004 (10)
Yin (15.4)(10)(8150)


The important feature of this result is not the ex-
pression for the optimum, but the insensitivity of the
solution. We note that if we make a 100% change in
any of the values in either the numerator or de-
nominator, the answer changes only from 0.002 to


0.008, which corresponds to fractional recoveries in
the range from 99.2% to 99.8%. This is the basis for
the well known heuristic:

It is desirable to recover more than 99% of all valuable
materials.

With this simple procedure we have been able to
derive most of the current heuristics used in process
design, and have also been able to discover new
heuristics for other design problems. Again, since we
derive our heuristics, the assumptions made in the
derivations will help to indicate the limitations of their
applicability.

CONCLUSIONS
With the new techniques described above, the en-
gineer now has the tools available to quickly evaluate
flowsheet alternatives. In Part II of this article [which
will be published in the next issue of CEE] we will
describe how these tools, along with a hierarchical de-
composition procedure to generate flowsheet alterna-
tives, are used in a systems approach to conceptual
design.


NOMENCLATURE
Aij = Margules constants of the solute and solvent
at infinite dilution
CN = annualized absorber cost per plate, $/plate
Cp = heat capacity, Btu/mol-F
Cs = value of solute, $/mol
G = carrier gas flowrate, mol/hr
AH, = heat of vaporization of solute, Btu/mol
L = solvent flowrate, mol/hr
m = slope of equilibrium line
N = number of theoretical plates
R = ideal gas constant, Btu/mol-F
TAC = total annualized cost, $/yr
TL = solvent temperature, deg. F.
X = mole fraction of solute in liquid
Y = mole fraction of solute in gas

REFERENCES

1. Kremser, A., Natl. Petrol. News, 22, (21), 42 (1930)
2. Pikulik, A., and H. E. Diaz, "Cost Estimating Major
Process Equipment," Chem. Eng., 84, (21), 106 (1977)
3. Teddar, William D., and Dale F. Rudd, "Parametric
Studies in Industrial Distillation: Part I. Design
Comparisons," AIChE J., 24, (2), 303 (1978)
4. Westerberg, A. W., "Optimization in Computer-Aided
Design," Foundations of Computer-Aided Chemical
Process Design, R. S. Mah and W. D. Seider (Eds), 1,
1949, Engineering Foundation (1981) 0


WINTER 1989










Random Thoughts ...





NOBODY ASKED ME, BUT ...


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

It will probably come as a shock to those who know
me, but I have some strong opinions about educational
matters. Very strong. Violent and unswerving pre-
judices, some would say. And since I will regularly be
using this forum to subject you to whatever is on my
mind, I thought it would be only fair to run through
these opinions for you. You may then feel free to dis-
miss things I say in future columns on the grounds of
my admitted bias. (However, anything I say about a
topic not on the list may be considered absolute truth.)
Ready? Here goes, beginning with the most violent
and unswerving prejudice of them all.

* I hate 7:50 classes.
* I don't like people knocking on my door when I'm doing
something I really want to do. I welcome them joyfully,
however, when I'm doing something I really don't want
to do, like grading papers or critiquing an incomprehen-
sible thesis draft.
People who assume that all engineers are culturally
ignorant, anti-environment, good at math and science
but little else, boring, etc., are irritating. On the other
hand, our increasingly specialized and elective-free en-
gineering curriculum almost seems designed to assure
that those stereotypes are valid.
I like summers that begin in early May and end in late
August (until it's late August).
There is no excuse for undergraduate textbooks written
for professors rather than students.
I value the autonomy that comes with this job-being
able to choose my research problems, work late and
sleep late, stay at home occasionally on days I don't
teach. I can't think of another lawful profession that
provides its practitioners with so much personal free-
dom.
* I don't like stress tensors.


Copyright ChE Division ASEE 1989


* The classroom occurrence that may be most conducive
to learning is spontaneous humor. (I've been using some
of the same spontaneous jokes for years.)
* I am bemused by students who walk into my office, see
me talking on the telephone with papers and open books
scattered all over my desk and another student sitting
across from me, and ask (all together now), "Are you
busy?"
* The term "real world" can be intensely annoying, espe-
cially coming from people who think they live in it and
I don't.
* Cheating is repugnant. Even more so is the system that
hangs students'futures on the grades they get on timed
tests.
* I like anything written by Octave Levenspiel.
* I hate walking down two flights of stairs to the depart-
ment office and then forgetting what I wanted there.
(This happens with increasing frequency-I don't want
to think about what that might mean.)
* Our second-worst assumption as teachers is that if we
don't cover something in class the students won't learn
it. Our worst assumption is that if we do, they will.
* I like word processing, spreadsheeting, computer
graphics, etc., but I'm worried about how dependent
I've become on the computer. At this point if it goes
down, I go right down with it.
* I don't like anything about the PhD qualifiers-making
them up, grading them, and especially discussing them
at faculty meetings.
* It is not pleasant to discover that I really don't under-



Richard M. Felder is a professor of ChE at
N.C. State, where he has been since 1969. He
received his BChE at City College of C.U.N.Y.
and his PhD from Princeton. He has worked at
the A.E.R.E., Harwell, and Brookhaven Na-
tional Laboratory, and has presented courses
on chemical engineering principles, reactor
design, process optimization, and radioisotope
applications to various American and foreign
industries and institutions. He is coauthor of
the text Elementary Principles of Chemical
Processes (Wiley, 1986).


CHEMICAL ENGINEERING EDUCATION










stand something I've been teaching for years.

* One of our best fringe benefits is getting to give semi-
nars in some of the world's most attractive places. (Get-
ting honoraria for them is not a bad deal either.)

* There is little value and much harm in tests on which
the average is in the low 30's. I'm bothered by instruc-
tors who would never admit or even consider the possi-
bility that such tests may have been unfair or the stu-
dents may have been poorly taught.

* A university administrator who says he won't do some-
thing can be upsetting. One who consistently says he
will and then doesn't (or who is incapable of giving a
straight answer) can be disastrous.

* Iget terminallygrumpy at badly delivered departmental
seminars on subjects I'm not the least bit interested in.

* I like engineering professors with interests and talents
outside of engineering. If I have a hero in our profes-
sion, it is Bob Bird.

* Few chores are as taxing as maintaining energy in a
class that acts like a wax museum.

* One that is as taxing is serving on a university commit-
tee that has no real function and never accomplishes
anything yet religiously meets every two weeks for at
least two hours.

I am filled with admiration for Professor Vincent M.
Foote of the N.C.S. U. School of Design [may his tribe
increase], who chaired a committee I served on last
year. Vince called meetings only when there was some-
thing to do started the meetings on time, had us do
what was needed, and adjourned. The average dura-
tion of the meetings was about 20 minutes. It was a
revolutionary experience.

* The most troublesome aspect of American engineering
education is the way it penalizes outstanding teachers
doing minimal research and rewards outstanding re-
searchers doing lousy teaching.

* The most puzzling aspect of American engineering edu-
cation is the notion that engineers with years of indus-
trial experience but few research publications don't be-
long on engineering faculties.

* The hardest thing I have to do as a teacher is decide
whether I should push the final grade of a borderline
student up (providing encouragement and a challenge
to live up to my high opinion) or down (maintaining
high standards and providing an incentive to work
harder next time).
I envy professors who believe in their hearts that this
is not a dilemma-that one of these choices is the cor-
rect one for all students on all occasions. I think they're


POSITIONS AVAILABLE
Use CEE's reasonable Rates to advertise.
Minimum rate, 1/8 page $80;
each additional column inch $25.



VIRGINIA POLYTECHNIC INSTITUTE
AND STATE UNIVERSITY

The Chemical Engineering Department at Virginia
Tech is seeking applicants and nominations for the
Alexander F. Giacco Presidential Professor in Chemical
Engineering. Applicants for this endowed professorship
should have a national/international reputation in an area
of chemical engineering research. Duties include
teaching at the undergraduate and graduate levels,
conducting funded research, and departmental and
university service. This appointment is at the Full
Professor level at a salary commensurate with the endowed
nature of the professorship and the applicant's
qualifications. Virginia Tech has approximately 18,500
undergraduates (5,000 in the College of Engineering,
including 150 in Chemical Engineering) and 4,180
graduate students (1,200 in the College of Engineering,
including 50 in Chemical Engineering). Send
nominations or applications to Chairman, Giacco
Professorship Search Committee, Chemical Engineering
Department, Virginia Polytechnic Institute & State
University, 133 Randolph Hall, Blacksburg, VA 24061.
Deadline for applications is April 30, 1989. Virginia Tech
hires only U.S. citizens and lawfully authorized alien
workers. Virginia Tech is an Affirmative Action/Equal
Opportunity Employer.




UNIVERSITY OF CINCINNATI

Visiting Research Professor Position in Chemical
Engineering. BS degree in Chemical Engineering is
required. MS or PhD in Chemical Engineering preferred.
Industrial experience, preferably in chemical plant design
and operation, expected. Job function would be to develop
and teach ChE junior and senior labs, assist in the
development of design projects, and interact with
undergraduate students. Candidates should have a strong
commitment to excellence in undergraduate education.
Base salary range $25,000 to $30,000. Non-tenure track
position. Send resume, references to: Dr. Rakesh Govind,
Chairman Search Committee, Mail Location 171,
University of Cincinnati, Cincinnati, Ohio 45221.
Affirmative Action/Equal Opportunity Employer.

dead wrong, but their lives are a lot easier than mine
at least twice a year.

* I like teaching and writing. I love having a job that
pays me to do both.

Help me out-what else should be on the list? The
best entry wins a free drink at the next Exxon Suite. []


WINTER 1989










curriculum I


AN ALTERNATE APPROACH TO THE

UNDERGRADUATE THESIS


P. R. AMYOTTE and M. FELS
Technical University of Nova Scotia
Halifax, Nova Scotia, Canada B3J 2X4

The chemical engineering department at the Tech-
nical University of Nova Scotia (TUNS) has recently
undertaken an approach to the senior undergraduate
thesis which is different from the more traditional
route. In the 1986-87 academic year, most of the thesis
projects involved the design, construction, and testing
of a piece of equipment for the undergraduate labora-
tory. In previous years, each student had selected a
topic which was based on a professor's area of expertise
and research.
Our method of organizing and handling the projects
is described here, and the benefits and disadvantages
of conducting undergraduate theses in this manner are
discussed. We have concentrated more on the educa


Paul Amyotte received his BEng from the Royal Military College of
Canada and his MSc (Eng) from Queen's University. He is a graduate
of the PhD program at the Technical University of Nova Scotia, where
he is an assistant professor in the chemical engineering department.
His interests are the drying of cereal grains, gas and dust explosions,
and engineering education. (L)
Mort Fels received his BEng from McGill University and his PhD
from the University of Waterloo. He has been teaching chemical en-
gineering for sixteen years and is currently a professor in the chemical
engineering department at the Technical University of Nova Scotia. His
research interests are biomedics (artificial kidney), energy conversion,
and computer-aided design. (R)
0 Copyright ChE Division ASEE 1989

28


TABLE 1
Staged Progression of Thesis Work

First Term
1. Topic Selection
2. Functional and conceptual design
3. Dimensional design
4. Framework and support structure requirements
5. Order list for components
6. Mid-term oral presentation
7. End-of-term oral presentation and written report
Second Term
1. Control panel dimensions and layout
2. Beginning and end of construction
3. Beginning and end of testing
4. Mid-term oral presentation
5. Final oral presentation and written report


tional aspects of our approach than on the projects
themselves.

ORGANIZATION
The chemical engineering department at TUNS is
relatively small, with a typical total enrollment of forty
to fifty undergraduates in the three years. In 1986-87,
our senior class consisted of twelve students. The stu-
dents worked singly on a project which was conducted
under the supervision of a professor (or professors) in
the department. One faculty member also served as
overall coordinator. As well as being an additional re-
source person for the students, he reviewed the final
designs before components were ordered and also gave
lectures on topics such as project management, in-
strumentation selection, and the design process.
A graduate student was assigned to the course as
a teaching assistant. The student was selected for his
practical knowledge of piping, electrical, and construc-
tion techniques and, as such, was invaluable as a re-
source person for the students. He also coordinated
the purchase orders from the twelve projects.
An important aspect of the course structure was a
schedule of events which the class was expected to


CHEMICAL ENGINEERING EDUCATION


JWhE









follow. Deadlines were established for the items shown
in Table 1.
PROJECTS
The twelve topics offered were categorized as
shown in Table 2. The three research-type projects all
have potential for use in the undergraduate laboratory.

BENEFITS
The most obvious benefit from this work has been
the addition of new experiments and the subsequent
deletion of outdated equipment. This has resulted in
a general strengthening of the undergraduate lab, par-
ticularly in the unit operations area. For example, we
have replaced a large plate heat exchanger with a smal-
ler, more versatile unit.
We have also been able to increase the use of com-
puters in the lab, primarily in the areas of

Data acquisition (drying)
Data acquisition and control (single and multi-variable con-
trol experiments)
Data reduction (plate heat exchanger)

There is no doubt that the work described here has
held significant advantages for the department; but
what about the students? Judging from their reaction
to the work (and the quality of the finished products),
they have also benefited from the experience. Student
development was fostered by several factors:

Familiarization with aspects of design and project manage-
ment
Knowledge of instrumentation
Hands-on, practical experience
Interaction with technicians, salesmen, etc.
Sense of pride in the work; enhancement of class spirit
Exposure to state-of-the-art equipment ( e.g., Laser Dop-
pler Velocimetry in the freeboard particle measurements)

Apart from the technical aspects listed above, each
student was required to give four oral presentations
during the course of the year, as well as two written
reports (Table 1). In all cases, a noticeable improve-
ment in communication skills occurred; with three stu-
dents the improvement was almost unbelievable.

PROBLEMS
An undertaking of this nature has its inevitable
drawbacks. Although, overall, the experience was con-


The most obvious benefit from this work
has been the addition of new experiments and
the subsequent deletion of outdated equipment.
This has resulted in a general strengthening
of the undergraduate lab, particularly
in the unit operations area.


TABLE 2
Thesis Projects

New Experiments for Undergraduate Lab
1. Air Conditioning
2. Drying
3. Ion Exchange
4. Wetted-Wall Gas Absorption
5. Fluidized Bed Heat Transfer
6. Plate Heat Exchanger
7. Single Variable Control (Temperature)
8. Multi-Variable Control (Temperature and Level)
Upgraded Experiment for Undergraduate Lab
9. Packed Column Gas Absorption
Work on Research Projects
10. R-Value Measurement of Building Materials
11. Particle Velocity Measurements in the Freeboard of a
Cold Fluidized Bed
12. Computer Control of a Coal Processing Mini Plant



sidered a success, several problems arose which are
described below.

Cost
Laboratory equipment is expensive, especially if
one wants to incorporate the latest advances in technol-
ogy. There is a big difference in measuring tempera-
ture with a thermometer and using thermocouples with
associated A/D conversion and computer data-logging.
We chose, in general, a middle ground, and installed
primary transducers with digital read-outs which
would allow eventual upgrading to computer data-log-
ging and control.
Total costs for each project varied from about $500
to $3,000. However, the alternative of purchasing off-
the-shelf units (if possible) would have been many
times more expensive. Some funds should be set aside
to purchase those forgotten or emergency items which
are always necessary at the end of the project or during
initial testing.

Time
Time plays a major role in this type of thesis ap-
proach. The students, faculty and support staff de-
voted many hours to the work. Normally, three hours


WINTER 1989









per week for twenty-six weeks is scheduled (78 hours).
It is estimated that the total time that the students
spent is closer to double this figure. However, the
nature of these projects is such that much of the time
must be spent at the end of the final term, which is,
of course, when it is the most scarce. We were con-
cerned that the students would be unable to complete
the projects in the available time. This is probably the
largest risk in such a venture. A high degree of success
was achieved, however, with most students meeting
the objectives of the work and producing a piece of
laboratory equipment which worked. Shortfalls in the
program occurred in testing and preparing detailed
laboratory procedures. In most cases, additional work
is needed in these areas so that the experiments can
be used routinely in the undergraduate laboratory.

Scheduling
The time for equipment which was slated for up-
grading and which was also part of a current laboratory
course required careful scheduling. Fortunately, only
one project (packed column gas absorption) fell into
this category. We found that it was necessary to run
all the laboratory course experiments on packed col-
umn gas absorption in one time block at the beginning
of the first term. Once this was accomplished, the
equipment was turned over to the thesis student and
the upgrading proceeded without interruption.

Type of Student
The laboratory projects require that a student have
a certain degree of mechanical know-how and dexter-
ity. Since technologist time is limited, a major amount
of actual construction is necessarily performed by the
student. There were a few students who lacked basic
skills in this area and who had no interest in learning
them. The result of this situation was that the faculty
member had to put in a fair amount of time doing the
actual construction.

Research Aspect
One disadvantage of this type of project is that
students wishing to pursue a post-graduate degree will
not be exposed to some of the concepts or techniques
of research. There is no doubt that development of
skills in the areas of literature searches, experimental
design and general research philosophy suffered. How-
ever, development of other skills relating to equipment
construction, communications and general project
management is also important in research.


SUGGESTIONS
In contemplating this type of project, the following
important points should be considered:

Only do as many projects for which there is adequate fund-
ing.
The larger projects would probably be more successful with
two students working together instead of only one.
Do not have only laboratory-type projects available; re-
search or theoretical projects should be provided for those
students who have no interest in a laboratory project.
Ensure that enough technical help is available. Machinists,
plumbers, and electricians are necessary resource people.

CONCLUSIONS
An alternate approach to the undergraduate thesis
has been described. This approach lies somewhere
between the traditional research-oriented thesis and
the work normally done in a process and plant design
course. The size of our senior class has made it pos-
sible for us to offer this experience to all members of
the group. In a large institution it would still be pos-
sible to adopt this scheme, but with a smaller percent-
age of the seniors. While a strategy of this sort is
neither desirable nor feasible to implement on a con-
tinuous basis, our one attempt has brought numerous
benefits to both the department and the students in-
volved. El


REVIEW: Direct Contact
Continued from page 11.
any wall resistance and low capital cost. In specialized
situations these advantages certainly will lead to further
commercial use of direct contact exchangers.
The book is the product of an NSF-supported work-
shop held at the Solar Energy Research Institute in 1985.
In contains fourteen chapters written by the organizers
and principal speakers. Five chapters deal with two-
phase fluid systems. Three chapters treat heat transfer
between particulate solids and gases. A chapter each
concerns evaporation and condensation processes.
Several valuable functions are fulfilled by this book.
At the most basic level it should serve to re-emphasize to
the heat transfer specialists that this kind of heat ex-
changer is an option with certain strong advantages. The
book is a good source of ideas and configurations for
possible applications. A valuable feature of the book is a
set of design examples included as six appendices. In the
final chapter the editors present a summary of research
needs. O


CHEMICAL ENGINEERING EDUCATION













CHEMICAL REACTOR DESIGN
by E. B. Nauman
John Wiley & Sons,, $53.70 (1987)

Reviewed by
P. A. Ramachandran
Washington University

Chemical reaction engineering has evolved to a ma-
ture discipline in the last two decades, and this has re-
sulted in a number of textbooks and monographs on the
subject. The computer revolution has embraced this
field in a big way, and the trend is towards detailed
modeling and optimization studies of industrial scale re-
actors. The textbook coverage on the application of nu-
merical methods in reaction engineering is, however,
minimal and the present book fills this important gap.
Thus the major contribution of the book is the detailed
presentation of the computer aids as problem solving
tools in reactor design. This naturally leads to applica-
tion to more realistic problems as opposed to simplified
artificial schemes such as A -4 B. This book is therefore
able to focus on the applications to practical industrial


1989



Chemical



Engineering



Texts from



Wiley


problems.
Chapter 1 introduces the basic concepts as applied to
simple reactions and ideal reactors. The rate of reaction
is nicely defined on a unit stoichiometric basis, and the
rate of formation of any given species is then related to
this quantity by using the stoichiometric coefficients.
Such an approach is necessary for computer based
simulations of more complex systems.
Chapter 2 extends the basic concepts for more com-
plex reaction schemes. The Runge-Kutta method for
solving a set of differential equations is introduced here
and then applied to a number of problems for plug flow
reactors. The analysis to a general reaction network is
introduced on the basis of a matrix formulation. The
Concepts of rank of matrix and its use in determining
the key limiting reactants is briefly presented. It would
have been useful to elaborate on these concepts in
somewhat more detail with additional solved problems
because the students usually have difficulties in this
area.
Chapter 3 introduces the solution methods for differ-
ent reactor types. The Newton-Raphson method for
solving a set of nonlinear algebraic equations is dis-
cussed and the application to a perfectly mixed reactor
handling a complex kinetic scheme is nicely presented.
Chapter 4 deals with the additional complications of
thermal effects. Again, numerical methods are exten-
Continued on page 49.


CHEMICAL AND ENGINEERING THERMODYNAMICS, 2/E
Stanley I. Sandier, The University of Delaware
0-471-83050-X, 656pp., Cloth, Available January 1989
A fully revised new edition of the well received sophomore/junior level thermo-
dynamics text, now incorporating microcomputer programs.

PROCESS DYNAMICS AND CONTROL
Dale E. Seborg, University of California, Santa Barbara,
Thomas R. Edgar, University of Texas, Austin,
and Duncan A. Mellichamp, University of California,
Santa Barbara
0-471-86389-0, 840pp., Cloth, Available February 1989
A balance in-depth treatment of the central issues in process control, including
numerous worked examples and exercises

REQUEST YOUR COMPLIMENTARY COPIES TODAY
Contact your local Wiley representative or write on your school's stationery to
Angelica DiDia, Dept. 9-0264, John Wiley & Sons, Inc., 605 Third Avenue, New York,
NY 10158. Please include your name, the name of your course and its enrollment,
and the title of your current text. IN CANADA- write to John Wiley & Sons Canada
Ltd, 22 Worcester Road Rexdale, Ontario, M9W ILl.


f JOHN WILEY & SONS, INC.
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WINTER 1989










Li laboratory


AN EXPERIMENT IN


AUTOTROPHIC FERMENTATION

Microbial Oxidation of Hydrogen Sulfide


KERRY L. SUBLETTE
The University of Tulsa
Tulsa, OK 74104


TABLE 1
Medium for Anaerobic Growth of Thiobacillus denitrificans


THERE HAS BEEN AN increasing effort in recent
years to introduce chemical engineering students
to biological processes. These efforts may be rather
modest, with the incorporation of one or more exper-
iments in enzyme kinetics or fermentation into the
undergraduate laboratory, or more broadly based with
formal course work in microbiology, biochemistry and
biochemical engineering, and blocks of time in the lab-
oratory devoted to bioengineering experiments. How-
ever, even in the more comprehensive programs the
chemical engineering student is typically exposed to
only one basic type of fermentation, that which is based
on heterotrophic metabolism. In other words, the
microorganisms which make up the fermentation cul-
ture utilize organic compounds as carbon sources and
light or the oxidation of organic compounds as a source


COMPONENT
Na2HPO4
KH2PO4
MgS04*7H20
NH4Cl
CaCl2
MnS04
FeC13
NaHCO3
KNO3
Na2S203 or H2S(g)
Trace metal solution*
Mineral water


PER LITER
1.2 g
1.8 g
0.4 g
0.5 g
0.03 g
0.02 g
0.02 g
1.0 g
5.0 g
10.0 g thiosulfatee)
15.0 ml
50.0 ml


* See reference (2).


Kerry L. Sublette obtained his BS in chemistry from the University
of Arkansas, his MS in biochemistry from the University of Oklahoma,
and his MSE and PhD in chemical engineering from the University of
Tulsa. After six years in research and development with Combustion
Engineering, he joined the chemical engineering faculty at the Univer-
sity of Tulsa in 1986. His research interests are in fermentation,
biocatalysis, microbial desulfurization of coal, and biological methods
of hazardous waste treatment.
Copright ChE Division ASEE 1989


of energy. Another way of life exists by which micro-
organisms may derive both carbon and energy from
inorganic sources. This is termed autotrophic
metabolism. Autotrophic organisms are becoming in-
creasingly important commercially in waste treatment,
coal and sour gas desulfurization, and mineral leaching
applications. This experiment is designed to introduce
the student to fermentation based on autotrophic
metabolism. The subject of substrate inhibition is also
addressed. This experiment is not recommended as a
first introduction to fermentation but as a demonstra-
tion of the wide range of metabolic capabilities of micro-
organisms.
Specifically this experiment utilizes the auto-
trophic bacterium Thiobacillus denitrificans to
anaerobically oxidize H2S(g) to sulfate in a batch stir-
red tank reactor. Hydrogen sulfide is shown to be an
inhibitory substrate for the bacterium; however, under
sulfide-limiting conditions rapid and complete oxida-
tion of H2S is observed with undetectable levels of H2S


CHEMICAL ENGINEERING EDUCATION









in the bioreactor outlet gas. Provided the bioreactor
can be sampled periodically over 1-2 days, the
stoichiometry of the reaction is readily determined.

BACKGROUND
In nature there exists a large and widely distrib-
uted group of microorganisms which play a central role
in the maintenance of the carbon, nitrogen, and sulfur
cycles. These microorganisms are termed lithotrophic
if they are capable of deriving energy and/or reducing
equivalents from the oxidation of inorganic compounds.
Chemolithotrophs derive both energy and reducing
equivalents from such reactions, while photolitho-
trophs derive energy from the absorption of radiant
energy and reducing equivalents from oxidation of in-
organic compounds. Those microorganisms capable of
also deriving carbon for biosynthesis from an inorganic
source (carbon dioxide) are termed autotrophic. Exam-
ples of inorganic energy sources for chemoautotrophs
include hydrogen, ammonia, iron (II) salts, elemental
sulfur, thiosulfates, and sulfides. The interrelationship
between substrate oxidation and biosynthesis in
chemoautotrophic organisms is illustrated in Figure 1.
Thiobacillus denitrificans is a strict autotroph and
facultative anaerobe first described in detail by Baals-
rud and Baalsrud [1]. Thiosulfate, elemental sulfur,
and soluble sulfide may be utilized as energy sources
with oxidation to sulfate. Under anaerobic conditions
nitrate may be used as a terminal electron acceptor
with reduction to elemental nitrogen.
Anaerobic growth of T. denitrificans on H2S(g) has
been described in detail by Sublette and Sylvester [2-
4]. The medium used to grow T. denitrificans is given
in Table 1. When H2S served as the energy source it
was bubbled into the reactor at a rate sufficiently low
as to maintain sulfide-limiting conditions. In other
words, H2S was introduced into the cultures at a rate
which was less than the maximum oxidation capacity



TABLE 2
Stoichiometry of Anaerobic H2S Oxidation by
T. denitrificans in Batch Reactors*


S04"2/H2S
NO3/H2S
NH4+/H2S
OH'/H2S
Biomass/H2S
* Average of four determinations


1.04 mole/mole
1.36 mole/mole
0.12 mole/mole
1.60 equivalents/mole
12.1 g/mole


INORGANIC
SUBSTRATES


ENERGY ,-


< REDUCING
EQUIVALENTS-


OXIDIZED
INORGANIC
SUBSTRATES


REDUCED
CARBON
COMPOUNDS

BIOSYNTHESIS


FIGURE 1. Chemoautotrophic metabolism

of the biomass. Stock cultures and start-up cultures
used thiosulfate as an energy source. Under anaerobic
conditions nitrate was the terminal electron acceptor.
Bicarbonate was the carbon source and ammonium the
source of reduced nitrogen. The medium also contained
a phosphate buffer and sources of various essential
mineral nutrients.
Sublette and Sylvester [2, 3] reported that when
H2S(g) was introduced into anaerobic cultures of T.
denitrificans previously grown on thiosulfate, the H2S
was immediately metabolized with no apparent lag.
Typically the feed gas contained about one mole per-
cent H2S. Initial loadings were in the range of 4-5
mmoles HgS/hr-g biomass. With sufficient agitation to
reduce the average bubble diameter to about 0.25 cm
and gas-liquid contact times of 1-2 sec, H2S was unde-
tectable in the reactor outlet gas by GC/MS. Less than
1 PM of total sulfide (H2S, HS-, S-) was observed in
the reactor medium during periods of up to thirty-six
hours of batch operation. No intermediates of sulfide
oxidation (elemental sulfur or sulfite) were detected;
however, sulfate accumulated in the reactor medium
as H2S was removed from the feed gas. Oxidation of
H2S to sulfate was accompanied by growth as indicated
by an increase in optical density and protein concentra-
tion and a decrease in the NH4 concentration in the
medium. The reaction was acid producing requiring
hydroxide (OH-) equivalents to be pumped into the
reactor to maintain an optimum pH of 7.0. Small
amounts (< 40 jiM) of nitrous oxide, N20, could be
detected in the reactor outlet gas. However, no other
intermediates of nitrate reduction were observed to
accumulate while nitrate was consumed. The
stoichiometry of anaerobic H2S oxidation by T. deni-
trificans in batch reactors as reported by Sublette and
Sylvester [2] is given in Table 2.
Sublette and Sylvester [2] also reported that H2S


WINTER 1989









is an inhibitory substrate for T. denitrificans. Inhibi-
tory effects were observed at total sulfide concentra-
tions as low as 200 1LM with total inhibition observed
at 1000 lpM. The total sulfide concentration in the
medium of batch anaerobic T. denitrificans reactors
operated under sulfide-limiting conditions was well
below inhibitory levels. However, these authors re-
ported that if the maximum capacity of the biomass
for H2S oxidation was exceeded, inhibitory levels of
sulfide quickly accumulated in the medium. This upset
condition was characterized by H2S breakthrough in
the outlet gas, release of large amounts of N20 and
accumulation of elemental sulfur in the medium. It was
observed that this upset condition was reversible if
the cultures were not exposed to the accumulated sul-
fide for more than two to three hours. Reduction in
the H2S feed rate following an upset condition reduced
the H2S and N20 concentrations in the outlet gas to
pre-upset levels with elemental sulfur oxidized to sul-
fate. The H2S loading at which the specific activity of
the T. denitrificans biomass was exceeded resulting
in upset was observed to be 5.4-7.6 mmoles H2S/hr-g
biomass under anaerobic conditions.
The autotrophic medium described in Table 1 will
not support the growth of heterotrophs since there is
no organic carbon source. However, Sublette and Syl-
vester [4] observed that if aseptic conditions were not
maintained a heterotrophic contamination developed
in a T. denitrificans culture growing on thiosulfate or
H2S. Evidently T. denitrificans releases organic mate-
rial into the medium in the normal course of growth
or through lysis of nonviable cells which supports the
growth of heterotrophs. Sublette and Sylvester re-
ported that the heterotrophic contamination had no
discernable effect on H2S metabolism by T. deni-
trificans.

EXPERIMENTAL PROCEDURE
Samples of Thiobacillus denitrificans may be ob-
tained from the American Type Culture Collection,
Rockville, Maryland, or from the author. Stock cul-
tures may be grown anaerobically on thiosulfate in 10
ml culture tubes at 300C. When dense qrowth appears
(three to four days with fresh inoculum) store at 4C
until used. Stocks should be transferred every thirty
to sixty days to maintain vigorous cultures. Stock cul-
tures do not need to be grown aseptically. Figure 2
presents a schematic diagram of the equipment re-
quired to culture T. denitrificans anaerobically on
H2S(g).
An investigation of the anaerobic oxidation of H2S
by T. denitrificans is described below. Details of the
analytical methods required for a thorough study of


the stoichiometry of the process are also presented.
It is intended that the experiment can be used to in-
troduce the subjects of autotrophic fermentation and
substrate inhibition at a number of levels of difficulty
and challenge to the students. A straightforward dem-
onstration of the detoxification of a hazardous material
by a bacterium can be conducted requiring less than
three hours of student participation. However, an in-
vestigation of the stoichiometry of the process would
require intermittent observation and sampling of H2S
cultures for one to two days plus time for sample
analysis.
Before describing the experimental protocol a
word of caution is in order. Hydrogen sulfide is a
highly toxic gas. The threshold limit value (time
weighted average) for H2S exposure is 10 ppm (7-8
hrs). The threshold limit value for short term expo-
sure is 15 ppm (15 minutes). It is therefore necessary
that the laboratory instructor carefully monitor all op-
erations involving H2S and, as indicated in Figure 2,
the entire fermentation system must be located in a
fume hood.

Anaerobic Oxidation of H2S
A working culture of T. denitrificans may be de-
veloped by growing on thiosulfate at 300C and pH 7.0
using the medium described in Table 1. The purpose
of this prior cultivation on thiosulfate is to develop a
sufficient concentration of biomass in the reactor so
that an appreciable rate of H2S can be fed to the reac-
tor without exceeding the biooxidation capabilities of
the biomass. Otherwise sulfide would accumulate in
the reactor medium to toxic levels.
The recommended culture vessel (see Figure 2) is
a 1-2 1 jacketed beaker with a large silicone rubber




EXHAUST
ROTAMETER EX T pH METER/
CONTROLLER
GAS
CYLINDER


NaOH
RESERVOIR
WATER .*


FUME HOOD

FIGURE 2. Schematic diagram of equipment required to
culture T. denitrificans anaerobically on H2S(g)


CHEMICAL ENGINEERING EDUCATION










Chemolithotrophs derive both energy and reducing equivalents from such reactions, while
photolithotrophs derive energy from the absorption of radiant energy and reducing equivalents from
oxidation of inorganic compounds. Those microorganisms capable of also deriving carbon for
biosynthesis from an inorganic source (carbon dioxide) are termed autotrophic.


stopper to support probes and inlet and outlet ports.
Temperature may be controlled by circulating water
at 300C through the jacket of the reactor. The pH may
be monitored and controlled by a pH meter/controller
which activates a peristaltic pump to deliver 6 N
NaOH to neutralize acid produced by the biooxidation
of thiosulfate or H2S. A pH stability of 0.2 units is
desirable. If the controller also activates a laboratory
timer, the rate of NaOH addition can be monitored.
A gas feed of 5 mole % C02 in nitrogen at 30 ml/min
is recommended during growth on thiosulfate to en-
sure the continuous availability of a carbon source.
Gas mixtures are fed to the reactors from cylinders of
compressed gas through two stage stainless steel reg-
ulators and rotameters. Gas is introduced into the cul-
ture medium by means of a glass fitted sparger. A
four or six bladed, flat disk impeller may be used for
agitation at 200-300 rpm to produce good gas-liquid
contacting.
As noted previously, heterotrophic contamination
has little or no effect on the growth of T. denitrificans
in an autotrophic medium. Therefore, it is not neces-
sary to sterilize the reactor or any associated equip-
ment.
When 1-2 1 of thiosulfate medium is inoculated with
20 ml of a fresh stock culture, a working culture is
produced in approximately sixty hours. The medium
described in Table 1 is nitrate limiting; therefore, when
the nitrate is depleted the culture stops growing. At
this point the culture will have an optical density at
460 nm of about 1.0.
The pathways for sulfide and thiosulfate oxidation
to sulfate in T. denitrificans are not independent but
have two common intermediates [5]. In the presence
of thiosulfate the rate of sulfide oxidation would be
reduced because of competition between intermediates
of thiosulfate and sulfide oxidation for the same en-
zymes of the sulfur pathway. Therefore, prior to the
introduction of H2S to T. denitrificans cultures, re-
sidual thiosulfate must be removed. This may be ac-
complished by sedimenting the cells by centrifugation
at 4900 x g for ten minutes at 25C. A refrigerated
centrifuge is preferred. However, any centrifuge is
acceptable if the temperature of the cell suspension
does not exceed 45C during harvesting. The superna-
tant is discarded and the cells resuspended in growth
medium without thiosulfate. Following a second cen-
trifugation the washed cells are resuspended in


medium without thiosulfate and transferred back to
the reactor. It is recommended that the reactor and
all probes be rinsed in distilled water to remove re-
sidual thiosulfate prior to reintroduction of cells.
Once thiosulfate has been eliminated, hydrogen sul-
fide can now be introduced into the culture by changing
the feed gas to include H2S. A composition of 1 mole
% H2S, 5 mole % C02 and balance N2 is recommended.
If the OD460 of the culture is at least 0.8, a feed rate
of about 50 ml/min will not exceed the biooxidation
capabilities of the culture. It is recommended that the
H2S feed rate be brought to this level stepwise over
about thirty minutes. With proper agitation to achieve
good gas-liquid contacting, H2S will be undetectable
in the gas outlet of the reactor.
The stoichiometry of anaerobic oxidation of H2S(g)
by T. denitrificans can be obtained by sampling the
reactor contents over a period of 24-48 hours as H2S
is removed from the feed gas. Of particular interest
would be the concentrations of sulfate (S042), nitrate
(NO3-), ammonium ion (NH4+), elemental sulfur and
biomass in the reactor medium. Analytical methods
are discussed below.
The inhibitory nature of H2S as a substrate can be
demonstrated by increasing the H2S feed rate stepwise
until H2S breakthrough is seen. When breakthrough
occurs, nitrous oxide (N20) will also be detected in the
outlet gas and elemental sulfur seen to accumulate in
the reactor medium. Sulfur will give the medium a
milky white color. As described in a previous section,
the upset condition is reversible if not prolonged. How-
ever, if the upset condition is allowed to persist the
outlet H2S concentration becomes equal to the inlet,
indicating complete loss of biooxidation activity in the
culture.

Analytical
Feed gas and reactor outlet gas may be analyzed
for H2S and N20 by gas chromatography. Using a
thermal conductivity detector the detection limit for
H2S is about 2-4 LM with a 0.25 ml sample. In our
laboratory a 10-ft by 1/8-in ID Teflon column containing
Porapak QS (Waters Associates) has been used with
a helium flow rate of 20 ml/min. A column temperature
of 70C and injector and detector temperatures of
200C are satisfactory. Under these conditions the re-
tention times of N2, CO2, N20, and H2S are 0.8, 1.8,


WINTER 1989










2.2, and 5.3 minutes, respectively. H2S is quantitated
by comparing chromatograms of samples to
chromatograms produced by a certified primary stand-
ard (Matheson Gas Co.). If a gas chromatograph is
unavailable, H2S and N20 may also be determined to
25% using Gastec Analyzer Tubes (Yokohama,
Japan).
Nitrate may be determined in thiosulfate free sam-
ples by the cadmium reduction method [6]. Ammonium
ion may be determined by the Nessler method without
distillation [6]. Sulfate is readily determined tur-
bidometrically [6]. Premeasured reagents for these
analyses may be purchased from Hach Chemical Co.
Thiosulfate may be determined by titration with
standard iodine solution using a starch indicator [7].
Elemental sulfur may be collected by filtration on 0.45
micron Millipore Type HA filters and determined by
reaction with cyanide to produce thiocyanate.
Thiocyanate may be quantitated as Fe(SCN)6- which
has a molar extinction coefficient in water at 450 nm
of 3.37 x 103 M-1 cm-1 [8].
Biomass may be determined in terms of whole cell
protein by sonication followed by colorimetric analysis
by the micro modification of the Folin-Ciocalteau
method [9, 10]. (Folin-Ciocalteau reagent may be
purchased from Anderson Laboratories.) Cells are sus-
pended in 10-20 ml of 20 mM phosphate buffer, pH
7.0, and sonicated with a sonic probe until the suspen-
sion is clarified. In our laboratory a Braun-Sonic 1510
with a 3/4 in. probe is used at 150 watts for two three-
minute periods with intermittent cooling. The result-
ing protein solution is analyzed directly without further
treatment. Bovine serum albumin (Sigma Chemical
Co.) is used as a standard. The protein content of T.
denitrificans cells grown on H2S(g) is 60 3% [2].
Using this figure the results of protein analyses may
be converted to dry weight T. denitrificans biomass.


SAMPLE RESULTS

In a typical batch experiment the oxidation of 18.3
mmoles of H2S was accompanied by the production of
18.8 mmoles sulfate and 246 mg of biomass. A total of
27.0 mmoles nitrate, 2.2 mmoles ammonium ion and
31.8 meq of hydroxide ion were utilized.
Figures 3a and 3b summarize the results of analysis
of the medium of an anaerobic reactor as H2S is
oxidized by the culture. Sulfate is seen to accumulate
in the medium. The concentration of biomass increases
as the cells grow using H2S as an energy source and
correspondingly the optical density increases with
time. Nutrient levels (NOs- and NH4+) decline as H2S


48 -


E
- '-a2
.1
i,



6

4

2


TIME (hours)


FIGURE 3a. Optical density, concentration of sulfate
(S04-2) and hydroxide ion (OH-) utilized in an anaerobic
T. denitrificans batch reactor receiving 1.25 mmoles/hr
hydrogen sulfide (H2S) feed. OD (e); S042 (N); OH- (A).


8.5 -


8.0


6.5 -


450 -


400 -


0
- 350-

- oo -


2501-


6.0 200 4
ol_ ol- o I L I I HII -I I
0 2 4 6 B 10 12 14 16 18 20
TIME (hours)

FIGURE 3b. Concentrations of nitrate (NO3-), biomass
and ammonium (NH4 +) in an anaerobic T. denitrificans
batch reactor receiving 1.25 mmoles/hr hydrogen sulfide
(H2S) feed. NO3- (0); NH4 + (A); biomass (0).


CHEMICAL ENGINEERING EDUCATION









is oxidized and the cell population increases. Lastly,
hydroxide is steadily consumed as acid is produced by
the process.
ACKNOWLEDGEMENT
The author wishes to express his appreciation for
the technical assistance of Dr. Marion Woolsey. Re-
search upon which this experiment is based was funded
by Combustion Engineering, Inc. of Stamford, Con-
necticut.
REFERENCES

1. Baalsrud, K., and K. S. Baalsrud, "Studies on
Thiobacillus denitrificans," Arch. Mikrobiol., 20, 34-62
(1954)
2. Sublette, K. L., and N. D. Sylvester, "Oxidation of Hy-
drogen Sulfide by Thiobacillus denitrificans: Desulfur-
ization of Natural Gas," Biotech. and Bioeng., 29 249-257
(1987)


3. Sublette, K. L., and N. D. Sylvester, "Oxidation of Hy-
drogen Sulfide by Continuous Cultures of Thiobacillus
denitrificans," Biotech. and Bioeng., 29, 753-758 (1987)
4. Sublette, K. L., and N. D. Sylvester, "Oxidation of Hy-
drogen Sulfide by Mixed Cultures of Thiobacillus deni-
trificans and Heterotrophs," Biotech. and Bioeng., 29,
759-761 (1987)
5. Suzuki, I., "Mechanisms of Inorganic Oxidation and
Energy Coupling," Ann. Rev. Micro., 28, 85-101 (1974)
6. American Public Health Association, Standard Methods
for the Examination of Water and Wastewater, 14th Ed.,
APHA, New York (1976)
7. Meites, L., Ed., Handbook of Analytical Chemistry,
McGraw-Hill Book Co., Now York (1963)
8. Schedel, M., and H. G. Truper, "Anaerobic Oxidation of
Thiosulfate and Elemental Sulfur in Thiobacillus deni-
trificans," Arch. Mikrobiol.,124, 205-210 (1980)
9. Folin, 0., and V. Ciocalteau, "On Tyrosine and Trypto-
phan Determinations in Proteins," J. Biol. Chem., 73,
627-649 (1927)
10 Lowry, 0. H., N. J. Rosebrough, A. L. Farr, and R. J.
Randall, "Protein Measurement with the Folinphenol
Reagent," J. Biol. Chem., 193, 265-275 (1951) 0


J@IAbook reviews


ADVANCES IN DRYING,
Volume 4
Edited by Arun A. Mujumdar
Hemisphere Publishing Corporation,
79 Madison Avenue, New York, NY 10016
421 Pages, $97.50
Reviewed by
E. Johansen Crosby
University of Wisconsin
The drying of solids is probably one of the oldest
unit operations practiced by man. In the past, this
process generally was considered to mean the removal
of moisture from matter when the amount of same
was relatively small. However, in the chemical proces-
sing industry of today, feedstocks to be dried may
contain as much as ninety percent moisture, and that
moisture many times may be nonaqueous and mul-
ticomponent. Moisture removal can be effected by (i)
condensed-phase separation, (ii) chemical decomposi-
tion, (iii) chemical precipitation, (iv) absorption, (v)
adsorption, (vi) expression and (vii) vaporization. Con-
vection drying, i.e., moisture removal by vaporization
with the drying medium being both the energy source
and moisture sink, is by far the most common method
used. The materials-handling considerations resulting
from many different feedstock and product require-
ments inevitably resulted in the development of many
types of equipment-each with its own operation
idiosyncrasies.


In recent years, the number of monographs, hand-
books, journals, proceedings and research reports de-
voted to this subject has increased markedly with the
series entitled Advances in Drying which was in-
itiated in 1980. In the preface of Volume 4, the editor
indicates that this ". series is designed to allow
individuals concerned with (various) aspects of drying
to access relevant information in a carefully reviewed
form with minimal time and effort." Like its predeces-
sors, this work consists of a number of reviews, up-
dates, and developments concerning theory, design,
and practice in connection with moisture transfer
through and/or removal from solids. Eight individual
topics are addressed from various viewpoints by con-
tributors from seven countries.
Computer-aided design of convection dryers is dis-
cussed in Chapter 1. The classification of mathemati-
cal models according to contact zones and flow pat-
terns, the systematic application of the overall mass
and energy balances, and the simplification of drying
mechanisms is presented. Most of the chapter is de-
voted to examples of recommended calculation proce-
dures for different types of dryers with the coverage
of spray and rotary dryers being especially minimal.
Chapter 2 deals with recent advances in the drying of
wood. A review of drying theory and modeling is fol-
lowed by a good summary of recent developments in
lumber and veneer drying. Recommendations for fu-
ture work are presented. Chapter 3 contains a con-
densed theoretical review of the drying of porous sol-
ids with stress on the internal mechanism of moisture
and energy transfer. Coupled heat and moisture
transfer in soil is reviewed in Chapter 4. Written from
Continued on page 43.


WINTER 1989










Slclassroom


EXPERIENCING TEAM RESPONSIBILITY

IN CLASS*


TABLE 1
Rules


THE ABILITY TO effectively manage a project
within a team of peers is one signature of a profes-
sional-one which is often ignored in engineering edu-
cation. However, such an experience can be success-
fully woven into the curriculum to the enhancement
of technical fundamentals.
Even as an entry-level engineer, a person must
plan, schedule, and then coordinate the work of
operators and technicians in adjacent groups. Soon
thereafter, one plans, influences priorities, and coordi-
nates peers' activities across organizational bound-
aries. In any case, that one person is solely responsi-
ble for timely results; but he or she must rely on the
contribution of others, must accommodate the
priorities of others, must foster effective interper-


















R. Russell Rhinehart is an assistant professor of chemical engineer-
ing at Texas Tech University. He received his PhD from North Carolina
State University after a 13-year industrial career as an engineer and
group leader which included development of reaction systems, process
control, solvent recovery, and process safety and reliability. His interest
in the special aspects of industrial process modeling, optimization, and
control techniques led to his pursuit of an academic career.
*Presented at the 1987 annual AIChE meeting November 17, 1987,
in New York, NY


The project descriptions I have written are suggestions based
on my experience, but may be changed. As you progress you will
find many other aspects of your topic and you will want to pursue
those that interest you. If you want to change the project scope,
however, be sure to coordinate that action with me. In any event,
you need to meet with me to ensure that your plans meet my
expectations.
I will grade the written report. It should be neat, organized,
and presented so that it teaches a technology or demonstrates an
application. Make it something which can be useful to you five
years from now. The grade will be weighted 50/50 on technical
accuracy and completeness and on communication effectiveness
(logical presentation, writing clarity, organization).
The written reports should be 15 to 25 handwritten, single-
spaced, or typed, double-spaced pages, including examples, fig-
ures, derivations, and computer code. Don't go for broke...this is
just a one-month project. But do present some meaningful and use-
ful work.
On the due date the leader will present a ten-minute oral
report for the class. The oral report will not be graded.
Take care of your group members. Plan ahead so they can
plan their own work schedule. Assign portions of the project that
interest them so that they do their best work for you. Use your
group members. Delegate, or else you will overwork yourself try-
ing to meet my expectations.
Use me as a consultant for personnel problems as well as
technical methodology.



sonal relations, and has input into the performance
rating of others. Key skills of a practicing engineer
include planning, communicating, interaction manage-
ment, accommodating, and listening. Key perspec-
tives include project ownership and accountability.
Such professional attributes, however, are not usually
descriptive of an engineer's formal education.
It is likely that at least 50% of an engineer's effec-
tiveness will depend on human team interaction skills.
However, the academic experience is largely indi-
vidualistic, and even the scant group exercises in lab
and design are often without assigned leadership re-
sponsibility and authority. In practice, a design en-
gineer must cooperate with others; for instance, he
must rely on an R&D engineer to generate design
data for his project. But we teach and test for indi-
,E Division ASEE 1989


CHEMICAL ENGINEERING EDUCATION


R. RUSSELL RHINEHART
Texas Tech University
Lubbock, TX 79409-3121










vidual performance. A process engineer must get the
cooperation of a production staff to run trials, and he
must rely on lab services to analyze the results. Yet,
throughout his education, we have encouraged, re-
warded, and prepared the graduate for individual per-
formance. Consequently, a student's perspective on
the practice of engineering is usually misdirected.
If education means developing life skills in prepa-
ration for social responsibility (as opposed to merely
developing a technical facility), then it is our responsi-
bility as professors to move beyond a technical/
academic focus and to incorporate life-relevant experi-
ences into the classroom. Success at human manage-
ment is a requirement for successful technology im-
plementation. As faculty who are concerned with indi-
vidual technical performance, we are sometimes un-
aware that we have omitted the development of the
interpersonal skills required for effective engineering.
The objectives of the in-class team responsibility
project are:


To integrate some of these professional perspectives into
the classroom

To coach students toward improved project and people
management effectiveness

To support the traditional educational objectives

To enjoy the experience.


As faculty who are concerned with
individual technical performance, we are
sometimes unaware that we have omitted the
development of the interpersonal skills
required for effective engineering.


ASSIGNMENT STRUCTURE AND RULES

Each student in the class becomes a project team
leader once and chooses a project topic from a pre-
pared list. The project will take about a month to com-
plete and will demonstrate relevant engineering skills.
Projects have included writing computer simulators,
technology reviews, a mini chapter for a text, and
conducting personnel surveys. The assignment state-
ment is shown in Table 1, and Table 2 lists the project
titles given to the students in a junior heat transport
course. (While the topics in the third section of Table
2 are non-technical, I think that they are important to
engineering success and, therefore, relevant to the
education of an engineer.)
Three other classmates are assigned to the project
leader as team members. Each student is a team
leader once and participates in a total of four projects.
The team leader has sole responsibility for the project
scope, its planning, work distribution, daily coordina-
tion, and for both the written and oral presentations.
(The oral is required but not graded.) The leader


TABLE 2
List of Projects for a Junior Heat Transport Course


Write a computer simulator and run "trials" of
A binary boiler
A condenser
A red-hot quench
The transient conduction in a rod
The steady state temperature profile in a slab of non-
constant thermal conductivity
The steady state performance of a shell-and-tube
liquid/liquid heat exchanger
The steady state temperature distribution in a fin of non-
constant cross sectional area
A steam traced pipeline
The transient response of a temperature detector in a
thermowell with external conduction

Write a technology report, a mini-chapter in a text, presenting an
overview of the topic, design equations, and original
examples of
Natural convection
Heat pipes
Coiled heat exchangers
Alternate boiling/condensing heat transfer fluids
Engineering/business economics
Heat transfer in two-phase flowing fluid
Human perception of hot and cold


Mechanical design criteria for baffles
Dehumidifiers and after-coolers
Thermosiphon and calendria reboilers
Insulation
Developing and validating correlations
Steam tracing
Evaporators/cooling towers
Temperature measurement device technology and
calibration

Write a mini-chapter to introduce the relevance and the
engineering skills associated with
Systematic diagnosis of process faults
The transition from student to engineer
Critical thinking to recognize and demythify technical
folklore
Personality development and inappropriate adult behavior
Decision analysis
Creativity
Social structure within human institutions
Perception of performance
Industrial performance reward systems
Temptations and attitudes that lead to less than desirable
engineering quality
The balance of power: marketing, finance, or engineering?


WINTER 1989










The nature of such an assignment is quite different from the highly structured, individual,
deterministic, short-term, private type assignment for which the student has been programmed
during his previous fifteen years of school. It is important that the students are comfortable with the change.


meets with me to learn what my expectations of an
appropriate project scope are, but then makes the
final decisions himself. The project grade is assigned
exclusively to the team leader; however, the leader
grades his team members. My grade of the project
contributes 15% to the leader's course grade, and each
of the three grades he receives as a team member
counts 5%. The combined four-project grade is 30% of
the course grade.
Projects are assigned near the beginning of the
semester but are due about one month after the funda-
mentals of a topic are covered in class lecture. The
projects require sustained effort during the last two-
thirds of the semester, and I reduce the extent of
weekly homework assignments as a result. Topics
from the last three weeks' lectures are not assigned
as projects. Students select their own project choices
from a list of topics that I have prepared. Students
can suggest other topics, but rarely do they have that
foresight in an unfamiliar technology. Not all of the
topics are specific to the course technology, but I
judge all to be relevant to the practice of engineering
(e.g., engineering economics, human perception of hot
and cold, systematic trouble diagnosis, debunking of
technical folklore). I match project leaders to one of
their first project choices and then assign other team
members in order to distribute their project due-dates
throughout the semester. I then assign other mem-
bers so that each student works on at least one project
of each type (computer simulator or report) and fi-
nally, to shuffle personnel as much as possible.

PREPARATION FOR SELF AND CLASS: A REQUIREMENT
The nature of such an assignment is quite different
from the highly structured, individual, deterministic,
short-term, private type assignment for which the
student has been programmed during his previous fif-
teen years of school. It is important that the students
are comfortable with the change. As adults they can
choose to put their personal energy where they per-
ceive it to benefit them the most, and it is important
that they "buy into" the objectives of this new type of
assignment. So, distributed over several early lec-
tures, I spend about one-half of a class previewing the
assignment, discussing the engineering work environ-
ment, discussing the experiences I want them to be
prepared for, presenting the objectives of the particu-
lar assignment, and offering assurances of my avail-


ability as both a personnel and a technical consultant.
As projects are in progress, I spend five minutes here
and five minutes there discussing group assignment
plans, coordination, flexibility, ways to handle intract-
able "employees" and other skills that I perceive are
relevant. I also reinforce the workplace/classroom dif-
ferences to periodically justify the project strangeness
in order to keep the adults "on board."
Problems occasionally arise: a failing student de-
cides to put his energy into other courses and fails to
contribute his share to the leader's project; a leader
plans too late and then unreasonably expects group
members to perform at a high level regardless of their
other commitments; one project turns out to be much
more difficult than the others. It requires a self-confi-
dent professor to calm the slighted student's panic, to
be flexible, and to assure students that, in spite of
individual situations, subjective grading can be fair.
The professor must be willing and able to manage such
common personnel situations as when a student feels
that events beyond his control will affect the reward
of his personal performance. These are common work-
place problems which a practicing engineer must han-
dle and that a student can preview in his education.
Success at human management is a requirement for
successful technology implementation.
RESULTS
Comments from the semester-end student course
evaluations are one source of results. Verbatim they
include:

The independent research is a great learning experience-
keep it!
Leading a team is super, have to deal w/ people not willing
to do their part and taking all the input & putting it into
1 report.
Learned TONS! I think it will be very helpful later on.
The [independent] research is a good change from number
crunching.
I learned that I need work on my organizational skills.
It is hard grading fellow classmates- but good experience.
Also learned a few more things on my own.
I enjoyed working as a team, it helped bring us closer to-
gether, and we learn more through research [independent
study].


CHEMICAL ENGINEERING EDUCATION









... has given us a big opportunity to learn to work together
and to be a responsible person in every aspect.
Heat transfer concepts as well as fundamental human in-
teractions were taught.
Required and inspired creative thinking in solving practi-
cal engineering problems.
I'm glad projects were assigned. They brought a special
type of learning into the course.
Keep it.
Do it again next year.

Overall, the positive evaluations (70%) outnumber
the negative evaluations (8%) by 9 to 1. The negative
comments concern either the unfairness in student
grading or the variable difficulty of the computer ver-
sus the independent study type of projects. I will ad-
dress these complaints later. The ambivalent re-
sponses, such as "grading of the projects was fair," or
"give more time to complete the projects," comprised
22% of the evaluation. The students felt that the exer-
cise achieved the desired results. So did I.
Along with my personal perception that the exer-
cise met its objectives, there has been one outstanding
tangible result. One student chose to investigate the
on-the-job transition one must make in the student-to-
engineer metamorphosis. Her group augmented their
literature review with personal interviews and a mail
survey to our graduates with two to five years' work
experience. The questionnaire was developed after
their initial investigations and focused on the suffi-
ciency and relevance of engineering education to the
skills necessary for life and the practice of engineer-
ing. The project report was excellent. It was accepted
for publication in the Texas Tech engineering student
journal [1].

DISCUSSION
I think that such an exercise is appropriate to the
maturity level and stability of juniors, seniors, and
graduates. I would anticipate that the mid-term drop-
out rate and marginal commitment of many freshmen
and sophomores would create severe personnel prob-
lems if such an assignment was included at their level.
The 15% and 5% grading schedule provides suffi-
cient incentives. The leader wants a quality report
and must rely on substantial team member contribu-
tions to meet my expectations. Additionally, the ap-
pearance of the half-letter grade control that the
leader has provides sufficient incentive to the member
for quality participation. In actuality, however, mem-
bers receive contribution grades from A to D-at


worst a sixth of a course letter grade per project. In
effect, as professor I really give up very little course
grade assignment authority.
With the 15% and three 5% project grades and
with homework counted as 20%, non-test grades count
50% of the course grade. Tests count as the remaining
50%. I have no problem with that weighting; however,
students occasionally suggest that tests should count
more.
Initial assignment descriptions are very brief, i.e.,
"Write a chapter on heat pipes for a heat transfer
text. Describe the phenomena, uses, operating condi-

there has been one outstanding tangible result.
One student chose to investigate the on-the-job
transition one must make in the student-
to-engineer metamorphosis.

tions, and fluids. Give design equations and create
examples." On that particular project, with initial re-
search the student finds that liquid-wicking
phenomena for zero-gravity applications, multicompo-
nent VLE behavior, rarified vapor fluid dynamics,
variable surface area control, and internal fins are
each of application's importance. The student chooses
the specific technology that he finds interesting and
relevant and, together with me, works out a project
scope that meets my expectations and my realization
of the limits of a month-long project that counts 15%
of one course in one semester.
I have not yet graded the oral presentations. To
some it is an intimidating event, and I wanted to
create a pressureless environment for the verbal class
presentation. Additionally, I did not want the stu-
dents to compete for fancy visual aids. However, the
oral presentations were often ill-prepared and of no
use to the other class members. In the course evalua-
tions, a few students suggested grading the oral pre-
sentation as a portion of the project grade and I plan
to try it next time.
A recurring student suggestion is that more time
should be allowed for completion of the projects. I
suspect, however, that some students shoot for sub-
stantial results and completeness, enjoy the indepen-
dence, and would write a book if allowed. I also sus-
pect that others get started late and would never have
enough time. Considering the planning and delegation
experiences I want to create, and the justifiable time
demand of the project portion of one course, I think
that the one-month duration is appropriate. Before
students err, however, it is necessary to preview
these time constraint aspects. The students must be
made aware of the need to limit project scope, to del-
egate, and to start early.


WINTER 1989










The reports submitted at the end of the semester
benefit from the grading, comments, and in-class dis-
cussions on the earlier reports. In spite of my pre-
views, the initial projects are at a grading disadvan-
tage. The students also come to recognize this, and to
be fair, I add a letter grade to projects due early in
the semester. The students seem satisfied. I have re-
served this option and keep it unannounced until I
grade the second set of projects, but I have felt that
it is appropriate each semester.
Students have a tendency to do most of their own
project work. Perhaps it is educational inertia. Lead-
ers' estimates of their personal effort ranged from 50%
to 90% of the total group effort. Delegation and coor-
dination are important job functions and, in discus-
sions with leaders, I have encouraged them to dele-
gate. Although I am satisfied with the average leader
contribution of 75%, I would prefer to push that to
60% and in subsequent classes will help leaders iden-
tify project portions that can be delegated.
As mentioned in the results section, there were


two student criticisms of the assignment. One of the
two negative evaluations concerned the assignment of
grades by the student leaders, and was characteristi-
cally stated as, "People give good grades to their
friends, without considering their actual work." The
objection is not to the student-grading-student aspect
of the exercise, but that student grading is not as
objective as one would like. Although project leaders
did assign D's, A's were assigned to 70% of the mem-
bers' contributions, and B's to about 25% of the contri-
butions. However, we all recognized that the inflated
grades are not indicative of a member's performance
and that friends may grade friends too leniently. I've
discussed optional grading policies, such as pass/fail
and S +/S/U with the classes. However pass/fail lacks
discrimination, and the S + /S/U is too similar to A/B/C
and may also be subject to grade inflation. I am now
trying an alternate approach. Leaders do not grade,
but fill out a "Group Member Evaluation Form" (see
Table 3) for each group member. The form originated
as an industrial performance review but has been


TABLE 3
Group Member Evaluation Form


NAME


Experiment No.


INSTRUCTIONS:
Place an "X" mark on each rating scale, over the descriptive phrase
which most nearly describes the person being rated. Evaluate each
quality separately. Avoid the common tendency to rate nearly
everyone as "average" on every trait instead of being more critical
in judgement. Also avoid another common tendency to rate the same
person "excellent" on every trait or "poor" on every trait based on
the overall picture one has of the person being rated.

ACCURACY is the correctness of work duties performed.


Made many Somewhat
errors careless


Avg. number of Accurate most
mistakes of the time


Exceptionally
accurate


ALERTNESS refers to the ability to grasp instructions, to learn from
research and to solve problems.
Slow to Needed more than Grasped Quick to under- Exceptionally
catch on average instructions with stand and learn keen and alert
instruction average ability
FRIENDLINESS refers basically to the ability to get along with team
members.
Distant & aloof Friendly once Warm, friendly, Very sociable & Excellent
known by others and sociable outgoing
PARTICIPATION is being available for and participating in group
activities.
Often absent or Lax in availability Usually available Very prompt & Outstanding,did
unavailable and participation and participating regular more than share


DEPENDABILITY is the ability to do assignments well with minimum
supervision.
Quite unreliable Sometimes re- Usually did assign- Very Outstanding in
quired prompting ments on time reliable reliability
JOB KNOWLEDGE is the information each individual had to know or
learn in order to do his/her part in all phases of the experiment
Poorly informed Lacked knowledge Moderately in- Understood Had mastery
of some phases formed all phases of all phases
QUANTITY OF WORK is the amount of work done by the individual
throughout the planning, conduction and documentation phases of
the experiment.
Unacceptable Did just enough Average volupne Did more than Superior work
to get by of work was required production
OVERALL EVALUATION in comparison with other group members.
Definitely Below average but Did an Definiely Outstanding
unsatisfactory made an effort average job above average
COMMENTS:


Group Leader
Group No.


CHEMICAL ENGINEERING EDUCATION









modified and used by laboratories in Mechanical and
Chemical Engineering and Engineering Technology at
Texas Tech. It contains a descriptive five-item scale
on each of eight team and technology performance at-
tributes. It also has a section for other comments. I
will compile the evaluation data, use that to assign a
team member grade, and share the compiled results
with the team member. There are several advantages
to such an approach. Student leaders can check off
attributes without the bias that grading carries and,
consequently, may produce a more accurate measure
of their team member's performance. Additionally,
discussion of the compiled data with each individual
may aid coaching for improved performance. Initial
feedback is positive.
The second negative evaluation concerned the
variable difficulty of the projects, and a typical com-
ment was, "How do you grade a hard program com-
pared to an easy project?" ". all projects should be
either programs or reports." "Don't compare apples
and oranges." Students perceive that the computer
projects are more difficult than the technology re-
ports. Considering the level of computer program-
ming expertise of our juniors, I must agree. Perhaps
two-thirds of the class have forgotten both the pro-
gramming language and the systematic approach to
programming learned in their freshman course. They
tend to write the entire program at once (without hav-
ing performed hand calculations for familiarity with
the procedure), then become extremely frustrated as
they debug simultaneous and interconnected syntax
and logic erors. Although I preview this, it remains a
problem, and I plan to reducing my expectations on
the computer assignment scope and strengthening my
message to the computer simulator project leaders.

SUMMARY
In an attempt to integrate project management
and interpersonal skills development into a junior
level transport course, student project exercises were
structured with one accountable leader who plans,
coordinates, and grades the work of three team mem-
bers. The exercise structure achieves its objectives
and is received well by the students. The course pro-
fessor must be prepared for the degree of subjectivity
introduced and be able to manage personnel problems.
Student-to-student evaluations may improve with a
non-grade rating form.

REFERENCES
1. Everett, Gayle L., "The Transition From Student To En-


gineer," TECHnology MAGAZINE, (a student engineering
publication of Texas Tech University, PO Box 4200, Lubbock,
TX, 79409), 1986/87, pp. 10-12. l


REVIEW: Advances in Drying
Continued from page 37.
the viewpoint of the soil scientist, the equations of
change for mass and energy transport, formulation of
the relevant mass fluxes, consideration of the trans-
port properties, and choice of boundary conditions are
covered. Experimental measurement of the transport
properties also is considered and the drying of soils by
buried heat sources is discussed. A mathematical
model for convective drying with the incorporation of
sorption isotherms is presented in Chapter 5. This
chapter is not a review but rather a research paper
concerned with the drying of a porous capillary body
and accompanied by a very limited bibliography.
Chapter 6 is primarily a descriptive review of the solar
drying of crops. After a brief discussion of drying prin-
ciples, the status of solar drying technology together
with equipment description is presented. This is fol-
lowed by a discussion of the design features and typi-
cal performance characteristics of solar heaters for
air. A very brief consideration of the relevant
economics concludes the review. Certain principles of
operation and design considerations for spouted-bed
drying are presented in Chapter 7. Emphasis is placed
on the selection of a spouted-bed system and its fluid-
mechanical characteristics. Three previously pub-
lished models for describing the performance of this
type of dryer are summarized and compared. Chapter
8 is a nontheoretical review of press drying. The prin-
ciples of operation are summarized and performance
data are presented. The mechanical features of exist-
ing pilot machines and proposals for full-scale dryers
as well as alternatives for improved paper densifica-
tion are given.
Those persons interested in drying should find the
individual contributions to this volume to be of some
interest. The authors of most of the chapters are gen-
erally recognized authorities in their field. Unfortu-
nately, much of the material seems to have been
edited and/or proofread very rapidly and/or poorly as
there are a number of instances of quite awkward
grammar, misspelling and, something especially dis-
concerting, incomplete nomenclature. The text is
type-set and production is good except for those few
figures which are reproduced by direct photocopy. As
with similar publications of this type, the price is high.
Because of its restricted technical content, this vol-
ume should be perused prior to purchase. [


WINTER 1989









m laboratory


UNSTEADY-STATE HEAT TRANSFER

INVOLVING A PHASE CHANGE

An Example of a 'Project-Oriented' Undergraduate Laboratory


D. C. SUNDBERG and A. V. SOMESHWAR
University of New Hampshire
Durham, NH 03824

THE CHEMICAL ENGINEERING laboratory experi-
ence for undergraduate students at the University
of New Hampshire is composed of a sequence of two
courses which are conducted during the second semes-
ter of the junior year and the first semester of the
senior year, respectively. The first course is dedicated
to experimentation in the areas of fluid mechanics and
heat transfer, while the second course involves mass
transfer and reaction kinetics. The students have
either had previous classroom courses in the subject
areas involved in the laboratory or take the classroom




'ft









Donald C. Sundberg is an associate professor of chemical engineer-
ing and Director of Industrial Research at the University of New Hamp-
shire. He received his BS from Worcester Polytechnic Institute and his
MS and PhD degrees from the University of Delaware. Before coming
to New Hampshire he was on the faculty at the University of Idaho
and prior to that spent five years with Monsanto Company. He is active
in polymer research with emphasis on polymerization kinetics, emul-
sion polymers and polymer morphology. (L)
Arun V. Someshwar is currently working as a research engineer
with the Institute for Environmental Studies at the University of Illinois,
Urbana-Champaign. After receiving his doctoral degree in chemical
engineering from Michigan State University in 1982 he served on the
faculty of the University of New Hampshire until July of 1988. His
research interests are in the field of air pollution control, primarily in
the use of electric fields and discharges for enhancing the desulfuriza-
tion and denoxing of post-combustion gases. (R)


courses concurrently with the lab. The laboratory
courses require the students to complete one in-depth
project as well as other short-term introductory ex-
periments in each of the subject areas. These in-depth
projects have a duration of five to six weeks each, are
done typically in groups of three students, involve
weekly and interim group written reports, and con-
clude with the submission of individual written re-
ports and group oral presentations. The oral presenta-
tions are delivered to the entire laboratory class, in-
cluding the instructors. The chemical engineering fac-
ulty and graduate students are also invited to attend.
Our objectives for these in-depth projects are to
require the students to become involved in the process
of thoughtful and effective experimentation as an al-
ternative to the weekly "cookbook" experiments com-
mon to their previous experience, to have them con-
front not-so-straightforward problems which require
the generation of the bulk of the individual experi-
ments which may need to be conducted, to have them
learn to integrate theoretical approaches and ex-
perimentation to complete the project, and last but
not least, to provide them with some unique oppor-
tunities to develop and demonstrate their written and
oral communicational skills. In some instances we
have been able to include the concepts of experimental
design into the projects, while in all cases we have
strongly advocated the use of theoretical models as
guides to the choice of useful experiments. The un-
steady-state radial freezing project described below is
one which is a good example of the type of experience
our students gain in their lab courses.

STRUCTURE OF THE LABORATORY PROJECT
In making up the projects for our lab courses we
try to structure the assignments so that they portray
a realistic problem which needs to be solved, rather
than merely the experimental verification of some
theoretical concept discussed in the classroom. This is
not always easy, but it does make a distinctive differ-
Copyright ChE Division ASEE 1989


CHEMICAL ENGINEERING EDUCATION










ence in the students' viewpoint of what the laboratory
is all about. The unsteady-state radial freezing project
discussed in this paper has been portrayed in the con-
text of having to predict the radial freezing of the
earth surrounding a proposed storage cavity for
liquified natural gas. A copy of the project assignment
sheet given to the students is shown in Table 1.
At the outset of the project we persuade the stu-
dents to approach the problem by first substituting
pure water for the earth surrounding the cavity and
to use dry ice as a substitute for the LNG. They are
rather quickly convinced that this would be an easier
system to evaluate, and that with the knowledge
gained here it would not be too difficult to extend the
analysis to the more practical case.
Since this is a laboratory course, the students
naturally think towards experimental equipment, and
so they quite rapidly decide upon an arrangement of
the type shown in Figure 1. Once this is in place we
can discuss with them some of the problems associated
with carrying out good experiments, such as insulat-
ing the top of the tank and the water bath, choosing
an appropriate temperature at which to keep the liq-
uid water, and developing enough data to not only
provide information about the thickness of the ice and


TABLE 1
Project Assignment Sheet


TO:
FROM:
RE:


Ms. Curie, Mr. Fermi, and Mr. Einstein
Dr. Jekylnhyde and the ChE Staff
ChE 612 Project II


The company in which you are employed manufactures
liquified natural gas (LNG) and stores it in underground caverns
which amount to nothing more than large holes in the ground
with suitable linings. When the extremely cold liquid contacts
the earth, it freezes the moisture in the soil and a relatively
impervious liner is built up around the LNG. The energy removed
from the soil is taken up by the LNG and results in some vapor-
ization of the liquid.
In order to project the extent of freezing in the surrounding
earth, to gauge its time dependency, and estimate the rate of
liquid vaporization, your group is asked to develop a laboratory
prototype unit in which such an event might be studied. It is sug-
gested that a simple system could be constructed using iso-
propanol/dry ice as a constant temperature vaporizable fluid (at
-78.4'C) contained in a metal cylinder surrounded by water. The
water would freeze around the cylinder and the front of the
freezing zone would progress outward with time. Thermocouples
could be placed at various intervals throughout the surrounding
water and the temperature, as well as the freezing zone front,
could be measured as a function of time. The rate of gas liberation
could also be measured. A mathematical model would be useful
for interpreting the above data and to make projections in the
actual application to LNG. More specifically, on the basis of
your model, you are to predict important details pertaining to
the storage of LNG in a 20 ft. deep well, 10 ft. in diameter, and
surrounded by earth with a moisture content of 10%.


Our objectives for these
in-depth projects are to require
the students to become involved in the process
of thoughtful and effective experimentation as an
alternative to the weekly "cookbook" experiments
common to their previous experience.


Insulation


FIGURE 1. Overall schematic of tank and ice front

the temperature profile in it, but also to be able to
close an energy balance. The latter point is stressed
in order to get the students to realize that they can
provide internal checks on the reliability of the data,
in addition to its reproducibility. The sublimed C02 is
normally directed through a wet test meter in order
to measure its volumetric flowrate and the students
quickly realize that they need to understand how such
an instrument works in order to convert the measure-
ments to mass flow rates.
Another point stressed prior to the time that ex-
perimentation begins concerns the water tempera-
ture. In discussing the impact that the water temper-
ature will have on the overall process, the students
are guided (the amount of guidance depends upon the
student group) to create an experimental arrange-
ment which can be most easily analyzed from a model-
ling point of view. The students are usually quite
pleased with their decision to keep the water temper-
ature at 0C by adding ice to the water bath when
they realize that not only did they create a situation
in which temperature gradients within the liquid
water surrounding the growing ice front do not have
to be considered in their analysis, but also that energy
input to the bath from the surroundings will not be a
source of experimental error.

MODELING WORK TO GUIDE EXPERIMENTATION
During the very early stages of the project the
students are required to begin their heat transfer
analysis. Most of the students begin the lab course


WINTER 1989









with the idea that one first runs the experiment and
then does the analysis, but our objective is to have
them use their analytical capabilities to guide their
experimental work and to have them design better
experiments.
Figure 2 shows the physical characteristics of the
heat transfer process to be analyzed. The tank which
holds the dry ice/isopropanol mixture is made from
brass and has an outside diameter of 68.3 cm and a
height of 13.3 cm. Due to the highly agitated state of
liquid isopropanol within the tank, the inside wall tem-
perature may be safely assumed to be at the sublima-
tion point of dry ice, -78.4C. At the other heat trans-
fer boundary, the advancing ice front will be at 0C
due to the addition of ice cubes to the liquid water
bath. We have insulated the flat bottom and top of the
tank with polyurethane foam in order to achieve only
radial freezing and to avoid edge effects which are
more difficult to analyze.
The important features of the analysis are as fol-
lows:
The heat flux at any time, q, is given as


r T -T (2L)(T T )
q = hb(2x r L) (T Tb ) = 2)
in(r2 1/r.

kice (21L)(T T2
In(r. /r2 )


In terms of the overall temperature difference


21cL(T Tb)
1 In r2/r1 In rice /r2
S+ ce
hb 1 kbr kice


Due to the large heat transfer coefficient of the
highly agitated isopropanol and the high thermal con-
ductivity of the brass relative to the ice, the flux may
be written as (except as very short times)
2nL(T Tb kice
q in(rice /r2)

Also implicit in Eq. (1) is the assumption of pseudo-
steady conduction, i.e., the characteristic conduction
velocity (a/lice) in the ice is much greater than the
velocity of the freezing front (Vice). The validity of this
assumption is to be checked against the data obtained.
Since all of the energy must come from the freezing
of water at the ice front and the cooling off of the


Brass Tank


FIGURE 2. Radial view of tank and ice front

block of ice, the flux may also be written as


rAHf + C (T Ta)]dmice


where AHf is the heat of fusion of water, Ta is the
average temperature within the ice and mice is the
mass of ice. As an approximation to Ta we normally
guide the students to take it as Ta = (To + Tb)/2, or
-39.20C.
Since


- r) Lice


the combination of Eqs. (1) and (2) yields
[AHf + C (T Ta)]Pice rice rice (T0 -Tb) ice
dt n ricee /r )
If Cp and kice are taken as constants evaluated at Ta,
the integration may be carried out to yield

(AHf + Cp (T -Ta))PiAce e (r i
t= --(T -T,)k e-)lc j[ L-I-'-]J- +-
0 Tb I ice
(3)
This expression gives a straightforward relationship
between the thickness of the ice and time.
We have found that the properties of ice at differ-
ent temperatures are not as readily available as we at
first assumed. Our recommendation is to use those
values found in N. H. Fletcher's book, The Chemical
Physics of Ice (Cambridge University Press, 1970).
As such, we use
AHf (at 0C) = 3.34x 10J/kg
Cp(at Ta =-39.2C) = 1806 J/kg,K
kice( at Ta = 39.2C) = 2.62 Watts/m,K
Pice( at Ta =-39.2C)= 920 kg/m3


CHEMICAL ENGINEERING EDUCATION


mice= x(r2
ice ice









As noted earlier, the measurement of the rate of
sublimation of the dry ice allows the students to meas-
ure the actual heat flux, and by its comparison to the
calculated heat flux (via Eq. (1)) to judge the goodness
of the data. The actual flux (neglecting heat gain
through the well-insulated top of the vessel) may be
given as
qexp =co2 AHSo2 = 2 PO 2 AH (4)


where V is the volumetric flowrate of the sublimed
dry ice, Pco2 its density, and AHsco2 is the heat of
sublimation of CO2 at one atmosphere. Although the
CO2 gas is certainly above its sublimation tempera-
ture by the time it passes through the wet test meter,
the use of that temperature is not too bad an assump-
tion (see next section) for calculating Pco2- In the fu-
ture we plan to require the students to be more aware
of the CO2 temperature within the wet test meter to
improve upon the accuracy of the heat flux measure-
ment.
The usefulness of having the students work with
the modeling during the early part of the project is
that not only have they had to think very hard about
the heat transfer process itself, but they gain firm
ideas about the time frame of a good experiment, the
eventual thickness of the ice formed during that time,
and the evolution rate of gaseous CO2-especially at
short times. We try very hard to get the students to
use this information to guide them in carrying out
good experiments.


EXPERIMENTAL WORK
In this project the experimental work is actually
quite straightforward. With the water bath main-
tained at 0C by using ice cubes, the only real diffi-
culty is associated with the very beginning of the ex-
periment. The preferred situation is to have the dry
ice/isopropanol mixture in the tank prior to the exper-
iment and then to instantly place the tank in the
water. There are some practical difficulties in ac-
complishing this, not the least of which is keeping
frost from forming around the outside of the brass
tank. Generally we have found that the easiest way to
get the experiment started is to place the tank, con-
taining only isopropanol, into the water bath and then
to add the dry ice to the tank. This procedure requires
a sacrifice of the early data for the sublimation rates
and the radial movement of the ice front due to the
necessity of cooling the isopropanol from about 0C to
the dry ice temperature. However, this does happen
fairly quickly and we find that it affects less than


MODEL PREDICTION
10.0

S9.00 -

8.00

7.00

6 .00 h h ` .
0. 5.00 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0
T [MINS)
FIGURE 3. Radius of ice front vs. time

about 10% of the time generally required to carry out
the experiment.
The students normally attach a plexiglass rod to
the side of the tank which holds a measuring rule and
to which can be attached a series of thermocouples.
Without an attachment point for the thermocouples
we have found that they tend to be displaced outward
by the advancing ice front. Once the dry ice is intro-
duced, data acquisition begins. The temperatures are
continuously read off the thermocouples. The gas sub-
limation rate is also obtained with the help of the wet
test meter. The ice front corresponds to an ice temper-
ature of 0C and the time at which a thermocouple
reading dips below 0C (corresponding to the ice front)
is noted for the five equally-spaced thermocouples (2/5
in. apart). A typical run lasts about an hour during
which the ice front would have advanced nearly two
inches.

RESULTS AND DISCUSSION
We have chosen to present the experimental re-
sults of a recent student group studying this subject
and judge these results to be about average for the
various groups which have been involved in this pro-
ject. The data represent a series of three experimental
runs and, as such, give a view of typical experimental
reproducibility.
Figure 3 shows the radial dimensions of the de-
veloping ice front (rice) as a function of time for three
separate experiments. For comparison we have plot-
ted the model predictions derived from Eq. (3). The
goodness of the agreement between theory and exper-
iment shown in Figure 3 is readily achieved by the
students when they use the proper thermal conductiv-
ity of ice. In the earlier years of this project assign-
ment, not enough attention was paid to obtaining a
representative value for kice. With regard to the


WINTER 1989









pseudo-steady assumption made in Eq. (1) a typical
calculation at t = 20 min in Figure 3 gives vice = 1.39
x 10- m/s, lice = 3.43 x 10-2m, and a/1 = 4.6 x 10-
m/s. Thus, this assumption is seen to be adequate at
t = 20 min.
Figure 4 gives an indication of the difficulties of
obtaining good values for the rate of C02 sublimation
early in the experiment. The data scatter is easily


0.60

0.50

0.40

0.30

0.20

0.10

0.


.. I.,, EXPERIMENT,. L COI. FLOW RAITES......
m o EXPERIMENTAL CO2 FLON RRTES


0


ID
U *-~


I


0. 5.00 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0
T (]MNS5

FIGURE 4. Carbon dioxide sublimation rate vs. time

+20% during the first few minutes while the iso-
propanol is achieving its cold temperature and the ice
buildup is small. As can be seen in the plot, the data
scatter reduced considerably with increasing time.
The dotted line in Figure 4 is simply a smooth curve
fitted to the data. A number of points along this line
are used to compute the average experimental heat
flux via Eq. (4). In Figure 5 these experimental heat
fluxes are compared with the predicted heat flux via
Eqs. (1) and (3). Although the agreement between
measured and predicted fluxes is not perfect over the
entire time frame of the experiment, it does provide
an adequate check upon the closure of the energy bal-
ance for a major portion of the experiment. In our
view this is quite adequate for a junior level project
of a relatively short time duration.
As an extension of the usefulness of the model de-
veloped and tested by the students, they are often
asked to apply this model to a more realistic problem
such as the one quoted in the assignment sheet de-
scribed earlier. In this case, using representative val-
ues for the properties of soil with 10% moisture and
LNG, they are then able to estimate the maximum
extent to which the LNG will vaporize underground
and the extent to which the surrounding soil will
freeze during a reasonable time frame.


EVALUATION OF THE PROJECT
For the seven years we have conducted the labora-
tory course on an in-depth project basis we have found
that about 80% of the students respond extremely
favorably. They especially enjoy being able to dig into
a problem in some detail and find it to be a welcome
change from the more common lab course approach
utilizing new experiments every week or two. The
other 20% have some difficulty with the unstructured
nature of such projects and would actually have pre-
ferred the more common approach, although in our
view they would probably do about the same quality
of work in either situation.
From the instructor's point of view the projects-
oriented laboratory course is as gratifying as it is dif-
ficult to manage. We feel that projects such as those
described in this paper give the instructor a real
chance to teach the students how to apply what they
are supposed to have learned in the classroom to a
realistic situation, and to guide them to thoughtful
and productive experimentation. This usually results
in the students feeling more like engineers in control
of the experiment rather than like technicians re-
sponding to a preset list of instructions. The difficulty
for the instructor is often in managing ten or more
simultaneous projects such as discussed here. Mur-
phy's Law is a constant companion.
A particularly interesting and useful part of the
project report is the oral presentation by each group.
We have tried a variety of formats for this report
including poster sessions and the seminar style of
presentation. We have also utilized the video tape and/
or color slides to allow the students to show their
equipment and experiments while presenting their


8.00
m AVERAGE EXPERIMENTAL FLUXES FROM CO2
SUBLIMATION RATES
7.00

6.00

5.00
THEORETICAL FLUX
4.00

3.00

2 .00 .... .. .. .........
0. 5.00 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0
T (MINSI

FIGURE 5. Comparison of heat flux from CO, sublima-
tion data


CHEMICAL ENGINEERING EDUCATION


Lmm mmi~ im i~m ii~~mj ma~~mm m~m [ II ~ Li m~m~ m ~ m~ m~ m ~ iL imm ~ m m i[ ... -










seminar-style report in a conference room. A gratify-
ing part of these presentations is the interest the
other student groups show towards the various pro-
jects and the thoughtful questions that are asked dur-
ing the discussion section of the presentations. In sum
total, we feel that the overall experience is extremely
beneficial to both the students and the instructors,
and is definitely worth all of the work both parties
have to do.

NOTATION
Cp = heat capacity of ice (J/kg K)
hb = boiling heat transfer coefficient (W/m2 K)
L = length of ice formation (m)
k = thermal conductivity (W/m K)
m = mass of ice at time t (Kg)
rh = mass flow rate of CO2 (Kg/s)
r = radius described in Figure 2 (m)
q = heat flux (W)
t = time (s)
T = temperature as described in Figure 2 (K)
Ta = average temperature of ice block (K)
V = volumetric flow rate of sublimed dry ice (m3/s)
p = density (Kg/m3)
AHf = heat of fusion of ice (J/Kg)
AH, = heat of sublimation of CO2 (J/Kg) []


REVIEW: Reactor Design
Continued from page 31.
sively used in problem solving. This chapter introduces
the concept of non-linear regression analysis and then
illustrates it to the problem of kinetic parameter estima-
tion.
Chapter 5 deals with the application of the concepts
of earlier chapters to design and optimization. A number
of case study examples are presented. The role of reac-
tor design on selectivity is not discussed satisfactorily.
Here an almost "Levenspielian" type of discussion
would have been extremely beneficial from both a
pedagogical and a practical point of view.
The coverage up to this point would probably fit
nicely into a senior class in chemical reaction engineer-
ing. The instructor could assign a number of "end of
chapter" problems in addition to assigning the case
studies as computer simulation exercises. This would al-
low the students to get a fairly good grip on the use of
modern computer based techniques.
The subsequent chapters cover more advanced top-
ics. Chapter 6 discusses the laminar flow reactor, and
this requires the solution of partial differential equation
in two variables. The technique presented is a finite dif-
ference method. The chapter also discusses problems


involving variable viscosity, which are important in
polymer processing. This chapter would blend in nicely
for those students simultaneously taking a graduate
level transport course.
The effect of non-idealities in the residence time is
discussed in Chapter 7 where the axial dispersion model
is discussed for both isothermal and non-isothermal re-
actions. The numerical solution strategy discussed here
for the solution of the two point boundary value prob-
lem is the shooting method. The orthogonal collocation
provides a more powerful solution method for these
types of boundary value problems, but there is no men-
tion of this method. A number of library packages such
as COLSYS or PDE/PROTRAN could be directly used
here, and it would have been useful to provide a brief
exposure to the use of one or two commercially avail-
able software to reaction engineering problems.
Chapter 8 deals with unsteady state analysis of reac-
tors. A number of examples are shown on the dynamics
and control aspects. I found the examples both real and
very illustrative.
Chapter 9 deals with the effect of mixing in continu-
ous flow systems. In addition to providing the necessary
mathematics, a valuable qualitative discussion on the
mixing effects on reactor performance is presented. This
should help the students to build a conceptual base.
However, the Zwietering differential equation is in-
troduced suddenly without any derivation or even a
qualitative basis. More discussion here would have been
useful.
Chapter 10 deals with heterogeneous catalysis, while
Chapter 11 deals with multiphase reactors. Some appli-
cations to new processes such as biochemical reactors
and electronic device fabrication are included. The
treatment on three phase reactors is very sketchy. The
emphasis on computer applications which was the
theme in the first half of the book is unfortunately lack-
ing here. For example, the author could have shown the
use of single point collocation in the evaluation of effec-
tiveness factors for nonlinear kinetics. A number of de-
sign problems in multiphase reactors can be solved by
simple computer programs. (The Omnibook gives a
rundown of typical examples.) These could have been
useful.
The final chapter is exclusively devoted to polymer
reaction engineering, which is unique since many books
do not even mention this word.
The second part of the book (Chapters 9 through 11)
provides sufficient content for a graduate course, al-
though the instructor would have to supplement the text
with additional reading materials or notes to provide
further details on many of the topics. The coverage of
emerging areas would be useful in such a course, and
the book would motivate the students to read more on
those topics. The incorporation of the computer methods
in the teaching of reaction engineering is vital, and the
book provides a valuable reference source in this field. 0


WINTER 1989











Classroom


LUBRICATION FLOWS


TASOS C. PAPANASTASIOU
The University of Michigan
Ann Arbor, MI 48109-2136

LUBRICATION FLOWS ARE perhaps the most ap-
L plicable material of fluid mechanics at both the
undergraduate and the graduate levels. At the under-
graduate level, important one-dimensional approxima-
tions such as channel, film, and coating flow equations
can be derived and studied from simplified mass and
momentum balances by means of the control volume
principle or else by simplifying the general equations
of change (Navier-Stokes). This leads to the cele-
brated Reynolds equation [1]


R(h,p, Ca) =0


where h is the thickness of the narrow channel or of
the thin film, p is a generalized pressure, p = P St g
where St = pgD2/pV is the Stokes number and g the
gravity acceleration in the direction of fluid motion.
The capillary number, Ca = pV/o-, usually enters


Tasos C. Papanastasiou received his Diploma in Chemical En-
gineering from the National Technical University of Athens, and his
MS and PhD in chemical engineering from the University of Minnesota.
His research interests are in fluid mechanics, rheology, and materials
processing.


through the balance of the normal stresses at a free
surface.

Eq. (1) can be solved:

To find the pressure distribution and relative quantities
(load capacity, friction and wear, cavitation, etc) when
the thickness h(x) is known. The most typical application
is journal-bearing lubrications.
To find the thickness h(x) when the pressure is known. The
most typical applications are formation of thin films and
coating applications.

Eq. (1) is not always solvable analytically. In some
extreme cases it is solvable by simplified perturbation
techniques. By the time the student reaches the solu-
tion, he/she must have dealt with

Derivation of governing differential equations by mass and
momentum balances on appropriately chosen control vol-
umes (or alternatively, the Navier-Stokes equations).
Order of magnitude analysis to derive the lubrication equa-
tions.
The solution of the differential lubrication equations sub-
ject to boundary conditions, to find the velocity profile.
The integral mass conservation equation to derive the
Reynolds equation.
The surface tension and the curvature of a thin film, to
find the pressure distribution.
The solution of the Reynolds equation, to find the film
thickness or the pressure distribution.
Simplified perturbation techniques to find limiting solu-
tions to the Reynolds equation.

Thus, lubrication flows cover most of the material
taught in undergraduate fluid mechanics and at the
same time are attractive to the student because they
deal with practical problems.


Copyright ChE Division ASEE 1989


CHEMICAL ENGINEERING EDUCATION










The most important applications of the thin film lubrication equations are films falling under
surface tension, nonisothermal films, dip and extrusion coating, and wetting and liquid spreading. A similar
class of problems includes centrifugal spreading, common in bell sprayers and in spin coating.

INTRODUCTION


The lubrication approximation for flows in nearly
rectilinear channels or pipes, of nearly parallel walls,
can be derived intuitively from the equations of flow
in rectilinear channels and pipes. The equations that
govern flows in rectilinear channels and pipes are the
continuity or mass conservation which demands con-
stant flow rate

x
-x = 0; u, = 0; u = f (z) (2)

and the equation of conservation of linear momentum
in the flow direction

dP a2 Ux
dx Z2

which under constant pressure gradient, dP/dx, pre-
dicts linear shear stress and parabolic velocity pro-
files. The gradient, dP/dx, is usually imposed mechan-
ically and, since the channel is rectilinear and the mo-


tion steady, it is constant along the channel (see Fi-
gure la), equal to AP/AL, where AP is the pressure
difference over distance AL. Thus, the mechanism of
motion is simple; flow of material from regions of high
pressure to regions of low pressure. This is Poiseuille
flow.
When one or both walls are in slight inclination, a,
to the midplane of symmetry, the same governing
equations are expected to hold which may now be lo-
cally weak functions of x, of order a. The most obvious
difference is the pressure gradient, dP/dx. In the case
of a lubrication flow which may be accelerating or de-
celerating, in a converging or diverging channel, re-
spectively, dP/dx is not constant along the channel
because the pressure forces needed to move two cones
of liquid of the same height dx at two different posi-
tions along the channel are different (see Figure ib).
Thus, dP/dx is a function of x and so is the velocity in
the governing equations


3x az


dP(x) 2 Ux
dx- = Z2


FIGURE 1. Force balance in a rectilinear flow, hodP =
2Tdx, and in lubrication flow, h(x) dP(x) = 2T(x)dx.


Both Eqs. (3) and (5) express conservation of linear
momentum or the Newton's law of motion that there
is no accumulation of momentum in a control volume
because there is no substantial net convection, and
the forces capable of producing momentum are in equi-
librium. According to Newton's law of motion there is
no acceleration (actually the acceleration is vanish-
ingly small in lubrication flows) because there is no
net force acting on a control volume. The forces on the
control volume, of height Ax, are net pressure force
(dP/dx)A(x) and shear stress force A(x)dxrxy (Figure
ib). The underlying mechanism is more complex than
in the Poiseuille flow. First, the moving wall on one
side sweeps fluid into a narrowing passage through
the action of viscous shear forces, which gives rise to
a local velocity profile of Couette-type ux = Vy/h,
with flow rate, Q = Vh/2. Because Q is constant by
continuity and h(x) is diminishing, the flow sets up a
pressure gradient to supply a Poiseuille component


WINTER 1989









that redistributes the fluid and maintains a constant
flow rate (Figure 2).

Derivation of Lubrication Equations by the
Navier-Stokes Equations
Alternatively, the lubrication equation can be de-
rived by order of magnitude and dimensionless
analysis of the full, two-dimensional, Navier-Stokes
equations

x z
+ ---0
ax 8z

-++ux x +u--z -1=- + -x (2)


f +u -' + U+-ap + + a (7)
a ax a z -az az2 ax2

where x- is the direction of flow and z- the gapwise
direction. The geometry of the flow is shown in Figure
2.
There are several good reasons to work with di-
mensionless equations and variables: to reduce the de-
pendence of the solution to minimum dimensionless
numbers; to simplify the equations judging from the
relative magnitude of a dimensionless number to one;
and to scale-up experiments to real applications of the
same dimensionless number.

To achieve these goals

* The dimensionless variable, say u*, must be of the
order of one. By using the boundary velocity V,
then u* = ux/V may at most vary between zero and
one, and so u* is of order one.
* If the problem lacks the characteristic dimensional
variable, V, in the previous paragraph, then it is
made-up by combining other characteristic vari-
ables. For example, for time, t* = t/(L/V). The
characteristic dimensional variable for pressure is
P = IxV/aL, because viscous forces, which resist
the motion, are in equilibrium with the pressure
forces, as shown by Figure 1.

Accordingly, define
x*= x_. z*=z--. t*= -- h*= h
L aL' L' aL '
u x Uz P*= P (8)
Ka2L

which upon substitution in the N-S equations, yields


FIGURE 2. Geometry of a two-dimensional lubrication
flow. The velocity profiles along the channel are mix-
tures of Couette and Poiseuille.


(with asterisk suppressed hereafter)

( au au u ap 2ux 2ux
aRe x+ + u = ---+c-- + (9)
S+x x azaz7 ax ax2 + 2


a a x axz az ax2 2


The lubrication equation holds in geometries
where a << 1. Since all the dimensionless terms and
derivatives in these two equations are of order one,
the resulting lubrication dimensionless equations are
in the limit of a = 0 and aRe = 0,
2 Ux
ax az2
ap 0 (12)
az

These equations are similar to those derived intui-
tively from channel flow [e.g., Eqs. (2) and (3)]. Notice
that high Reynolds numbers are allowed as far as the
product aRe is vanishingly small and the flow remains
laminar.
The appropriate boundary conditions to Eqs. (5)
and (11) are


CHEMICAL ENGINEERING EDUCATION









At z = 0, ux = V (no-slip boundary condition)
At z = h, ux = 0 (Slit Flow), (no slip boundary con-
dition)
or z = h, zx = 0 (Thin Film), (zero shear stress at
free surface)

Under these conditions the solution to Eq. (5) is

ux = dP(zh -z2) + V- -V (Slit Flow) (13)
24 dx h
= 1 --(2 zh z2) + V (Film Flow) (14)

The volume flux and the pressure distribution in
the lubricant layer can be calculated when the flow
rate Q, and the inclination a, are known. A lubrication
layer will generate a positive pressure and thus load
capacity, normal to this layer, only when the layer is
so arranged that the relative motion of the two sur-
faces tends to drag fluid by viscous stresses from the
wider to the narrower end of the layer [2]. The load,
W, supported by the pressure is

W= (P-P.)dx= log -2 ()

Thus, the inclination a, is responsible for the pressure
build-up by decelerating the flow and transmitting
momentum and thus load capacity to the upper boun-
dary.

Reynolds Equation for Lubrication
Mass conservation on an infinitesimal volume
yields

Q +d. + Q. = dx (16)
-Q+d (16)
which states that the net mass convection in the con-
trol volume is being used to increase the volume at
rate d/dt (dxdh) where dx and dh are the width in the
flow direction and the height of the volume, respec-
tively. Rearrangement yields

dQ dh (17)
dx dt


which for confined and film flows reduces to


d 1 dP + hV-- dh (Slit Flow) (18)
dx L 2|T dx 6 2 dt


d 1 dP 1 dh
d [-L dx 3 +hV ] t- (FilmFlow) (19)

respectively.

Solution of Steady Reynolds Equation for Slit Flow
The steady-state form of Eq. (18)

d 1_dP h3 hV
dx 2g dx 6 2+ 0

is integrated to

1 dP h hV
2R dx 6 2

and one proceeds according to Batchelor [2] and Denn
[3] to the calculation of pressure
x x
P(x)=Po + EV dx -12Qj dx (19a)
0 h (x) o h(x)

where


L
p p j h 2 (x)dx
Q o 0L V o
L 2L
12 h3 (x)dx f 03(x)dx
o


(19b)


Then one can proceed to the evaluation of load capac-
ity


w = J [Po -P(x)]ds


(19c)


and of shear or friction


F= f ,x ds


(19d)


on the surface, S. It is easy to show that the load
capacity is of order a-2 whereas the shear or friction
is of order a-1. Thus the ratio load/friction increases
with a t.
The most important application of the lubrication
theory for confined flows in journal-bearing [4] and
piston-ring [5] systems of engines. Other flows that
can be studied at the undergraduate level by means
of the lubrication equations, include wire coating [3],
forward roll coating [6], and many polymer applica-
tions [7]. The solution to these problems follows the
procedure outlined above, starting from Eq. (17). The
flow rate is usually given by


Q=V hf


WINTER 1989










where V is the speed of production and hf the final
thickness. The boundary condition on the pressure at
the outlet may vary [8]. P(L)=0, dP(L)/dx=0, or
P(L) = 2/(hf)2.


Solution of Steady, Reynolds Equations for Film Flow
In confined lubrication flows there is pressure
build-up due to inclination, a, and backflow of some of
the entering liquid. The pressure is then usefully used
to support loads. In thin film lubrication flows, any
pressure build-up is due to surface tension, and in fact
if the surface tension is negligible the pressure gra-
dient is zero.

The steady-state form of Eq. (19)


d -[ dP h +Vh =0
dx [ 9dx 3 J

is integrated to

1 dP h3
+ Vh = Q = Vh (21)
1 dx 3 f

The film thickness, h, is not known. However, the
pressure drop, dP/dx, can be deduced from the surface
tension by means of the Young-Laplace equation
under the lubrication requirement that the slope, dh/
dx, must be much less than unity

d2h
d2 d2 h
a -
-p dx2 dh (22)

Cdh 2
+ dx) J

Here h(x) is the elevation of the free surface from
the x-axis, and u the surface tension of the liquid.
Then

dP d3h (23)
dx dx(23)

and substitution of dP/dx in Eq. (21) yields
oh3 d3h
3 Gdx + hV=Vhf (24)


which is rearranged to

h + 3 Ca(h-hf) = 0 (25)
dx3


The capillary number Ca = poV/a is another di-
mensionless number and measures the viscous to sur-
face tension forces. Eq. (24) is highly nonlinear and
cannot be solved analytically.
The most important applications of the thin film
lubrication equations are films falling under surface
tension, nonisothermal films, dip and extrusion coat-
ing, and wetting and liquid spreading. A similar class
of problems includes centrifugal spreading, common
in bell sprayers and in spin coating. A rich collection
of lubrication problems from polymer processing can
be found in Pearson [7, 9] and from coating in several
theses under Scriven [10].


CONCLUSIONS
Lubrication flows are ideal for undergraduate stu-
dents to cover and learn a significant amount of fluid
mechanics material. This material includes the differ-
ential Navier-Stokes equations, dimensional analysis
and simplified dimensionless numbers, control volume
principles, the Reynolds lubrication equation for con-
fined and free surface flows, capillary pressure, and
simplified perturbation techniques. Problems and sol-
utions can be easily chosen from practical and interest-
ing applications such as journal bearing, expanding
pipe flow, film flow, and several polymer and coating
operations.

REFERENCES

1. Reynolds, 0., "Papers on Mechanical and Physical
Aspects," Phil. Trans. Roy. Soc. 177, 157 (1986)
2. Batchelor, G. K., An Introduction to Fluid Dynamics,
Cambridge University Press, New York (1979)
3. Denn, M. M., Process Fluid Mechanics, Prentice Hall,
New York (1980)
4. Tipei, N., Theory of Lubrication, Stanford University
Press (1962)
5. Miltsios, G. K., D. J. Patterson, and T. C. Papanastasiou,
"Solution of the Lubrication Problem and Calculation of
the Friction Force on the Piston Rings," submitted to J.
Tribology (1988)
6. Middleman, S., Fundamentals of Polymer Processing,
McGraw-Hill, New York (1977)
7. Pearson, J. R. A., Mechanical Principles of Polymer
Processing, Pergamon Press, Oxford (1965)
8. Bixler, N. E., "Mechanics and Stability of Extrusion
Coating," Ph.D. Thesis, University of Minnesota (1983)
9. Pearson, J. R. A., Mechanics of Polymer Processing,
Elsevier Applied Science Publishers, London and New
York (1985)
10. Scriven, L. E., "Fluid Mechanics, Lecture Notes,"
University of Minnesota (1980-88)
11. Papanastasiou, A.C., A. N. Alexandrou, W. P. Graebel,
"Rotating Thin Films in Bell Sprayers and Spin
Coating," J. Rheology, 32, 485 (1985)


CHEMICAL ENGINEERING EDUCATION










APPENDIX


Vertical Dip Coating
An example of thin lubrication film under gravity,
surface tension, and viscous drag arises in dip coating, shown
in Figure 3. This method of coating is practiced to cover met-
als with anticorrosion layers and to laminate paper and
polymer films. The substrate is being withdrawn at speed V
from a liquid bath of density p, viscosity g, and surface ten-
sion a. The analysis will predict the final coating thickness
as a function of the processing conditions (withdrawal speed)
and of the physical characteristics of the liquid (p, 4, and c).


Solution

The governing momentum equation, with respect to the
shown cartesian system of coordinates is

2
dP + g u pg= 0
dz ay 2 (Al)

The boundary conditions are

uz(y= 0)= V (A29


du
Tzy (y = H)= d = 0

The particular solution is

Uz -+ pg H + V

The resulting Reynolds equation is

-P + pg)-+VH= Q= VHf

where Hf is the final coating thickness.
The pressure gradient

dP d3 H
dz dz3


is replaced in Eq. (A5) to yield the final Reynolds equation

I d H _Pg)H +V(H- Hf)= 0
9 dz' 3 (A

which is rearranged to the form
H3 d3H pg H3 V=
3 dz3 a 3 +-r-(H H)0 =0


By identifying the dimensionless numbers


Ca= -


Solution


- -


FIGURE 3. Dip Coating: A coated plate is being with-
drawn from a coating solution. A final thin film or coat-
ing results on the plate under the combined action of
gravity, surface tension, and drag by the moving sub-
strate.


pgH2
St= f
MV
Eq.(A8) becomes
33 3
H d-H St H+3(H-HO =0
Ca dz3 2
f


(A1O)


(All)


which can be solved directly for the following limiting cases:

1. Negligible surface tension (Ca -+ c-)
Eq. (All) reduces to the third-order algebraic equation


311 311
3 f f
H St H + 0


In the limit of infinite St (i.e., very heavy liquid!), the only
solution is H = 0, i.e., no coating. In the limit of zero St (i.e.,
horizontal arrangement), H = Hf, i.e., plain Couette (plug)
7) flow. For finite values of St the solution is independent of z,
which predicts a flat film throughout.

2. Infinitely large surface tension (Ca -4 0)


Eq. (A10) reduces to

d3 H
--=0
dz3
with general solution

H(z) = C -+ C2 z+ C3


(A9)


(A14)


WINTER 1989


(A12)











along with the boundary conditions

H(z=0) = W/2, H(z=L) = Hf, (dH/dz)z=L = 0

The solution is


H(z) = W 2 zL)+ W


which is a parabolic film thickness.

3. Finite surface tension (0 < Ca < k)

Eq. (All) is cast in the form


H d3 H St Ca + 3Ca(H- H =0
dz H 2 f)


(A15)


(A16)


with no apparent analytic solution. For a special case of hori-
zontal coating (St = 0), and since usually Hf / W << 1, the
transformation


H* H
W'


. = Z
zW
W


(A17)


reduces Eq. (A16) to

H*3 H +3Ca H*- =0
dz*3 W (A18)

which predicts that near the inlet, where H* = 1, the film de-
cays with rate depending on the Ca. Near the other end, where
H* = 2Hf/W, the film becomes flat, surface tension becomes
unimportant, and therefore the slope is zero. Eq. (A18) can be
solved asymptotically by perturbation techniques. 0




CHEATING
Continued from page 17.


this paper. Perhaps these considerations will motivate
us to develop innovative ethics curricula and to im-
prove monitoring of course activities, so that our dis-
ciplines may be able to better safeguard (and perhaps
even increase) their already high levels of excellence.


REFERENCES

1. Tom Nicholson with William D. Marbach, "A Dead Stop in the
Ford Pinto Trial?," Newsweek 95:25 February 1980 pp. 65-66.
2. Neil R. Luebke, "How to Interest Engineering Ethics Stu-
dents in Philosophical Ethics," Proceedings of the 19th An-
nual Midwest Section Meeting of the American Society for
Engineering Education, March 21-23, 1984 IIA p. 3.
3. Charles E. Reagan and John 0. Mingle, "Engineering
Ethics," Proceedings of the 19th Annual Midwest Section
Meeting of the American Society for Engineering Education,
March 21-23, 1984 IIA p. 5.
4. John S. Baird, "Current Trends in College Cheating,"
Psychology in the Schools, 1980:17 p. 517.


5. Arizona State University College of Engineering and Applied
Sciences Student Conduct Committee, Halt Cheating, Re-
vised August 1982 p. 9.
6. Edwin A. Sisson and William R. Todd-Mancillas, "Cheating
in Engineering Courses: Short- and Long-term Conse-
quences," Proceedings of the 19th Annual Midwest Section of
the American Society for Engineering Education. March 21-
23, 1984 IC p. 4.
7. David C. Barnett and Jon C. Dalton, "Why College Students
Cheat," Journal of College Student Personnel, 22(6) 1981 p.
549-550.
8. Richard A. Dienstbier, Lynn R. Kahle, Keith A. Willis, Gil-
bert B. Tunnel, "Impact of Moral Theories on Cheating,"
Motivation & Emotion, Volume 4. No. 3, 1980, pp. 193-216.
9. Jack B. Evett, "Cozenage: A Challenge to Engineering In-
struction," Engineering Education: February 1980, p. 434.
Gerald R. Peterson, "Further Comments on Cozenage," En-
gineering Education: November 1980, p. 182.
10. William R. Todd-Mancillas and Edwin A. Sisson, "Cheating
Among Engineering Students: Some Suggested Solutions,"
Engineering Education: May 1986, p. 757, 758.
11. Richard M. Felder, "Cheating-An Ounce of Prevention,"
Chemical Engineering Education: Winter 1985, pp. 12-17. EO




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PAGE 1

z 0 u :::::, C w C) z 01:: w w z a z w 01:: 0 LL LL 0 z 0 in > 0 C) z c2 w w z C) z w _, < u i ::c u VOLUME XXIII NUMBER 1 Warren Stewart ... of Wisconsin by R. B. Bird Accred I tat ion SL.E/OfER Lubrication Flows PAPANASTASIOU Design Education In Chemical Engineering DOUGLAS, KIRKWOOD Experiencing Team Responsibility In Class RHINEHART An Experiment In Autotrophlc Fermentation SUBLETTE An Alternate Approac" to the Undergraduate Thesis AMYOTTE, FELS A Course to Examine Contemporary Thermodynamics LEE Unsteady-State Heat Transfer Involving a Phase Change SUNDBERG, SOMESHWAR Cheating Among Engineering Students: Reasons for Concern TODD-MANCILLAS, SISSON and.ChEat. .. RENSSELAER WINTER 1989

PAGE 2

We wish to acknowledge and thank ... 3M FOUNDATION .. for supporting CHEMICAL ENGINEERING EDUCATION with a donation of funds.

PAGE 3

EDITORIAL AND BUSINESS ADDRESS: Chemical Engineering Education Department of Chemical Engineering University of Florida Gainesville, FL 32611 EDITOR: Ray W. Fahien (904) 392-0857 ASSOCIATE EDITOR : T. J. Andenon CONSULTING EDITOR: Mack Tyrn!r MANAGING EDITOR: Carole Yocum (904) 392-0861 PUBLICATIONS BOARD CHAIRMAN Gary Poehlein Georgia Institute of Technology PAST CHAIRMEN Klaus D. Timmerhaus University of Colorado Lee C. Eagleton Pennsylvania State University MEMBERS, South Richard M. Felder North Carolina State University Jack R. Hopper Lamar University Donald R. Paul University of Texas James Fair University of Texas Central J. S. Dranoff Northwestern University West Frederick H. Shair California Institute of Technology Alexis T. Bell University of California, Berkeley li2.t1hw1 Angelo J. Perna New Jersey Institute of Technology Stuart W. Churchill University of Pennsylvania Raymond Baddour Massachusetts Institute of Technology Northwest Charles Sleicher University of Washington Canada Leslie W. Shemilt McMaster University Library Representative Thomas W. Weber State University of New York WINTER 1989 Chemical VOLUME XXIII Engineering Education NUMBER l WINTER 1989 EDUCATOR 2 Warren E. Stewart of Wisconsin, R. Byron Bird DEPARTMENT 6 Rensselaer Polytechnic Institute, Michael M. Abbott 12 VIEWS AND OPINIONS Accreditation: Changes are Needed, Charles A. Sleicher CLASSROOM 16 Cheating Among Engineering Students: Reasons for Concern, William R. Todd-Mancillas, Edwin A. Sisson 18 A Course to Examine Contemporary Thermodynamics William E. Lee Ill 38 Experiencing Team Responsibility in Class, R. Russell Rhinehart 50 Lubrication Flows, Tasos C. Papanastasiou CURRICULUM 22 Design Education in Chemical Engineering: Part 1 Deriving Conceptual Design Tools, J. M. Douglas, R. L Kirkwood 28 An Alternate Approach to the Undergraduate Thesis, P. R. Amyotte, M. Fels RANDOM THOUGHTS 2.i Nobody Asked Me, But..., Richard M. Felder LABORATORY 32 An Experiment in Autotroph ic Fermentation: Microbial Oxidation of Hydrogen Sulfide, Kerry L. Sublette 44 Unsteady-State Heat Transfer Involving a Phase Change: An Example of a 'Project-Oriented' Under graduate Laboratory, D. C. Sundberg, A V. Someshwar 10 Lett.er to the Edit.or 27 Positions Available 11, 31, 37 Book Reviews CHEMICAL ENGINEERING EDUCATION ( ISSN 0009! 479 ) iA publiAhed quarterly by Chemu:al E'fl{Jineeri'fl{J Diviswn Anwrican Society far E'fl{Jineeri'fl{J Edooatwn and ;., edited at the University of Ftarida. Correspondenc e regardi'fl{J editorial matter, cireutatwn and c ha'fl{JBB of address slwutd be sent to GEE Chemical Engineering Department University of Florida, Gainesville, FL 32611. Advertising mate rial may be sent directly to E 0. Painter Printing Co., P 0 Box 877, DeLeon Springs FL 32028. Copyright Q 1989 by the Chemical Engineerin~ Division, American Society for Engineering Education. The statements and opiruo!lll expressed in this penodical are those of the writers and not necessarily those of the ChE Division, ASEE, which bod,v asswnes no responsibility for them Defective copies replaced if notified with 120 days of publication Wnte for information on subscription costs and for back copy cost and availability. POSTMASTER: Send address cha'fl{Jes to GEE, Chemical E'fl{Jineeri'fl{J Department Uni v er:ri.ty of Ftarida, Gainesville, FL 3 611 1

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[j ;j a educator Warren E. Stewart of Wisconsin R. BYRON BIRD University of Wisconsin Madison, WI 53706-1691 Warren received his BS and MS in chemical en gineering at the University of Wisconsin in 1945 and 1947 respectively, and then he migrated eastward to study at MIT, where he received his ScD in 1951. I started graduate school at Wisconsin in 1947 and just missed meeting Warren then. However I heard many tales about him from the chemical engineering stu dents at the AXI house who had been classmates of his. They uniformly sang his praises and mentioned time and again what a brilliant student he was, how they always got help from him on difficult homework problems, and that he was the first person to go through the undergraduate chemical engineering cur riculum with a straight-A average. Within a few months he had become a legendary figure, and it was with this mythical Warren Stewart that I became ac quainted in 1947. In 1948 I took Joe Hirschfelder's course in quan tum mechanics. Joe assigned Pauling and Wilson as the text for the course but said that we might find it helpful to study some mimeographed materials that he distributed to the class. These were Warren Stewart's notes of Joe's lectures in 1946, and Joe said they were much better than his own. So my next en counter with Warren was by studying quantum mechanics from his careful transcriptions of Joe's lec tures. After graduate work at MIT, where he did his thesis on heat, mass, and momentum transfer, War ren became a Project Engineer at Sinclair Research, ... in 1960 the hardback textbook Transport Phenomena appeared. Warren was a superb contributor to the project for a number of reasons: he has exceptionally high standards for teaching and writing; he has a photographic memory of where things are in the literature; he insists on accuracy. Copyright ChE Di vision ASEE 19 8 9 2 1988 1945 Inc., in Harvey, Illinois. There he participated in the development of a catalytic reforming process and also in early work on computerized process simulation. In 1953 I joined the chemical engineering depart ment staff at UW. Here Warren's name came up often in conversations when faculty members recalled how scary it was to teach classes in which both Warren Stewart and Ed Daub were present (Ed was another legendary figure whose scholastic performance and keen mind had dazzled both staff and students). In 1956 I finally had the chance to meet Warren, when he came to the department to interview for an assistant professorship that had opened up; shortly thereafter he joined our faculty. This was the begin ning of a long friendship which I have very much val ued through the years. Warren lived up to the legend, and more. I found him to be a great scholar with an awesome grasp of science and engineering, as well as a compassionate teacher, a dedicated family man, and a marvelous raconteur of jokes. Those who see only CHEMICAL ENGINEERING EDUCATION

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the serious side of Warren don't realize that his reper toire of jokes, puns, and conundrums is every bit as impressive as his uncanny ability to solve complex sci entific problems. By 1957 Warren Stewart, Ed Lightfoot, and I had joined forces to prepare mimeographed material for a new course on transport phenomena. This occupied much of our time in the fall of 1957 and the spring of 1958; our green paperback book, Notes on Transport Phenomena, was published by Wiley in the fall of 1958 as a "preliminary edition." Then we spent another two years revising the "Notes," and in 1960 the hardback textbook Transport Phenomena appeared. Warren was a superb contributor to the project for a number of reasons: he has exceptionally high standards for teaching and writing; he has a photographic memory of where things are in the literature; he insists on accrt:racy; he is a meticulous proofreader (his ability to detect the smallest of errors earned him the nickname "Gimlet-Eye"); and-very important in book-writing -he has a wonderful sense of humor. During the man uscript preparation I felt that I was continually learn ing about transport phenomena from Warren (just as I had learned quantum mechanics from him a decade earlier). He had had after all, a lot of experience in transport phenomena in boundary layers during his thesis work at MIT as well as some five years of prac tice in solving industrial problems. That period of in tense work, 1957-1960 formed particularly strong bonds within the triumvirate-bonds that have sur vived for many years. A few years later Warren started studying Spanish, an effort which has given him another "di mension." He has made Latin America his primary overseas field of interest. He provided assistance to the translator who prepared the Spanish Edition of Transport Phenomena. He was a Visiting Professor at the Universidad Nacional de la Plata (Argentina) in 1962, and a Visiting Lecturer at the Instituto Tec nol6gico de Celaya (Mexico) in 1983 and at the Univer sidad N acional Aut6noma de Mexico in 1985. He has also given seminars (usually in Spanish) at a number of other Latin American institutions. It is rare for engineering professors to take the trouble to learn another language well enough to be able to lecture in it. Of course, this carries with it certain dangers. War ren attained instant fame in Mexico because of a lin guistic blunder he committed in a lecture at the In stituto Tecnol6gico de Monterrey. Someone in the au dience asked him a question to which he unfortunately didn't know the answer. So he wanted to say to the audience something like, "I'm very embarrassed that I don't know the answer to that question. Now when WINTER 1989 A few years later Warren started studying Spanish, an effort which has given him another "dimension." ... He provided assistance to the translator who prepared the Spanish Edition of Transport Phenomena. Warren and Jean (bottom row) in 1982 at a family gathering. we speak foreign l a ngua ges we often encounter words that are not in our v ocabulary and so we make a guess and hop e the listener s will understand. This works pretty well for an English speaker talking Spanish. Warren didn t know the word for embarrassed but boldl y produced the sentence "Estoy muy em barazado, que no se la respuesta a ese pregunta" (in stead of "Es embarazoso que .... "). Well, it turns out that e s toy muy embarazado" means "I am very pregnant." Understandably the audience exploded with laughter. (See what fun you miss out on if you don't try learning a foreign language!) This story pop ped up in a limerick read at Warren's 60th birthday party on July 2, 1984: He tackles tough tasks with bravado With the verve of a wild desperadoBut he s really quite droll When he talks espaiiol And says that he 's embarazado. Anne Nonimus De s pite his occasional problems with Spanish, Warren has for several decades administered the departmen tal PhD Spanish reading exam. He and his wife Jean (who for many years has been the "alderperson" for Madi s on's 20th District), have often shared the hospi tality of their home with visitors from Latin America (and from other part s of the globe as well). They and their children have been gracious hosts on many occa sions, and countless vi s itors will long remember their pleasant evenings at the Stewart home Warren's linguistic accomplishments are not re stricted to Spanish. He is also very fluent in "Alfalfa." 3

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This is a pig-Latin-like way of speaking where you insert "LF" in the middle of the predominant vowel in each word; thus "seem" transforms into "seelfeem." Since I also learned "Alfalfa" as a youngster, Warren and I often carry on long conversations in our "secret language" much to the astonishment of bystanders Warren can even speak Alfalfanized Spanish! But, we digress. Let's get back to Warren and chemical engineering. Warren is one of the most ver satile people that I know. I think he has taught almost every course in the department. His list of research publications is also characterized by great diversity. How many chemical engineers could write significant contributions on such widely varying topics as predic tion of vapor pressures; reciprocal variational princi ples; kinetics of benzene hydrogenation; multicomponent diffusion; orthogonal collocation; measurement of diffusivities; droplet vaporization; kinetic theory of rigid-dumbbell suspensions; tokamak reactors; ther mal diffusion; catalysis; corrosion; parameter-estima tion ; Bayesian statistics; viscoelastic fluid dynamics; sensitivity analysis; and distillation column design? Whereas most professors work in rather narrow areas, Warren has been an impressive generalist. When he was chairman of the chemical engineering department (1973-1978), he was able to discuss details of research projects being carried out by all of his departmental colleagues; no other chairman before or since has been able to do that. This was one of his great strengths when he served the department so ably as our chairman. Warren's enormous breadth of interest has reSTEWART'S TOP TEN 4 1. Forced Convection in Three-Dimensional Flows: I. Asymp totic Solutions for Fixed Interfaces, by W. E. Stewart, AIChE Journal, 9 528-535 (1963) This deals with the prediction of heat and mass transfer in thin boundary layers at rigid interfaces, with given interfacial shape and velocity gradient. A prediction o f the Nusselt number for a packed bed is given The importance of this paper was not widely appreciated until the publication of [ 6] eleven years later 2. Matrix Calculation of Multicomponent Mass Transfer in Isothermal Systems, by W. E. Stewart and R. Prober, Ind Eng. Chem Funds 3, 224-235 (1964). This paper (and another that y e ar by Herb Toor at CMU) showed how to solve a large class of multicomponent mass-transfer problems realistically by transforming the problem to a set of binary problems; this method is used extensively in the current literature on distilla tion and absorption. 3. Solution of Boundary-Value Problems by Orthogonal Collo cation, by J V. Villadsen and W E Stewart, Chem Eng Sci 22, 1483-1501 (1967) ; ibid., 23, 1515 (1968). This paper (which was designated as a "Citation Classic in Current Contents on 9/21/81) has been widely adopted by reactor designers for calcu lating radial profiles in reactor tubes and catalyst particles. This method of computation combines the simplicity of colloca tion with the efficiency of orthogonal polynomial interpretation. 4. Forced Convection in Three-Dimensional Flows: IL Asymp totic Solutions for Mobile Interfaces, by W E. Stewart, J B. Angelo, and E. N. Lightfoot, AIChE Journal, 16, 771-786 (1970) Here single-phase transfer coefficients in fluid-fluid contactors are related to the fluid properties and interfacial motion This theory should eventually supplant the penetration and surface renewal theories, and it includes time-dependent and turbulent flows. Comparisons with experiment show good agreement 5. Practical Models for Isothermal Diffusion and Flow in Porous Media, by C. Feng and W E Stewart, Ind. Eng Chem Funds 12 143-146 (1973) This paper gives extensive data on 3component diffusion in catalyst pellets and thereby tests several diffusion models; it has been widely cited in works on realistic modeling of catalyst particle performance. 6. Computation of Forced Convection in Slow Flow Through Ducts and Packed Beds, by J. P S0rensen and W E Stewart, Chem. Eng Sci., 29, 811-837 (1974) In this 4-part pioneering study the fluid dynamics and mass-transfer processes in regu lar packed beds are studied Impressive agreement with exper iments is found for the appropriate ranges of Reynolds and Peclet numbers. 7. Computer-Aided Modelling of Reaction Networks, by W E. Stewart and Jan P. S0rensen, in Foundations of Computer Aided Process Design (R. S. H. Mah and W. D. Seider Eds.), Vol. II, Engineering Foundation, New York 335-366 (1981) This survey paper summarizes the work of Warren's group on digital analysis of reaction models and on parameter estima tion from multiresponse reactor data Expert programs are provided for use by kinetics researchers The programs auto matically evaluate reaction schemes for their fit of data and then estimate the parameters that are determinable from the data given 8. Simulation of Fractionation by Orthogonal Collocation, by W. E Stewart, K L Levien, and M. Morari, Chem Eng Sci 40, 409-421 (1985) Whereas in [3] above Jacobi polynomials were found to be optimal for continuous systems, here it is shown that for discrete systems Hahn polynomials should be used Hence, stagewise processes can be analyzed and designed very effectively 9. Sensitivity Analysis of Initial-Value Problems with Mixed ODEs and Algebraic Equations, by M Caracotsios and W E. Stewart, Comput Chem. Eng., 9, 359-365 (1985) This work gives an efficient method for computing the sensitivity of a process model to its parameters. The algorithm is implemented on a modern differential-algebraic equation solver and is illus trated by a reaction modeling problem. Sensitivity calculations are widely useful in modeling, control, and optimization. 10. Forced Convection: IV. Asymptotic Forms for Laminar and Turbulent Transfer Rates by W. E Stewart, AIChE Journal, 33, 2008-2016 (1987 ) ; 34, 1030 (1988). Here dominant-balance ar guments are used to get information about heat and mass transfer rates without integrating any differential equations. New results are obtained for turbulent flows, and this work sup plements [1] and [4] above The celebrated Chilton-Colburn factors correspond to the leading term of the long-time expansion C HEMI C AL ENGINEERING EDUCATION

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sulted in the fact that he frequently functions as an "in-house consultant" to colleagues and students in chemical engineering as well as from other depart ments. It's not unusual to see him conferring in his office with a professor of zoology on heat transfer through fur, with a student from nuclear engineering on a problem related to controlled nuclear fusion, or with a chemical engineering graduate student on vis coelasticity. I've never heard of an undergraduate or graduate student ever being turned away by Warren. His door is always open for i n terruptions, and he has always been very generou ~ wi t h his time and very patient with his "customers." H is willingness to help others by sharing his talent is the subject of this bit of doggerel: A student came in to see Warren And said in a voice quite forlor'n "I can't find a path Through this quagmire of math; These nab/as are terribly foreign." So Warren (who's also called Earl) Proceeded to help this young girl. Without using a book He unt1inchingly took The Laplacian of grad div curl curl. Anne 0. Nimes Well now you know what the E" stands for in Warren E. Stewart. All researchers have publications of which they are especially proud. Warren feels that the box on the opposite page lists his ten best research publica tions. He is currently working on the manuscript of a book on computer-aided modeling of reacting systems which promises to be a thorough, scholarly, and useful work. Warren is a quiet and modest person. He never talks about the many awards that have come his way, including honorary membership in Phi Beta Kappa, the ASEE Chemical Engineering Lectureship Award, the Alpha Chi Sigma Award and the Computing in Chemical Engineering Award of AIChE, the Benja min Smith Reynolds Teaching Award at UW, and the McFarland-Bascom Professorship at UW. In 1989 he will receive the Murphree Award of ACS. He should also receive a special award for being able to meet deadlines in a photo-finish. At 10:59 am he can be seen frantically xeroxing materials for an 11:00 am class. At 11:59 pm on April 14th he can be seen speeding up to the main post office in Madison with his income tax return. And I recall the time when several of us de cided to see Warren and his family off at the airport when they were headed for the Middle East where Warren was to give some lectures At 10 minutes be fore plane time, the Stewarts were still not at the WINTER 1989 Warren takes time out of a typically busy da y to welcome a visitor. airport; at -5 minutes still no sign of them; at -2 mi nutes they scrambled out of a taxi cab and they did make the plane. Apparently Warren thrives on the excitement of seeing how close he can come to not quite missing a deadline. One of Warren's most outstanding contributions has been the development of the powerful technique of "orthogonal collocation and according to Harmon Ray it is probably one of the most significant original contributions to numerical analysis ever made by a chemical engineer. Here again, this activity has been memorialized in a poem inflicted on the audience at Warren's 60th birthday party: He's often referred to as "WES". He s known from Rangoon to Loch Ness For fast collocation In flash distillationAnd multicomponent, no less! U. N. Bekannt No doubt about it-Warren has had a distin guished career. And he is still going strong with a very active research program, book-writing activities, consulting, memberships on editorial boards, public and community service activities, and music (he plays the trombone!). He has certainly earned a place in the "ChE Hall of Fame." ACKNOWLEDGEMENT Many thanks to ENL, EED, WHR, and REF for constructive criticisms of the original manuscript. D 5

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lib I department RENSSELAER POLYTECHNIC MICHAEL M. ABBOTT Rensselaer Polytechnic Institut e Troy, NY i2180 Rensselaer Polytechnic Institute was founded as the Rensselaer School in 1824, "for the purpose of in structing persons who may choose to apply themselves in the application of science to the common purposes of life." It has evolved into a university comprising five schools, 400 faculty and full-time researchers, and 6400 students. Of the latter, approximately 1900 are graduate students. Chemical engineering at Rensselaer began seventy years ago as a program in the Department of Chemis try. In 1943, it became a separate academic unit, with Lewis S. Coonley as its first head. It is now one of the eight departments and five centers which compose the School of Engineering. Chemical engineering has eigh teen active faculty members; another three from other departments hold joint appointments with us. Under graduate enrollment is approximately 175, and graduate students number about 60, with 75% pursu ing the PhD. We have a building largely to ourselves. Separated by a comfortable 100 yards of football field from the Engineering-School administration, the Ricketts Building is our home. Ricketts contains offices, class rooms, a unit-operations laboratory, and about 14,000 square feet of research laboratorie s. An in-house elec tronics/machine shop is available for use by students and staff. The perceived heart of a contemporary engineering department is the range and strength of its research interests. In that respect, chemical engineering at Rensselaer is fortunate to have coverage in many areas ... ID C or,yright ChE D ivision ASEE 1989 6 INST/TL Our research labs are relatively new, the result of an extensive renovation undertaken in 1978 Since then, a central graduate-student office/study area has been constructed and furnished. Most recently, through the generosity of Howard Isermann (a Rensselaer chemical engineering alumnus), we have been able to renovate and outfit 3000 square feet of new laboratory space for our biochemical engineers. This facility will help us to compete successfully with other first-class programs in biochemical engineering. BREADTH AND DEPTH The perceived heart of a contemporary engineering department is the range and strength of its research interests. In this respect, chemical engineering at Rensselaer is fortunate to have coverage in many areas: air resources, advanced materials, biochemical engineering, control and design, fluid-particle sys tems, interfacial phenomena, kinetics and reactor de si gn, polymer engineering, separation processes, ther modynamics, and transport processes. A special pride is our biochemical engineering group, with a critical mass of three (approaching four) specialists. Interdisciplinary interactions are currently encour aged at Rensselaer, and chemical engineering benefits from numerous collaborations. Belfort works with Don Drew from mathematics, Gill with Marty Glicksman from materials engineering, and Nauman with various polymeric enthusiasts from chemistry and materials engineering. Rensselaer's Center for Integrated Elec tronics provides one of several foci for those (e.g., Gill, Wayner) with interests in advanced materials. Belfort, CHEMICAL ENGINEERING EDUCATION

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'E Home Sweet Home: The Ricketts Building. Local legend has it that Palmer C. Ricketts (a former Rensselaer president) is interred behind his memorial plaque in the foyer. On moonless nights, his shade perturbs unattended experiments. Littman, Morgan, and Wayner are members of the Center for Multiphase Flow; Belfort, Bungay, Cramer, Gill, Morgan, and Nauman, of the Bioseparations Re search Center; and Cramer, of the Biophysics Re search Center. And the Department of Electrical, Computer, and Systems Engineering harbors like minded souls with whom Bequette exchanges ideas on process dynamics and control. What makes academic research "go"? Money, of course, and a dedicated and energetic faculty. We, like others in this business, must scramble for the former. The latter, fortunately, is a given. Our research envi ronment is healthy; we are better than competitive, and yearly attract a strong group of graduate students. Problems of student support are mitigated by fifteen new Isermann Graduate Fellowships which are en dowed in perpetuity. F AC ULTY S NAP S HOT S R. H. Wentorf is Distinguished Research Professor of Chemical Engineering. Bob is inventor or coinventor of techniques for commercial production of very hard materials (Borazon, diamond). He has many technical interests, ranging from polymer-fiber fabrication to semiconductor processing. After-hours, Bob is a farmer and a glider pilot. P. C. Wayner, Jr. studies transport phenomena in evaporating menisci and in ultra-thin films. His arsenal of experimental techWINTER 1989 niques includes scanning microphotometry and photo scanning ellipsometry. For analysis, he uses capillarity concepts and London/van der Waal s theory. Pete en joys tennis and skiing. H. C. Van Ness is Institute Professor of Chemical Engineering He specializes in the measurement, reduction and correlation of ther modynamic properties of liquid mixtures. Hank's equipment designs have been widely adopted, and are the source of many of the world's heat-of-mixing and VLE data. Hank golfs and plays the piano. J. L. Plawsky works with optical substances. He seeks to understand how the various transport phenomena affect the processing of wave-guide de vices. Related interests include d e veloping novel ma terials based upon inorganic/organic copolymer sys tems and investigating complex mixing effects in flow ing glasses. Joel plays rock guitar and swims. E. B. Nauman is director of the Industrial Liason Program for chemical engineering. His principal research in terests are in polymer processing and polymer-reaction engineering. Much of his current work relates to the compositional-quenching process which he invented. Bruce characterizes his hobby as "pure and applied flamboyance"; he is the only R.P.I. prof whose winter car is a Jag XJS. C. Muckenfuss shepherds our seniors through the final year of chemical engineering; he is responsible for their advising and eventual clearance. His research centers on first-principle studies of trans7

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Bruce Hoolc adjusts a data point. Behind him: Littman's cat combustor, a.le.a. High-Temperature Gas-Phase Spouted-Bed Catalytic Reactor. port phenomena, i.e., on the application of kinetic theory and irreversible thermodynamics to multicom ponent, reacting systems. Charlie is an avid bicyclist/ traveler. M. H. Morgan III works with fluid/particle sys tems. His current research focuses on the development of reactor theories and of fluid-mechanical models for spouted beds with draft tubes. Experimental and theoretical studies abound. Morris is a serious competi tive runner: in 1988 he took a Submaster's gold medal with a 2:03 half-mile in New York's Empire State Games. H. Littman conducts basic research on gas/liq uid and fluid/particle systems. Ongoing efforts include studies on the dynamics and control of spouted-bed reactors, pneumatic transport of fine particles, and jet stability and the transition to bubbling. Howard is a 1988 recipient of Rensselaer's Distinguished Faculty Award. He hikes and runs for fun. P. K. Lashmet is Executive Officer of chemical en gineering. His research concentrates on process en gineering and on the improvement of basic design pro cedures. Currently, he explores the effects of parame ter uncertainties and process variations on non dynamic equipment performance, employing Monte Carlo simulation techniques. P.K. enjoys his family and power-boating (in that order). W. N. Gill is Head of chemical engineering; his research is in the applied transport areas. Current efforts include studies in membrane separation tech niques and the design and modeling of chemical vapor deposition reactors. Of special interest are experimen tal and theoretical investigations of dendritic growth of ice and ofsuccinonitrile, and the non-linear dynamics of pattern formation in crystal-growth systems. Bill likes films (classic and foreign), music, plays, running, and martinis. A. Fontijn studies combustion. The major efforts of his group concern the high-tempera ture reaction kinetics of combustion intermediates. For the experimental studies Fontijn has developed spe cial fast-flow and pseudostatic thermal reactors. Ar thur hikes and travels for relaxation. S. M. Cramer specializes in biochemical engineering. His interests "As soon seelc ice in June": Bill Gill does. This dendrite began life as a smooth disk. Bill studies its evolution with digital image analysis, and pre dicts its development with theory. "Fringe benefits": Wayner's scanning ellip someter with interferometer and laser light source Mounted on a vibration-proof table, it is immune to the shocks of Ric lcetts's frequent renovations. Nauman's compositional quencher. Bruce probes the depths of the spinodal re gion, seeking to produce rub ber-modified polymers with controlled particle-size distri butions. 8 An unattended experiment? Not to worry. This machine (Cramer's new Delta Prep chromatographic unit) practically runs it self. CHEMICAL ENGINEERING EDUCATION

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center on the synthesis and separation of biomolecules. Research efforts include experimental and theoretical studies of preparative chromatographic techniques (especially displacement chromatography), and enzy matic organic synthesis. Steve is an accomplished jazz pianist who performs regularly with High Society, a group of professional musicians. H. R. Bungay III conducts research into microbial growth and biomass refining. Capillary microelec trodes with tips a few microns in diameter are used to study oxygen transfer in various microbial systems. Intensive efforts are geared toward eventual commer cialization of processes for conversion of wood chips to salable chemicals. Harry is a licensed pilot and a bridge Life Master. W. D. Bradley is an essential contributor to our undergraduate instructional program. He brings to us forty years of experience as a practicing chemical engineer. Bill's technical interests span the spectrum of design topics and focus on the ultimate questions: Will it work? Will it make money? His hobbies include beekeeping and herb-gardening. B. W. Bequette seeks to integrate the traditionally separate issues of model ing, design, optimization, and control into a consistent methodology. Emphasis is on applications to the man ufacture of semiconductor devices. Nonlinear control theory is a special enthusiasm. Wayne's outside in terests include collision theory and trajectory analysis (softball) and high altitude inefficient conversion of po tential to kinetic energy (skiing with reckless aban don). G. Belfort studies the fundamentals of synthetic membrane processes and applications of these pro cesses to biotechnology. Fluid-mechanical concepts are used to analyze membrane particulate fouling and to develop rational design procedures. Flow cytometry and NMR imaging are among the experimental tech niques employed in Belfort's work. Georges coaches soccer and plays squash. E R. Altwicker works in selected areas of air pollution control and atmospheric chemistry. Current efforts include studies ofS(IV) oxi dation and of the heterogeneous combustion of waste fuels. A falling-drop reactor allows controlled investi gation of scavenging and scrubbing operations, and complements theoretical studies of mass transfer with chemical reaction. Elmar skis and plays tennis and the violin. M. M. Abbott does thermodynamics. Technical interests include phase equilibria, solution ther modynamics, and the PVTx equation of state. His pro fessional passion is the classroom. Mike reads history, poetry, and music. DISTINGUISHED COLLEAGUES Outside recognition by one's peers is an indicator WINTER 1989 Is there professional life beyond the laboratory? We hope so. Education is still our major business, and service to the profession is a close second. Van Ness, Cramer, Bungay, and Abbott have all won major teaching awards: ... Fontijn's HTFFR (pronounced "aitch-tuffer"}, with Clyde Stanton at the controls. With this and other devices, Arthur studies gas-phase kinetics over humongous tem perature ranges. of the strength of a department, and we enjoy a share of such honors. In 1985, Fontijn received the ACS Award for Creative Advances in Environmental Sci ence and Technology. Bill Shuster (just retired from Rensselaer) was a 1987 recipient of AIChE's Award for Service to Society. And 1988 has been an especially happy year for us, with Bungay obtaining the ACS Marvin J. Johnson Award in Microbial and Biochemical Technology and Van Ness receiving AIChE's Warren K. Lewis Award. Four Rensselaer faculty (Bungay, Nauman Van Ness, and Wayner) are AIChE Fellows. Wentorf is a member of the National Academy of Engineering. Gill, Littman, and Van Ness have done Fulbrights. Gill was the first Glenn Murphy Distinguished Professor at Iowa State University. In 1988, Belfort was Flint Scho lar at Yale University, and Van Ness was Phillips Petroleum Company Lecturer at Oklahoma State Uni versity. And so it goes: we enjoy our share. LAST, BUT NOT LAST Is there professional life beyond the laboratory? We hope so Education is still our major business, and service to the profession is a close second Van Ness, Cramer, Bungay, and Abbott have all won major teach9

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ing awards; Abbott has just finished a two-year stint as a Rensselaer Distinguished Teaching Fellow. We currently have in print ten textbooks and mono graphs: Basic Engineering Thermodynamics, 2nd Ed. (Zemansky, Abbott, and Van Ness); BASIC Environ mental Engineering (Bungay); Chemical Reactor De sign (Nauman); Classical Thermodynamics of Nonelectrolyt e Solutions (Van Ness and Abbott); ComJYU,ter Games and Simulation for Biochemical En gineering (Bungay); Energy: The Biomass Option (Bungay); Introduction to Chemical Engineering Thermodynamics, 4th Ed. (Smith and Van Ness); Mix ing in Continuous Flow Systems (Nauman and Buff ham); Schaum's Outline of Theory and Problems of Thermodynamics (Abbott and Van Ness); and Under standing Thermodynamics (Van Ness). Several of us serve on AIChE technical program ming committees. Most of us are members of one or more editorial boards. And, of course, Rensselaer is the home of Chemical Engineering Communications, edited by Bill Gill. CEC receives about 400 manuscripts each year, thus providing valuable interaction between Rensselaer and the international chemical engineering community. Douglas R. Hofstadter asks if the soul of a collection of individuals can be greater than the hum of its parts. We believe so. With strong commitments to education, to professional service, and to research and scholar ship, chemical engineering at Rensselaer is certainly a humming place. A diversity of styles and interests, a healthy dedication to the principle of Iese majesty, and a sense of collegiality combine to provide our de partment with a lively atmosphere in which to pursue one's professional goals. It's a great place to work and study. ti b#I letters I LEVENSPIEL CLAIM DISPUTED To the Editor: We wish to reply to Dr. Octave Levenspiel's letter published in your Summer 1988 issue which erroneously compares Chemical Engineering Science with Chemical Engineering Communications as to both cost and price. Doctor Levenspiel's analysis is incorrect in just about every respect imaginable. Unfortunately, the sorry busi ness could have been avoided had Dr Levenspiel verified his information with us prior to publication. I hope that in view of the facts as outlined below, he will retract his let ter and save further embarrassment. 1. The subscription prices quoted by Dr Levenspiel 10 for the present calendar year in his letter article are false He quotes a price of $296 for a volume. In fact the aca demic library rate is $184, substantially less that {sic] the figure quoted in his letter. Furthermore, there is an individual subscription rate at 50% of the library rate, or $92 per volume. 2. In a comparison, these rates are further reduced by the fact that our rates include airmail postage and handling charges all over the world, while in other publications, these costs may be added separately. So a comparable library subscription rate with a publisher who charged separately for these services, would be about $25 lower or about $169. 3. We did study a recent front matter of an issue cho sen at random of Chemical Engineering Science It was volume 43, number 7 of that publication. In that issue the 1988 institutional subscription rate for a single year is listed at 1400 DM. We telephoned a major subscription agent who today [August 24, 1988) advised us that the present price in dollars of an academic subscription was $862.50, about twice as expensive as the rate of $435 quoted in Dr. Levenspiel's letter. Incidentally, having chosen this particular article quite by chance, we were surprised that the lead article was the Third P. V. Danckwerts Memorial Lecture by 0. Levenspiel and that the front matter included a photograph taken in May 1988 showing Dr. Levenspiel together with the Editorial Director of Pergamon Press as well as the Executive Editor of Chemical Engineering Science. We did not verify the other columns of pages and words per page as in Dr. Levenspiel's article but in view of the fact of the other distortions of price and size, we have no reason to accept these as being any less biased. 4. As to the change in format, there was a change in format of Chemical Engineering Communications but the amount of material offered subscribers per volume has always been adjusted and remained the same. The num ber of pages per volume was increased to compensate for the decreased amount of material per page for the change from a double-column to a single-column format. Dr. Levenspiel suggests that the change in format was made to deceive readers; this is simply untrue. We have always published on a flow basis in that we estimate the number of pages and/or volumes for publi cation in the upcoming 12-month period. Rather than delay publication of articles to conform to a fixed number of pages, articles are published as ready for most rapid publication. In prior years, as the number of pages billed was reached earlier or later than anticipate d renewals were either advanced or delayed accordingly. In the last two years, we have changed this policy so that iss u es are published on a calendar-year basis. The number of pages for the coming year is estimated and this determines the subscription price for that year. Should the number of pages be over or underestimated, the price is adjusted accordingly in the subsequent renewal period. In the year 1987, we overestimated the number of pages which would be supplied. Accordingly the subscription price for CHEMICAL ENGINEERING EDUCATION

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1988 was reduced by 38% in the present subscription year. Each month, the number of pages ready for publi cation is published so that individual issues may vary widely in size. Thus a 250 page issue may be followed by a 1000 page issue in the next month, and so on. Any single issue which Dr. Levenspiel uses in his comparison is therefore likely to distort the results. 4. [sic] Furthermore, the comparison with CES is further distorted by other erroneous information. I cannot directly comment on the difference in subscriber bases and cannot comment on the differences in publication methods, except to say that unless a complete analysis of the subscriber bases and international markets are [sic] made, no cost comparison can be made. For example, a society publication, say, may have other sources of editorial funding such as page charges or distribution methods such as bulk society purchase would no doubt have other ways of generating revenue which would supplement the subscription price. Some publications accept advertising and are distributed on a controlled circulation basis, while others are not. In any event the scopes of the publication are quite different. Chemical Engineering Communications provides "a forum for the rapid publication of papers in all areas of chemical engineering." A recent issue of CES states in its scope "The object of the journal is to publish papers dealing with the application to chemical engineering of the basic sciences and mathematics .. . The other areas of distortion in a valid comparison can include such factors as complexity of typesetting and quality of materials For example, CEC offers free publi cation of color photographs as well as other special ser vices In addition libraries subscribing to CEC can, for an additional nominal $5 per volume receive a photocopy licence [sic] allowing them unlimited photocopying thus providing a very low cost of dissemination The true current cost to subscribers of CEC is about half of that quoted in Dr. Levenspiel's letter and com pares favorably with other commercial, international journals. In a major pricing study recently prepared by a major university library system our company was ranked 18th. In fact, we are quite concerned about the current li brary budget crisis. We have been trying for some time now to find a way to defer or lessen the effect of inflation and currency problems on our regular subscribers. We are enclosing a press release of a program which we are announcing to further reduce the costs to existing sub scribers. Our prices, after adjustment for changes in numbers of pages, have increased only 10% in the last three years despite a higher inflation rate and a falling dollar Unfortunately, damaging false analyses like Dr Levenspiel's serve only to raise prices by reducing units, not to lower them. We work in an intellectual area with intellectual prod uct and try to orient our services to the needs of the community. Libelous attacks made without fact or WINTER 1989 knowledge and without verification like those of Dr. Lev enspiel serve no useful purpose in this enterprise. Martin B. Gordon Gordon and Breach, Science Publishers, Inc. Editor's Note: The Press Releases enclosed with the above letter describe a "Subscriber Incentive Plan" (SIP) that would result in 10-20% discounts when certain con ditions are satisfied. A basic membership earns a 10% discount which will be automatically granted for the 1988-89 period, with future discounts dependent on membership in SIP ; a 5% discount voucher "credit memo" good on future renewals will be extended with enrollment in the SIP; and an additional 5% discount is offered to the subscriber if the order is placed through their preferred agent, STBS. The offer will initially be restricted to North American libraries ( iJ ;j a book r ev i e ws DIRECT CONTACT HEAT TRANSFER by Frank Kreith and R. F. Boehm Hemisphere Publishing Corp., 1988 Reviewed by Joseph J. Perona The University of Tennessee: Knoxville The term "di r ect-contact heat transfer" denotes the physical contacting of media for heat exchange purposes in the absence of a s e parating barrier such as a tube wall. Some applications are quite old, e.g cooling towers and barometric condensers. The concept is not mentioned by such modern textbooks on heat transfer as those by Lienhard and by lncropera and DeWitt. A chapter is de voted to it in Kern's book, published in 1950. D i rect contact operations are fundamental to chemi c a l engineering. N ea rly all mass transfer processes are direct contact operations. From an analysis or modeling standpoint, direct-contact heat transfer is not signifi cantly different from nonisothermal mass transfer, un less radiation is important. The state-of-the-art is the same. For transfer between fluid phases, interfacial areas are usually not known and experiments produce volu metric coefficients, in which the transfer coefficient and interfacial area are lumped together. Similar contacting devices are used. Since mass transfer inevitably accom panies direct-contact i ng, its extent must be evaluated in any heat transfer application. It may or may not be desirable for the objectives of the operation The primary advantages of direct-contact heat transfer over surface exchangers are the elimination of C o n t i n ue d on page 3 0. 11

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lil ;j ?lviews and opinions ACCREDITATION Changes Are Needed CHARLES A. SLEIGHER University of Washington Seattle, WA 98195 T HE PRIMARY PURPOSE of accreditation of under graduate engineering programs is to protect stu dents by assuring a set of minimum academic stand ards. A secondary purpose is to protect the public, companies, governments, and professional engineers themselves from employment of ill-qualified individu als, which is to say anyone who graduates from a pro gram that is not accredited. This purpose will always be secondary, for no program can guarantee the qual ifications of every graduate. That is the purpose of licensing, whereas accreditation is simply the academic equivalent of the Good Housekeeping Seal of Approval. There is a price to be paid for accreditation, and it is therefore appropriate to ask if we gain as much as we lose by the accreditation process and to examine what can be done to overcome some of the negative aspects of accreditation. The four principal benefits of accreditation to a department are: 1. It is an asset to enrollment. Students seek to enroll in accredited programs. (In some states one must be a graduate of an accredited program in order to take the E. I. T. exam.) 2. Accreditation suppresses competition. Accreditation is usually necessary for survival of the program, but de veloping the resources necessary for accreditation is ex pensive and, therefore, not easily undertaken. 3. Accreditation protects its graduates from quacks, char latans, and graduates of non-accredited programs who . chemical engineering is a dynamic profession It is constantly changing ... chemical engineering education must change too or it will become irrelevant and die. ii:> Copyright ChE Divis ion ASEE 1989 12 Charles A. Sleicher is Chair of the Department of Chemical Engineer ing at the University of Washington a position he has held since 1977 He has a BS in chemistry from Brown University, and the MS and PhD degrees in chemical engineering from M. I. T and the University of Michigan respect i vely He worked for the Shell Development Company for four years before joining the faculty of the University of Washington in 1960. seek the same jobs. That is important. Most companies that hire BS chemical engineers do not hire them from non-accredited programs. On the other hand, most com panies do not need accreditation to tell them what pro grams are of high quality, so this consideration is of little importance. 4. Accreditation affects the administration's view of the department and, therefore, its budget. That is, of course, important, but should be regarded as a necessary evil in the sense that Program A needs accreditation only be cause it might otherwise be regarded sometimes even by the Dean, as inferior to accredited programs B, C, and D. This argument cuts both ways; in some cases an ac creditation report that faults a department might result in decreased support, while in other cases threatened loss of accreditation might result in increased support to re medy deficiencies The sacrifices a department makes for accreditation are these: 1. It is a modest direct expense. The current minimum cost of accreditation is $1025, plus $1025 for each proC HEMICAL ENGINEERING EDUCATION

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Can accreditation requirements accommodate the range of changes discussed in the Amundson report ... ? The answer is no. What will happen instead is that no department will wish to endanger its accreditation, and the rigidity of the ABET requirements will severely restrict the scope and implementation of those changes. gram, plus $50-150 per year, plus other miscellaneous charges. 2. It is a large indirect expense and a gigantic headache for the department. Extensive documentation of every aspect of the department as we ll as supporting facilities and departments is required. Hundreds of hours of fac ulty and staff time go into the preparation of the required reports. 3. Many faculty members spend much time on ABET committee work or act as program evaluators. Through a sense of obligation to the profession, they sacrifice val uable time to undertake these tasks (and they deserve more credit and thanks than they usually get). 4. The fourth cost, and by far the most important, is that accreditation requirements place constraints on cur ricula that unduly limit creative experimentation in cur riculum design and that severely limit the capacity of departments to respond to changes in the profession. Moreover, present requirements leave almost no time for electives. This cost is borne not alone by departments but by their students and the profession as well. The remainder of this paper concerns certain nega tive effects of accreditation on chemical engineering curricula and what might be done to make improve ments. We all know that chemical engineering is a dynamic profession. It is constantly changing, but the rate of change, like that of evolution, is uneven. Periods of slow change are punctuated by periods of sudden change, such as the one we have gone through in the past five years. Chemical engineering education must change too or it will become irrelevant and die. Indeed, signs of change in curricula are apparent. Many departments have made, or are about to make, changes in curricula in response to recent changes in the profession, and the "Amundson Report" will cer tainly stimulate more. The central theme in most of these revisions is increased flexibility-more options for the students. A thoughtful and provocative article on this theme appeared in the spring 1987 issue of Chemical En gineering Education by Richard Felder and entitled, "The Future Chemical Engineering Curriculum Must One Size Fit All?" Professor Felder argues per suasively for flexibility in the curriculum. He asks why not "abandon the pretense that all of our students WINTER 1989 have the same needs and can therefore be served by the same curriculum, give or take a few electives?" He then proposes some steps towards restructuring a chemical engineering curriculum. Neither he nor ap parently anyone else, however, is proposing radical changes. The basic chemical engineering material will still be there, but there is obsolete material in our curricula that should be removed. In fact, in the same issue Phil Wankat has some suggestions as to what should be removed to make room for new material. No two chemical engineering faculties are alike, and so if the curricula of many departments are re structured, there will inevitably be less uniformity among departments than there is now, and therein lies the rub with accreditation. Can accreditation re quirements accommodate the range of changes dis cussed in the Amundson report now being considered by many departments? The answer is no. What will happen instead is that no department will wish to en danger its accreditation, and the rigidity of the ABET requirements will severely restrict the scope and im plementation of those changes. For many departments the principal accreditation problem centers on the ABET engineering science re quirement, which is one year or thirty-two semester credits of a narrowly restrictive definition of engineer ing science. There are two subsets of problems here: the distinction between engineering science and basic science on one hand and between engineering science and engineering design on the other. We will look at each. First, the engineering science/basic science problem. One of the great strengths of chemical engineering curricula is that their graduates are adaptable to a wide range of technologies and, moreover, are able relatively easily to change career directions in mid stream. They are able to do so because they are well grounded in basic science and fundamentals. Com pared with other engineering disciplines, chemical en gineering students take about the same amount of math and physics but a vastly larger amount of chemistry (typically twenty-six semester credits ver sus about four for other disciplines). But the heavy dose of basic science takes a big chunk out of the cur riculum. In fact, basic science and engineering science together take up almost exactly two years, or one-half of the curriculum. The reason that engineering science is a problem 13

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lies in its ABET definition and the interpretation of that definition by evaluators. The relevant words are: The objective of the studies in basic science is to acquire fundamental knowledge about nature and its phenomena, in cluding quantitative expression. The engineering sciences have their roots in mathematics and basic science, but carry knowledge further toward creative application. These studies provide a bridge between mathematics/basic sciences and en gineering practice While it is recognized that some subject areas may be taught from the standpoint of either basic sci ence or engineering science, the ultimate determination of engineering science content is based on the extent to which there is extension of knowledge toward creative application." Clearly, the foregoing definition requires judg ment, and opinions will differ. However, the guidelines of the Engineering and Accreditation (E&A) Commit tee c>f the AIChE state that: "Instruction in this cate gory (engineering science) will ordinarily be given both by the chemical engineering faculty and the faculty of other engineering departments." Therefore, although the disclaimer "ordinarily" is in place, the practic e of some accrediting evaluators has been to define basic science as science taught in basic science departments and engineering science as science taught in engineer ing departments, and in practic e it is rare that a course taught outside of an engineering department is allowed to count as engineering science. The E&A Committe is, of course, aware of this basic science/engineering science problem and has taken four steps to alleviate it. The first and most important step was taken some years ago when 1/5 year of advanced chemistry was allowed to count to ward the engineering science requirement, i .e ., it could be double counted as engineering science and advanced chemistry. That simple idea was a great help to cur riculum planning and flexibility The next step was in December 1984 when Bryce Andersen, then chair of the E&A Committee, wrote a memo to all chemical engineering department chairs on the subject, "A Possible Change in the Chemical Engineering Program Criteria." The memo said that the committee was considering a change in require ments and asked for comment. The proposed change was to allow 1/4 year of advanced science instead of 1/5 year of advanced chemistry, to count as engineering science. The proposed change was a step in the right direc tion but was too small to be significant. It meant that and additional 1-1/2 semester credits, i.e., about 1/2 of a course, could be counted as engineering science A better choice would be to permit 1/3 to 1/2 year of 14 advanced science to count as engineering science. There are two reasons for this suggestion. First, basic science and engineering science are sometimes difficult to distinguish. There are, of course, extremes of sci ence and applied or engineering science, but there is also a huge range of grey in between that often makes the distinction irrelevant. Today many courses in such disciplines as chemistry, phy s ic s, biochemistry and even genetics microbiology and applied mathematics are more applied, more engineering-oriented than are other courses in those departments, i e., these courses contain a substantial element of engineering science Second, chemical engineers pride themselves on their flexibility and their ability to change the direction of their careers in response to the vagaries of the job market. This flexibility can only be provided if the chemical engineer ha s a s trong background in funda mentals As new technologies develop this flexibility becomes ever more important. The change of 1/5 to 1/4 year proposed by the com mittee was put into practice except that only advanced chemistry, not advanced science, was allowed to count. Strong letters of support from several department chairmen urging a change to 1/3 year did not affect the committee decision. The final two changes to increase flexibility oc curred just last year. One was to combine the math and basic science requirement. Instead of 1/2 year of each the requirement is now one year of both pro vided the math includes differential equations. That is an ABET requirement applicable to all engineering disciplines. But since chemical engineering has so much basic science the new requirement amounts to allow ing a decrease in mathematics. That provides a little flexibility, but not much. Most chemical engineering departments probably will not reduce their math re quirement. Finally, the latest change in requirements allows certain courses to qualify as advanced chemistry. The wording is: "If a course deals with changes in compo sition, structure and properties of matter at an ad vanced level then it may qualify as an advanced chemistry course r e gardl e ss of the d e part men t in wh ic h i t is ta u ght (emphasis added). Again, that i s a step in the right direction, but only a tiny one. What is needed is to replace the previously quoted and misleading sentence, "Instruction in this category ... ," by a statement that would explicitly allow a course to count toward the engineering science requirement even if taught outside of engineering. That would really help. E&A Committee guidelines might go something like this: "Instruction in engineerCHEMICAL ENGINEERING EDUCATION

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ing science will ordinarily be given by the faculty of an engineering department, but up to six semester credits of courses in other departments that extend basic science toward creative application may also count toward the engineering science requirement." Now let us look at the engineering science/en gineering design problem. Like the distinction be tween basic and engineering science, the distinction between engineering science and design is not always clear. In fact, the ABET definition of design is quite broad 1 ; some topics straddl e the line and whether pigeonholed in one slot or the other might depend on where or how they are taught or on the judgment or prejudice of the teacher. Moreover, a new topic has appeared, design science. Which pigeonhole will that fit in? At present, every engineering cou r se must be assigned x credits of engineering science and y credits of design. Then the credits for all courses are totaled and the hope is that it sums to 1. 0 year for engineering science and 0.5 for design. If it does not, then the figures are juggled a little, or cour s e substitutions are made, or a course is actually restructured until the count comes out exactly right, 1.00 and 0.50. Those minimum figures are seldom exceeded. The E&A Committee is concerned about this prob lem also. In fact, there has been some discussion and writing 2 about discarding the rigid requirement of a half a year of design and one year of engineering science and replacing it with one and a half years of both with certain restrictions, the principal one being a require ment for "a meaningful design experience." I think that appropriate wording could be found for such a change which would be a considerable help in obtaining the sort of flexibility in our curricula that will be re quired to meet the challenge of new technologies It is my understanding that this change is now under consideration by the committee. WH AT C AN BE DONE ? Quality control of chemical engineering education, accreditation, is in the hands of the profession itself. It is a voluntary, peer-review process involving both 1 The ABET definition of design has little to do with whether instruc tion is "practical or not. Rather, the essence of the definition is that instruction include design problems that are open-ended and require innovative and creative intellectual activity to arrive at one of many possible solutions. Consideration of competing constraints such as economics, safety, reliability aesthetics, ethics, and environ mental impact are inevitably and explicitly required. Memorandum from John W Prados, Chairman, E&A Committee, to Chemical Engineering Department Chairmen, 26 November 1986 WINTER 1989 academic and industrial engineers who must develop criteria that do not stifle innovation, yet provide reasonable assurance of competent graduates. If we do not do the job well, the government will do it for us, and that threat ought to provoke at least some readers to make their views known to the E&A Com mittee. The members of the ABET and of the E&A Com mittee represent all of us. Many of their members, however, apparently think that accreditation require ments are already flexible enough. ABET Curriculum Policy #8 is: To avoid rigid stan d ards as a basis for accreditation in order to prevent st an da r dization or ossification of e n gi n eering education, a nd to e n courage wellp lanne d ex p eri m entation. The E&A Committee has a similar statement. The job for those ofus in the trenches is to convince ABET and the E&A Committee that in order to abide faith fully by this policy statement, they must further liberalize the curriculum requirements. The wheels of ABET and the E&A Committee grind so slowly that any changes made might be both too little and too late. The profession will suffer as a result. Therefore, the effort should be made to influ ence them now. As experience has shown, letters from half a dozen chairmen have little effect. We need much more support than that. What we must do is to express our concerns vocally, in writing, and often to members of the Committee and to the AIChE Council itself. Letters can be addressed to committee members at their addresses or to them through AIChE at 345 East 47 Street, New York, 10017. The 1988-1989 members of the AIChE E&A Com mittee are John W. Prados (Chairman), Robert R. Furgason (Vice Chairman), L. Bryce Andersen (Past Chairman), Dan Luss (Council Liaison), Harold I. Ab ramson (Staff Liaison), Donald K. Anderson*, Edward L. Cussler, John L. Hudson Gilbert V McGurl, Stan ley I. Proctor, Herman Bieber, Charles A. Eckert, Larry A. Kaye, Francis S. Manning, T. W. Fraser Russell, Warrren D. Seider, David T. Camp*, Robert A. Greenkorn*, James G. Knudsen, William H. Man ogue*, Richard C. Seagrave. A CKNOWLEDGMENT The author acknowledges with thanks helpful dis cussion and correspondence with Prof. John W. Prados. D AIChE representative on the ABET E&A Commission 15

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[iJ n I classroom CHEATING AMONG E NGINEER I NG STUDENTS Reason s for Concer n WILLIAM R. TODD-MANCILLAS California State University, Chico Chico, CA 95929-0502 and EDWIN A. SISSON Goodyear Tire and Rubber Co. Akron, OH I N RECENT DECADES, our society has become in creasingly dependent upon engineers. As it be comes more technologically complex, engineers will be called upon to make decisions of ever greater im portance to society. Recent events, however, cast serious doubt upon the capaoility of some engineers to make appropriate ethical decisions in their work. There are several recent and catastrophic exam ples of unethical behavior among some engineers. In cluded among these is the decision of Ford Motor Company to market the Pinto automobile, even though testimony indicates that at least one high ranking engineer considered the design unsafe [1]. Another example concerns the B. F. Goodrich conWillia m R Todd Mancilla s received his PhD in lnterpersonol ond Instructional Communication from Florida State University He has con ducted interpersonal and instructional research at Rutgers and Pace Universities, the University of Nebraska Lincoln, and at Chico State University. (L) Edw i n Si s son attended the University of Nebraska Lincoln, and has B S degrees in chemical engineering and communication He i s currently enrolled in Case Western Reserve University s MBA program and is employed by the Goodyear Tire and Rubber Company He has held jobs in production, development and marketing (R) 16 tract to develop a 4-rotor brake. When tested, the brake failed to meet specifications, but regardless of the contradictory test data, the engineers involved were instructed to draft a positive qualification re port. In order to do this, the engineers had to use falsified data. One of them consulted an attorney and was advised to inform the FBI, eventually exposing the fraud, but only after-not before-his complicity in the fraud. A third example of unethical behavior concerns the 1974 Paris crash of a DC-10 airplane. One engineer thought that the cargo door and passenger supports should be redesigned, yet his supervisor decided against modifications for fear that their firm would have to pay for the redesign costs. Although they now know that should have been the proper course of ac tion, they both admitted that at the time it posed "an interesting legal and moral problem." Apparently not interesting enough. Of course, only a small percentage of engineers engage in such behavior, and even those who do are seldom responsible for consequences as serious as those described above. Nonetheless only a few such occurrences are enough to make us consider how to better he l p engineers avoid such situations To begin with, one might examine the extent and quality of ethics instruction received by most en gineering students. Two observations are pertinent. First, one notes that there are few, if any, courses in engineering ethics offered in most engineering pro grams. Second, and perhaps more problematic, is the inadequate action taken by most engineering faculty and departments to prevent or respond to academic dishonesty. Academic dishonesty is a serious problem: if students learn to c h eat with impunity in the class room, they might continue to cheat when gainfully employed. Inasmuch as cheating appears to be pervasive, on the increase, and perceived by many studer.ts ai:; legitimate, there is need to be concerned about its impact. One study, conducted by the Arizona State University College of Engineering and Applied Sci ences, found that 56% of 364 students polled had <0 Copyrig ht ChE Divi,,ion ASEE 19 88 CHEMICAL ENGINEERING EDUCATION

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Despite the serious nature of the possible consequences of academic dishonesty, too few instructors implement measures for prevention, controlling, or detecting the problem. Reasons for this may be a lack of departmental or university support in prosecuting offenders, an attitude that teachers ought not act as police officers ... cheated [5]. Sisson and Todd-Mancillas found that 56% of the entire graduating class of engineers (287) had in one way or another cheated [6]. Instructor complacency, pressure to win, and stu dent ignorance appear to be the main reasons why cheating is widespre~d and increasing. Also, some re search has been done which helps us to better under stand how cheaters justify their behavior [8]. Dienstbier's findings lead him to conclude that stu dents are most likely to cheat when they feel sub jected to intense and seemingly unjustified pressure. He further concludes that eventually cheaters learn to perceive their academic dishonesty not as morally unjustified or even as questionable, but rather as a necessary and rational way of coping with the pres sure to get good grades. Having developed a perspec tive justifying and promoting academic dishonesty, it is probable that the cheater goes on to apply this self-serving perspective to a variety of other cir cumstances, which, like stressful academic environ ments, pose no assurance of success yet great pres sure to succeed. Thus, upon graduation and finding oneself in the midst of a highly competitive work environment, an engineer (one who formerly developed the ability to rationalize academically dishonest behaviors) may cheat on the job as well. This cheating may be man ifested in defrauding documents, such as those forged by B. F. Goodrich engineers discussed earlier. Just as students cheat in school as a means of coping with academic pressure, these engineers cheated as a means of coping with the professional demands of the marketplace. Regretfully, these engineers will now have to suffer the long-term psychic and financial cost of their involvement in the fraud. There is, then, reason to be concerned about the long-range conse quences of cheating on cheaters themselve s But what of the consequences to other students? The non-cheat ing student suffers at least as much as the cheating student does. Statistically, even a small percentage of cheating students will create distorted grades, putting an honest student at severe disadvantage. Further more, this distortion is exacerbated in engineering courses where partial credit and curving are common grading practices. For instance by merely glancing at another's paper a dishonest student ma y learn how to set up a problem. Later, that student may claim, "At least I set up the problem correctly, and that WINTER 1989 should be worth at least 60 percent." While dishonesty in the classroom puts honest stu dents at a disadvantage at least insofar as achieving high grades is concerned, two other consequences are even more serious. First, dishonest students obtain an unfair advantage when seeking employment, as employers prefer to hire applicants with better academic records. Second, the dishonest student has an unfair advantage when applying for scholarships and admission to graduate school. Presume, for instance, that a company hires an engineering graduate of University X who had dishon estly obtained a high G.P.A. Subsequently, the com pany discovers that the engineer's job performance is far below what had been anticipated, given the en gineer s impressive undergraduate record. In the fu ture, that company may be less likely to rely on the academic records of other students graduating from University X, or perhaps the company s experience with this particular engineer will be so disappointing that they will recruit from other universities in the future. A similar predicament may occur when a stu dent is admitted to graduate school on the basis of a dishonestly obtained (inflated) G.P.A. Conceivably, the student might be unable to perform at the level of competence expected of him, resulting in failure to complete the program. Disappointment in this stu dent s performance may cause this graduate program to excercise greater caution when selecting future ap plicants from University X. This would be unfair to future applicant s whose competencies may be very real but whose grade point averages are lower than the one obtained dishonestly by the previously admit ted student. Despite the serious nature of the possible conse quences of academic dishonesty, too few instructors implement measure s for prevention, controlling, or detecting the problem. Reasons for this may be a lack of departmental or university support in prosecuting offenders, an attitude that teachers ought not act as police officers, a disregard for either the high fre quency of cheating or its serious shortand long-term consequences, or simple ignorance of how to prevent and control cheating in engineering courses. Some of the reason s listed above seem to account for inaction, and it was for this reason that a detailed consideration of the consequences of cheating has been presented in C o n t inue d o n '{JQ, g e 56 17

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til Na classroom A COURSE TO EXAMINE CONTEMPORARY THERMODYNAMICS WILLIAM E. LEE III University of South Florida Tampa, FL 33620 O UR VISION OF nature is undergoing a radical change toward the multiple, the temporal, and the complex." These are the opening words of the pre face to Order Out of Chaos by Ilya Prigogine and Isabelle Stengers [1]. Many instructors of engineering thermodynamics would probably agree that there is little evidence of anything "radical" going on in re gards to the content of the typical undergraduate courses in thermodynamics. Engineers are taught basic thermodynamic principles with which they can eventually enter the world of industry and enjoy meaningful technical careers. These principles as preWill i am E Lee Ill is currently an Assistant Professor of Chemical Engineering at the University of South Florida. General research in terests involve the application of chemical engineering science, particu larly contemporary thermodynamics, to problems in the biological and medical sciences. Current projects involve cancer research chranabial ogy, sensory perception, and biological aging. He also has an active interest in the philosophy of thermodynamic~ and complex systems. *This is based on a presentation made at the American Institute of Chemical Engineers 1987 Annual Meeting, Nov. 15-17, in New York City (Paper no. 146b). ----------C opyright C hE D ivisi on ASEE 19 8 9 18 sented in the various textbooks on the subject have undergone little change in the recent past. This in itself is not necessarily bad, for many have recognized that this thermodynamic "toolkit" with which we are equipping our students (or, as H. G. Jones calls them, "thermodynamic plumbers" [2]) is really a powerful collection of ideas and methodologies. Keeping within the narrow confines of chemical or mechanical en gineering, students often fail to realize just how pow erful their thermodynamic "toolkits" can be. For example, anyone who is aware of recent developments I. TABLE 1 Course Outline An introduction to philosophy of science A. Logic, reasoning processes, and logical fallacies B. Scientific method Inductivism Falsification Other methods c. Theories, hypotheses, etc. II. Entropy and its many forms . . A. The second law and its histoncal and sC1enhf1c basis B. Forms of entropy "Steam engine" entropy Statistical entropy Informational (Shannon) entropy Others (e.g., "negentropy") C. Irreversibility and its implications III. Contemporary thermodynamic concepts and related topics A. Time and time's arrows B. "Brussels school" concepts and theories C. Bifurcation and catastrophe theory D. Cybernetics, synergctics, systems theory, and related theories E. Fractals F. Non-Western viewpoints IV. Thermodynamic analysis in other disciplines A. Biology First law: Does it apply? Second law: Docs it apply? B. Psychology, social sciences, etc. CHEMICAL ENGINEERING EDUCATION

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... there have been many exciting developments in such diverse fields as psychiatry, biology, and social science. Thermodynamicists are providing new insights into these fields--fields which many scientists previously thought were not amenable to thermodynamic "intrusions." in the application of thermodynamic concepts knows that there have been many exciting developments in such diverse fields as psychiatry, biology and social science. Thermodynamicists are providing new in sights into these fields-fields which many scientists previously thought were not amenable to ther modynamic "intrusions." Most engineering students are unaware of this. They think thermodynamics is something confined to heat engines and not much more. Even when the discussion is confined to more tech nical matters of physical science, students are often unaware of the recent advances in thermodynamics. Most of them leave with their Bachelor of Science de grees, never having heard of such things as dissipa tive structures" and having received only limited ex posure to the general field of irreversible ther modynamics. "Catastrophies may be associated more with test performance rather than with a powerful analytical tool. In many ways, their knowledge of thermodynamics may be more reflective of the closed system close-to-equilibrium mentality of the past. Finally, their understanding of very basic concepts such as entropy and the second law is often poor As one person lamented, One of the most highly de veloped skills in contemporary Western civilization i s dissection: the split-up of problems into their smallest possible components . we often forget to put the pieces back together again" (A. Toffler in [l]). Indeed, many professors have noted that engineering students probably work harder than other students, but may not possess sufficient critical analytical skills or ph i losophical abilities This is not all that surprising, given the pragmatic or empirical nature of engineer ing "science." We teach students how to work prob lems, often resorting to "black box strategies, but rarely do they get to sit back and just "think," particu larly in a more qualitative philosophical sense. With these things in mind we developed a course which would give students a chance to critically think about and otherwise analyze the contents of their thermodynamic "toolkits." In addition, the students would be exposed to recent developments in ther modynamics and related topics, including attempted applications to fields other than the physical sciences. Finally, students were exposed to the general field of philosophy of science in an attempt to stimulate further development of their critical skills. WINTER 1989 COURSE OBJECTIVES AND OUTLINE The course was organized to achieve four broad objectives: To critically discuss and analyze fundamental ther modynamic concepts such as entropy To expose the student to contemporary thermodynamic concepts such as those put forth by the "Brussels group" and to related topics such as bifurcation theory To critically discuss attempted applications of the above objectives to other fields, particularly to the life sciences To introduce the student to the field of philosophy of sci ence, including logic and scientific method. Table 1 presents the course outline. The course was run in a seminar fashion to encourage student discussions. During the first offering of the course the books presented in Table 2 were utilized, and TABLE 2 Books Utilized in the Course R e quir e d T e xts Tim e 's Arrows, by R. Morris: Simon & Schuster, New York, 1985 Ord e r Out of Chaos, by I. Prigogine, I. Stengers; Bantam Books Toronto, 1984 The Syst e ms Vi e w of the World, by E. Laszlo; George Braziller Inc., New York, 1972 An Introduction to Catastrophe Theory, by P T. Saunders; Cambridge University Press, New York 1980 Ref ere n ce d T e xts (T ex ts which wer e r e ferr e d to repeatedly durin g the cour se .) The Tao of Physics, by F Capra; Shambhala, Berkeley, 1975 Entropy by J D. Fast; Gordon & Breach, New York, 1968 A g ainst Method, by P. Feyerabend; Thetford Press Limited, Thetford, 1978 The Structure of Scientific Revolutions, by T S Kuhn; University of Chicago Press, Chicago, 1970 Conj e ctures and R e futations : The Growth of Scientific Kno w ledge, by K. R. Popper; Harper & Row Publishers, Inc., New York, 1965 Entropy : A New World View by J Rifkin; Viking Press, New York, 1980 The Tragicomical History of Thermodynamics 1822-1854, by C. Turesdell; Springer-Verlag, New York, 1980 Catastrophe Theory, by A. Woodcock, M. Davis; E P. Dutton, New York, 1978 19

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numerous journal articles were discussed. A list of the more useful journal articles is presented in Table 3 While the course was basically run by myself, I found that the presentation of scientific method by an actual philosopher of science to be particularly effec tive. The typical assignment was to read the assigned materials and be prepared to discuss them but there were also several assignments which required some library work. For example, students were instructed to find specific examples of the application of catas trophe theory and present them to the class. Overall grading was based on a consideration of in-class par ticipation (reflecting preparation), the written assign ments, and performance on a comprehensive final exam. DISCUSSION On the first day, I gave a simple quiz that consisted of two parts: 1) define the words entropy, time, order, and stability; 2) define hypothesis, law, and theory, and outline how you would prove a given hypothesis. The answers to the first part were rather poor. In fact, blanks appeared with an alarming frequency. An swers to the second part were typically inductive in nature--"go run experiments." Following the quiz, students readily admitted their personal embarrass ment over their performances. But while a few egos may have been bruised, students for the most part had a clearer understanding of the importance of the class objectives. A point had been made. Further in-class discussion on the nature of en tropy revealed the usual associations with order and chaos. Others have written on this superficial under standing as expressed by "naive" students (for exam ple, see [3]). All students challenged the idea that movement further and further away from equilibrium could possibly lead to the creation of stable structures. Again, it was clear that the students' basic under stand ing of the thermodynamic fundamentals was nar row and shallow. The typical class consisted of some initial lecturing, usually outlining the basic ideas associated with the assigned readings and sometimes presenting historical perspectives. Most of the class time was devoted to free-style discussions. A key to this sort of format is to maintain several opinions for a while and not to converge on a "right" answer (if there even is one) too quickly. In fact, sometimes there may be several ten able explanations (for example, what is time?) and the students are left to make up their own minds. I found it was a good strategy to present the 20 TABLE 3 Selected Journal Articles Utilized in the Course "Equilibrium, Entropy, and Homeostasis: A Multidisciplinary Legacy," by K. D. Baily; Systems Res. 1, 1984; 25-43 "The Theory of Open Systems in Physics and Biology," by L. von Bertalanffy; Science, III, 1950; 23-29 "Life, Thermodynamics, and Cybernetics," by L. Brillouin; Am. Scientist, 37, 1949; 554-568 "Entropy and Disorder," by J.M. Burgers; Brit. J. Phil. Sci., 5, 1954; 70-71 "The Interdisciplinary Study of Time," by J. T. Fraser;Ann. NY Acad. Sci., 138 (art. 2), 1967; 822-847 "Entropic Models in Biology: 1l1e Next Scientific Revolution?" by D. P. Jones; Persp Biol. Med., 20, 1977; 285-299 "Order and Irreversibility," by P Kroes; Nature and System, 4, 1982; 115-129 "Gibbs vs. Shannon Entropies," by R. L. Liboff; J. Stat. Phys., 11, 1974; 343-357 "Maxwell Demon and the Correspondence Between Information and Entropy," by R P. Poplavskii; Sov. Phys. Usp., 22, 1979; 371-380 "Time's Arrow and Entropy," by K. Popper; Nature,207, 1965; 233-234 "Can Thermodynamics Explain Biological Order?" by I Prigogine; Impact Sci. Soc., 23, 1973; 151-179 "Should Irreversible Thermodynamics be Applied to Metabolic Systems?" discussion forum; Trends Biochem. Sci., 7, 1982; 275-279 "Entropy, Not Ncgentropy," by J. A. Wilson; Nature, 219, 1968; 535-536 philosophy of science topics first. It provided a framework for later critical discussions. Q~estions s uch as, "Is it a testable hypothesis?" or, ''What logical fallacy is being committed?" could be posed more intel ligently. The main scientific method lecture was pre sented by a philosopher of science. This proved to be a good move since it gave the students a chance to see that philosophers might actually have something of value to offer engineering students. Also, students found the discussion on various scientific methods (e.g., inductivism, falsification, etc.) to be very st imulating. I also tried to present conflicting views whenever appropriate. The article "Gibbs vs. Shannon En tropies" (see Table 3) is an example of this. The forum style article "Should Irreversible Thermodynamics be Applied to Metabolic Systems?" (see Table 3) is another example. In general, a fair presentation of the strong points and the weak points of a given view point should always be made. The books Time's Arrows and Order Out of Chaos were excellent choices. I currently plan to use the book What is This Thing Called Science [4] as the third principle text the next time the course is offered. It is a good overview of recent topics in scientific method. However, there are probably other available CHEMICAL ENGINEERING EDUCATION

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books that could also serve this purpose. The remain ing topics in Table 1 can be handled with lecture notes and relevant journal articles. I judged this course to be effective based on sev eral observations. First the same quiz previously given on the first day was also given near the end of the class, and needless to say, the answers were much more satisfactory. In fact, students felt they did not have enough time to respond completely. Second the students themselves seemed to feel more confident of their understanding of ther m odynamics While there may have been periods of c o nfu s ion (probably a good sign) during the semester students generally emerged on a firmer basis. Finally, several students stated that they planned to continue their self-educa tion in the topics they were exposed to during the course. ACKNOWLEDGEMENTS The author wishe s t o thank the D e partment of Chemical Engineering for supporting the develop ment and offering of this course. Professor J. A. Bell of the Department of Philosophy was also extremely supportive. REFERENCES 1. P rig o gine, I. and I Stengers, O rde r Ou t of Cha os, B an tam B oo k s, T o ro nto, 1 984 2 Jo n es, H G., Th e r mo d ynamics: A Pr a ct i cal Su b j e c t," Ph ys E duc 19 ( 1 ) 15-1 8, 19 84 3 John st on e, A. H ., J J MacDon a ld, and G. W e bb, M is c onception s in S c ho o l Th e r m odyn a mic s, Ph ys. E duc 12 (4), 248 -2 5 1 1 97 7 4. C h a lm e r s, A F. Wh a t I s Th is Th ing Call e d S cie n ce?, U ni v ers i ty of Qu ee n s l a nd Pr es s, St. Lu c i a, Que e n s l a nd 1 98 60 DISCUSSION: The reviewers of this paper presented some interesting comments of their own. We feel their views deserve consideration and present them here for our reaclers' infonnation Review #1: Although I have serious reservations about the course described by Lee, I am not inclined to recommend rejection of his manuscript. Thus while I may deplore his poor taste ( . applications of thermodynamics to problems in psychiatry and social science? Why not throw in psychohistory and social Darwinism as well? and .. [exposure to] philosophy of science in an attempt to stim ulate .. critical skills. He apparently has had much better experiences with philosophers of science than I), he has taught the course and so does have something to report If there is a single "fault" to the plan, it is Lee's strategy of bolstering students admittedly inadequate understanding of a well-defined subject (thermodyna mics) by exposing them to ideas about other topics namely, the philosophy of science (a discipline that is itself disdained by many knowledgeable scientists and scientific historians for whom I have great respect), Prigogine's dissipative structures stuff, and the pseudo scientific applications of thermodynamic terminology to psychiatry and social science. That last one really gets me. These are interesting items, perfectly suitable for dinner table conversation, but unlikely to advance the understanding of thermodynamics. Still, I doubt that it can hurt ... and it is comforting to see that the simple quiz" ... doesn't include the Mumbo Jumbo. If the course enhances the students' understanding of these terms and concepts, then it probably is worthwhile. I would opt for more attention to these and less for the topics about which I c..lready have vented my spleen. Finally, a course that attempts to cover so many complex topics surely must be superficial: how do students discuss whether WINTER 1989 irrever s ibl e th e rmodynam i cs should b e appl ie d to m e tabolic s ys t e ms .. w i th o ut a th o r o u g h grounding in irrev e rsible thermod y nam ic s ? In summar y, I recomm e nd that the manuscript be published so that others can judge for themselves whether this or a related course should be included in their own curricula Review #2: John S. Dahler University ofMinncsota Minneapolis, MN 5.5455 I agree with the author that man y undergraduates do not develop a good understanding of thermodynam ics especially of the Second Law. There are several rea sons for this including hasty e x posure and emphasis on routine and mechanized problem solving, overloading with other courses, etc. The cure, in my opinion, is em phasis on critical understanding, more interesting prob lems and more substantial injection of statistical thermodynamics As for irreversible thermodynamics of the Prigogine fame, this reviewer believes that the subject is practically useless to chemical engineering. The only contribution that irreversibl e thermodynamics has made to our disci pline stems from the Onsager relations which provide a framework for constitutive transport relations. Ap plications to social sciences or medicine are best tackled by more experienced workers and not by the un dergraduates who struggle with basic physics and chemistry. G. R. Gavalas California Institute of Technology Pasadena, CA 91125 21

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(9j ft I curriculum DESIGN EDUCATION IN CHEMICAL ENGINEERING PART 1 : Der i v ing C once p tu al Design T oo ls J. M DOUGLAS and R. L. KIRKWOOD* University of Massachusetts Amherst, MA 01003 M OST OF THE CHEMICAL engineering curriculum is focused on the analysis of either engineering science problems or single unit operations. That is, very well-defined physical systems that normally in volve chemical (or biological) reactions and/or separa tions, are investigated in considerable detail. Students usually do not encounter any synthesis problems until their senior year design course, where one of the goals is to integrate the complete curriculum by demon strating how the individual process units fit togther into a large system, i.e., a chemical process. However, because of time constraints, usually only a narrow range of design problems is considered. The purpose of this paper is to describe the spec trum of process design problems and to suggest a methodology for teaching the important concepts used in design. The topics that will be considered are: the types of processes considered and their designs, some new tools that are useful in conceptual design, and a strategy for developing conceptual designs. CLASSIFICATION OF PROCESSE S W e can classify processes in a variety of ways, inc ludin g t h e type of operation, what they produce, and t h e types of products they make. There are two main types of operations: continuous and batch. Con tinuous processes are designed to operate twenty-four hours a day, seven days a week, for 300 to 350 days a year, and hopefully, nothing changes with time. In contrast, batch plants contain units that are deliber ate l y started and stopped according to some schedule. They may operate twenty-four hours a day, or they m i g h t b e designed to operate for only a single shift. *Current Address: E. I. Du Pont de Nemours & Company, Polymer Products Department, Experimental Station, E262/314, Wil Batch plants are more flexible, but they are usually less efficient than continuous processes. In general, continuous processes are associated with large pro duction capacities, whereas batch plants are as sociated with specialty chemicals. Another way of classifying processes depends on the number of products they produce. Some plants produce only a single product stream, whereas others might produce several products simultaneously. Still others might produce different products in the same equipment, but at different times of the year. We can further define a process based on the characteristics of the product. Sometimes we may wish to produce pure chemical compounds (pet rochemical processes), while at other times the final product is a mixture (there are hundreds of comJ. M Do ug l a s is a professor of chemical engineering at the Univer sity of Massachusetts, Amherst He received his BS in chemical en gineering from John Hopkins UnivPrsity and his PhD from the Univer sity of Delaware He worked at ARCO and taught at the University of Rochester before joining the faculty at the University of Massachusetts His research interests include conceptual design, control system synthe s i s, and reaction engineering (L) R ob ert Kirkw oo d, a research engineer in the Polymer Products De partment of E. I. du Pont de Nemours & Co has been involved with process design and synthesis since 1982 He received his BS degree in chemical engineering from Lehigh University in 1982 and his PhD mington, Delaware 19898 ______ f_ro_m_th_e_U_niversity of Massachusetts in 1987 (R) :> Copyright ChE Division ASEE 19 8 9 22 CHEMICAL ENGINEERING EDUCATION

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Exper i ence i ndicates that l ess tha n 1 % of t h e i deas fo r new designs ever becomes commercialized I n order to avoid ex pensive failures i t i s common practice for process engineers t o develop a heirarchy of design s where the accuracy of t he design calculations and t he amount of detail conside r ed i ncrease s as t he next l eve l i n the he i rarch y is considered pounds in gasoline or furnace oil streams). In still other instances we produce materials that are de scribed by distribution functions (solid products are usually characterized by a particle size distribution and polymer products are normally characterized as a function of their molecular weight distribution. Since such a wide variety o f processes exists, it is not surprising that different design techniques and criteria are applicable. Moreover it should be appar ent that there is not enough time in an under graduate's program to discuss all of these types of problems. Thus, it has been common practice to have undergraduates consider the design of only one type process (usually a petrochemical process that pro duces a single, pure product) in the design course. A G ENERA L S TRA T EGY FOR APPROACHING DESIGN PROBLE MS Experience indicates that less than 1 % of the ideas for new designs ever becomes commercialized. In order to avoid expensive failures, it is common practice for process engineers to develop a hierarchy of designs where the accuracy of the design calculations and the amount of detail considered increases as the next level in the hierarchy is considered (see Table 1, from [2]). The design course in chemical engineering looks at Level 2 for a single process. That is the students are given a flowsheet, i.e., a description of the process units and the interconnections between these units. They calculate the process material and energy bal ances, the required equipment sizes, the utility flows the capital and operating costs, and the process prof itability. The design calculation routines used are fairly rigorous so that obtaining a solution normally requires extensive iteration, which often becomes quite tedious. Most design research has focused on Levels 2 and 3 in the hierarchy. The emphasis has been on the de velopment of improved algorithms for the rigorous de sign of a variety of types of equipment or complete flowsheets. Similarly improved optimization proce dures for various types of problems have received con siderable attention. Level 1 in the hierarchy of Table 1, also known as the conceptual design phase, is usually undertaken by experienced engineers. They use numerous heuristics and back-of-the-envelope calculations to develop the WINTER 1989 T AB LE 1 Ty pes o f Des ign s 1. Order of magnitude estimate (Error about 40 % ) 2. Factored estimate (Error about 25 % ) 3. Budget authorization estimate (Error about 12%) 4. Project control estimate (Error about 6 % ) 5. Contractor's estimate (Error about 3 % ) first design, i. e ., the base-case design, and then to screen the process alternatives. In some companies an engineer is sent to a chemist's laboratory as soon as the chemist has discovered a new reaction or a new catalyst, and the engineer is expected to complete a base-case design within a period of two days to one week. The results of this design study are then used to help guide the development of the project. TEACHING CONCEPTUAL DESIGN Conceptual design is a creative activity where the goal is to find the best flowsheet from a large number of process alternatives. If one were to blindly consider all of the possible alternatives, it would be necessary to consider something like 104 to 10 9 flowsheets. Ac cording to Westerberg [ 4], each flowsheet is described by about 10,000 to 20,000 equations, and there are usually ten to twenty optimization variables as sociated with each alternative. It is necessary to com pare these alternatives at close to the optimum design conditions in order to determine the best flowsheet. Typical of design problems in other disciplines, chem ical process design problems are characterized by the combinatorially explosive nature of the possible solu tions. The question then arises as to whether it is possi ble to teach undergraduates how to complete a first design in a two-day to one week period, and how to determine the best flowsheet in another two day to one-week time frame. This requirement implies that it will be necessary to teach them how to derive back of-the-envelope calculation procedures and how to de rive heuristics since these are the tools used by ex perienced engineers. It will also be necessary to teach the undergraduates a systems approach to synthesis which emphasizes the interactions that may occur when we put a complete process together. A discus sion of some new tools of this type follows. 23

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DERIVING BACK OF-THE -E NVELOP E DESIGN MODEL S Chemical engineers are used to having a hierarchy of models, with increasing orders of complexity and accuracy available for solving various problems. For example, the Na vier-Stokes equations used in fluid mechanics are sufficiently complex that it is necessary to use order-of-magnitude (or scaling) arguments to simplify them in order to obtain an answer. It is sur prising that no one seems to have attempted to use this same approach to simplify models in other prob lem areas, such as equipment or process design. One cimld use order-of-magnitude arguments to derive a back-of-the-envelope model for an isothermal, plate-type gas absorber used to recover solutes from a dilute feed stream. For this special class of absorber problems there is an analytical solution, called the Kremser equation [1], which most undergraduates have studied. N + 1= {[ L ][yin -mX ] } Zn ~-1 you t -mX: + 1 zn[;GJ (1) We would like to develop a short-form of this equation to further simplify our analysis. Since we do not need great accuracy for conceptual design (see Level 1 in Table 1) our criterion will be to drop any term that does not affect the answer by more than 10 %. We first note that most gas absorbers encountered in practice contain 10 to 20 trays, and therefore we are interested in obtaining accurate solutions when N is of the order of 10 to 20. When we examine Eq. (1) we see that order-of-magnitude arguments yield N + l=N (2) For gas absorbers with pure solvent streams X lil 0. From other arguments it can be shown that L/ mG = 1.4, approximately, and that YinlYou t = 100, or so. When we compare the orders-of-magnitude of the terms in the numerator on the right-hand-side of Eq. (1), we see that Since L/mG = 1.4, we could replace the de nominator in Eq. (1) by its Taylor series expansion and write, approximately (4) 24 Our result becomes, after replacing ln by log 2.3log[:G 1][ :: ] N = ______ ..::;__~ 0.4 (5) If we are willing to sacrifice accuracy for simplicity the final form is Y N+ 2=6log~ yrut (6) and we have achieved our goal of developing a back-of the-envelope model. Of course, it is essential to check our simple model against the more rigorous expression. For the case of 99% recoveries, where Y in/Y o u t = 100 Eq. (6 ) pre dicts 10 trays versus the rigorous value of 10.1, and for 99.9 % recoveries where Yin/You t = 1000, Eq. (6) gives N = 16 versus the correct value of 16.6. We have used this same procedure to develop short-cut models for process material and energy balances, a variety of equipment design procedures cost expres sions etc. DERIV I NG E RROR BOUNDS FOR DESIGN MODEL S The simple models used to describe process units or other physical relationships normally have specific limitations ( i .e., the Kremser equation is valid for isothermal, dilute systems and the ideal gas law is valid only for low molecular weight non-polar mate rials at low pressure). Of course, students need to know when they can use these simplified models and it is easy to quantify when these approximations are valid simply by applying Taylor series expansions. For example, in order to assess the validity of the assumption of dilute, isothermal operation in a plate type gas absorber, we can use Taylor series expan sions around the condition of infinite dilution, along with some back-of-the-envelope approximations (i.e., that high recoveries are equivalent to complete recov ery) to show that the value of the distribution coeffi cient will change by less than 10 % if yin [ 1 + J 2( A21 2Al2) + 2 ]] < 0.1 (7) l RCPT L Thus, the dilute, isothermal assumption depends on the heat of vaporization of the solvent, as well as the inlet solute composition. We can develop a similar expression for how this assumption affects the number of plates required in the absorber by considering how CHEMICAL ENGINEERING EDUCATION

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changes in m affect N in Eq. (1). This approach is simple to teach, and it provides a way of making deci sions that can be used instead of experience. DERIVING DESIGN HEUR I S TICS Design heuristics were originally proposed by ex perienced engineers who solved similar problems many times, and then noticed common features of the solution. At the present time however they are being developed by graduate students who solve hundreds of case studies on a computer and then attempt to generalize the results (see Tedder and Rudd [3]). The fact that heuristics exist implies that their solutions must be insensitive to almost all of the design and cost parameters. Therefore, by eliminating these insensi tive terms using order-of-magnitude arguments, it should be possible to derive heuristics. As an example of a derivation of a heuristic we again look at the design of the simple gas absorber problem that we considered above. The number of trays selected for the gas absorber depends on an economic trade-off, i. e ., as we increase the number of trays we increase the cost of the absorber but we decrease the amount (and therefore the value) of the material that is not recovered. If we express the cap ital cost of the absorber on an annualized basis and assume that the total cost depends only on the number of trays and the annual value of the lost solute we obtain Now if we substitute Eq. (6) for N and find the op timum value of Y 0utfYim we obtain Yout = (6)( CN) Yin (Cs )(G)(Yin )( 8150hr/yr) (9) and by substituting some reasonable values for the parameters, we find Yoot ( 6 )(850) 0 004 (10) = (15.4)(10)(8150) 1n The important feature of this result is not the ex pression for the optimum, but the insensitivity of the solution. We note that if we make a 100% change in any of the values in either the numerator or de nominator, the answer changes only from 0.002 to WINTER 1989 0.008, which corresponds to fractional recoveries in the range from 99.2% to 99.8 % This is the basis for the well known heuristic: It is desirable to recover more than 99% of all valuable materials. With this simple procedure we have been able to derive most of the current heuristics used in process design, and have also been able to discover new heuristics for other design problems. Again, since we derive our heuristics, the assumptions made in the derivations will help to indicate the limitations of their applicability. C ONCLU S ION S With the new techniques described above, the en gineer now has the tools available to quickly evaluate flowsheet alternatives. In Part II of this article [which will be published in the next issue of GEE] we will describe how these tools along with a hierarchical de composition procedure to generate flowsheet alterna tives, are used in a systems approach to conceptual design. N OMENCLATUR E Aij = Margules constants of the solute and solvent at infinite dilution m N = annualized absorber cost per plate, $/plate = heat capacity Btu/mol-F = value of solute, $/mol = carrier gas flowrate, mol/hr = heat of vaporization of solute, Btu/mol = solvent flowrate, mol/hr = slope of equilibrium line R TAC TL X = number of theoretical plates = ideal gas constant Btu/mol-F = total annualized cost, $/yr = solvent temperature, deg. F. = mole fraction of solute in liquid = mole fraction of solute in gas y REFE R ENCE S 1. Krems e r A ., Natl. P e trol. News, 22 (21), 42 (1930) 2. Pikulik, A. and H E. Diaz, Cost Estimating Major Process Equipment ," Chem. Eng., 84, (21), 106 (1977) 3 Tedd a r, William D. and Dale F Rudd Parametric Studi e s in Industrial Distillation: Part I. Design Comparisons," AIChE J., 24, (2), 303 (1978) 4. Westerberg, A. W "Optimization in Computer-Aided Design, Foundations of Computer Aided Chemical Proce s s D e sign R. S Mah and W. D. Seider (Eds), 1, 1949, Engineering Foundation (1981) 0 25

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Random Thoughts . NOBODY ASKED ME, BUT RICHARD M FELDER North Carolina State University Raleigh, NC 27695 It will probably come as a shock to those who know me, but I have some strong opinions about educational matters. Very strong. Violent and unswerving pre judices, some would say. And since I will regularly be using this forum to subject you to whatever 'is on my mind, I thought it would be only fair to run through these opinions for you. You may then feel free to dis miss things I say in future columns on the grounds of my admitted bias. (However, anything I say about a topic not on the list may be considered absolute truth.) Ready? Here goes, beginning with the most violent and unswerving prejudice of them all. I hate 7:50 classes. I don't like people knocking on my door when I'm doing something I really want to do. I welcome them joyfully however, when I'm doing something I really don 't want to do like grading papers or critiquing an incomprehen sible thesis draft. People who assume that all engineers are culturally ignorant, anti-environment, good at math and science but little else, boring, etc. are irritating. On the other hand, our increasingly specialized and elective-free en gineering curriculum almost seems designed to assure that those stereotypes are valid. I like summers that begin in early May and end in late August (u ntil it's late August). There is no excuse for undergraduate textbooks written for professors rather than students. I value the autonomy that comes with this job-being able to choose my research problems work late and sleep late, stay at home occasionally on days I don't teach. I can't think of another lawful profession that provides its practitioners with so much personal free dom. I don't like stress tensors. Copyright C hE Di visio n ASEE 1989 26 The classroom occurrence that may be most conducive to learning is spontaneous humor (I've been using some of the same spontaneous jokes for years.) I am bemused by students who walk into my office see me talking on the telephone with papers and open books scattered all over my desk and another student sitting across from me, and ask (all together now) ''Are you busy?" The term "real world" can be intensely annoying espe cially coming from people who think they live in it and I don 't Cheating is repugnant. Even more so is the system that hangs students' futures on the grades they get on timed tests. I like anything written by Octave Levenspiel. I hate walking down two flights of stairs to the depart ment office and then forgetting what I wanted there. ( This happens with increasing frequency-I don 't want to think about what that might mean. ) Our second-worst assumption as teachers is that if we don 't cover something in class the students won 't learn it. Our worst assumption is that if we do they will. I like word processing, spreadsheeting, computer graphics, etc., but I'm worried about how dependent I've become on the computer. At this point if it goes down I go right down with it. I don 't like anything about the PbD qualifiers-making them up grading them, and especially discussing them at faculty meetings. It is not pleasant to discover that I really don 't underRichard M Felder is a professor of ChE at N C. State, where he hos been since 1969. He received his BChE at City College of C.U.N.Y. and his PhD from Princeton He hos worked at the A.E R E., Harwell, and Brookhaven No tional Laboratory, and hos presented courses on chemical engineering principles, reactor design, process optimization, and radioisotope applications to various American and foreign industries and institutions. He is coauthor of the text Elementary Principles of Chemical Processes (Wiley, 1986) "' ,JI . 't / ~ CHEMICAL ENGINEERING EDUCATION

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stand something I've been teaching for years. One of our best fringe benefits is gett1ng to give semi nars in some of the world's most attractive places. (Get ting honoraria for them is not a bad deal either.) There is little value and much harm in tests on which the average is in the low 30's. I'm bothered by instruc tors who would never admit or even consider the possi bility that such tests may have been unfair or the stu dents may have been poorly taught. A university administrator who says he won 't do some thing can be upsetting. One who consistently says he will and then doesn't (or who is incapable of giving a straight answer) can be disastrous. I get terminally grumpy at badly delivered departmental seminars on subjects I'm not the least bit interested in. I like engineering professors with interests and talents outside of engineering. If I have a hero in our profes sion, it is Bob Bird. Few chores are as taxing as maintaining energy in a class that acts like a wax museum. One that is as taxing is serving on a university commit tee that has no real function and never accomplishes anything yet religiously meets every two weeks for at least two hours. I am filled wi,th admiration for Professor Vincent M. Foote of the N.C.S.U. School of Design[may his tribe increase], who chaired a committee I served on last year. Vince called meetings only when there was some thing to do started the meetings on time, had us do what was needed, and adjourned. The average dura tion of the meetings was about 2 0 minutes. It was a revolutionary experience. The most troublesome aspect of American engineering education is the way it penalizes outstanding teachers doing minimal research and rewards outstanding re searchers doing lousy teaching. The most puzzling aspect of American engineering edu cation is the notion that engineers with years ofindus trial experience but few research publications don't be long on engineering faculties. The hardest thing I have to do as a teacher is decide whether I should push the final grade of a borderline student up (providing encouragement and a challenge to live up to my high opinion) or down (maintaining high standards and providing an incentive to work harder next time). I envy professors who believe in their hearts that this is not a dilemmar--that one of these choices is the cor rect one for all students on all occasions. I think they'r e WINTER 1989 POSITIONS AVAILABLE Use CEE's reasonable Rates to advertise Minimum rate, 1 18 page $80; each additional column inch $25 VIRGINIA POLYTECHNIC INSTITUTE AND STATE UNIVERSITY The Chemical Engineering Department at Virginia Tech is seeking applicants and nominations for the Alexander F. Giacco Presidential Professor in Chemical Engineering. Applicants for this endowed professorship should have a national/international reputation in an area of chemical engineering research. Duties include teaching at the undergraduate and graduate levels, conducting funded research, and departmental and university service. This appointment is at the Full Professor level at a salary commensurate with the endowed nature of the professorship and the applicant's qualifications. Virginia Tech has approximately 18,500 undergraduates (5,000 in the College of Engineering, including 150 in Chemical Engineering) and 4,180 graduate students (1,200 in the College of Engineering, including 50 in Chemical Engineering). Send nominations or applications to Chairman, Giacco Professorship Search Committee, Chemical Engineering Department, Virginia Polytechnic Institute & State University, 133 Randolph Hall Blacksburg, VA 24061. Deadline for applications is April 30, 1989. Virginia Tech hires only U S. citizens and lawfully authorized alien workers. Virginia Tech is an Affirmative Action/Equal Opportunity Employer. UNIVERSITY OF CINCINNATI Yisitio!l Re sea rch Professor Position in Chemical En gi neeri ng BS degree in Chemical Engineering is required. MS or PhD in Chemical Engineering preferred. Industrial experience, preferably in chemical plant design and operation, expected. Job function would be to develop and teach ChE junior and senior labs, assist in the development of design projects, and interact with undergraduate students. Candidates should have a strong commitment to excellence in undergraduate education. Base salary range $25,000 to $30,000. Non-tenure track position Send resume, references to: Dr. Rakesh Govind, Chairman Search Committee, Mail Location 171, University of Cincinnati, Cincinnati, Ohio 45221. Affirmative Action/Equal Opportunity Employer. dead wrong, but their lives are a lot easier than mine at least twi,ce a year. I like teaching and writing. I love having a job that pays me to do both. Help me out-what else should be on the list? The best entry wins a free drink at the next Exxon Suite. D 27

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(eJ ij I curriculum AN ALTERNATE APPROACH TO THE UNDERGRADUATE THESIS P.R. AMYOTTE and M. FELS Technical University of Nova Scotia Halifax, Nova Scotia, Canada B3J 2X4 The chemical engineering department at the Tech nical University of Nova Scotia (TUNS) has recently undertaken an approach to the senior undergraduate thesis which is different from the more traditional route. In the 1986-87 academic year, most of the thesis projects involved the design, construction, and testing of a piece of equipment for the undergraduate labora tory. In previous years, each student had selected a topic which was based on a professor's area of expertise and research. Our method of organizing and handling the projects is described here, and the benefits and disadvantages of conducting undergraduate theses in this manner are discussed. We have concentrated more on the educa Paul Amyotte received h i s BEng from the Royol Military College of Canada and his MSc (Eng) from Queen's University. He is a graduate of the PhD program at the Technical University of Novo Scotia where he is on assistant professor in the chemical engineering deportment His interests ore the drying of cereal groins, gos and dust explosions, and engineering education {l) Mort Fels received his BEng from McGill University and his PhD from the University of Waterloo He hos been teaching chemical en gineering for sixteen years and is currently a professor in the chemical engineering deportment at the Technical Univ ersity of Novo Scotia His research interests ore biomedics (artificial kidney), energy conversion and computer aided design (R)
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follow. Deadlines were established for the items shown in Table 1. PROJECTS The twelve topics offered were categorized as shown in Table 2. The three research-type projects all have potential for use in the undergraduate laboratory. BENEFITS The most obvious benefit from this work has been the addition of new experiments and the subsequent deletion of outdated equipment. This has resulted in a general strengthening of the undergraduate lab, par ticularly in the unit operations area. For example, we have replaced a large plate heat exchanger with a smal ler, more versatile unit. We have also been able to increase the use of com puters in the lab primarily in the areas of Data acquisition (drying) Data acquisition and control (single and multi-variable con trol experiments) Data reduction (plate heat exchanger) There is no doubt that the work described here has held significant advantages for the department; but what about the students? Judging from their reaction to the work (and the quality of the finished products), they have also benefited from the experience. Student development was fostered by several factors: Familiarization with aspects of design and project management Knowledge of instrumentation Hands-on, practical experience Interaction with technicians, salesmen, etc. Sense of pride in the work; enhancement of class spirit Exposure to state-of-the-art equipment ( e.g., Laser Dop pler Velocimetry in the freeboard particle measurements) Apart from the technical aspects listed above, each student was required to give four oral presentations during the course of the year, as well as two written reports (Table 1). In all cases, a noticeable improve ment in communication skills occurred; with three stu dents the improvement was almost unbelievable. PROBLEMS An undertaking of this nature has its inevitable drawbacks. Although, overall, the experience was conWINTER 1989 The most obvious benefit from this work has been the addition of new experiments and the subsequent deletion of outdated equipment. This has resulted in a general strengthening of the undergraduate lab, particularly in the unit operations area. TABLE 2 Thesis Projects New Experiments for Undergraduate Lab 1. Air Conditioning 2 Drying 3. Ion Exchange 4. Wetted-Wall Gas Absorption 5. Fluidized Bed Heat Transfer 6. Plate Heat Exchanger 7. Single Variable Control (Temperature) 8 Multi-Variable Control (Temperature and Level) Upgrad e d Exp eri ment for Undergraduate Lab 9. Packed Column Gas Absorption Work on Research Proiects 10. R-Value Measurement of Building Materials 11. Particle Velocity Measurements in the Frecboard of a Cold Fluidized Bed 12 Computer Control of a Coal Processing Mini Plant sidered a success, several problems arose which are described below. Cost Laboratory equipment is expensive, especially if one wants to incorporate the latest advances in technol ogy. There is a big difference in measuring tempera ture with a thermometer and using thermocouples with associated AID conversion and computer data-logging. We chose in general, a middle ground, and installed primary transducers with digital read-outs which would allow eventual upgrading to computer data-log ging and control. Total costs for each project varied from about $500 to $3,000. However, the alternative of purchasing off the-shelf units (if possible) would have been many times more expensive. Some funds should be set aside to purchase those forgotten or emergency items which are always necessary at the end of the project or during initial testing. Time Time plays a major role in this type of thesis ap proach. The students, faculty and support staff de voted many hours to the work. Normally, three hours 29

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per week for twenty-six weeks is scheduled (78 hours). It is estimated that the total time that the students spent is closer to double this figure. However, the nature of these projects is such that much of the time must be spent at the end of the final term, which is, of course, when it is the most scarce. We were con cerned that the students would be unable to complete the projects in the available time. This is probably the largest risk in such a venture. A high degree of success was achieved, however, with most students meeting the objectives of the work and producing a piece of laboratory equipment which worked. Shortfalls in the program occurred in testing and preparing detailed laboratory procedures. In most cases, additional work is needed in these areas so that the experiments can be used routinely in the undergraduate laboratory. Scheduling The time for equipment which was slated for up grading and which was also part of a current laboratory course required careful scheduling. Fortunately, only one project (packed column gas absorption) fell into this category. We found that it was necessary to run all the laboratory course experiments on packed col umn gas absorption in one time block at the beginning of the first term. Once this was accomplished, the equipment was turned over to the thesis student and the upgrading proceeded without interruption. Type of Student The laboratory projects require that a student have a certain degree of mechanical know-how and dexter ity. Since technologist time is limited a major amount of actual construction is necessarily performed by the student. There were a few students who lacked basic skills in this area and who had no interest in learning them. T~e result of this situation was that the faculty member had to put in a fair amount of time doing the actual construction. Research Aspect One disadvantage of this type of project is that students wishing to pursue a post-graduate degree will not be exposed to some of the concepts or techniques of research. There is no doubt that development of skills in the areas of literature searches, experimental design and general research philosophy suffered. How ever, development of other skills relating to equipment construction, communications and general project management is also important in research. 30 SUGGESTIONS In contemplating this type of project, the following important points should be considered: Only do as many projects for which there is adequate fund ing. The larger projects would probably be more successful with two students working together instead of only one. Do not have only laboratory-type projects available; re search or theoretical projects should be provided for those students who have no interest in a laboratory project. Ensure that enough technical help is available. Machinists, plumbers, and electricians are necessary resource people. CONCLUSIONS An alternate approach to the undergraduate thesis has been described. This approach lies somewhere between the traditional research-oriented thesis and the work normally done in a process and plant design course. The size of our senior class has made it pos sible for us to offer this experience to all members of the group. In a large institution it would still be pos sible to adopt this scheme, but with a smaller percent age of the seniors. While a strategy of this sort is neither desirable nor feasible to implement on a con tinuous basis, our one attempt has brought numerous benefits to both the department and the students in volved. D REVIEW: Direct Contact Continued from page 11. any wall resistance and low capital cost In specialized situations these advantages certainly will lead to further commercial use of direct contact exchangers. The book is the product of an NSF-supported work shop held at the Solar Energy Researsh Institute in 1985. In contains fourteen chapters written by the organizers and principal speakers. Five chapters deal with two phase fluid systems. Three chapters treat heat transfer between particulate solids and gases. A chapter each concerns evaporation and condensation processes Several valuable functions are fulfilled by this book. At the most basic level it should serve to re-emphasize to the heat transfer specialists that this kind of heat ex changer is an option with certain strong advantages The book is a good source of ideas and configurations for possible applications A valuable feature of the book is a set of design examples included as six appendices. In the final chapter the editors present a summary of research needs. 0 CHEMICAL ENGINEERING EDUCATION

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[i)bli book reviews CHEMICAL REACTOR DESIGN by E. B. Nauman John Wiley & Sons,, $53. 70 (1987) Reviewed by P.A. Ramachandran Washington University problems. Chapter 1 introduces the basic concepts as applied to simple reactions and ideal reactors. The rate of reaction is nicely defined on a unit stoichiometric basis, and the rate of formation of any given species is then related to this quantity by using the stoichiometric coefficients. Such an approach is necessary for computer based simulations of more complex systems. Chemical reaction engineering has evolved to a ma ture discipline in the last two decades, and this has re sulted in a number of textbooks and monographs on the subject. The computer revolution has embraced this field in a big way, and the trend is towards detailed modeling and optimization studies of industrial scale re actors The textbook coverage on the application of nu merical methods in reaction engineering is, however, minimal and the present book fills this important gap. Thus the major contribution of the book is the detailed presentation of the computer aids as problem solving tools in reactor design. This naturally leads to applica tion to more realistic problems as opposed to simplified artificial schemes such as A B. This book is therefore able to focus on the applications to practical industrial Chapter 2 extends the basic concepts for more com plex reaction schemes. The Runge-Kutta method for solving a set of differential equations is introduced here and then applied to a number of problems for plug flow reactors. The analysis to a general reaction network is introduced on the basis of a matrix formulation. The Concepts of rank of matrix and its use in determining the key limiting reactants is briefly presented. It would have been useful to elaborate on these concepts in somewhat more detail with additional solved problems because the students usually have difficulties in this area. Chapter 3 introduces the solution methods for differ ent reactor types. The Newton-Raphson method for solving a set of nonlinear algebraic equations is dis cussed and the application to a perfectly mixed reactor handling a complex kinetic scheme is nicely presented Chapter 4 deals with the additional complications of thermal effects. Again, numerical methods are exten Continued on pag e 49. 1989 Chemical Engineering Texts from Wdey WINTER 1989 CHEMICAL AND ENGINEERING TIIERMODYNAMICS, 2/E Stanley I. Sandler, The University of Delaware 0-471-83050-X 656 pp. Cloth Available January 1989 A fully revised new edition of the well received sophomore/junior level thermo dynamics text now incorporating microcomputer programs PROCESS DYNAMICS AND CONTROL Dale E. Seborg, University of California, Santa Barbara, Thomas R Edgar, University of Texas, Austin, and Duncan A Mellichamp University of California, Santa Barbara 0-471-86389-0, 840 pp., Cloth, Available February 1989 A balanced, in-depth treatment of the central issues in process contro~ including numerous worked examples and exercises. REQUEST YOUR COMPLIMENTARY COPIES TODAY Contact your local Wiley representative or write on your school's stationery to Angelica DiDia, Dept. 9-0264,John Wiley & Sons, Inc., 605 Third Avenue, New York, NY 10158. Please include your name, the name of your course and its enrollment, and the title of your current text IN Q\NADA write to John Wiley & Sons Canada ltd 22 Worceste r Road, Rexdale Ontario, M9W ILi II WILEY JOHN WILEY & SONS, INC. 605 lbird Avenue New York, NY10158 sah/km 31

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[iJ ;j ?I laborator y AN EXPERIMENT I N AUTOTROPHIC FERMENTATION Microbial Oxidat i on ol Hydrogen Sulfide KERRY L. SUBLE'CTE The University of Tulsa Tulsa, OK 74104 T HERE HAS BEEN AN increasing effort in recent years to introduce chemical engineering students to biological processes. These efforts may be rather modest, with the incorporation of one or more exper iments in enzyme kinetics or fermentation into the undergraduate laboratory or more broadly based with formal course work in microbiology, biochemistry and biochemical engineering, and blocks of time in the lab oratory devoted to bioengineering experiments. How ever, even in the more comprehensive programs the chemical engineering student is typically exposed to only one basic type offermentation, that which is based on heterotrophic metabolism. In other words, the microorganisms which make up the fermentation cul ture utilize organic compounds as carbon sources and light or the oxidation of organic compounds as a source Kerry l S ublette obtained his BS in chemistry from the Univers i ty of Arkansas, his MS in biochemistry from the University of Oklahoma, and his MSE and PhD in chemical engineering from the University of Tulsa. After six years in research and development with Combustion Engineering, he joined the chemical engineering faculty at the Un i ver sity of Tulsa in 19B6 His research interests are in fermentation biocatalysis, microbial desulfurizatian of coal, and biological methods of hazardous waste treatment C> Copyright ChE DiVU1W1t ASEE 1989 32 TABLE 1 Medium for Anaerobic Growth of Thiobacillus denitrificans COMPONENT Na2HP04 KH2P04 MgS04H20 NH4Cl CaCl2 MnS04 FeCl3 NaHC03 KN03 Na2S203 or HzS(g) Trace metal solution* Mineral water See reference (2). PER LITER 1.2 g 1.8 g 0.4 g 0.5 g 0.03 g o.oz g 0.02 g 1.0 g 5.0 g 10.0 g (thiosulfate) 15.0 ml 50 0 ml of energy. Another way of life exists by which micro organisms may derive both carbon and energy from inorganic sources. This is termed autotrophic metabolism. Autotrophic organisms are becoming in creasingly important commercially in waste treatment, coal and sour gas desulfurization and mineral leaching applications. This experiment is designed to introduce the student to fermentation based on autotrophic metabolism. The subject of substrate inhibition is also addressed. This experiment is not recommended as a first introduction to fermentation but as a demonstra tion of the wide range of metabolic capabilities of micro organisms. Specifically this experiment utilizes the auto trophic bacterium Thiobacillus denitrificans to anaerobically oxidize H 2 S(g) to sulfate in a batch stir red tank reactor. Hydrogen sulfide is shown to be an inhibitory substrate for the bacterium; however, under sulfide-limiting conditions rapid and complete oxida tion of H 2 S is observed with undetectable levels of H 2 S CHEMICAL ENGINEERING EDUCATION

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in the bioreactor outlet gas. Provided the bioreactor can be sampled periodically over 1-2 days, the stoichiometry of the reaction is readily determined. BACKGROUND In nature there exists a large and widely distrib uted group of microorganisms which play a central role in the maintenance of the carbon, nitrogen, and sulfur cycles. These microorganisms are termed lithotrophic if they are capable of deriving energy and/or reducing equivalents from the oxidation ofinorganic compounds. Chemolithotrophs derive both energy and reducing equivalents from such reactions, while photolitho trophs derive energy from the absorption of radiant energy and reducing equivalents from oxidation of in organic compounds. Those microorganisms capable of also deriving carbon for biosynthesis from an inorganic source (carbon dioxide) are termed autotrophic. Exam ples of inorganic energy sources for chemoautotrophs include hydrogen ammonia, iron (II) salts, elemental sulfur, thiosulfates, and sulfides. The interrelationship between substrate oxidation and biosynthesis in chemoautotrophic organisms is illustrated in Figure 1. Thiobacillus denitrificans is a strict autotroph and facultative anaerobe first described in detail by Baals rud and Baalsrud [1] Thiosulfate, elemental sulfur, and soluble sulfide may be utilized as energy sources with oxidation to sulfate. Under anaerobic conditions nitrate may be used as a terminal electron acceptor with reduction to elemental nitrogen. Anaerobic growth of T. denitrificans on H 2 S(g) has been described in detail by Sublette and Sylvester [24] The medium used to grow T. denitrificans is given in Table 1. When H 2 S served as the energy source it was bubbled into the reactor at a rate sufficiently low as to maintain sulfide-limiting conditions. In other words, H 2 S was introduced into the cultures at a rate which was less than the maximum oxidation capacity TABLE 2 Stoichiometry of Anaerobic H2S Oxidation by T. denitrificans In Batch Reactors* S042 IH2S N03-/H2S NH4+/H2S OW/H2S Biomass/H2S Average of four determinations WINTER 1989 1.04 1.36 0.12 1.60 12.1 mole/mole mole/mole mole/mole eq ui val en ts/mole g/mole INORGANIC SUBSTRATES OXIDIZED INORGANIC SUBSTRATES REDUCING EQUIVALENTS REDUCED CARBON COMPOUNDS + BIOSYNTHESIS FIGURE 1. Chemoautotrophic metabolism of the biomass. Stock cultures and start-up cultures used thiosulfate as an energy source. Under anaerobic conditions nitrate was the terminal electron acceptor. Bicarbonate was the carbon source and ammonium the source ofreduced nitrogen. The medium also contained a phosphate buffer and sources of various essential mineral nutrients Sublette and Sylvester [2, 3] reported that when H 2 S(g) was introduced into anaerobic cultures of T. denitrificans previously grown on thiosulfate, the H 2 S was immediately metabolized with no apparent lag. Typically the feed gas contained about one mole per cent H 2 S. Initial loadings were in the range of 4-5 mmoles H 2 S/hr-g biomass. With sufficient agitation to reduce the average bubble diameter to about 0.25 cm and gas-liquid contact times of 1 2 sec, H 2 S was unde tectable in the reactor outlet gas by GC/MS. Less than 1 M of total sulfide (H 2 S, HS s ~ ) was observed in the reactor medium during periods of up to thirty-six hours of batch operation. No intermediates of sulfide oxidation (elemental sulfur or sulfite) were detected; however, sulfate accumulated in the reactor medium as H 2 S was removed from the feed gas. Oxidation of H 2 S to sulfate was accompanied by growth as indicated by an increase in optical density and protein concentra tion and a decrease in the NH 4 + concentration in the medium. The reaction was acid producing requiring hydroxide (OH-) equivalents to be pumped into the reactor to maintain an optimum pH of 7.0. Small amounts ( < 40 M) of nitrous oxide, N 2 0, could be detected in the reactor outlet gas. However, no other intermediates of nitrate reduction were observed to accumulate while nitrate was consumed. The stoichiometry of anaerobic H 2 S oxidation by T. deni trificans in batch reactors as reported by Sublette and Sylvester [2] is given in Table 2. Sublette and Sylvester [2] also reported that H 2 S 33

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is an inhibitory substrate for T. denitrificans. Inhibi tory effects were observed at total sulfide concentra tions as low as 200 M with total inhibition observed at 1000 M. The total sulfide concentration in the medium of batch anaerobic T. denitrificans reactors operated under sulfide-limiting conditions was well below inhibitory levels. However these authors re ported that if the maximum capacity of the biomass for H 2 S oxidation was exceeded, inhibitory levels of sulfide quickly accumulated in the medium. This upset condition was characterized by H 2 S breakthrough in the outlet gas, release of large amounts of N 2 0 and accumulation of elemental sulfur in the medium. It was observed that this upset condition was reversible if the cultures were not exposed to the accumulated sul fide for more than two to three hours. Reduction in the H 2 S feed rate following an upset condition reduced the H 2 S and N 2 0 concentrations in the outlet gas to pre-upset levels with elemental sulfur oxidized to sul fate. The H 2 S loading at which the specific activity of the T. denitrificans biomass was exceeded resulting in upset was observed to be 5.4-7.6 mmoles H 2 S/hr-g biomass under anaerobic conditions. The autotrophic medium described in Table 1 will not support the growth of heterotrophs since there is no organic carbon source. However, Sublette and Syl vester [4] observed that if aseptic conditions were not maintained a heterotrophic contamination developed in a T. denitrificans culture growing on thiosulfate or H 2 S. Evidently T. denitrificans releases organic mate rial into the medium in the normal course of growth or through lysis of nonviable cells which supports the growth of heterotrophs. Sublette and Sylvester re ported that the heterotrophic contamination had no discernable effect on H 2 S metabolism by T. deni trificans. EXPERIMENTAL PROCEDURE Samples of Thiobacillus denitrificans may be ob tained from the American Type Culture Collection Rockville, Maryland, or from the author. Stock cul tures may be grown anaerobically on thiosulfate in 10 ml culture tubes at 30 C. When dense growth appears (three to four days with fresh inoculum) store at 4 C until used. Stocks should be transferred every thirty to sixty days to maintain vigorous cultures. Stock cul tures do not need to be grown aseptically. Figure 2 presents a schematic diagram of the equipment re quired to culture T. denitrificans anaerobically on H 2 S(g). An investigation of the anaerobic oxidation of H 2 S by T denitrificans is described below. Details of the analytical methods required for a thorough study of 34 the stoichiometry of the process are also presented. It is intended that the experiment can be used to in troduce the subjects of autotrophic fermentation and substrate inhibition at a number of levels of difficulty and challenge to the students. A straightforward dem onstration of the detoxification of a hazardous material by a bacterium can be conducted requiring less than three hours of student participation. However, an in vestigation of the stoichiometry of the process would require intermittent observation and sampling of H 2 S cultures for one to two days plus time for sample analysis. Before describing the experimental protocol a word of caution is in order. Hydrogen sulfide is a highly toxic gas. The threshold limit value (time weighted average) for H 2 S exposure is 10 ppm (7-8 hrs). The threshold limit value for short term expo sure is 15 ppm (15 minutes). It is therefore necessary that the laboratory instructor carefully monitor all op erations involving H 2 S and, as indicated in Figure 2, the entire fermentation system mu st be located in a fume hood. Anaerobic Oxidation of H 2 S A working culture of T den i trificans may be de veloped by growing on thiosulfate at 30C and pH 7.0 using the medium described in Table 1. The purpose of this prior cultivation on thiosulfate is to develop a sufficient concentration of biomass in the reactor so that an appreciable rate of H 2 S can be fed to the reac tor without exceeding the biooxidation capabilities of the biomass. Otherwise sulfide would accumulate in the reactor medium to toxic levels. The recommended culture vessel (see Figure 2) is a 1-2 1 jacketed beaker with a large silicone rubber GAS CYLINDER WATER BATH 30C ROTAMETER TO EXHAUST NaOH RESERVOIR FUME HOOD FIGURE 2. Schematic diagram of equipment required to culture T. denitrificans anaerobically on H 2 S(g) CHEMICAL ENGINEERING EDUCATION

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Chemolithotrophs derive both energy and reducing equivalents from such reactions, while photolithotrophs derive energy from the absorption of radiant energy and reducing equivalents from oxidation of inorganic compounds. Those microoganisms capable of also deriving carbon for biosynthesis from an inorganic source (carbon dioxide) are termed autotrophic. stopper to support probes and inlet and outlet ports. Temperature may be controlled by circulating water at 30 C through the jacket of the reactor. The pH may be monitored and controlled by a pH meter / controller which activates a peristaltic pump to deliver 6 N NaOH to neutralize acid produced by the biooxidation of thiosulfate or H 2 S. A pH stability of 0.2 units is desirable. If the controller also activates a laboratory timer, the rate of NaOH addition can be monitored. A gas feed of 5 mole % CO 2 in nitrogen at 30 ml/min is recommended during growth on thiosulfate to en sure the continuous availability of a carbon source. Gas mixtures are fed to the reactors from cylinders of compressed gas through two stage stainless steel reg ulators and rotameters. Gas is introduced into the cul ture medium by means of a glass fritted sparger A four or six bladed flat disk impeller may be used for agitation at 200-300 rpm to produce good gas-liquid contacting. As noted previously, heterotrophic contamination has little or no effect on the growth of T. denitrificans in an autotrophic medium. Therefore, it is not neces sary to sterilize the reactor or any associated equip ment. When 1-2 1 of thiosulfate medium is inoculated with 20 ml of a fresh stock culture, a working culture is produced in approximately sixty hours. The medium described in Table 1 is nitrate limiting; therefore, when the nitrate is depleted the culture stops growing. At this point the culture will have an optical density at 460 nm of about 1.0. The pathways for sulfide and thiosulfate oxidation to sulfate in T denitrificans are not independent but have two common intermediates [5]. In the presence of thiosulfate the rate of sulfide oxidation would be reduced because of competition between intermediates of thiosulfate and sulfide oxidation for the same en zymes of the sulfur pathway. Therefore, prior to the introduction of H 2 S to T. denitrijicans cultures, re sidual thiosulfate must be removed. This may be ac complished by sedimenting the cells by centrifugation at 4900 x g for ten minutes at 25C. A refrigerated centrifuge is preferred. However, any centrifuge is acceptable if the temperature of the cell suspension does not exceed 45C during harvesting. The superna tant is discarded and the cells resuspended in growth medium without thiosulfate. Following a second cen trifugation the washed cells are resuspended in WINTER 1989 medium without thiosulfate and transferred back to the reactor. It is recommended that the reactor and all probes be rinsed in distilled water to remove re sidual thiosulfate prior to reintroduction of cells. Once thiosulfate has been eliminated, hydrogen sul fide can now be introduced into the culture by changing the feed gas to include H 2 S. A composition of 1 mole % H 2 S, 5 mole % CO 2 and balance N 2 is recommended. If the OD 460 of the culture is at least 0.8, a feed rate of about 50 mVmin will not exceed the biooxidation capabilities of the culture. It is recommended that the H 2 S feed rate be brought to this level stepwise over about thirty minutes. With proper agitation to achieve good gas-liquid contacting, H 2 S will be undetectable in the gas outlet of the reactor. The stoichiometry of anaerobic oxidation of H 2 S(g) by T d e nitrificans can be obtained by sampling the reactor contents over a period of 24-48 hours as H 2 S is removed from the feed gas. Of particular interest would be the concentrations of sulfate (SO 4 --2 ), nitrate (NO 3 ), ammonium ion (NH 4 + ) elemental sulfur and biomass in the reactor medium. Analytical methods are discussed below. The inhibitory nature of H 2 S as a substrate can be demonstrated by increasing the H 2 S feed rate stepwise until H 2 S breakthrough is seen. When breakthrough occurs, nitrous oxide (N 2 O) will also be detected in the outlet gas and elemental sulfur seen to accumulate in the reactor medium. Sulfur will give the medium a milky white color. As described in a previous section, the upset condition is reversible if not prolonged. How ever, if the upset condition is allowed to persist the outlet H 2 S concentration becomes equal to the inlet, indicating complete loss of biooxidation activity in the culture. Analytical Feed gas and reactor outlet gas may be analyzed for H 2 S and N 2 O by gas chromatography. Using a thermal conductivity detector the detection limit for H 2 S is about 2-4 M with a 0.25 ml sample. In our laboratory a 10-ft by 1/8-in ID Teflon column containing Porapak QS (Waters Associates) has been used with a helium flow rate of 20 mVmin. A column temperature of 70C and injector and detector temperatures of 200C are satisfactory. Under these conditions the re tention times of N 2 CO 2 N 2 O, and H 2 S are 0.8, 1.8, 35

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2.2, and 5.3 minutes, respectively. H 2 S is quantitated by comparing chromatograms of samples to chromatograms produced by a certified primary stand ard (Matheson Gas Co.). If a gas chromatograph is unavailable, H 2 S and N 2 0 may also be determined to 25% using Gastec Analyzer Tubes (Yokohama Japan). Nitrate may be determined in thiosulfate free sam ples by the cadmium reduction method [6]. Ammonium ion may be determined by the Nessler method without distillation [6]. Sulfate is readily determined tur bidometrically [6]. Premeasured reagents for these analyses may be purchased from Hach Chemical Co. Thiosulfate may be determined by titration with standard iodine solution using a starch indicator [7]. Elemental sulfur may be collected by filtration on 0.45 micron Millipore Type HA filters and determined by reaction with cyanide to produce thiocyanate. Thiocyanate may be quantitated as Fe(SCN) 6 --3 which has a molar extinction coefficient in water at 450 nm of 3.37 x 10 8 M 1 cm 1 [8]. Biomass may be determined in terms of whole cell protein by sonication followed by colorimetric analysis by the micro modification of the Folin-Ciocalteau method [9, 10]. (Folin-Ciocalteau reagent may be purchased from Anderson Laboratories.) Cells are sus pended in 10-20 ml of 20 mM phosphate buffer, pH 7.0, and sonicated with a sonic probe until the suspen sion is clarified. In our laboratory a Braun-Sonic 1510 with a 3/4 in. probe is used at 150 watts for two three minute periods with intermittent cooling. The result ing protein solution is analyzed directly without further treatment. Bovine serum albumin (Sigma Chemical Co.) is used as a standard. The protein content of T denitrificans cells grown on H 2 S(g) is 60 3% [2]. Using this figure the results of protein analyses may be converted to dry weight T denitrificans biomass. SAMPLE RESULTS In a typical batch experiment the oxidation of 18.3 mmoles of H 2 S was accompanied by the production of 18.8 mmoles sulfate and 246 mg of biomass. A total of 27.0 mmoles nitrate, 2.2 mmoles ammonium ion and 31.8 meq of hydroxide ion were utilized. Figures 3a and 3b summarize the results of analysis of the medium of an anaerobic reactor as H 2 S is oxidized by the culture. Sulfate is seen to accumulate in the medium. The concentration of biomass increases as the cells grow using H 2 S as an energy source and correspondingly the optical density increases with time. Nutrient levels (NO 3 and NH 4 + ) decline as H 2 S 36 48 44 40 36 32 .,. ., 28 E 0 l!:: 24 0 <( \z: 20 0 16 12 8 4 0 24 22 20 18 16 14 :;; E ~12 I 1iii 0 6 z L,J 0 ...J 0 5 <( 0 t 0 4 0 0 1 0 o 2 4 6 8 10 12 14 16 18 20 TIME (hours) FIGURE 3a. Optical density, concentration of sulfate (S0 4 2 ) and hydroxide ion (OH-J utilized in an anaerobic T. denitrificans batch reactor receiving 1.25 mmoles/hr hydrogen sulfide (H 2 S) feed. OD(); S0 4 2 (); OH -( ~) 9 0 500 52 8 5 450 8 0 400 36 :;:: 32 "' :E E :E E ~350 E 7 5 28 +; V) ,......., <( 1.., :i:: :E 124 0 ., 7.0 300 20 16 6 5 250 12 8 6.0 200 4 oL ol 00 2 4 6 8 10 12 14 16 18 20 TIME (hours) FIGURE 3b. Concentrations of nitrate (N0 3 -J, biomass and ammonium (NH 4 + ) in an anaerobic T. denitrificans batch reactor receiving 1.25 mmoles/hr hydrogen sulfide (H 2 S) feed. N0 3 (0); NH 4 + {Ll); biomass (DJ. CHEMICAL ENGINEERING EDUCATION

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is oxidized and the cell population increases. Lastly, hydroxide is steadily consumed as acid is produced by the process ACKNOWLEDGEMENT The author wishes to express his appreciation for the technical assistance of Dr. Marion Woolsey. Re search upon which this experiment is based was funded by Combustion Engineering, Inc. of Stamford, Con necticut. REFERENCE S 1. Baalsrud K., and K. S. Baalsrud, "St udies on Thiobacillus denitrificans," Arch. Mikrobiol ., 20, 34-62 (1954) 2. Sublette, K. L and N D. Sylvester, "Oxidation of Hy drogen Sulfide by Thiobacillus denitrificans: Desulfur ization of Natural Gas," Biotech and Bioeng 29 249-257 (1987) ,.,n pW"book rev i ews ADVANCES IN D R YING, Vol um e 4 Edited by Arun A. Mujumdar Hemisphere Publishing Corporation, 79 Madison Avenue, New York, NY 10016 4 2 1 Pages, $97.50 Reviewed by E. Jo h a n sen Crosby University of Wisconsin The drying of solids is probably one of the oldest unit operations practiced by man. In the past, this process generally was considered to mean the removal of moisture from matter when the amount of same was relatively small. However, in the chemical proces sing industry of today, feedstocks to be dried may contain as much as ninety percent moisture, and that moisture many times may be nonaqueous and mul ticomponent. Moisture removal can be effected by (i) condensed-phase separation, (ii) chemical decomposi tion, (iii) chemical precipitation, (iv) absorption, (v) adsorption, (vi) expression and (vii) vaporization. Con vection drying, i.e., moisture removal by vaporization with the drying medium being both the energy source and moisture '3ink, is by far the most common method used. The materials-handling considerations resulting from many different feedstock and product require ments inevitably resulted in the development of many types of equipment--each with its own operation idiosyncrasies. WINTER 1989 3. Sublette, K. L. and N D. Sylvester, "Oxidation of Hy drogen Sulfide by Continuous Cultures of Thiobacillus denitrificans," Biotech. and Bio e ng., 29, 753-758 (1987) 4. Sublette, K. L., and N D. Sylvester, "Oxidation of Hy drogen Sulfide by Mixed Cultures of Thiobacillus deni trificans and Het e rotrophs, Biotech. and Bioeng., 29, 759-761 (1987) 5. Suzuki, I., "Mechanisms of Inorganic Oxidation and Energy Coupling," Ann. R eu. Micro., 28, 85-101 (1974) 6. American Public Health Associ atio n, Standard Methods for the Examination of Water and Wastewater, 14th Ed., APHA, New York (1976) 7. Meites, L., Ed., Handbook of Analytical Chemistry, McGraw-Hill Book Co., New York ( 1963) 8 Schedel, M., and H. G. Truper, "Anaerobic Oxidation of Thiosulf ate and Elemental Sulfur in Thiobacillus deni trificans," Arch. Mikrobiol.,124, 205-210 (1980) 9. Folin, 0., and V. Ciocalteau, "On Tyrosine and Trypto phan Determinations in Proteins," J. Biol. Chem., 73, 627 -649 ( 1927) 10 Lowry, 0. H., N. J. Rosebrough, A. L. Farr, and R. J. Randall "Protein Measurement with the Folinphenol Reagent ," J. Biol Chem., 193 265-275 (1951) 0 In recent years, the number of monographs, hand books, journals, proceedings and research reports de voted to this subject has increased markedly with the series entitled Advances in Drying which was in itiated in 1980. In the preface of Volume 4, the editor indicates that this ... series is designed to allow individuals concerned with (various) aspects of drying to access relevant information in a carefully reviewed form with minimal time and effort." Like its predeces sors, this work consists of a number of reviews, up dates, and developments concerning theory, design, and practice in connection with moisture transfer through and/or removal from solids. Eight individual topics are addressed from various viewpoints by con tributors from seven countries. Computer-aided design of convection dryers is dis cussed in Chapter 1. The classification of mathemati cal models according to contact zones and flow pat terns, the systematic application of the overall mass and energy balances, and the simplification of drying mechanisms is presented. Most of the chapter is de voted to examples of recommended calculation proce dures for different types of dryers with the coverage of spray and rotary dryers being especially minimal. Chapter 2 deals with recent advances in the drying of wood. A review of drying theory and modeling is fol lowed by a good summary of recent developments in lumber and veneer drying. Recommendations for fu ture work are presented. Chapter 3 contains a con densed theoretical review of the drying of porous sol ids with stress on the internal mechanism of moisture and energy transfer. Coupled heat and moisture transfer in soil is reviewed in Chapter 4. Written from Continued on p
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[iJ n I classroom EXPERIENCING TEAM RESPONSIBILITY IN CLASS R. RUSSELL RHINEHART Texas Tech Uni v ersity Lubbock, TX 794093 1 2 1 T HE ABILITY TO effectively manage a project within a team of peers is one signature of a profes sional-one which is often ignored in engineering edu cation. However, such an experience can be success fully woven into the curriculum to the enhancement of technical fundamentals. Even as an entry-level engineer, a person mu s t plan, schedule, and then coordinate the work of operators and technicians in adjacent groups. Soon thereafter, one plans, influences priorities, and coordi nates peers activities across organizational bound aries. In any case, that one person is solely responsi ble for timely results; but he or she must rely on the contribution of others, must accommodate the priorities of others, must foster effective interperR Rus s ell Rhinehart is an assistant professor of chemical engineer ing at Texas Tech University. He received his PhD from North Carolina State University after a 13-year industrial career as an engineer and group leader which included development of react i on systems proce s s control solvent reca.very and process safety and reliability His interest in the special aspects of industrial process modeling optimization, and control techniques led to his pursuit of an academic career *Presented at the 1987 annual AIChE meeting November 17, 1987 T ABLE 1 Rules The project descriptions I have writt e n are s uggestions based on my e x perience, but may be changed. As you progress you will find many other aspects of your topic and you will want to pursue those that in t erest you. If you want to change the project scope, however be sur e to coordinate that acti o n with m e In any event, you ne e d to m ee t with me to e nsure that your plans meet my e xpectations. I will g rad e th e writt e n r e port It s h o uld be neat organized, and pr ese nt e d so that it t e a c h es a t e chn o l og y or d e monstrat es an appli c ati o n. Mak e it so methin g which ca n be u se ful to yo u five ye ar s fr o m n o w The g rade will b e w e i g ht e d 50/ 5 0 on t e chnical a cc ura cy and c o mpl e t e n ess and o n communicati o n e ff e cti v eness (l og i c al pr e s e nt a ti o n, writing cl a rity, or ga ni z ati o n) Th e writt e n r e ports should be 15 to 25 handwritten, single spac e d, or t y p e d, d o uble spaced pa ges, including ex ampl e s, fig ure s d e rivations, and comput e r cod e. Don t go for broke ... this is ju s t a one-month proj e ct. But do present s ome meaningful and use ful w o rk. On the due d a t e th e l e ad e r will pr es ent a ten-minute oral r e p o rt for the cla s s. The oral r e port will not be graded Take care of your group members Plan ahead so they can plan th e ir own w o rk s ch e dule Assign portions of the project that interest th e m so that they do th e ir best work for you. Use your group members Delegate, or el s e you will overwork yourself try ing to meet my expectations Use me as a consultant for personnel problems as well as technical methodology. sonal relations, and has input into the performance rating of others. Key skilts of a practicing engineer include planning communicating, interaction manage ment accommodating, and listening. Key perspec tives include project ownership and acco un tability. Such professional attributes, however, are not usually descriptive of an engineer's formal education. It is likely that at least 50% of an engineer's effec tiveness will depend on human team interaction skills. However, the academic experience is largely indi vidualistic, and even the scant group exercises in lab and design are often without assigned leadership re sponsibility and authority. In practice, a design en gineer must cooperate with others; for instance, he must rely on an R&D engineer to generate design data for his project. But we teach and test for indiin New York, NY ----------10 C opyri{/ ht C hE Di viswn ASEE 1 9 89 38 CHEMICAL ENGINEERING EDUCATION

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mdual performance. A process engineer must get the cooperation of a production staff to run trials, and he must rely on lab services to analyze the results. Yet, throughout his education, we have encouraged, re warded, and prepared the graduate for individual per formance. Consequently, a student's perspective on the practice of engineering is usually misdirected. If education means developing life skills in prepa ration for social responsibility (as opposed to merely developing a technical facility), then it is our responsi bility as professors to move beyond a technical/ academic focus and to incorporate life-relevant experi ences into the classroom. Success at human manage ment is a requirement for successful technology im plementation. As faculty who are concerned with indi vidual technical performance, we are sometimes un aware that we have omitted the development of the interpersonal skills required for effective engineering. The objectives of the in-class team responsibility project are: To integrate some of these professional perspectives into the classroom To coach students toward improved project and people management effectiveness To support the traditional educational objectives To enjoy the experience. As faculty who are concerned with individual technical performance, we are sometimes unaware that we have omitted the development of the interpersonal skills required for effective engineering. ASSIGNMENT STRUCTURE AND RULES Each student in the class becomes a project team leader once and chooses a project topic from a pre pared list. The project will take about a month to com plete and will demonstrate relevant engineering skills. Projects have included writing computer simulators, technology reviews, a mini chapter for a text, and conducting personnel surveys. The assignment state ment is shown in Table 1, and Table 2 lists the project titles given to the students in a junior heat transport course. (While the topics in the third section of Table 2 are non-technical, I think that they are important to engineering sucess and, therefore, relevant to the education of an engineer.) Three other classmates are assigned to the project leader as team members. Each student is a team leader once and participates in a total of four projects. The team leader has sole responsibility for the project scope, its planning, work distribution, daily coordina tion, and for both the written and oral presentations. (The oral is required but not graded.) The leader TABLE 2 List of Projects for a Junior Heat Transport Course Write a computer simulator and run "trials" of A binary boiler A condenser A red-hot quench The transient conduction in a rod The steady state temperature profile in a slab of non constant thermal conductivity The steady state performance of a shell-and-tube liquid/liquid heat exchanger The steady state temperature distribution in a fin of non constant cross sectional area A steam traced pipeline The transient response of a temperature detector in a thermowell with external conduction Write a technology report, a mini-chapter in a text, presenting an overview of the topic, design equations, and original examples of Natural convection Heat pipes Coiled heat exchangers Alternate boiling/ condensing heat transfer fluids Engineering/business economics Heat transfer in two-phase flowing fluid Human perception of hot and cold WINTER 1989 Mechanical design criteria for baffles Dehumidifiers and after-coolers Thermosiphon and calendria reboilers Insulation Developing and validating correlations Steam tracing Evaporators/cooling towers Temperature measurement device technology and calibration Write a mini-chapter to introduce the relevance and the engineering skills associated with Systematic diagnosis of process faults The transition from student to engineer Critical thinking to recognize and demythify technical folklore Personality development and inappropriate adult behavior Decision analysis Creativity Social structure within human institutions Perception of performance Industrial performance reward systems Temptations and attitudes that lead to less than desirable engineering quality The balance of power: marketing, finance, or engineering? 39

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The nature of such an assignment is quite differen t fr om the highly st ructured i nd i vidua l, determin is tic short-term private type assignment fo r which the student ha s been programmed dur i ng his previous fifteen years of schoo l. It is important that th e students are c omfortab le w i t h th e c hange meets with me to learn what my expectations of an appropriate project scope are, but then makes the final decisions himself. The project grade is assigned exclusively to the team leader; however, the leader grades his team members. My grade of the project contributes 15% to the leader's course grade, and each of the three grades he receives as a team member counts 5%. The combined four-project grade is 30% of the course grade. Projects are assigned near the beginning of the semester but are due about one month after the funda mentals of a topic are covered in class lecture. The projects require sustained effort during the last two thirds of the semester, and I reduce the extent of weekly homework assignments as a result. Topics from the last three weeks' lectures are not assigned as projects. Students select their own project choices from a list of topics that I have prepared. Students can suggest other topics, but rarely do they have that foresight in an unfamiliar technology. Not all of the topics are specific to the course technology, but I judge all to be relevant to the practice of engineering (e.g. engineering economics, human perception of hot and cold, systematic trouble diagnosis, debunking of technical folklore). I match project leaders to one of their first project choices and then assign other team members in order to distribute their project due-dates throughout the semester. I then assign other mem bers so that each student works on at least one project of each type (computer simulator or report) and fi nally, to shuffle personnel as much as possible. PREPARATION FOR SELF AND CLASS : A REQU I REMEN T The nature of such an assignment is quite different from the highly structured, individual, deterministic, short-term, private type assignment for which the student has been programmed during his previous fif teen years of school. It is important that the students are comfortable with the change. As adults they can choose to put their personal energy where they per ceive it to benefit them the most, and it is important that they ''buy into" the objectives of this new type of assignment. So, distributed over several early lec tures, I spend about one-half of a class previewing the assignment, discussing the engineering work environ ment, discussing the experiences I want them to be prepared for, presenting the objectives of the particu lar assignment, and offering assurances of my avail40 ability as both a personnel and a technical consultant. As projects are in progress, I spend five minutes here and five minutes there discussing group assignment plans, coordination, flexibility, ways to handle intract able "employees" and other skills that I perceive are relevant. I also reinforce the workplace/classroom dif ferences to periodically justify the project strangeness in order to keep the adults "on board." Problems occasionally arise: a failing student de cides to put his energy into other courses and fails to contribute his share to the leader's project; a leader plans too late and then unreasonably expects group members to perform at a high level regardless of their other commitments; one project turns out to be much more difficult than the others. It requires a self-confi dent professor to calm the slighted student's panic, to be flexible, and to assure students that, in spite of individual situations, subjective grading can be fair. The professor must be willing and able to manage such common personnel situations as when a student feels that events beyond his control will affect the reward of his personal performance. These are common work place problems which a practicing engineer must han dle and that a student can preview in his education. Success at human management is a requirement for successful technology implementation. RESULT S Comments from the semester-end student course evaluations are one source of results. Verbatim they include: The indepen d ent research is a great learning experience keep it! Leading a team is super, have to deal w/ people not willing to do their part and taking all the input & p u tting it into 1 report. Learned TONS! I think it will be very helpful later on. The [i n dependent] research is a good change from number crunching. I learne d that I need work on my orga n izatio n al skills. It is hard gra d ing fellow classmatesbut good experie n ce. Also learned a few more things on my own. I enjoyed working as a team, it helped bring us closer to gether and we learn more through research [independent study]. CHEMICAL ENGINEERING EDUCATION

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... has given us a big opportunity to learn to work together and to be a responsible person in every aspect. Heat transfer concepts as well as fundamental human in teractions were taught. Required and inspired creative thinking in solving practi cal engineering problems. I'm glad projects were assigned. They brought a special type of learning into the course. Keep it. Do it again next year. Overall, the positive evaluations (70%) outnumber the negative evaluations (8%) by 9 to 1. The negative comments concern either the unfairness in student grading or the variable difficulty of the computer ver sus the independent study type of projects. I will ad dress these complaints later. The ambivalent re sponses, such as "grading of the projects was fair," or "give more time to complete the projects," comprised 22% of the evaluation. The students felt that the exer cise achieved the desired results. So did I. Along with my personal perception that the exer cise met its objectives, there has been one outstanding tangible result. One student chose to investigate the on-the-job transition one must make in the student-to engineer metamorphosis. Her group augmented their literature review with personal interviews and a mail survey to our graduates with two to five years' work experience. The questionnaire was developed after their initial investigations and focused on the suffi ciency and relevance of engineering education to the skills neceasary for life and the practice of engineer ing. The project report was excellent. It was accepted for publication in the Texas Tech engineering student journal [1]. DISCUSSION I think that such an exercise is appropriate to the maturity level and stability of juniors, seniors, and graduates. I would anticipate that the mid-term drop out rate and marginal commitment of many freshmen and sophomores would create severe personnel prob lems if such an assignment was included at their level. The 15% and 5% grading schedule provides suffi cient incentives. The leader wants a quality report and must rely on substantial team member contribu tions to meet my expectations. Additionally, the ap pearance of the half-letter grade control that the leader has provides sufficient incentive to the member for quality participation. In actuality, however, mem bers receive contribution grades from A to D-at WINTER 1989 worst a sixth of a course letter grade per project. In effect, as professor I really give up very little course grade assignment authority. With the 15% and three 5% project grades and with homework counted as 20%, non-test grades count 50% of the course grade. Tests count as the remaining 50%. I have no problem with that weighting; however, students occasionally suggest that tests should count more. Initial assignment descriptions are very brief, i.e., ''Write a chapter on heat pipes for a heat transfer text. Describe the phenomena, uses, operating condi... there has been one outstanding tangible result. One student chose to investigate the on-the-job transition one must make in the student to-engineer metamorphosis. tions, and fluids. Give design equations and create examples." On that particular project, with initial re search the student finds that liquid-wicking phenomena for zero-gravity applications, multicompo nent VLE behavior, rarified vapor fluid dynamics, variable surface area control, and internal fins are each of application's importance. The student chooses the specific technology that he finds interesting and relevant and, together with me, works out a project scope that meets my expectations and my realization of the limits of a month-long project that counts 15% of one course in one semester. I have not yet graded the oral presentations. To some it is an intimidating event, and I wanted to create a pressureless environment for the verbal class presentation. Additionally, I did not want the stu dents to compete for fancy visual aids. However, the oral presentations were often ill-prepared and of no use to the other class members. In the course evalua tions, a few students suggested grading the oral pre sentation as a portion of the project grade and I plan to try it next time. A recurring student suggestion is that more time should be allowed for completion of the projects. I suspect, however, that some students shoot for sub stantial results and completeness, enjoy the indepen dence, and would write a book if allowed. I also sus pect that others get started late and would never have enough time. Considering the planning and delegation experiences I want to create, and the justifiable time demand of the project portion of one course, I think that the one-month duration is appropriate. Before students err, however, it is necessary to preview these time constraint aspects. The students must be made aware of the need to limit project scope, to del egate, and to start early. 41

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The reports submitted at the end of the semester benefit from the grading, comments, and in-class dis cussions on the earlier reports. In spite of my pre views, the initial projects are at a grading disadvan tage. The students also come to recognize this, and to be fair, I add a letter grade to projects due early in the semester. The students seem satisfied. I have re served this option and keep it unannounced until I grade the second set of projects, but I have felt that it is appropriate each semester. Students have a tendency to do most of their own project work. Perhaps it is educational inertia. Lead ers' estimates of their personal effort ranged from 50% to 90% of the total group effort. Delegation and coor dination are important job functions and, in discus sions with leaders, I have encouraged them to dele gate. Although I am satisfied with the average leader contribution of 75%, I would prefer to push that to 60% and in subsequent classes will help leaders iden tify project portions that can be delegated. As mentioned in the results section, there were two student criticisms of the assignment. One of the two negative evaluations concerned the assignment of grades by the student leaders, and was characteristi cally stated as, "People give good grades to their friends, without considering their actual work." The objection is not to the student-grading-student aspect of the exercise, but that student grading is not as objective as one would like. Although project leaders did assign D's, A's were assigned to 70% of the mem bers' contributions, and B's to about 25% of the contri butions. However, we all recognized that the inflated grades are not indicative of a member's performance and that friends may grade friends too leniently. I've discussed optional grading policies, such as pass/fail and S + /SIU with the classes. However pass/fail lacks discrimination, and the S + /8/U is too similar to A/B/C and may also be subject to grade inflation. I am now trying an alternate approach. Leaders do not grade, but fill out a "Group Member Evaluation Form" (see Table 3) for each group member. The form originated as an industrial performance review but has been TABLE 3 Group Member Evaluation Form NAME INSTRUCTIONS: Experiment No. __ Place an mark on each rating scale, over the descriptive phrase which most nearly describes the person being rated. Evaluate each quality separately. Avoid the common tendency to rate nearly everyone as 'average' on every trait instead of being more critical in judgement. Also avoid another common tendency to rate the same person 'excellent' on every trait or 'poor' on every trait based on the overall picture one has of the person being rated. ACCURACY is the correctness of work duties performed Made many errors Somewhat Avg number of Accurate most Exceptionally careless mistakes of the time accurate ALERTNESS refers to the ability to grasp instructions to learn from research and to solve problems. Slow to Needed more than Grasped Quick to underExceptionally catch on average instructio ns with stand and learn keen and alert instruction average abilny FRIENDLINESS refers basically to the ability to get along with team members. Distant & aloof Friendly once Warm friend l y Very sociable & Excellent known by others and sociable outgoing PARTICIPATION is being available for and participating in group activities. O ft en absent or Lax i n availability Usually ava ilabl e Very prompt & Outstand ing. d i d unavailable and participation and participating regular more than share 42 DEPENDABILITY is the ability to do assignments well with minimum supervision. Qune unrel ia b le Sometimes reUsually did assign quired prompt ing men t s on t ime Very reliable Outstanding in rel iabiln y JOB KNOWLEDGE is the information each individual had to know or learn in order to do his / her part in all phases of the experiment Poorly i nfonmed La cked knowledge Moderately inUnderstood Had mastery of some phases formed all phases of all phases QUANTITY OF WORK is the amount of work done by the individual throughout the planning conduction and documentation phases of the experiment. Unacceptable Did jus t enough Average vol~e Did more than Superior work to get by of work was requ ire d production OVERALL EVALUATION in comparison w it h other group members. Definitely Below average but Did an Definitely Outstanding unsat isfacto ry made an ettort average job above average COMMENTS : Group Leader _________ Date __ Group No. ____ CHEMICAL ENGINEERING EDUCATION

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modified and used by laboratories in Mechanical and Chemical Engineering and Engineering Technology at Texas Tech. It contains a descriptive five-item scale on each of eight team and technology performance at tributes. It also has a section for other comments. I will compile the evaluation data, use that to assign a team member grade, and share the compiled results with the team member. There are several advantages to such an approach. Student leaders can check off attributes without the bias that grading carries and, consequently, may produce a more accurate measure of their team member's performance. Additionally, discussion of the compiled data with each individual may aid coaching for improved performance. Initial feedback is positive. The second negative evaluation concerned the variable difficulty of the projects, and a typical com ment was, "How do you grade a hard program com pared to an easy project?" ... all projects should be either programs or reports." "Don't compare apples and oranges." Students perceive that the computer projects are more difficult than the technology re ports. Considering the level of computer program ming expertise of our juniors, I must agree. Perhaps two-thirds of the class have forgotten both the pro gramming language and the systematic approach to programming learned in their freshman course. They tend to write the entire program at once (without hav ing performed hand calculations for familiarity with the procedure), then become extremely frustrated as they debug simultaneous and interconnected syntax and logic erors. Although I preview this, it remains a problem, and I plan to reducing my expectat~ons on the computer assignment scope and strengthemng my message to the computer simulator project leaders. SUMMARY In an attempt to integrate project management and interpersonal skills development into a junior level transport course, student project exercises were structured with one accountable leader who plans, coordinates, and grades the work of three team mem bers. The exercise structure achieves its objectives and is received well by the students. The course pro fessor must be prepared for the degree of subjectivity introduced and be able to manage personnel problems. Student-to-student evaluations may improve with a non-grade rating form. REFERENCES 1. Everett, Gayle L., "The Transition From Student To En WINTER 1989 gineer," TECHnology MAGAZINE, (a student engineering publication of Texas Tech University, PO Box 4200, Lubbock, TX 79409), 1986 / 87, pp. 10-12. REVIEW: Advances i n Drying Con ti nued f r om pag e 37. the viewpoint of the soil scientist, the equations of change for mass and energy transport, formulation of the relevant mass fluxes, consideration of the trans port properties, and choice of boundary conditions are covered. Experimental measurement of the transport properties also is considered and the drying of soils by buried heat sources is discussed. A mathematical model for convective drying with the incorporation of sorption isotherms is presented in Chapter 5. This chapter is not a review but rather a research paper concerned with the drying of a porous capillary body and accompanied by a very limited bibliography. Chapter 6 is primarily a descriptive review of the solar drying of crops. After a brief discussion of drying prin ciples, the status of solar drying technology together with equipment description is presented. This is fol lowed by a discussion of the design features and typi cal performance characteristics of solar heaters for air. A very brief consideration of the relevant economics concludes the review. Certain principles of operation and design considerations for spouted-bed drying are presented in Chapter 7. Emphasis is placed on the selection of a spouted-bed system and its fluid mechanical characteristics. Three previously pub lished models for describing the performance of this type of dryer are summarized and compared. Chapter 8 is a nontheoretical review of press drying. The prin ciples of operation are summarized and performance data are presented. The mechanical features of exist ing pilot machines and proposals for full-scale dryers as well as alternatives for improved paper densifica tion are given. Those persons interested in drying should find the individual contributions to this volume to be of some interest. The authors of most of the chapters are gen erally recognized authorities in their field. Unfortu nately, much of the material seems to have been edited and/or proofread very rapidly and/or poorly as there are a number of instances of quite awkward grammar, misspelling and, something especially di~ concerting, incomplete nomenclature. The text 1s type-set and production is good except for those few figures which are reproduced by direct photocopy. As with similar publications of this type, the price is high. Because of its restricted technical content, this vol ume should be perused prior to purchase. D 43

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[iJ ;j #I laboratory UNSTEADY STATE HEAT TRANSFER INVOLVING A PHASE CHANGE An Example o f a Project -Orient ed Und er graduate L aboratory D. C. SUNDBERG and A. V. SOMESHW AR U n iversity of New Hampsh i re Durham, NH 038 2 4 T HE C HEMICAL ENGINEERING laboratory e x peri ence for undergraduate students at the University of New Hampshire is composed of a sequence of two courses which are conducted during the second semes ter of the junior year and the first semester of the senior year, respectively. The first course is dedicated to experimentation in the areas of fluid mechanics and heat transfer while the second course involves mas s transfer and reaction kinetics. The students have either had previous classroom courses in the subject areas involved in the laboratory or take the classroom Donald C Sundberg is on associate professor of chemical engineer ing and Director of Industrial Research at the University of New Hamp shire He received his BS from Worcester Polytechnic Institute and his MS and PhD degrees from the University of Delaware. Before c oming to New Hampshire he was on the faculty at the University of Idah o and prior to that spent five years with Monsanto Company He is active in polymer research with emphasis on polymerization kinetics, emul sion po l ymers and polymer morphology (L) Arun V. Someshwa r is currently work i ng as a research eng i ne e r w ith the Institute for Environmental Studies at the University of Illinois, Urbano-Champaign After receiving h i s doctoral degree in chemical engi n eering from Michigan State University in 1982 he served on the faculty of the University of New Hampshire unt i l July of 1988 His research interests ore in the field of air pollution control, primarily in the use of e l ectric fields and discharges fo r enhanci n g the desulfurizo tion a n d denoxing of post-combustion gases. ( R ) 44 courses concurrently with the lab. The laboratory courses require the students to complete one in-depth project as well as other short-term introductory ex periments in each of the subject areas. These in-depth projects have a duration of five to six weeks each, are done typically in groups of three students, involve weekly and interim group written reports, and con clude with the submission of individual written re ports and group oral presentations The oral presenta tions are delivered to the entire laboratory c l ass, in cluding the instructors. The chemical engineering fac ulty and graduate students are also invited to attend. Our objectives for these in-depth projects are to require the students to become involved in the process of thoughtful and effective experimentation as an al ternative to the weekly cookbook" experiments com mon to their previous experience, to have them con front not-so-straightforward problems which require the generation of the bulk of the individual experi ments which may need to be conducted, to have them learn to integrate theoretical approaches and ex perimentation to complete the project, and last but not least to provide them with some unique oppor tunities to develop and demonstrate their written and oral communicational skills. In some instances we have been able to include the concepts of experimental design into the projects, while in all cases we have strongly advocated the use of theoretical mode l s as guides to the choice of useful experiments. The un steady-state radial freezing project described below is one which is a good example of the type of experience our students gain in their lab courses. STRUCTURE O F THE LABORATORY PROJEC T In making up the projects for our lab courses we try to structure the assignments so that they portray a realistic problem w h ich needs to be solved, rat h er than merely the experimental verification of some theoretical concept discussed in the classroom. This is not always easy, but it does make a distinctive differ10 Copyrig h t C hE Divisi.on AS EE 19 89 CHEMICAL ENGINEERING EDUCATION

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ence in the students' viewpoint of what the laboratory is all about. The unsteady-state radial freezing project discussed in this paper has been portrayed in the con text of having to predict the radial freezing of the earth surrounding a proposed storage cavity for liquified natural gas. A copy of the project assignment sheet given to the students is shown in Table 1. At the outset of the project we persuade the stu dents to approach the problem by first substituting pure water for the earth surrounding the cavity and to use dry ice as a substitute for the LNG. They are rather quickly convinced that this would be an easier system to evaluate, and that with the knowledge gained here it would not be too difficult to extend the analysis to the more practical case. Since this is a laboratory course the students naturally think towards experimental equipment, and so they quite rapidly decide upon an arrangement of the type shown in Figure 1. Once this is in place we can discuss with them some of the problems associated with carrying out good experiments, such as insulat ing the top of the tank and the water bath choosing an appropriate temperature at which to keep the liq uid water, and developing enough data to not only provide information about the thickness of the ice and TO: FROM: RE: T AB LE 1 Pro j ec t Ass i gnment Shee t Ms Curie, Mr. Fermi, and Mr. Einstein Dr. Jekylnhyde and the ChE Staff ChE 612 Project II The company in which you are employed manufactures liquified natural gas (LNG) and stores it in underground caverns which amount to nothing more than large holes in the ground with suitable linings. When the extremely cold liquid contacts the earth, it freezes the moisture in the soil and a relatively impervious liner is built up around the LNG The energy removed from the soil is taken up by the LNG and results in some vapor ization of the liquid. In order to project the extent of freezing in the surrounding earth, to gauge its time dependency, and estimate the rate of liquid vap o rization, your group is asked t o develop a laboratory prototype unit in which such an event might be studied. It is sug gested that a simple system could be constructed using iso propan o l/dry ice as a constant temperature vaporizable fluid (at -78.4'C) contained in a metal cylinder surrounded by water. The water would freeze around the cylinder and the front of the freezing zone would progress outward with time. Thermoc o uples could be placed at vari o us intervals through o ut the surrounding water and the temperature, as well as the freezing zone front, could be measured as a function of time. The rate of gas liberation could also be measured. A mathematical model would be useful for interpreting the above data and to make projections in the actual application to LNG. More specifically, on the basis of your model, you are to predict important details pertaining to the storage of LNG in a 20 ft. deep well, 10 ft. in diameter, and surroun d ed by earth with a moisture content of 10%. WINTER 1989 Ou r objectives for these i n-depth pro j ects are to require the students to become involved in the process of thoughtful and effective experimentation as an alternative to the weekly cookbook" experiments common to their previous experience Insulation Thermoco u ple Assembly FIGURE 1. Overall schemat i c o f tank and ice fron t the temperature profile in it, but also to be able to close an energy balance. The latter point is stressed in order to get the students to realize that they can provide internal checks on the reliability of the data, in addition to its reproducibility. The sublimed CO 2 is normally directed through a wet test meter in order to measure its volumetric flowrate and the students quickly realize that they need to understand how such an instrument works in order to convert the measure ments to mass flow rates Another point stressed prior to the time that ex perimentation begins concerns the water tempera ture. In discussing the impact that the water temper ature will have on the overall process, the students are guided (the amount of guidance depends upon the student group) to create an experimental arrange ment which can be most easily analyzed from a model ling point of view. The students are usually quite pleased with their decision to keep the water temper ature at 0C by adding ice to the water bath when they realize that not only did they create a situation in which temperature gradients within the liquid water surrounding the growing ice front do not have to be considered in their analysis, but a l so that energy input to the bath from the surroundings will not be a source of experimental error. MODELING WORK TO GUIDE EXPERIMENTATION During the very early stages of the project the students are required to begin their heat transfer analysis. Most of the students begin the lab course 45

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with the idea that one first runs the experiment and then does the analysis, but our objective is to have them use their analytical capabilities to guide their experimental work and to have them design better experiments. Figure 2 shows the physical characteristics of the heat transfer process to be analyzed. The tank which holds the dry ice/isopropanol mixture is made from brass and has an outside diameter of 68.3 cm and a height of 13.3 cm. Due to the highly agitated state of liquid isopropanol within the tank, the inside wall tem perature may be safely assumed to be at the sublima tion point of dry ice -78.4 C. At the other heat trans fer boundary, the advancing ice front will be at 0 C due to the addition of ice cubes to the liquid water bath. We have insulated the flat bottom and top of the tank with polyurethane foam in order to achieve only radial freezing and to avoid edge effects which are more difficult to analyze. The important features of the analysis are as fol lows: The heat flux at any time q is given as k i ce (21tL) ( To -T2) ln(rice /r2) In terms of the overall temperature difference Due to the large heat transfer coefficient of the highly agitated isopropanol and the high thermal con ductivity of the brass relative to the ice, the flux may be written as (except as very short times) 21tL(T -T)k. O b ice q= ln (r Ir ) !C e 2 (1 ) Also implicit in Eq. ( 1) is the assumption of pseudo steady conduction i e the characteristic conduction velocity (a/lic e ) in the ice is much greater than the velocity of the freezing front (vi ce ). The validity of thi s assumption is to be checked against the data obtained. Since all of the energy must come from the freezing of water at the ice front and the cooling off of the 46 FIGURE 2. Radial view of tank and ice front block of ice, the flux may also be written as q = [t.Hf + CP (T 0 Ta)]dmic e dt (2) where LlHr i s the heat of fu s ion of water T a i s the average temperature within the ice and mi ce is the mass of ice. As an approximation to T a we normally guide the students to take it as Ta = (T 0 + Tb) / 2, or -39.2 C. Since m = 1t(r 2 r 2 ) Lp i ce ice 2 ic e the combination of Eqs. (1) and (2) yields [ t.H + C ( T T )] p r d r f P O a ice ic e ice (T o -T b )~c e d t l n (r I r ) i c e 2 If CP and kic e are taken as constants evaluated at Ta the integration may be carried out to yield t = ( t.Hf + CP (To -Ta) )P i c e 17c e (z [ ~ce ].!._ ) ) ( T T b ) k 2 n 2 2 + 4 O i c e ( 3 ) This expression gives a straightforward relationship between the thickness of the ice and time We have found that the properties of ice at differ ent temperatures are not as readily available as we at first assumed. Our recommendation is to use those values found in N. H. Fletcher's book, Th e Chemical Physics of Ice (Cambridge University Press, 1970). As such, we use t.H f (at ff' c) = 3. 34 x 10 5 J/kg Cp( at Ta =-39.2C)=1806 J/kg K kice ( at Ta = 39 .2c) = 2. 62 Watts /m, K P i ce(at T .. =-39.2C) = 920 kg/m3 CHEMICAL ENGINEERING EDUCATION

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As noted earlier the measurement of the rate of sublimation of the dry ice allow s the s tudent s to mea s ure the actual heat flux, and by its comparison to the calculated heat flux (via Eq. (1) ) to judge the goodness of the data. The actual flux (neglecting heat gain through the well-insulated top of the vessel) may be given as H V .6H q e xp =mco .6 s co = co P c o sco 2 222 ( 4 ) where V is the volumetric flowrate of the sublimed dry ice, P co 2 it s density, and dH s,co 2 is the heat of sublimation of CO 2 at one atmosphere. Although the CO 2 gas is certainly above its sublimation tempera ture by the time it passes through the wet test meter the use of that temperature is not too bad an assump tion (see next section) for calculating P co 2 In the fu ture we plan to require the s tudents to be more aware of the CO 2 temperature within the wet test meter to improve upon the accuracy of the heat flux measure ment. The usefulness of having the students work with the modeling during the early part of the project is that not only have they had to think very hard about the heat transfer process itself but they gain firm ideas about the time frame of a good experiment the eventual thickness of the ice formed during that time and the evolution rate of gaseous COz----especially at short times. We try very hard to get the s tudent s to use this information to guide them in carrying out good experiments. EXPERIMENTAL WORK In this project the experimental work is actually quite straightforward. With the water bath main tained at 0 C by using ice cubes the only real diffi culty is associated with the very beginning of the ex periment. The preferred situation is to have the dry ice / isopropanol mixture in the tank prior to the exper iment and then to instantly place the tank in the water. There are some practical difficulties in ac complishing this not the least of which is keeping frost from forming around the outside of the brass tank. Generally we have found that the easiest way to get the experiment started is to place the tank, con taining only isopropanol into the water bath and then to add the dry ice to the tank. This procedure requires a sacrifice of the early data for the sublimation rates and the radial movement of the ice front due to the necessity of cooling the isopropanol from about 0 C to the dry ice temperature. However, this does happen fairly quickly and we find that it affects less than WINTER 1989 I 3 ,0 12,0 I I ,Q ; .., = JO 0 N 0 9 .oo 7 00 6,00 I!> o E XPERIM E N T AL ICE F RO N TS .. MODEL PRED I CTI O N .. o. 5 00 10 0 )5 0 20,0 25,0 30,0 35,0 4 0,0 45,0 50 0 T I Ml N S I FIGURE 3. Radius of ice front vs. time about 10 % of the time generally required to carry out the experiment. The s tudents normally attach a plexiglass rod to the s ide of the tank which holds a measuring rule and to which can be attached a series of thermocouples. Without an attachment point for the thermocouples we have found that they tend to be displaced outward by the advancing ice front. Once the dry ice is intro duced, data acquisition begins. The temperatures are continuously read off the thermocouples. The gas sub limation rate is also obtained with the help of the wet test meter. The ice front corresponds to an ice temper ature of 0 C and th e time at which a thermocouple reading dips below 0 C ( corresponding to the ice front) is noted for the five equally-spaced thermocouples (2/5 in. apart) A typical run lasts about an hour during which the ice front would have advanced nearly two inches. RESULTS AND DISCUSSION We ha v e chosen to present the experimental re sults of a recent student group studying this subject and judge these results to be about average for the various groups which have been involved in this pro ject. The data represent a series of three experimental runs and as such, give a view of typical experimental reproducibility. Figure 3 shows the radial dimensions of the de veloping ice front (r ice ) as a function of time for three separate experiments. For comparison we have plot ted the model predictions derived from Eq. (3). The goodness of the agreement between theory and exper iment shown in Figure 3 is readily achieved by the student s when they use the proper thermal conductiv ity of ice. In the earlier years of this project assign ment not enough attention was paid to obtaining a representative value for kic e With regard to the 47

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pseudo-steady assumption made in Eq. (1) a typical calculation at t = 20 min in Figure 3 gives Vice = 1.39 x 10--S mis, li ce = 3.43 x 1~ m, and a .s o 0 .so 0 .40 ;:: 0 .3 0 _J 0.20 0. 10 0. o. s.oo 10.0 1s.o 20.0 2s.o 30.0 35.o 40.o 45.o so a T I Ml NS l FIGURE 4. Carbon dioxide sublimation rate vs time 20% during the first few minutes while the iso propanol is achieving its cold temperature and the ice buildup is small. As can be seen in the plot, the data scatter reduced considerably with increasing time. The dotted line in Figure 4 is simply a smooth curve fitted to the data. A number of points along this line are used to compute the average experimental heat flux via Eq. (4). In Figure 5 these experimental heat fluxes are compared with the predicted heat flux via Eqs. (1) and (3). Although the agreement between measured and predicted fluxes is not perfect over the entire time frame of the experiment, it does provide an adequate check upon the closure of the energy bal ance for a major portion of the experiment. In our view this is quite adequate for a junior level project of a relatively short time duration. As an extension of the usefulness of the model de veloped and tested by the students, they are often asked to apply this model to a more realistic problem such as the one quoted in the assignment sheet de scribed earlier. In this case, using representative val ues for the properties of soil with 10% moisture and LNG, they are then able to estimate the maximum extent to which the LNG will vaporize underground and the extent to which the surrounding soil will freeze during a reasonable time frame. 48 EVALUATION OF THE PROJECT For the seven years we have conducted the labora tory course on an in-depth project basis we have found that about 80% of the students respond extremely favorably. They especially enjoy being able to dig into a problem in some detail and find it to be a welcome change from the more common lab course approach utilizing new experiments every week or two. The other 20% have some difficulty with the unstructured nature of such projects and would actually have pre ferred the more common approach, although in our view they would probably do about the same quality of work in either situation. From the instructor's point of view the projects oriented laboratory course is as gratifying as it is dif ficult to manage. We feel that projects such as those described in this paper give the instructor a real chance to teach the students how to apply what they are supposed to have learned in the classroom to a realistic situation, and to guide them to thoughtful and productive experimentation. This usually results in the students feeling more like engineers in control of the experiment rather than like technicians re sponding to a preset list of instructions. The difficulty for the instructor is often in managing ten or more simultaneous projects such as discussed here. Mur phy's Law is a constant companion. A particularly interesting and useful part of the project report is the oral presentation by each group. We have tried a variety of formats for this report including poster sessions and the seminar style of presentation. We have also utilized the video tape and/ or color slides to allow the students to show their equipment and experiments while presenting their a.co 7 oo s.oo 0 s.oo 0 4 .oo 3.00 2 .oo o. s.oo 10.0 1s.o 20.0 2s .o 30.0 3s.o 40.o 45.o so.a T I MINS l FIGURE 5. Comparison of heat flux from CO 2 sublima tion data CHEMICAL ENGINEERING EDUCATION

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seminar-style report in a conference room. A gratify ing part of these presentations is the interest the other student groups show towards the various pro jects and the thoughtful questions that are asked dur ing the discussion section of the presentations. In sum total, we feel that the overall experience is extremely beneficial to both the students and the instructors and is definitely worth all of the work both parties have to do. NOTATION CP heat capacity of ice (J/kg K) hb boiling heat transfer coefficient (W/m 2 K) L length of ice formation (m) k thermal conductivity (W / m K) m mass of ice at time t (Kg) rh mass flow rate of CO 2 (Kg/s) r radius described in Figure 2 (m) q = heat flux (W) t = time (s) T = temperature as described in Figure 2 (K) T a average temperature of ice block (K) V volumetric flow rate of sublimed dry ice (m 3 /s) p density (Kg/m 3 ) .:iHr heat of fusion of ice (J /Kg) .:iH 8 = heat of sublimation of CO 2 (J/Kg) 0 REVIEW: Reactor Design Continued from page 31. sively used in problem solving. This chapter introduces the concept of non-linear regression analysis and then illustrates it to the problem of kinetic parameter estima tion. Chapter 5 deals with the application of the concepts of earlier chapters to design and optimization A number of case study examples are presented. The role of reac tor design on selectivity is not discussed satisfactorily. Here an almost "Levenspielian" type of discussion would have been extremely beneficial from both a pedagogical and a practical point of view. The coverage up to this point would probably fit nicely into a senior class in chemical reaction engineer ing. The instructor could assign a number of "end of chapter" problems in addition to assigning the case studies as computer simulation exercises. This would al low the students to get a fairly good grip on the use of modern computer based techniques. The subsequent chapters cover more advanced top ics. Chapter 6 discusses the laminar flow reactor, and this requires the solution of partial differential equation in two variables. The technique presented is a finite dif ference method. The chapter al8'> discusses problems WINTER 1989 involving variable viscosity, which are important in polymer processing This chapter would blend in nicely for those students simultaneously taking a graduate level transport course. The effect of non-idealities in the residence time is discussed in Chapter 7 where the axial dispersion model is discussed for both isothermal and non-isothermal re actions. The numerical solution strategy discussed here for the solution of the two point boundary value prob lem is the shooting method. The orthogonal collocation provides a more powerful solution method for these types of boundary value problems, but there is no men tion of this method. A number of library packages such as COLSYS or PDE/PROTRAN could be directly used here, and it would have been useful to provide a brief exposure to the use of one or two commercially avail able software to reaction engineering problems. Chapter 8 deals with unsteady state analysis ofreac tors. A number of examples are shown on the dynamics and control aspects. I found the examples both real and very illustrative. Chapter 9 deals with the effect of mixing in continu ous flow systems. In addition to providing the necessary mathematics, a valuable qualitative discussion on the mixing effects on reactor performance is presented. This should help the students to build a conceptual base. However, the Zwietering differential equation is in troduced suddenly without any derivation or even a qualitative basis More discussion here would have been useful. Chapter 10 deals with heterogeneous catalysis, while Chapter 11 deals with multiphase reactors. Some appli cations to new processes such as biochemical reactors and electronic device fabrication are included The treatment on three phase reactors is very sketchy. The emphasis on computer applications which was the theme in the first half of the book is unfortunately lack ing here. For example, the author could have shown the use of single point collocation in the evaluation of effec tiveness factors for nonlinear kinetics. A number of de sign problems in multiphase reactors can be solved by simple computer programs (The Omnibook gives a rundown of typical examples.) These could have been useful. The final chapter is exclusively devoted to polymer reaction engineering, which is unique since many books do not even mention this word. The second part of the book (Chapters 9 through 11) provides sufficient content for a graduate course, al though the instructor would have to supplement the text with additional reading materials or notes to provide further details on many of the topics. The coverage of emerging areas would be useful in such a course, and the book would motivate the students to read more on those topics. The incorporation of the computer methods in the teaching of reaction engineering is vital, and the book provides a valuable reference source in this field. a 49

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[eJ n ?I classroom LUBRICATION FLOWS TASOS C. PAPANASTASIOU The University of Michigan Ann Arbor, MI 48109-2136 L UBRICATION FLOWS ARE perhaps the most ap plicable material of fluid mechanics at both the undergraduate and the graduate levels. At the under graduate level, important one-dimensional approxima tions such as channel, film, and coating flow equations can be derived and studied from simplified mass and momentum balances by means of the control volume principle or else by simplifying the general equations of change (Navier-Stokes). This leads to the cele brated Reynolds equation [1] R ( h, p, Ca) = 0 (1) where h is the thickness of the narrow channel or of the thin film, p is a generalized pressure, p = P St g where St = pgD 2 / Vis the Stokes number and g the gravity acceleration in the direction of fluid motion. The capillary number, Ca = V / rr, usually enters Tasos C Papanastasiou received his Diploma in Chemical En gineering from the National Technical University of Athens, and his MS and PhD in chemical engineer i ng from the University of M i nnesota His research interests are in fluid mechanics, rheology, and materials processing through the balance of the normal stresses at a free surface. Eq. (1) can be solved: To find the pressure distribution and relative quantities (load capacity, friction and wear, cavitation, etc) when the thickness h(x) is known. The most typical application is journal-bearing lubrications. To find the thickness h(x) when the pressure is known. The most typical applications are formation of thin films and coating applications. Eq. (1) is not always solvable analytically. In some extreme cases it is solvable by simplified perturbation techniques. By the time the student reaches the solu tion, he /s he must have dealt with Derivation of governing differential equations by mass and momentum balances on appropriately chosen control vol umes (or alternatively, the Navier-Stokes equations). Order of magnitude analysis to derive the lubrication equa tions. The solution of the differential lubrication equations sub ject to boundary conditions, to find the velocity profile. The integral mass conservation equation to derive the Reynolds equation. The surface tension and the curvature of a thin film, to find the pressure distribution. The solution of the Reynolds equation, to find the film thickness or the pressure distribution. Simplified perturbation techniques to find limiting solu tions to the Reynolds equation. Thus lubrication flows cover most of the material taught in undergraduate fluid mechanics and at the same time are attractive to the student because they deal with practical problems. ---------Co pyright C hE D iviswn ASEE 1989 50 CHEMICAL ENGINEERING EDUCATION

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The most important applications of the thin film lubrication equations are films falling under surface tension, nonisothermal films, dip and extrusion coating, and wetting and liquid spreading. A similar class of problems includes centrifugal spreading, common in bell sprayers and in spin coating. INTRODUCTION The lubrication approximation for flows in nearly rectilinear channels or pipes, of nearly parallel walls, can be derived intuitively from the equations of flow in rectilinear channels and pipes. The equations that govern flows in rectilinear channels and pipes are the continuity or mass conservation which demands con stant flow rate crux -=0 ax uz = O; u, =f(z) (2) and the equation of conservation of linear momentum in the flow direction dP dx (3) which under constant presure gradient, dP/dx, pre dicts linear shear stress and parabolic velocity pro files. The gradient, dP/dx, is usually imposed mechan ically and, since the channel is rectilinear and the mo(a) dx (b) dx P+dP FIGURE 1. Force balance in a rectilinear flow, h 0 dP = 2rdx, and in lubrication flow, h(x) dP(x) = 2r(x)dx. WINTER 1989 tion steady, it is constant along the channel (see Fi gure la), equal to aP/aL, where aP is the pressure difference over distance aL. Thus, the mechanism of motion is simple; flow of material from regions of high pressure to regions of low pressure. This is Poiseuille flow. When one or both walls are in slight inclination, a, to the midplane of symmetry, the same governing equations are expected to hold which may now be lo cally weak functions of x, of order a. The most obvious difference is the pressure gradient, dP/dx. In the case of a lubrication flow which may be accelerating or de celerating, in a converging or diverging channel, re spectively, dP/dx is not constant along the channel because the pressure forces needed to move two cones of liquid of the same height dx at two different posi tions along the channel are different (see Figure lb). Thus, dP/dx is a function of x and so is the velocity in the governing equations au,. au. --+-=0 ax az 2 dP(x) a Ux --=-dx az2 (4) (5) Both Eqs. (3) and (5) express conservation oflinear momentum or the Newton's law of motion that there is no accumulation of momentum in a control volume because there is no substantial net convection, and the forces capable of producing momentum are in equi librium. According to Newton's law of motion there is no acceleration (actually the acceleration is vanish ingly small in lubrication flows) because there is no net force acting on a control volume. The forces on the control volume, of height ax, are net pressure force (dP/dx)A(x) and shear stress force A(x)dxTxy (Figure lb). The underlying mechanism is more complex than in the Poiseuille flow. First, the moving wall on one side sweeps fluid into a narrowing passage through the action of viscous shear forces, which gives rise to a local velocity profile of Couette-type ux = Vy/h, with flow rate, Q = Vh/2. Because Q is constant by continuity and h(x) is diminishing, the flow sets up a pressure gradient to supply a Poiseuille component 51

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that redistributes the fluid and maintains a constant flow rate (Figure 2). Derivation of Lubrication Equations by the Navier-Stokes Equations Alternatively, the lubrication equation can be de rived by order of magnitude and dimensionless analysis of the full, two-dimensional, Na vier-Stokes equations aux au. --+-=0 ax ] az [ 2 2 ] aux aux aux aP a Ux a ux p[-+u --+u -=--+ --+-at X ax z az ax ax 2 az 2 (6) ] [ 2 2 ] au. au. au. aP a Uz a Uz p[-+u -+u =--+ --+-at X ax z az az az 2 ax 2 (7) where x is the direction of flow and z the gapwise direction. The geometry of the flow is shown in Figure 2. There are several good reasons to work with di mensionless equations and variables: to reduce the de pendence of the solution to minimum dimensionless numbers; to simplify the equations judging from the relative magnitude of a dimensionless number to one; and to scale-up experiments to real applications of the same dimensionless number. To achieve these goals The dimensionless variable, say u*, must be of the order of one. By using the boundary velocity V, then ut = uxN may at most vary between zero and one, and sou* is of order one. If the problem lacks the characteristic dimensional variable, V, in the previous paragraph, then it is made-up by combining other characteristic vari ables. For example, for time, t* = t/(LN). The characteristic dimensional variable for pressure is P = V/aL, because viscous forces, which resist the motion, are in equilibrium with the pressure forces, as shown by Figure 1. Accordingly, define x*=..!... L' u* X z*= _z_. a.L' t*=.!:{ L' h*= -1l.. a.L' u. Uz = a.V; P*=-P_. V a.2L (8) which upon substitution in the N-S equations, yields 52 Translationally Symmetric d z I .... -Flow k\ X V V FIGURE 2. Geometry of a two-dimensional lubrication flow. The velocity profiles along the channel are mix tures of Couette and Poiseuille. (with asterisk suppressed hereafter) ( ) ( 2 2 J au. au. au. aP a u a u cil Re -;:+ u x-a+ u.-a= -a + a.4-- + a.2 __ z (10) UL X Z Z ax 2 az2 The lubrication equation holds in geometries where a < < 1. Since all the dimensionless terms and derivatives in these two equations are of order one, the resulting lubrication dimensionless equations are in the limit of a = 0 and aRe = 0, 2 aP a ux --+--=0 ax az 2 aP =O az (11) (12) These equations are similar to those derived intui tively from channel flow [e.g., Eqs. (2) and (3)]. Notice that high Reynolds numbers are allowed as far as the product aRe is vanishingly small and the flow remains laminar. The appropriate boundary conditions to Eqs. (5) and (11) are CHEMICAL ENGINEERING EDUCATION

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At z = 0, Ux = V (no-slip boundary condition) At z = h, ux = 0 (Slit Flow), (no slip boundary con dition) or z = h, Tzx = 0 (Thin Film), (zero shear stress at free surface) Under these conditions the solution to Eq. (5) is u = ..1.... dP ( zhz 2 ) + V V x 2 dx h (Slit Flow) (13) u = J:... dP ( 2 zh z 2 ) + V x 2 dx (Film Flow) (14) The volume flux and the pressure distribution in the lubricant layer can be calculated when the flow rate Q, and the inclination a, are known. A lubrication layer will generate a positive pressure and thus load capacity, normal to this layer, only when the layer is so arranged that the relative motion of the two sur faces tends to drag fluid by viscous stresses from the wider to the narrower end of the layer [2]. The load W, supported by the pressure is J L 6V [ d ( aL )~ W = (PP 0 )dx= log daL -2 2 daL 0 (15) Thus the inclination a, is responsible for the pressure build-up by decelerating the flow and transmitting momentum and thus load capacity to the upper boun dary. Reynolds Equation for Lubrication Mass conservation on an infinitesimal volume yields dh Qx + dx + Qx = dxdt (16) which states that the net mass convection in the con trol volume is being used to increase the volume at rate d/dt (dxdh) where dx and dh are the width in the flow direction and the height of the volume, respec tively. Rearrangement yields (17) which for confined and film flows reduces to d [ 1 dP Ji3 h v] dh ----+=-(Sht Flow) dx 2 dx 6 2 dt (18) and WINTER 1989 .J!...[_ 1.. dP h 3 + hV]= dh dx dx 3 dt respectively. (Film Flow) Solution of Steady Reynolds Equation for Slit Flow The steady-state form of Eq. (18) is integrated to (19) and one proceeds according to Batchelor [2] and Denn [3] to the calculation of pressure X d X d P(x)= P 0 + 6V J ~12 Q J (19a) 0 Ji ( X) 0 Ji ( x) where Q= L J n 2 (x)dx 0 L f n 3 (x)dx 0 (19b) Then one can proceed to the evaluation of load capac ity (19c) and of shear or friction F= f 't ds B zx (19d) on the surface, S. It is easy to show that the load capacity is of order a2 whereas the shear or friction is of order a1 Thus the ratio load/friction increases with a1 The most important application of the lubrication theory for confined flows in journal-bearing [ 4] and piston-ring [5] systems of engines. Other flows that can be studied at the undergraduate level by means of the lubrication equations, include wire coating [3], forward roll coating [6], and many polymer applica tions [7]. The solution to these problems follows the procedure outlined above, starting from Eq. (17). The flow rate is usually given by (20) 53

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where V is the speed of production and hr the final thickness. The boundary condition on the pressure at the outlet may vary [8]. P(L) = 0, dP(L)/dx = 0, or P(L) = 2/(hr)2. Solution of Steady, Reynolds Equations for Film Flow In confined lubrication flows there is pressure build-up due to inclination, a, and backflow of some of the entering liquid. The pressure is then u sefu lly used to support loads. In thin film lubrication flows, any pressure build-up is due to surface tension, and in fact if the surface tension is negligible the pressure gra dient is zero. The steady-state form of Eq. (19) _A_ [1. dP ..!{_ + Vh] = O dx dx 3 is integrated to 1 dP }{ -+ Vh = Q = Vh dx 3 f (21) The film thickness, h, is not known. However, the pressure drop, dP/dx, can be deduced from the surface tension by means of the Young-Laplace equation under the lubrication requirement that the slope dh/ dx, must be much less than unity ih cr-d-x2 i h --="---~cr-dx2 -P= (22) Here h(x) is the elevation of the free surface from the x-axis, and rr the surface tension of the liquid. Then dP ih -=cr-dx dx3 and substitution of dP/dx in Eq. (21) yields cr h 3 i h ---+hV=Vh 3 dx3 f which is rearranged to ih Jr 3 + 3 Ca ( h hr) = o dx 54 (23) (24) (25) The capillary number Ca = V/rr is another di mensionless number and measures the viscous to sur face tension forces. Eq. (24) is highly nonlinear and cannot be solved analytically. The most important applications of the thin film lubrication equations are films falling under surface tension, nonisothermal films, dip and extrusion coat ing, and wetting and liquid spreading. A similar class of problems includes centrifugal spreading, common in bell sprayers and in spin coating. A rich collection of lubrication problems from polymer processing can be found in Pearson [7, 9) and from coating in several theses under Scriven [10). CONCLUSIONS Lubrication flows are ideal for undergraduate stu dents to cover and learn a significant amount of fluid mechanics material. This material includes the differ ential Na vier-Stokes equations, dimensional analysis and simplified dimensionless numbers, control volume principles, the Reynolds lubrication equation for con fined and free surface flows, capillary pressure and simplified perturbation techniques. Problems and sol utions can be easily chosen from practical and interest ing applications such as journal bearing, expanding pipe flow, film flow, and several polymer and coating operations. REFERENCES 1. Reynolds 0., "Papers on Mechanical and Phy sic al Asp ects," Phil. Trans. Roy Soc. 177, 157 (1986) 2. Batchelor G K. An Introduction to Fluid Dynamics, Cambridge University Pr ess, New York (1979) 3. Denn, M. M., Process Fluid Mechanics, Prentice Hall, New York (1980) 4. Tipei, N., Theory of Lubrication, Stanford University Press (1962) 5. Miltsios, G. K., D. J. Patterson, and T C. Papanastasiou, "Solution of the Lubrication Problem and Calculation of the Friction Force on the Piston Rings," submitted to J. Tribology (1988) 6. Middleman S., Fundamentals of Polymer Processing, McGraw-Hill, New York (1977) 7. Pearson, J. R. A Mechanical Principles of Polymer Processing, Pergamon Press, Oxford (1965) 8. Bixler, N. E., "Mechanics and Stability of Extrusion Coating," Ph.D. Thesis, University of Minnesota (1983) 9. Pearson, J. R. A., Mechanics of Polymer Processing, Elsevier Applied Science Publishers, London and New York (1985) 10 Scriven, L. E., "Fluid Mechanics, Lecture Notes," University of Minnesota (1980-88) 11. Papanastasiou, A.C., A. N. Alexandrou, W. P Graebel, Rotating Thin Films in Bell Sprayers and Spin Coating," J. Rheology, 32,485 (1985) CHEMICAL ENGINEERING EDUCATION

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APPENDIX Vertical, Dip Coanng An example of thin lubrication film under gravity, surface tension and viscous drag arises in dip coating, shown in Figure 3. This method of coating is practiced to cover m et als with anticorrosion layers and to laminate paper and polymer films. The substrate is being withdrawn at speed V from a liquid bath of density p, viscosity and surface ten sion a. The analysis will predict the final coating thickness as a function of the processing conditions (withdrawal speed) and of the physical characteristics of the liquid (p, and cr). So/,ution The governing momentum equation, with respect to the shown cartesian syst e m of coordinates is 2 dP a uz --+---pg= 0 dz ay2 The boundary conditions are uz(y=0)=V and duz 'tzy ( y = H) = -= 0 dy The particular solution is 1 (dP )(y 2 J u = + pg -Hy + V z dz 2 The resulting Reynolds equation is 1 ( dP )H 3 + pg + VH = Q = VHf dz 3 where Hr is the final coating thickness The pressure gradient dP iH -=-cr-dz dz 3 (Al) (A2) (A3) (A4) (AS) ( A6 ) is replaced in Eq (AS) to yield the final Reynolds equation ( cr :z~ pg) + V ( HHr) = 0 (A 7 ) which is rearranged to the form 3 3 3 !!_ d H_ pg.!!_+ V(H-H )=0 3 dz3 cr 3 cr f By identifying the dimensionless numbers and WINTER 1989 V Ca= cr (AB) (A9) Plat e V r ~ .: . ... .~ .. w FIGURE 3 D i p Coat i ng : A coated plate i s being w i th drawn from a coating solut i on. A f i na l thin f il m or coat i ng results on t he p l a t e under the c ombined action of gravity, s urface tension and drag by the moving sub s trate Eq. ( A8 ) becomes 2 pgHf St=V 3 3 3 !!_ d H St...!!_ +3(H-H ) =0 Ca dz3 H2 r f (Al0) (All) which can be solved directly for the following limiting cases: 1. Negligible surface tension (Ca oo) Eq. (All) reduces to the third-order algebraic equation 3H 2 3H 3 H3 _ r_ H + _ r_ = 0 St St (A12) In the limit of infinite St (i.e., very heavy liquid!), the only solution is H = 0, i e no coating. In the limit of zero St (i.e., horizontal arrangement), H = Hr i.e., plain Couette (plug) flow. For finite values of St the solution is independent of z, which predicts a flat film throughout. 2. Infinitely large surface tension (Ca 0) Eq ( Al0 ) reduces to iH --=0 dz 3 with general solution (A l 3) (A14) 55

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along with the boundary conditions H(z=0) = W/2, H(z=L) =Hr (dH/dz)z:L=0 The solution is ( W-2HrJ( 2 ) w H(z)= L2 z2 -zL +2 (A15) which is a parabolic film thickness 3. Finite surface tension (O < Ca < kl Eq. (All) is cast in the form H 3 [iH_ S;Ca]+3Ca(H-H )=0 dz3 H2 f f (A16) with no apparent analytic solution. For a speci a l case of hori zontal coating (St = 0 ) and since usu a lly Hr I W << 1, th e transformation H=l!_ W z z =w ( A17 ) reduc e s Eq. (A16) to iH ( Hr) H -+ 3 Ca H = 0 dz w (Al8) which predicts that near th e inlet, where H* "' 1, the film de cays with rate depending on the Ca. Near the oth e r end, wh e re H* "' 2Hf/W, the film becomes flat, surface tension becomes unimportant, and therefore the slope is zero. Eq (A18) can be solved asymptotically by perturbation techniques. 0 CHEATING Cont i nued from pag e 17. this paper. Perhaps these considerations will motivate us to develop innovative ethics curricula and to im prove monitoring of course activities, so that our dis ciplines may be able to better safeguard (and perhaps even increase) their already high levels of excellence. REFERENCES 1. Tom Nicholson with William D. Marbach, "A Dead Stop in the Ford Pinto Trial?," Newsw e ek 95: 25 February 1980 pp 65-66 2. Neil R. Luebke, "How to Interest Engineering Ethics Stu dents in Philosophical Ethics," Proc e edings of the 19th An nual Midwest Section M ee ting of the American Soci e ty for Engineering Education, March 21-23, 1984 IIA p 3. 3 Charles E. Reagan and John 0 Mingle Engineering Ethics," Proceedings of the 19th Annual Midwest S ec t i on Meeting of the American Society for Engineering Education March 21-23, 1984 IIA p. 5 4 John S Baird, "Current Trends in College Cheating," Psychology in the Schools, 1980:17 p. 517. 56 5. Arizona State University College of Engineering and Applied Sciences Student Conduct Committee Halt Cheat i ng, Re vised August 1982 p. 9 6 Edwin A Sisson and William R. Todd-Mancillas "C heating in Engineering Courses: Short and Long-term Consequences," Proce e dings of th e 19th Annual Midwest S e ction of the American Soc ie ty for Eng ine ering Education March 2123, 1984 IC p. 4. 7. David C. Barnett and Jon C. Dalton, "Why College Students Cheat," Journal of College Stud e nt Personn e l, 22(6) 1981 p. 549 550 8. Richard A. Dienstbier Lynn R Kahle Keith A. Willis Gil bert B Tunnel "Impact of Moral Theorie s on Cheating ," Moti v ation & Emotion, Volume 4. No. 3, 1980, pp. 193-216. 9. Jack B. Evett "Cozenage: A Challenge to Engineering In struction Eng ineeri ng Ed uc at ion: February 1980, p 434 Gerald R Peterson, Further Comment s on Cozenage, En gineering Education : November 1980, p. 182. 10. William R. Todd-Mancillas and Edwin A Sisson, "Cheating Among Engineering Students : Some Suggested Solutions," Engineering Educat i on : May 1986, p. 757 758. 11. Richard M. Felder, "Cheating-An Ounce of Prevention, Chem ic al Engine e ring Education : Winter 1985, pp. 12-17. D !, P~,,. !>-->C t STATEM i:NT OF OWNrnS HIP MANA GE M E NT AN O C I RC U LA TI O N ,-,.,..,,,J,,. JYl. JC JNJ 5 c ..... ~i.,o ""-"""; 1.00,eu ol 111e M aouan.,, ol Cir..,.,a1 IVl,...n Olloc:H 01 ,._.,.., t.._ _,,,, Oieiucal E..'l9.a.neer1ng Division, /.,,Jrican society for t:ng1neering tducat.:i.on 11 DuPont Cl.rcle, \o/ash1n9ton, DC 2D030 & FuM "-mu nd Comi,!ace 1l,ng AOT., Wa .d J PuDhln" tl\u...,a,..JCo,yi,i Mol,~1Atl,J ,. 1C>81 R 1 I H ID# M S.,.. 1J /2 -')J ln1 ..... ,~-... o -p,0 01 n.,.., ol ., ..... 1 i.n .... -I IIII U I ,_ F_ .. ......... .. _..., .. /01,,d '" ~. :c: o~~~~"::!,~ ~ ""t u,...,. ,"' .....,,..,, ....., .,,..__., II~ Mu -1 E.i 1 nt 1 n<1 utu, 1 o!C,.cut 1 uon 1S, ,,..,,,,, ,.,,...., ,, w,. St4t/ A To1elN1>Co; ,. ,to;,.,-,..,,_ .,,, 1 ,.,. ,.o.,.Ro<,, .... 11<1c .. a,1e,_ I S !e tlvaulJ" cle1Je11 0""'" """" w1noo,1 c.....,., '1 ~ 5uDICIICl1'Clfl ,,_..,,,,,.,,,~.,"'I C T o 11 ll'a,d1Nlo ~o u ut dC"c u1tuon ,s.,,..,, /01111>"4/0IJlJ 0 f, .. o,,,,....,,_ DY M al, c ... . "' O u , M s. c ............. ..... 0t M, f, ... CF Coo
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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 edu cation. Papers generally describe a course, a laboratory, a ChE depart ment, a ChE educator, a ChE curriculum, research program, machine computation, special instructional programs or give views and opinions on various topics of interest to the profession. Specific suggestions on preparing papers TITLE. Use specific and informative titles. They should be as brief as possible con si stent 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 the footnote on title page. TEXT Consult recent issues for general style. Assume your reader is not a novice in the field. Include only as much h i story 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 which 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 un its of measurement and give dimensions for all terms Write all equations and formulas clearly, and number important equations consecutively ACKNOWLEDGMENT Include in acknowledgment only such credits as are essential. LITERATURE CITED. References should be numbered and listed on a separate sheet in order occurring in text. COPY REQUIREMENTS. Send two legible copies of manuscript, typed (double-spaced) on 8 X 11 inch paper. Clear duplicated copies are acceptable. Submit original drawings (or sharp prints) of graphs and diagrams, and clear glossy prints of photographs. Prepare original drawings on tracing paper or high quality paper; use black India ink and a lettering set Choose graph papers with blue cross-sectional lines; other colors interfere with good reproduction Label ordinates and abscissas of graphs along the axes and outside the graph proper Figure captions and legends may 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 If drawings are mailed under separate cover identify by name of author and title of manuscript State in cover letter if drawings or photographs are to be returned Authors should include brief bio graphical sketches and recent photographs with the manuscript

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