Chemical engineering education ( Journal Site )

Material Information

Chemical engineering education
Alternate Title:
Abbreviated Title:
Chem. eng. educ.
Physical Description:
v. : ill. ; 22-28 cm.
American Society for Engineering Education -- Chemical Engineering Division
Chemical Engineering Division, American Society for Engineering Education
Place of Publication:
Storrs, Conn
Publication Date:
annual[ former 1960-1961]


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


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-

Record Information

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

Full Text

ceial engineeri g edcaio

We wish to

acknowledge and thank...



...for supporting

with a donation of funds.

Chemical Engineering Education
Department of Chemical Engineering
University of Florida
Gainesville, FL 32611

EDITOR: Ray W. Fahien (904) 392-0857
MANAGING EDITOR: Carole Yocum (904) 392-0861


Gary Poehlein
Georgia Institute of Technology

Klaus D. Timmerhaus
University of Colorado

Lee C. Eagleton
Pennsylvania State University


Richard M. Felder
North Carolina State University

Jack R. Hopper
Lamar University

Donald R. Paul
University of Texas

James Fair
University of Texas

J. S. Dranoff
Northwestern University

Frederick H. Shair
California Institute of Technology

Alexis T. Bell
University of California, Berkeley

Angelo J. Perna
New Jersey Institute of Technology

Stuart W. Churchill
University of Pennsylvania

Raymond Baddour
Massachusetts Institute of Technology
Charles Sleicher
University of Washington

Leslie W. Shemilt
McMaster University

Library Representative
Thomas W. Weber
State University of New York

Chemical Engineering Education


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


6 Rensselaer Polytechnic Institute, Michael M. Abbott


12 Accreditation: Changes are Needed,
Charles A. Sleicher


16 Cheating Among Engineering Students: Reasons for
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


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


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


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.


I educator

Warren E. Stewart

of Wisconsin

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-
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


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


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
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."


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-


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

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


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
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."

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


m[J^ departmentt



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


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.

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,


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.
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-


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/
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-

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


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-
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.

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.

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-


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
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


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


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

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.


n3views and opinions


Changes Are Needed

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
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-


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

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
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-
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
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


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
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-
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-


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.

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-
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.

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

*AIChE representative on the ABET E&A Commission.




Reasons for Concern

California State University, Chico
Chico, CA 95929-0502
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
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


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.





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

Course Outline

I. An introduction to philosophy of science
A. Logic, reasoning processes, and logical fallacies
B. Scientific method
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
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.


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
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.


The course was organized to achieve four broad
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

Books Utilized in the Course

Required Texts

Time's Arrows, by R. Morris: Simon & Schuster, New York,
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,
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


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-
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

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

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;
"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;

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
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


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

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

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
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
G. R. Gavalas
California Institute of Technology
Pasadena, CA 91125


curriculum :



PART 1: Deriving Conceptual Design Tools

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.

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



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.

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

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.

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-
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.


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)

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.

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


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.

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

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

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

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

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


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


Random Thoughts ...


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-
* 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
* 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
* 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).


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

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


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.


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. []


curriculum I



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


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

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



follow. Deadlines were established for the items shown
in Table 1.
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.

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-
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.

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.

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.

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 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


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.

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.

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

Only do as many projects for which there is adequate fund-
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.

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


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




Texts from


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
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.

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.

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

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.

605 Third Avenue
WILEY NewYork, NY10158 sah/m


Li laboratory



Microbial Oxidation of Hydrogen Sulfide

The University of Tulsa
Tulsa, OK 74104

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

Na2S203 or H2S(g)
Trace metal solution*
Mineral water

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-
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


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

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

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

* Average of four determinations

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







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


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-

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
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
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




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


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
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-
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

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,


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,
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.


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 -

- '-a2




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 -


6.5 -

450 -

400 -

- 350-

- oo -


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).


is oxidized and the cell population increases. Lastly,
hydroxide is steadily consumed as acid is produced by
the process.
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-

1. Baalsrud, K., and K. S. Baalsrud, "Studies on
Thiobacillus denitrificans," Arch. Mikrobiol., 20, 34-62
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

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

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

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.






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
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


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.


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

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
Developing and validating correlations
Steam tracing
Evaporators/cooling towers
Temperature measurement device technology and

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
Personality development and inappropriate adult behavior
Decision analysis
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?


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.

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.
Comments from the semester-end student course
evaluations are one source of results. Verbatim they

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
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


... 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].

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
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.


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

Group Member Evaluation Form


Experiment No.

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


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
Distant & aloof Friendly once Warm, friendly, Very sociable & Excellent
known by others and sociable outgoing
PARTICIPATION is being available for and participating in group
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
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

Group Leader
Group No.


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.

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.

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. [


m laboratory



An Example of a 'Project-Oriented' Undergraduate Laboratory

University of New Hampshire
Durham, NH 03824

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


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.

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


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

Project Assignment Sheet


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.


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.

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


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
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-
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

- 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
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


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-
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.

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


S9.00 -



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
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

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
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


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










U *-~


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.

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





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

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


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.

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-
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
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
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
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




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

through the balance of the normal stresses at a free

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-
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


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.


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 = 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
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


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

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
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)

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)

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
The appropriate boundary conditions to Eqs. (5)
and (11) are


At z = 0, ux = V (no-slip boundary condition)
At z = h, ux = 0 (Slit Flow), (no slip boundary con-
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-

Reynolds Equation for Lubrication
Mass conservation on an infinitesimal volume

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)


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)


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


Then one can proceed to the evaluation of load capac-

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


and of shear or friction

F= f ,x ds


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


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

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.

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)

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].

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


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)



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).


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

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

The boundary conditions are

uz(y= 0)= V (A29

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= -


- -

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-

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



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
with general solution

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





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)



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

H* H

. = Z


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

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.


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.
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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LL ~cemcal Engineering Davision, 11 Dpont circle, Washington, DC 20030
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