to Ailing Thermodynamics
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Contents for Volume 1, No. 3, Apr. '66
37 First Aid To Ailing Thermodynamics
H. T. Bates
44 Shri Jyant Saraiya, Engineer
46 Unit Operations To Transport
M. T. Willis
52 Evaluation Of An Approach
To Plant Design
D. R. Woods
and A. E. Hamielec
iii Editors' Corner
45 Speaking Out
48 What They're Using
R. L. Kenyon
K. M. Kiser
To the question "What is engineering?" there are
a variety of answers given today. Some are help-
ful, many are confused, a few border on nonsense.
Their variegation is impressive, their capacity for
mutual contradiction startling. But within the
broad range of ideas about engineering there is
wide agreement that design-itself a subject of
diversified definition-is a central engineering
function and an earmark of the field. It is heart-
ening, therefore, to see a renascense of process
design courses in chemical engineering curricula.
The significantly creative efforts in process design
pedogogy at McMaster University, M.I.T., Dart-
mouth, and Michigan, to name a few, promise a
bright future for the teaching of design to chemi-
cal engineering undergraduates, graduate students,
and industrial practitioners.
Process design is as complex as it is important,
and to strive for it to yield increasingly optimum
plants is to move toward complexity and difficulty
that are orders of magnitude greater. In an
engineering world where the system seems to be
a new discovery in mechanical and electrical
realms, the chemical design engineer is an old
and calloused hand at dealing with the super
system: a chemical manufacturing process that is
a linkage of components each of which itself may
be a quite sophisticated system. It is appropriate,
then, that process design become an unparalleled
illustration of splendid systems engineering. The
challenge that it do so is matched by a remarkable
convergence of favorable conditions: necessary
knowledge was never more plentiful, technique
never more advanced, computation never more
facile, the incentive never stronger.
CHEM ENG ED commends to its readers the
significant articles on process design pedagogy
carried in this issue and in the preceding one.
Others will follow from time to time. Watch for
Chemical Engineering Division, American Society for Engineering Education
Editor Shelby A. Miller
Consulting Editor Albert H. Cooper
Assistant Editor John W. Bartlett
Publications Committee of CED
L. Bryce Andersen Chairman
Charles E. Littlejohn
E. P. Bartkus
James H. Weber
Executive Committee of CED
Chairman John B. West
Chairman-elect J. A. Bergantz
Secretary-Treasurer William H. Honstead
Elected Committeemen J. T. Banchero
W. H. Corcoran
Past Chairman George Burnet
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The official journal of the
CHEM ENG ED
to Ailing Thermodynamics
H. T. Bates
Professor of Chemical Engineering
Kansas State University, Manhattan, Kansas
Engineering educators stand accused by
those investigating the drop in engineering
enrollment, of practices that tend to dis-
courage students (2). It appears that there
may be just basis for the accusation, par-
ticularly apropos of some of the literature
with which students are forced to contend.
There is a literary form called the objec-
tive correlative. It was used extensively by
T. S. Eliot. It has been likened to beefsteak
that a burglar carries to divert the watch-
dog while he robs the safe (3). Mr. Eliot's
poetry abounds in this sort of thing; the
casual reader gets something-the beef-
steak-but it takes real digging to find the
underlying idea-the contents of the safe.
Eliot must have felt a little sorry for his
readers, because he later published foot-
notes to trace some of his ideas. His good
friend, Ezra Pound, on the contrary, felt
that it wasn't sporting to put in any foot-
notes at all.
Even some of the scientific disciplines are
producing technical literature that re-
sembles the objective correlative in the
confusion it offers the reader. (Nicholas
Vanserg's pieces "Mathmanship" and "How
to Write Geologese" are entertaining com-
mentaries on publications in two fields
(6, 7).) Engineering has not been a major
offender in this respect, although examples
of misleading prose and illogical termin-
ology can be found in our literature (1, 5).
An important instance occurs in the sub-
ject of thermodynamics. It is the purpose
of this article to propose reforms in the
subject; to rearrange the concepts into
forms that are more logical under modern
conditions; to alter some definitions and
conventions in the interest of clarity; and
to propose a unifying treatment that can
be presented immediately to beginning
If this objective is to be successful, a
certain amount of re-education of faculty
members and research workers will be nec-
essary in advance of its introduction to
students in the classroom. It should be
emphasized at the outset that these pro-
posals represent some changes in point of
view, but they are in every respect alge-
braically compatible with the more tradi-
tional treatment. These changes, evolved
from experience with the difficulties that
learners have with the subject, were ac-
ceptable to those students who were
honestly trying to get the picture.
Improving the Terminology
A little investigation will reveal a number
of examples of confusing nomenclature in
thermodynamics. It is almost as if the
terminology had not been brought up to
date for 40 years. Surely it is time for a
reappraisal in the educational methods that
are needed today.
We may start with the word thermo-
dynamics itself, which means literally "heat
in motion," although other kinds of energy
transformation are just as important to the
subject as heat. A better term would be
energetic. It is really redundant to say
thermodynamics because any proper defi-
nition of heat must include the idea that it
is energy in motion. Heat, work, and elec-
tricity are all - by definition - manifesta-
tions of energy in motion. Unlike stored
energy, they are not associated with any
particular mass of material. They may flow
across the boundaries of a system and they
may flow through the interior. They are not
point functions. The quantity of energy
transferred across the boundaries of a sys-
tem as heat, work, or electricity depends
upon the path as well as upon the initial
and final values of state conditions such as
temperature, pressure, volume, and voltage.
The terms thermostatics, stored heat,
heat content, heat capacity, stored work,
and stored electricity are misnomers. They
conflict with the definitions; they confuse
students. We must stop using them if we
are to have a truly logical body of knowl-
edge. The idea of dividing all energy first
THE DICHOTOMY OF ENERGY
Energy in Motion
into two classes of energy in motion and
stored energy is basic to the understanding
of the subject, but we should not allow the
idea to be undermined by the use of un-
precise and contradictory terms.
Stored energy should be represented by
a number of names corresponding to all the
commonly recognized classifications. It is
worth noting that the classification is com-
plex. The early workers appear to have been
afraid that some little understood kind of
energy might be left out. As a result they
organized a dichotomy of energy. This is
outlined in Table I. Notice that the sub-
divisions are always made by dividing into
two classes-those that do and those that
do not meet some criterion. Thus stored
energy is divided into external energy and
internal energy. At the next level both of
these are divided into kinetic energy and
potential energy. Now there are clearly
several kinds of potential energies on the
external side and two of these are shown-
but one must remember that in certain
special kinds of problems magnetic poten-
tial energy, surface potential energy, or
other kinds must be included.
All stored energy terms are associated
with a mass of material. They are point
functions; differences in their values asso-
ciated with a change of state of the system
are determined solely by the initial and
final conditions and are independent of
Certain common energy terms have been
left out of Table I deliberately: non-flow
work, internal energy, enthalpy, and Gibbs
free energy. Some of these have their uses,
but none of them should be taught to
students at first. The reason for this is
CHEM ENG ED
that each of these terms represents an arbi-
trary combination of simpler terms, as can
be seen from the following equations
dW = dW, + d(PV) (1)
dU = dA + d(TS) (2)
dH = dU + d(PV) (3)
dF = dH - d(TS) (4)
where A = Helmholtz free energy, F =
Gibbs free energy, H = enthalpy, P =
absolute pressure, S = entropy, T = abso-
lute temperature. U = internal energy,
V = volume, W = non-flow work, and
W- = shaft work.
A Canon for the First Law
The first law of thermodynamics is an
energy balance. Unfortunately, the litera-
ture is full of different statements of this
law. There seems to be no clearly recog-
nized, generally agreed upon, form that
could always be used as a starting point.
Students need such a statement which they
can use to avoid the possibility of leaving
out some energy terms that are important
to their problem. If they were to be given
a universal formulation or canon to begin
every problem, and it were clearly stated
that subsequent manipulations apply only
to a particular situation, it would be easier
to break the habit of formula snatching
which many of them attempt to practice.
In view of the fact that the first division
employed in the dichotomy of energy, Table
I, is that between energy in motion and
stored energy, it is suggested that an equal-
ity be used to relate the two kinds of
quantities in a system. As a matter of fact,
some textbooks do this by putting heat,
work, and electricity on the left side and
all stored energy terms on the right side.
On the stored energy side it is recom-
mended that one term be provided for each
kind of energy, all combination terms being
avoided. It is also recommended that the
standard form of the energy balance be
written with differentials, since deltas and
integral signs raise questions about datum
levels, the initial and final states, or con-
stants of integration-all matters having to
do with a particular problem. Beginning
engineering students should be able to per-
form the necessary integration.
With these recommendations in mind a
canonical statement of the first law can be
formulated as follows:
dQ - dW. - dE = dA + d(TS) + d(PV)
+ NgX\ NU2 (5)
+ )-+d -2)
where E = electricity, g = acceleration of
gravity, g, = gravitational conversion
factor, N = mass, Q = heat, U = velocity,
and X = absolute elevation.
What Is Work?
The so-called work terms in the energy
balance do not always satisfy the criterion
of representing energy in motion. Lectures
intended to establish the principle that
heat, work, and electricity are always
energy in motion are weakened by the
algebra in many textbooks. That which is
usually called non-flow work (W) in a
batch process is one such instance. This
can be shown by algebraic manipulation to
W = W, + A(PV) (6)
The shaft work (W, ) clearly satisfies the
definition of work; i.e., it is energy in
motion. It requires a machine with a rotat-
ing shaft or a moving piston rod. The so-
called flow work or flowing energy term,
A(PV), is a different matter. It represents
stored energy, for it is a point function. For
this reason the terms flow work and flow
energy also should be avoided.
An excellent exercise to give students
early in their course work involves them in
a pressure-volume graph. They are asked
to choose points on the graph representing
arbitrary initial and final states and to draw
two arbitrary paths between these points
with a French curve. They are then asked
to evaluate graphically for each path the
PdV + f2 VdP
and to compare the two values with the
value of the function P2V2 - PiV Since all
of the expressions give the same result, the
students can see readily that A(PV) is a
point function and that the individual in-
tegrals are not point functions, for they do
depend upon the path.
Another approach is to write A(PV) as
N A (P/p). The mass N is the capacity
factor and P/p is the intensity factor of the
energy term. The later is readily recogniz-
able as the pressure head in Bernoulli's
equation. Therefore, A(PV) is really pres-
sure potential energy. For example: putting
work into a compressor that delivers com-
pressed air to a pressure tank at the corner
service station is analogous to putting work
into a pump that supplies water to an
elevated tank at the water works. Both the
air in the pressure tank and the water in
the elevated tank possess stored potential
energy. In order to differentiate them
Ng AX/g. should be called elevation poten-
tial energy and A(PV) should be called
pressure potential energy.
Thus W turns out to be a mixture of
work and stored energy, and it should no
longer be referred to as work. Some books
try to make W look like pure work by
attempting to show that A(PV) is work.
The explanation usually goes something like
this: "The gas that goes into the process
enclosure is pushed in by the gas that
follows it, and the gas that leaves the en-
closure pushes back the atmospheric air."
This is very confusing to students because
they cannot visualize other gas or air as
being the same as the face of a piston.
They also find it hard to follow an imagin-
ary boundary that shifts as the gas passes
through it. The educational advantage of
the new point of view should be clear, for it
does not require such explanation.
The Trouble With Enthalpy
Kammerling Onnes (4) invented the term
enthalpy as a substitute for such terms as
stored heat and heat content. Although it
was a worthwhile advance, it still gives
trouble. Some students tend to equate
enthalpy with heat without regard to the
effects of other terms in the energy balance.
Of course enthalpy is a hybrid concept con-
sisting of part internal energy and part
external pressure potential energy. Such a
mixture is quite illogical though convenient
in many practical problems. A logical alter-
native would be to discard enthalpy and
return to internal energy. Unfortunately,
this is not likely to come to pass; for the
literature is full of tables and graphs of
enthalpy, and there are comparatively few
data in the form of internal energy.
The progress of understanding would be
aided, however, if the terms heat capacity
and latent heat were abandoned. These
terms provide a misleading connection be-
tween heat and enthalpy that should be
discouraged. Students will get along with
much less trouble with the terms enthalpy
capacity instead of "heat capacity at con-
stant pressure," internal energy capacity
instead of "heat capacity at constant vol-
ume," latent enthalpy instead of "latent
heat at constant pressure," and latent in-
ternal energy instead of "latent heat at
constant volume." At first these new names
seem cumbersome to old timers, but this
is not the case with beginning learners.
Extending the First Law of Energetics
In Table I and Equation 5 internal
energy is divided into internal potential
energy and internal kinetic energy. This is
done arbitrarily, calling TS the internal
kinetic energy and A (the Helmholtz free
enery) the internal potential energy. In
view of the statistical difficulties of dealing
with the interactions of all of the molecules
and sub-atomic particles this may seem to
be questionable. However, in view of the
relationship of Equation 2, the fact that
there are only two subdivisions under inter-
nal energy (no unknown form of energy
thus being overlooked), and the convention
of a form of the first law that includes no
combination terms, it is logical to make
such a division.
Handling Irreversible Processes
For a reversible process,
dQreversible = Tds (7)
The canonical statement of the energy bal-
ance for such a process results from the
substitution of Equations 7 and 8 into
Equation 5 (with electricity assumed to be
TdS + VdP = dA + (TdS + SdT)
Ng N (v2\ (9)
+ (VdP + PdV) + - dX + - d
gc c I
For the reversible case the like terms on
both sides of the equation may be cancelled.
But wait! All actual processes are irrevers-
CHEM ENG ED
- t-- --o-p
P1 = 14.7 psia
P2= 85.0 psia
VA= 0.0255 ft3
VB= 0.850 ft3
VC = 0.2245 ft3
VD = 0.00675 ft3
Cp= 7.00 Btu/lLb mole-"R)
Cv = 5.01 Btu/(Lbmole-�R)
K = 1.400
n = 1.318
I I I I
TA a TB = 530. OR
Tc = 808. OR
TD a 700. OR
SA = + 0.040 X 103Btu/OR
SB U + 3.91 X 10-3
Sc = + 2.377 X 10-3
So a + 0.157 X 103
NA N = 0.000,0764 Lb
N 8 Nc 0.00220 Lbmole
B C mole
Function AB BC CD DA A BCD
Q 0.00 -0.76 - 1.67 +0.11 - 2.32
Ws 0.00 -5.05 0.00 +0.15 -4.90
W +2.24 -3.82 -3.43 +0.11 - 4.90
A (PV) +2.24 +1.23 -3.4-3 - 0.04 0.00
AU 0.00 +3.05 -0.47 0.00 +2.5 8
AH +2.24 +4.28 - 3.90 - 0.04 +2.5 8
TAS +1.86 -0.76 - 1.67 - 0.09 - 0.66
A (T S) t 0.004 0.00 - 0.004 0.00 0.0 0
AA - 0.004 +3.05 - 0.466 0.00 +2.58
A F +. 2.236 +4.28 - 3.896 - 0.04 + 2.5 8
ASxI O3 +43.510 - 1.155 - 2.22 - 0.1 17 0.00
A reversible diesel engine
Energies in Calories
Function AB BC CD DA ABCD
Q 41,400. 41,780. -1,001. -1,375. + 804.
Ws O0. +1,780. + 399. -1,375. + 804.
W + 399. +1,780. 0. -1,375. +- 804.
A (PV) +4- 399. 0. - 399. 0. 0.
A U +1,003. 0. -1,003 0. 0.
A H +1,400. 0. -1,400. 0. 0.
TA S +1,400 +1,780. -1,001. -1,375. + 804.
A F 0. -1,780. - 399. +1,375. - 804.
AS + 3.58 + 3.56 - 2.57 - 4.57 0.
CHEM ENG ED
ible. The right side of the equation repre-
sents stored energy; all of the functions on
the right side are point functions. The left
side of the equation represents energy in
motion, namely heat and work. If the work
goes into the enclosure and heat comes out,
irreversibilities and friction increase both
heat and work beyond the limiting case.
Now either the Tds or the VdP term on
the left side will have to be integrated
(graphically or formally) over the actual
path. It is not necessary to integrate both
terms, for the energy balance can be solved
for the second term on the left side. The
right side can be evaluated with the aid of
the second law.
Many textbooks seem to place too much
emphasis on reversible cases. In engineering
the greatest emphasis should be on the ir-
reversible. A useful technique in teaching
students is to represent cycles, reversible
or irreversible, on both P-V and T-S plots.
The various steps of the cycle and the com-
plete cycle should be investigated com-
pletely. All of the terms and their compon-
ents should be calculated, and all of the
numbers should be tested in the light of the
first and second laws and the various defin-
ing equations to locate errors and reinforce
understanding. A few such exercises are the
equivalent of a much larger number of
discrete one-step, one-question, one-answer
problems. Tables II and III illustrate this
technique. Students to whom algebraic
equations are somewhat unreal achieve
quicker understanding when they are re-
quired to substitute numbers, and the
inevitable mistakes that crop up are illumi-
What Sign Should the Work Term Have?
The usual convention is that heat flowing
into the system is positive and work flowing
out of the system is also positive. This
appears so illogical that teachers should
keep their eyes open for a clue showing
which of these signs can be changed the
more reasonably. Evidence appears very
quickly. Inasmuch as work input, like heat
inflow, is associated with an increase in the
value of such thermodynamic properties of
the system as enthalpy and free energy, its
sign should be positive for consistency with
the general convention. If it were, both heat
and work would be positive for flow into
the system and negative for flow out of the
system-a much more satisfactory situation.
Thermodynamics energeticc, that is) is
ailing-or, speaking more precisely, its
pedagogy is. The illness is neither organic
nor incurable, but it is debilitating and it
should be checked. This critique has sug-
gested some therapeutic measures. Will they
be effective? Can they help students under-
stand one of the foundation subjects of their
engineering education? The experience of
one instructor is affirmative, but in the end
each must try them himself to find out.
1. Anderson, H. J., J. Eng. Education, 53, (3),
2. Bronwell, A. B., et al., J. Eng. Education, 53,
3. Davis, E., "The Quelle Lectures," Kansas State
Univ., Manhattan, Kansas, 1963.
4. Hougen, 0. A., Watson, K. M., and Ragatz, R.
A., "Chemical Process Principles, Part I," 2nd
ed., footnote p. 247, John Wiley and Sons, New
5. Inveiss, J. H., J. Eng. Education, 53, (9), xx, xxi,
6. Vanserg, N., Am. Scientist, 46, 94a, 96a, 98a,
7. Vanserg, N., Econ. Geol., 47 220-3, (1952).
A=Helmholtz free enregy
F = Gibbs free enregy
g= Acceleration of gravity
gc= Gravitational conversion factor
P= Absolute pressure
Q = Heat
S = Entropy
T = Absolute temperature
U= Internal energy
W= Non-flow work
Ws = Shaft work
X= Absolute elevation
p = Density
Professor of Chemical Engineering,
Montana State University, Bozeman, Montana
At 9:30 P.M. on a cold, windy night in January,
1966, the telephone rang at the Sixth Street home
of Mr. and Mrs. Jayant Saraiya in Sinclair,
Wyoming. Jay, who was watching TV, got up
and answered. "Jay? This is Sam at the plant.
The temperature on the regenerator has been
slowly dropping all evening. Thought I better tell
you." "Thanks," said Jay. "I'll be right over."
He hung up, walked over to the kitchen window
where he could see an outside thermometer
which indicated a cool seven below zero, and pro-
ceeded to don a ski parka, boots, and leather cap
with ear flaps. "I'll be at the plant for awhile;
don't wait up for me," he called to his wife. He
stepped into his 1963 Falcon, and drove the four
blocks to the plant. The plant is Sinclair Refining
Company's refinery at Sinclair, near Rawlings,
Going directly to the control house, Jay talked
with Sam Watkins, the shift supervisor. He
studied the temperature, pressure, and throughput
logs of the refinery that the recording instruments
spewed out steadily. "Sam," Jay said finally,
"Let's go down to the blower house and look
around." Donning their heavy parkas and caps,
they went out into the icy wind and across the
refinery yard to a small galvanized iron building
which housed the blower for the regenerator. This
machine gulps in the enormous quantities of air
required to burn the carbon off the catalyst and
forces it into the burning vessel, called the regen-
erator. The blower was screaming at a high pitched
roar in its usual manner and at its designed
speed. Jay had noted in the control room a
reduced air flow from the blower. Now by in-
specting the blower equipment carefully, he finally
noted that the air intake duct above the roof had
built up a ring of ice which was restricting the
flow of air to the blower. Pointing this out to Sam,
he suggested that Sam call the maintenance fore-
man and ask him to chip off the ice. "I'm sure
that will correct the trouble and I'm going home,"
he told Sam. "If the temperature doesn't start
back up after they finish knocking off the ice,
Just another common incident in the working
life of an industrial chemical engineer, with this
difference. Jay Saraiya is an Indian national
trained as a chemical engineer in the United
States who plans to spend his professional career
in the U.S. A lack of interest in chemical engi-
neering on the part of U.S. youth and a burgeon-
ing demand has created an opportunity that
foreigners are taking advantage of. Some educa-
tors have estimated that we may soon reach the
point where one fifth of all chemical engineers
being graduated by U.S. engineering schools will
Jay's experience is typical. Born and raised in
Bombay as the son of a moderately wealthy
importer, Jay went to the University of Bombay
and majored in chemistry and physics. In 1959,
by straining the family's financial resources almost
to the breaking point, he went to the United
States and enrolled as a freshman in chemical
engineering at Montana State University. Tech-
nical education in India is conducted in English,
so language was no handicap. Four years later
he was graduated as a B.S. in Chemical Engineer-
ing. Immediately upon graduation he was hired by
Sinclair. Desperately short of chemical engineers
and located in what many Americans consider
"Nowheresville," Sinclair and Rawlins welcomed
Jay with open arms. Company employees found
Jay a comfortable apartment in Rawlins for $35
per month and the local newspaper ran a feature
article on Jay and his history.
Feeling that he would be a happier and more
stable employee if he were married, Sinclair
encouraged him to take his vacation ahead of
schedule to go to India to get his bride. Accord-
ingly, in January Jay married Jayshee Asher,
a Bombay girl selected with his family's approval
according to the Indian tradition.
Jay and Jayshee returned to the high, barren,
wind-swept plains of Wyoming in February.
After having spent her entire life in steaming,
teeming, tropical Bombay, Rawlins seemed like
another planet to Jayshee. But there were com-
pensations. The apartment was warm, comfort-
able, and convenient-and then there were the
stores, particularly the supermarket with its
abundance and cleanliness like nothing she had
ever experienced in India.
Spring comes late at 6500 feet altitute but it
does ccme eventually. In summer there were trips
to the nearby Wind River and Teton mountain
ranges and to Yellowstone Park.
In November, their son Monal was born. Now
the difference between India and America really
became apparent to Jayshee. What with the
washer and drier, the canned milk and baby food,
the abundance of shots, pills and vitamins, the
baby was never sick. A major crisis was narrowly
(continued on page 51)
CHEM ENG ED
R. L. Kenyon
Director of Publications SPEAKING
American Chemical Society. Washington. D.C
ABOUT - Skepticism Being Better than
It could be argued that what the world
offers to this year's scientific or engineering
graduate represents the greatest promise
ever held out to his kind as individuals.
Arguments on the other side are easier to
find and they agitate and stimulate. What
historian Richard Hofstadter calls the "para-
noid style" is enjoying popularity in the
United States. We can build black worries
on all sides: Business life is enforced con-
formity; technology is dominating human-
ity instead of serving it; government for the
people is perishing; and the free intellectual
stimulation of the university has succumbed
to the scramble for federal grants.
General day-to-day progress usually is
stumbling and uneven. Worthy minds are
inspired by and aspire to the high peaks of
human works. The inclination to match this
week's failures against mankind's better
achievements-as they stood out against
the poorer levels of their times--can bring
discouragement and feelings of frustration.
We hear and see evidence that among
college students there may be greater than
usual discontent with the world. Students
are reported discontented over too few
opportunities for having a hand in making
human society better. This is admirable
insofar as the attitude is based on under-
standing. But viewing a mountain from one
position doesn't tell much about how hard
it would be to climb the unseen side. Some
skepticism and probing to learn just what
can be done should be a part of the ap-
proach of any technically trained person.
Society is changing and is likely to
change with increasing speed. Such ele-
ments as business, technology's influence,
government, and the university atmosphere
all could stand some improvement. But all
of these are likely to remain influential
elements of society and, if they are to be
improved, they will have to have the driving
efforts of able people. Therein lie challenges
to the worthiest of idealists who want to
improve the human lot.
After baccalaureate (at Illinois) and doctoral
(at North Carolina) degrees in chemistry,
Dr. Richard L. Kenyon became a research
chemist with DuPont. During four years of
research, a strong interest in people and in
professional communication persisted and
ultimately led him to join the publications
staff of the American Chemical Society. As
a field editor of Chemical and Engineering
News and Industrial and Engineering
Chemistry, as managing editor of the Jour-
nal of Agriculture and Food Chemistry, as
editor of C & E N, as editorial director of
ACS's applied journals, and finally as
Director of Publications for ACS, he has
devoted two extremely fruitful decades to
the challenging business of more accurate,
more literate, more readable, and more
exciting communication in the world of
applied chemistry and chemical engineering.
Many of our readers doubtlessly have
enjoyed Dr. Kenyon's scholarly, arresting
editorials in C & E N. The message of a
recent one was so timely a piece of mature
opinion that we wished to have it respoken
from our pages. It is reprinted from the
Career Opportunities Supplement of the
March 14, 1966, issue of Chemical and
Engineering News. CHEM ENG ED is
grateful to the American Chemical Society
for permission to reprint it.
The new graduates at all levels of chem-
istry and chemical engineering probably
are, on the average, the best trained ever.
The demands for excellent training prob-
ably also will be the greatest ever. And not
only will demands for high training be the
greatest, but demands for breadth also are
There appears to be exciting opportunity
for competent, well-trained and educated
chemists and chemical engineers far beyond
the numbers that will be produced. This
is true not only in the highest form of
"pure" research, but in applied research,
technology, commerce, politics, and a host
of other pursuits. Those who want a feeling
of contributing to the improvement of
society should not turn theit backs on what
appears to be a slightly tawdry mess in
comparison to one's ideal society. There lies
a very real challenge.
Unit Operations to Transport Phenomena
M. S. Willis
Assistant Professor of Chemical Engineering
University of Dayton, Dayton, Ohio
Engineering as a profession was first
identified with weaponry and military
works. The demand by the civilian populace
for structures primarily designed for com-
merce and trade led only in the last 250
years to "civil" engineering and the civil
engineer, whose job was defined in 1828 in
the charter of the Institute of Civil Engi-
neers. Civil engineering was "the art of
directing the great sources of power in
nature for the use and convenience of man,
as the means of production and of traffic in
states, both for external and internal trade,
as applied in the construction of roads,
bridges, aqueducts, canals, river navigation
and docks for internal intercourse and ex-
change, and in the construction of ports,
harmors, moles, breakwaters and light-
houses, and in the art of navigation by
artificial power for the purposes of com-
merce, and the construction and adaptation
of machinery, and in the drainage of cities
and towns " (2). This early definition of
engineering is primarily concerned with
construction not design, and with art rather
than science. It is because of this latter
point, in addition to the very ambitious
nature of the defininition, that it became
necessary to divide the field of engineering.
The mechanical engineer came to be identi-
fied with "the construction and adaptation
of machinery," the naval engineer with the
"art of navigation by artificial power," and
the sanitary engineer with "the drainage
of cities and towns." Once under way, the
subdivision of engineering increased as the
demands of industry became more spe-
The chemical engineer did not appear
until about 70 years ago. The construction
and selection of equipment for chemical
plants was once largely in the hands of
mechanical engineers who knew some chem-
istry or chemists who knew some mechani-
cal engineering. As the process industry
grew, the problems became more complex
and peculiar, until it finally appeared that
there was a need for a distinct branch of
engineering to which such problems might
be assigned. "In response . . . we have the
development of chemical engineering, not
as a composite of chemistry and mechanical
or civil engineering, but as a separate
branch of engineering, the basis of which
is those unit operations . . . which, in their
proper sequence and coordination, consti-
tute a chemical process as conducted on the
industrial scale" (2). The unit operations
really became the defining concept for
chemical engineering and allowed the chem-
ical engineer to use a systematic approach
to the solution of complex industrial prob-
lems. The distinction between industrial
chemistry and chemical engineering, in fact,
is that the former is concerned with indi-
vidual processes as entities in themselves,
whereas the latter focuses attention on the
unit operations common to many processes
and on the proper grouping of these unit
operations to produce a desired product.
In 1915 Arthur D. Little formally defined
the unit operations of chemical engineering,
and in 1923 the text by Walker, Lewis and
McAdams entitled "Principles of Chemical
Engineering" appeared. During the period
from 1923 until 1960, this work and its two
revisions served as models for subsequent
chemical engineering text books (1-6).
In the mid 1950's, it became apparent to
some chemical engineers that, because of
the economic demands, there had to be a
departure form the traditional approach of
multiple scale-up in the design of chemical
plants. Some chemical engineering teachers
were finding that "too often the fundamen-
tal concepts and laws have been slighted
in the haste to teach application. The result
has frequently been that a practicing engi-
neer or graduate student, faced with prob-
lems for which his empirical training has
not prepared him, has first had to learn the
fundamental principles of the transport
processes before he could proceed" (3). The
transport porcesses underlie the unit oper-
ations of chemical engineering, for "the unit
operations themselves, although carried out
CHEM ENG ED
in a wide variety of equipment types that
apparently have nothing in common are,
from the point of view of the theory in-
volved, applications of a very few funda-
mental laws. In fact, these laws are the
fundamental laws of physical sciences that
underlie practically all technology . . .
[They] are: first, the conservation of mat-
ter and energy; second, the relations per-
taining to the equilibria of physical and
chemical processes; and third, the laws
governing the rate of change in systems not
in equilibrium" (2). The recent innovation,
then, is not in recognizing that the unit
operations are based on a few fundamental
laws but in teaching these laws (particu-
larly those that describe process rates) in
a separate course which "should rank along
with thermodynamics, mechanics, and elec-
tromagnetism as one of the key engineering
What Is Meant by Transport Phenomena?
Courses in transport phenomena consist
of the study of the transfer of momentum,
energy, and mass. In order to transfer any
of these quantities, a non-equibibrium situ-
ation must exist. For example, if internal
energy is to be transferred, there must be
a temperature difference. The temperature
difference is the driving force and the
quantity which is moved by this tempera-
ture difference is called the heat flux. From
the observational point of view, a linear
relation is postulated between the flux and
the driving force in which the coefficient of
proportionality is a property of the sub-
stance in which the energy transfer is
occurring. In the case of heat transfer, the
coefficient of proportionality is the thermal
The observational or phenomenological
approach is not concerned with the mechan-
ism for the transfer of this energy. For the
mechanism, the kinetic theory of molecular
motion must be considered. From the sim-
plified theory, the kinetic energy of a
spherical molecule is directly related to the
-mu2= 3KT (1)
The tendency toward equilibrium of tem-
perature then is a result of the transport
of molecules with high kinetic energy to
regions where the molecules have low kin-
etic energies and vice-versa. But while a
molecule, by its change of location, is trans-
ferring kinetic energy, it must at the same
time transfer mass, m, and momentum, mu.
On a microscopic level, the mechanism for
the transport of mass, momentum, and
energy is fundamentally molecular diffu-
From the observational point of view,
the following laws for the transfer of mo-
mentum, energy, and mass under the condi-
tion of constant density and heat capacity
define the transport properties of viscosity,
M, thermal conductivity, k, and mass diffu-
v d(pvx (2)
Newton's Law of Viscosity
___ d(PCp T) (3)
Fourier's Law of Heat Conduction
DA dPA (4)
Fick's First Law of Diffusion
From the simplified kinetic theory, the ex-
pressions for transport properties are:
3 7r3/2 d '
k = J-K3T1/2
S 2 ( K3 /2
where d is the molecular diameter. Experi-
ment agrees with the temperature and pres-
sure dependence of the transport properties
as shown in Equations 5-7 and therefore
verifies the molecular transport mechanism.
This is of engineering value in that for
moderate ranges, the temperature and pres-
sure dependence of the transport properties
can be predicted.
What other information of engineering
value can be obtained from these rate
equations? The dimensions of I/a= v, DAB,
and k/ocp= a are (length) 2/time.
(continued on page 49)
FUNDAMENTALS OF CHEMICAL REAC-
TION ENGINEERING, by Walter Brotz;
translation from German by D. A. Diener and
J. A. Weaver; Addison-Wesley Publishing Com-
pany, Reading, Mass., 1965. 325 pages. $15.00.
It is stated in the translators' preface of
this book that the book can be used at the
senior or first-year-graduate level. Most
seniors will in fact find it to be a rather
sophisticated mathematical treatment not
only of reaction engineering but also of
some conventional unit operations as well.
Though sophisticated, the mathematics are
not beyond that to which current under-
graduates are exposed.
Much of the material contained in the
first 183 pages is not directly related to
reaction engineering and will not be new to
a fourth-year student. In the first 68 pages,
the reader is taken through stoichiometry
and thermodynamics and introduced to
chemical kinetics and catalysis, the last two
subjects in 24 succinct pages. Primarily
these 183 pages contain a wealth of design
information about fluidized beds, packed
beds, and heat exchangers. Much of this
information is very skillfully organized into
tables and graphs. The text is short on
theory but long on application.
The remaining 231 pages are concerned
with various types of reactors and their
design. The presentation is good. More
emphasis is put on the derivation of the
equations here than in the first section and
this is as it should be. In keeping with the
first part of the book, the heat and mass
transfer aspects of reactor design are em-
phasized. The book should be of value to
those wishing to bring themselves up to
date on the subject of reaction engineering.
This reviewer attempted to use the book
for a fourth-year, one-semester course cov-
ering applications of transport theories,
including reactor design. The sections cover-
ing the conventional unit operations were
well-received. Students found the charts
and graphs particularly useful. Most dis-
turbing to them was the lack of problems
and a sufficient number of illustrative ex-
amples. While the symbols in the text have
been properly "Americanized," the formu-
lation of the equations is not always that of
the more conventional texts. As a result, the
students encountered some difficulty when
problems were assigned from other texts.
One final point: few undergraduate courses
are so broadly based that this book can be
used in its entirety. With the present curri-
culum at the State University of New York
at Buffalo this reviewer probably would try
to use it again.
For a first printing there are surprisingly
few errors. To show that it is not perfect,
however, the section on multiphase reactors
(pp. 232-246) is singled out. Here signs are
lost and notation is poor. For some reason
the symbols for the mass transfer coeffi-
cients are changed from that introduced
earlier (p. 108). Concepts like conversion
are introduced for no apparent reason. More
importantly, the development of the trans-
fer coefficients on page 235 is at best mis-
leading. Does the author (or do the trans-
lators) really mean k , and k G, to be the
film coefficients pertaining to the case of
absorption without chemical reaction? Since
no use is ever made of this concept the
reader never finds out.
CHEM ENG ED
Review by K. M. Kiser
Assistant Professor of Chemical Engineering
State University of New York at Buffalo
(continued from page 4 7)
By analogy with the mass diffusivity,
DAB, v is called the momentum diffusivity
and a is called the thermal diffusivity.
Since these three quantities have the same
units, dimensionless numbers can be formed
from the ratio of any two of them. For
example, the Prandtl number is given as
PCp V momentum diffusivity
Prandtl number . .=
k a thermal diffusivity
and can be interpreted as a measure of
the capacity of a fluid to diffuse momentum
as compared with its capacity to diffuse
heat. The Prandtl numbers for air, water
and mercury are approximately 1.0, 5.0 and
The next question is how do the trans-
port properties fit into the conservation
statements for mass, momentum, and en-
ergy? The conservation statements must be
applicable to all substances and, further-
more, they must be independent of any
reference frame. The transport properties
serve as parameters in the conservation
statements and permit a distinction to be
made when the same conservation state-
ment is applied to two different substances.
For the latter requirement the conservation
statements must be expressed by a mathe-
matics which is also independent of coor-
dinate system, The calculus of vectors and
tensors transforms the basic laws from re-
ference frame to reference frame with no
change in the fundamental law.
Consider now the application of the three
conservation statements to a single one-
dimensional, time-dependent system:
8 8T\ 8T
8y \y/ 8t
Conservation of Energy
8 Y 8(PVx)\ 8(P t)
8y 8y at
Conservation of Momentum
A8 ) 8PA PA
- (DA Bp 8
sy y at
Conservation of Chemical Species
These equations are all of the same form.
Consequently, under certain conditions,
there is an analogy among the conservation
statements as well as an analogy among
the mechanisms for transfer. This analogy
can be very useful in the solution of cer-
tain engineering problems. For example, the
transfer of momentum in a wire-coating
operation where the coating is applied by
pulling the wire through a die is exactly
analogous to the flux of heat in the insula-
tion on a steam pipe. Information about
the first system can be inferred by a study
of the second, since the systems are analo-
Methodology of Transport Phenomena
In order to justify the statement made
earlier that a course in the transport pro-
cess should be ranked along with thermo-
dynamics, let us compare the derivations of
the Bernoulli equation.
In most unit operations texts, the deriva-
tion is limited to a steady flow system
consisting of a pump which takes an in-
compressible liquid at one elevation and
raises it to a second elevation at mass flow
rate w. A pound of liquid at the entrance
has a potential energy gh,, a kinetic
energy < v1>2i/p, where p3 = 1 for lam-
inar flow and p = 2 for turbulent flow,
and a pressure volume work, p,/p, which
the fluid needs to enter the system. The
pump must raise the liquid and adds work
W/w to the liquid. At the exit, the fluid has
a potential energy gh2, a kinetic energy
2/f and has a pressure volume work
of p'2/p. The Bernoulli equation is simply
written then as
< v>2 PI W
gh, + ---- +-+--E,
3 p w (11)
(9) where E. is a correction factor necessary
for the equality.
In the study of transport phenomena, the
starting point in the derivation is the local
conservation statement for momentum or
Newton's second law of motion for a fluid.
p-O: = E ' Fi -V" - V p +pg (12)
This statement says that on a unit volume
basis, the mass times acceleration of a fluid
particle is equal to the sum of the viscous
forces, the pressure forces and the gravita-
tional forces. Since mechanical energy is the
product of a force and a displacement, this
equation can be multiplied by the fluid
velocity to obtain the local time rate of
change of mechanical energy.
D (1 \ r 1
PO- -v }2=-) V pg T* pU*g\
+PV.7 +.r: Vj
The left hand term represents the accumu-
lation of kinetic energy and the term in
brackets on the right side represents pro-
ducts of forces and velocities and hence the
rate of mechanical work done by pressure,
viscous and gravity forces. In order to
explain the last two terms, the equation of
thermal energy must be examined.
P-- - V. q- (pV. v.+ T :Vv_) (14)
The term of the left represents the accu-
mulation of internal energy and the first
term on the right represents heat conduc-
tion. The last two terms in the internal
energy equation also appear in the mechan-
ical energy equation but with opposite
signs. The term p V. . represents compres-
sibility effects and may be either positive
or negative. The term (-. : V v), for New-
tonian fluids, is always positive which
means that this term always causes a de-
crease in mechanical energy and an increase
in thermal energy. This term then repre-
sents the irreversible degradation of me-
chanical energy into thermal energy.
In order to obtain the Bernoulli equation,
the mechanical energy equation is inte-
grated over an arbitrary volume consisting
of three types of surfaces: inlet and exit
surfaces, fixed surfaces and moving sur-
faces. The moving surfaces provide a means
of adding or removing work from'the sys-
tem, the fixed surfaces represent the con-
fines of the system and the inlet and exit
surfaces allow mass to enter and leave the
system. After integration, the result is de-
pendent only upon the inlet and outlet con-
editions and for an unsteady state system is
- (K tot + 4b tot +A tot) =
-A - + + G) w + W - E,
2 V W
where Ktot, D tot and Atot , are respec-
tively, the total kinetic energy, potential
energy and thermodynamic work content;
W is the rate at which the surroundings
perform mechanical work on the system;
and E, is the "friction loss." This term is
E, = -_ (. : v) dV (16)
and represents the irreversible conversion of
mechanical energy to thermal energy.
For a steady-state liquid system, Equa-
tion 15 becomes
1 Pl W Ev
gh, + - - -+--
2 P w w
= gh2 + - - -
A comparison of this equation with Equa-
tion 11 indicates that
This derivation proceeds from a funda-
mental law to a general equation of engi-
neering utility by logical and reasonable
steps. The scope of the equation, its rela-
tion to fundamentals, and the lack of
balancing "fudge factors" illustrates to the
student the scientific basis of engineering
and gives him confidence in the application
of this equation and others of similar origin.
Permission of the McGraw-Hill Book Company
to quote and paraphrase passages from the intro-
duction and first chapter of Badger and McCabe's
"Elements of Chemical Engineering" and from
the preface of Bennett and Myers' "Momentum,
Heat, and Mass Transfer"; and of John Wiley &
Sons to quote a passage from the preface of Bird,
Stewart, and Lightfoot's "Transport Phenomena"
is gratefully acknowledged.
(continued on page 51)
CHEM ENG ED
Dimensions are given in terms of mass (M),
length (L), time t, and temperature (T.) Vec-
tors have a single underline and tensors have a
double underline. Force is not considered a funda-
mental dimension, but is assigned instead the
dimensions of mass-acceleration instead the
dimensions of mass-acceleration product (ML/t2).
This "absolute" system of dimensions is com-
monly used by physicists, much less commonly
A = thermodynamic work function, ML2/t2.
Cp = heat capacity at constant pressure per
unit mass, L2/t2T.
DAB = binary diffusivity for system of species
d = molecular diameter, L.
E, = total rate of viscous dissipation of me-
chanical energy, ML2/t3.
G = Gibbs free-energy per unit mass,
g = gravitational acceleration, L/t2.
h,. h2 = elevation, L.
= mass flux of species A in the y-direc-
A y tion, M/tL2.
K = kinetic energy, ML2/t2.
K = Boltzmann constant, ML2/t2T.
k = thermal conductivity, ML/t3T.
m = mass of molecule, M.
p = fluid pressure, M/Lt2.
qy = y-component of the heat flux vector,
T = absolute temperature, T.
t = time, t.
u = mean molecular speed, L/t.
v = mass average velocity, L/t.
= space average value of velocity, L/t.
W = rate of doing work on system, ML2/t3.
w = mass flow rate, M/t.
a = thermal diffusivity, L2/t.
p = velocity function (defined in Equation
It = viscosity, M/Lt.
v = kinematic viscosity, L2/t.
P = density, M/L3.
1 = shear stress tensor, M/t2L.
> = potential energy, ML2/t2.
1. Badger, W. L., and Banchero, J. T., "Introduc-
tion to Chemical Engineering," McGraw-Hill
Book Co., New York, 1955.
2. Badger, W. L., and McCabe, W. L., "Elements
of Chemical Engineering," McGraw-Hill Book
Co., New York, 1931.
3. Bennett, C. 0., and Meyers, J. E., "Momentum,
Heat and Mass Transfer," McGraw-Hill Book
Co., New York, 1962.
4. Bird, R. B., Stewart, W. E., Lightfoot, E. N.,
"Transport Phenomena," John Wiley and Sons,
5. Brown, G. G., and associates, "Unit Opera-
tions," John Wiley and Sons, New York, 1950.
6. Coulson, J. M., and Richardson, J. F., "Chemi-
cal Engineering," 2 volumes, McGraw-Hill Book
Co., New York, 1954.
7. McCabe, W. L., and Smith, J. C., "Unit Opera-
tions of Chemical Engineering," McGraw-Hill
Book Co., New York, 1956.
8. Walker, W. H., Lewis, W. K., McAdams, W. H.,
and Gilliland, E. R., "Principles of Chemical
Engineering," 3rd ed., McGraw-Hill Book Co.,
New York, 1937.
(continued from page 44)
averted the following spring. Jay's parents insisted
that he bring his son home for a family inspec-
tion. Jay and Jayshee realized that a six-month
old child from antiseptic America would have an
extremely difficult time in India, possibly even
dying of dysentery. They finally persuaded Jay's
family to come to Wyoming instead.
Jay has moved steadily ahead with Sinclair.
Shortly after his son was born, they asked him to
move out to the company town of Sinclair so that
he would be more readily available whenever
technical difficulties arose. For $50 per month, he
rents a two-bedroom, one-floor company-owned
house. At his present salary rate of $700 per
month, he has been able to live well and still help
his family. Until his brother completed college
last summer, he contributed $100 per month
towards his expenses. Financial help to his family
in India has been accomplished with the aid of a
favorable exchange rate which converts one dollar
into four rupees.
This true story points to one way that the
continued shortage of U.S. chemical engineers is
being met. Not an isolated example by any means,
Jay Saraiya is only one of sixteen non-citizen
chemical engineers graduated and placed in per-
manent positions in the U.S. by one educational
institution, Montana State University, in the past
six years. The employers of these men include
some of the U.S.'s leading companies at some of
their most attractive locations. Just as nature
abhors a vacuum, so good jobs are going to be
filled whether or not American boys want them.
Evaluation of an Approach to Plant Design
D. R. Woods and A. E. Hamielec
Associate Professors of Chemical Engineering
McMaster University, Hamilton, Ontario, Canada
Plant Design is taught at McMaster University
in two courses. The theory and design of pieces
of equipment are discussed as part of a four
credit course called Economics and Technology.
This is taught to fourth-year students for both
the fall and spring terms for two hours a week.
In addition to this course, three credits are given
to a senior project laboratory: an 80-hour work-
shop in the spring term. This paper evaluates
a novel approach to the project laboratory. The
major novelty arose in (1) the student's respon-
sibility, (2) the time allocation, (3) the staff
supervision, (4) the outside judging committee,
and (5) the problem specification. These are
discussed, and the evaluation follows.
The Student's Responsibility:
Each student decides how he is going to make
the quantity of specification material, designs his
own plant, submits a complete report, and verb-
ally defends his approach and design before an
Eighty hours and only 80 hours are to be
spent on this project. Each student draws up a
time schedule for his calculations; then the
students meet as a committee and draw up a
work schedule that will be adhered to by each.
The schedule breaks into a number of major
stages. At the end of each of these, the students
meet with the staff for an hour of constructive
criticism about how each has handled the assign-
The 80 hours are divided into a 12-hour/week
design laboratory that simulates an industrial
situation. A room is booked, a filing cabinet is
placed at the student's disposal, and the design
laboratory is not supervised; but the students are
expected to be either in the booked room or in
the library during the design laboratory time. We
emphasize that they are not to work outside of
Full marks are given for the most efficient use
of the time the student allots himself for each
calculation. Marks are deducted if he does not
have each project finished on time; if he does
a five-minute calculation for a three-hour period
or if he spends time doing unimportant and unre-
lated calculations, he loses marks.
The marking scheme for each criticism session
is based on a total of 10 marks for every hour of
design laboratory that has elapsed since the last
The Staff Supervision:
1. Give constructive criticism after each major
design effort. While each completed project is
fresh in the student's mind we explain how he
could have saved himself time, and suggest
reliable short cuts and good design technique.
The staff members with the most experience
in the given field criticize the effort.
2. Are prepared to present request-lectures
before each major design effort. Any staff
member will present a maximum of a one-
hour workshop or discussion session provided
such a workshop is requested by the students
at least two days in advance of the lecture
time and provided that hour is the first hour
of the allocated project for the topic under
The staff are not consulted otherwise. All the
staff are involved in this project.
The Outside Judging Committee:
The students design their plant for three out-
side judges, and not for the staff members.
To the judges we suggest a complicated mark-
ing scheme for the oral presentation. (The four
page, typed report from each student that is
given to the judges provides background informa-
tion for the judges. We feel that it is too burden-
some to ask them to mark the written reports).
After each presentation, the judges are given as
much time as they want to finish evaluating one
speaker before the next starts.
The Problem Specification:
Little information is provided in the specifica-
tion. The quantity and quality of a given product
and the utilities available-these alone are given.
Table I is a typical specification.
The students are informed also of the emphasis
expected and the report specifications.
All calculations are to include assumptions
and limitations and estimated accuracy for each
answer. The calculations must be legible and easy
Specifications are required for each major
piece of equipment. For heat exchangers, a stand-
ard 1-in. nominal tube is stipulated and details
required include approximate tube count, tube
length, and pitch; shell diameter; baffle spacing;
pipe connections; material of construction; work-
ing pressure; and mounting instructions. A de-
tailed calculation for the selection of one pump
is needed. The types of control required must be
indicated but not specified. The mechanical design
of the reactor and of one of the major pieces of
separation equipment is to be included.
The production and the capital investment costs
are to be calculated.
The design report must be turned in one week
before the presentation day and later is filed in
CHEM ENG ED
the chemical engineering department library. The
report consists of two parts: the body and the
The body is a four- to five-page, double-
spaced, typed summary report of what was done,
why it was done, how it was done, and what
conclusions were drawn from the calculations.
The purpose of the report is to convince the out-
side committee that the best possible design has
been turned out in the time available. The readers
are the outside committee, a group with chemical
engineering training who may or may not be
familiar with the subtleties of the design topic.
Four copies of the body of the report are required.
The appendix of the report is a well-indexed
collection of all of the actual calculations done,
together with appropriate summary pages inter-
spersed throughout the work. The calculations
need not be typed; but they must be legible and
indicate the calculation approach. The purpose of
the appendix is to supply a complete record of all
of the calculations done on the design project so
that anyone who had to do a more elaborate
design can go one from where each student
stopped rather than be forced to recalculate work
that has been done. The average reader of the
appendix will have a chemical engineering back-
ground, will probably know nothing about the
design topic, and will be interested in learning
what has been done and what are the limitations
and assumptions involved in the calculations.
The advantages and the weaknesses of this
approach to design teaching are outlined as
We have found the following advantages:
1. The outside committee adds reality to the
project for the students. The students' em-
phasis is shifted so that they are working
against the outside committee and its evalu-
ation, rather than against a staff member for
a grade. The students feel .their reputations
are at stake. Twenty percent of the final
class mark depends on the outside commit-
tee's judgment. Our outside committee mem-
bers not only have been very learned in the
field but have asked stimulating and probing
questions. The committee for the styrene
project included a senior process designer
from Dow Chemical (who produce styrene),
a senior chemist in the petrochemicals divi-
sion from Polymer Corporation (who also
make styrene), and a University of Toronto
colleague who ran the plant project design
2. The students enjoy the individual responsi-
bility. Since we do not form companies, each
student has to do his own creative design and
TABLE I. DESIGN PROJECT SPECIFICATION
Desired: A plant to produce
50 long tons/24 hr. of 95% pure monomeric
300 long tons/24 hr. of 95% pure monomeric
Cooling water: Lake water 50�C. (winter) and
City water (same average
Steam: 200 psig, 100 psig, and 50 psig
justify it on the basis of economics.
3. The students enjoy the diversity of responsi-
bility, including choice of process, design, and
cost estimation. They say they prefer to make
an overall, high-spot design of a complete
process rather than a detailed design of an
element of a process.
Twelve hours of design laboratory time are
free between the time the students hand in
their reports and the oral presentations. We
use this time to build a scale model of one
student's plant. For the degree of accuracy
required, we found that this could be done
for a styrene plant for about $10. The scale
was 1/4 in = 1 ft.
4. Lectures are given only at the students'
request. Most want to get on with the job;
few lectures are required. This pleases the
students and the staff alike because we feel
that they are asking and answering their own
5. The criticism periods after each major design
effort give rapid feed-back of suggested im-
provements and the type of assumptions to
make. Since any lectures are at the request of
the students, we want strong feed-back on
their approach as they proceed.
6. The limitation for the time spent on this
project is worthwhile. The students do not
jeopardize their standing in other courses by
devoting excessive extra time to this course;
they learn to match their designs to the time
available. The marking scheme for the criti-
cism sessions accentuates matching time with
7. The marking scheme specified to the judges
requires about 10 minutes per speaker.
Although the judges think the marking
scheme cumbersome, we find it very helpful
to the students.
8. It is easy to rate each student.
9. Staff load for the course is distributed among
the staff members. Furthermore, the students
gain from the background experience of staff
specialists in the criticism periods.
Some weaknesses of this approach are:
1. An apparent lack of understanding of the role
of plant design in an economics analysis. The
students do not seem to realize that the pre-
liminary plant design is done to improve their
accuracy in their economic assessment of the
process. We think that the onus of this is not
upon the design course but rather on the
economics and technology course which one
of us also taught. In the future we plan to
be more specific in the students' purpose in
doing the plant design.
2. Inadequacy of decision-making theory. The
students do not fully appreciate the conse-
quences of the various decisions made. More
emphasis will be given to this topic in the
economics and technology courses in the
future. For example, not only will we crea-
tively look at process flow sheets as we do
now, but we will do exercises on getting quick
numbers for equipment cost for several dif-
ferent flow-sheets. This training in cursory
equipment costing should help them to allo-
cate their design time for any preliminary
design project itself.
3. Inadequacy of the criticism sessions. Whether
the improvement is achieved by converting
the sessions into a verbal presentation to the
combined staff after each sub-project or by
supplying more staff manpower to correct
and criticize individual efforts, the whole key
is the constructive criticism of the student's
effort at various stages along the way imme-
diately after he has completed his work.
4. Poor distribution of staff responsibility. The
staff coordinators sometimes do not call on
other staff members to help out enough.
5. Paucity of time available for the design. The
completeness of the project could be improved
either by requiring the students to do some
work outside the specified hours, by forming
companies of design engineers, or by reducing
the scope of the project. Increasing the stu-
dent's homework is easy to justify because
our fourth year, second term load is relatively
light. The formation of companies requires
careful consideration. The advantages for
individual design that both the staff and the
students have appreciated are
(a) each student is completely responsible
for all of the decisions and calculations.
(b) each sees all facets of the design rather
than working on his specialty with
figures that are handed to him by
(c) each realizes that the individual mark
can be given at the end of the project.
It would be interesting to see if we can in-
corporate all of these advantages by forming
companies of two students and by insisting
that each student be able to defend any
part of the final design. The suggestion of
reducing the scope of the project has received
a negative reaction by the students..
6. Poor technical communication. Although the
general reaction to the student's oral presen-
tation has been favorable, the written reports
are poor. We have introduced a two-credit
course in technical communication into our
second-year program in an attempt to remedy
' A novel approach to teaching plant design is
being developed at McMaster University. The
uniqueness of this approach lies in the method
of handling the student's responsibility, the time
allocation, the staff supervision, the judging com-
mittee, and the problem specification.
An evaluation of the approach, based on its
application to one project with a class of fourth-
year students, shows that it has many advantages
and several weaknesses. With the correction of
the latter, the approach should offer great
promise as a powerful method of teaching design.
CHEM ENG ED
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Fundamentals of Statistical
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Diffusional Separation Processes:
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Heat Exchanger Design
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Boiling Heat Transfer
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Techniques of Process Control
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Principles of General
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Professors, Employers of Chemical Engineers,
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