Stuart W. Churchill
University of Michigan
Early Days
I was born in 1920 in Imlay City, a small agricultural community in the “thumb” of Michigan, and grew up there during the Great Depression. I had never heard of chemical engineering until a visiting high school counselor suggested it as a possible choice of career. Although I did not realize it then, that was the turning point of my life. Because I was slated by my family to attend the University of Michigan, I was pleased to learn that it had one of the best programs in the country in that field. I also applied to Harvard University in chemistry and was accepted, and was offered an athletic scholarship to Hillsdale College by my former high school coach, but the subsequent offer of a scholarship to any school in Michigan wiped out all indecision.
At the University of Michigan
I had less preparation for engineering than many of my classmates from the technical high schools that then existed in large cities, but my skills in mathematics and English were sufficient to serve as a psychological counterbalance. Indeed, my first teacher in mathematics, Clyde Love, became a mentor and persuaded me to pursue a joint degree. I played in the marching and concert bands, and as a consequence my companions throughout college were students in music rather than engineering. The degree in mathematics proved to be advantageous through out my career in distinguishing me nominally from other chemical engineers. The time required for participation in the band was somewhat of a burden, but the experience broadened my outlook for the rest of my life.
My teachers in chemical engineering had an aura of confidence and superiority related to their perception of Michigan as the best, and that attitude inoculated and inspired my classmates and me. The faculty shared their experiences as consultants in our classes, and thereby helped us to envision ourselves as future professionals. They were all involved in the AIChE and gave the impression that active participation as well as membership was to be expected of us. As an example, four of them served as President, A. H. White in 1929–1930, G.G. Brown in 1944, D. L. Katz in 1959, and J.J. Martin in 1971. An undergraduate research project on retrograde phase-behavior with Don Katz, and my admiration in general for the faculty inspired me to undertake graduate work and become a teacher, but that dream had to be deferred.
A Spell in Industry
United States entered World War II during my senior year, eliminating the possibility of going to graduate school at that time. Instead, I accepted a position with the Shell Oil Company as a technologist in their Wood River, Illinois refinery. Because of the sudden demand for aviation gasoline and other matériel of war, and because of the lack of hiring of engineers by industry during the era of the Great Depression, those of us who began our professional career in 1942 were given unusual responsibilities involving many new and different processes such as fluidized-bed catalytic cracking and butane isomerization. At the time, this responsibility was overwhelming, but in retrospect, it was a formative element in my development as an engineer. The experienced engineers at Shell, although few in number, taught me lessons in process design and operation that I could never have learned from books or when working for a small company, as I was to do later.
I participated in the activities of the AIChE local section and looked forward to attending, at least in part, the Annual Meeting in nearby St. Louis in 1944. My superior at Shell declined my request to take time off but I did attend one evening. With the exception of the following two years, I have attended every ensuing Annual Meeting. Because so many U of M graduates and faculty attend, and because I have encouraged my students to attend, it has become a yearly “family” reunion.
Although the war ended in 1945, I was still subject to Selective Service and not free to go to graduate school. Instead, I accepted a position as Technical Supervisor of the Frontier Chemical Company in Denver City, Texas – a small company started by three young entrepreneurs, one of whom, Curtis Cannon, was a former colleague at Shell Oil. A plant was to be constructed and operated to make caustic soda and hydrochloric acid for the petroleum drilling industry using a new process uniquely adapted to the locality. The venture was almost too successful, leading, after less than a year, to the sale of the plant to a large chemical company. No longer having a personal connection, I resigned to follow my twice-postponed dream of graduate school. My experiences at Frontier were completely different from those at Shell. Those two complementary experiences have been invaluable to me in terms of teaching process design, which I continue to do to this day.
My return to the University of Michigan
Returning to the U of M for graduate work in 1947, I found myself in the midst of a huge class generated by the “GI” bill. After five years in industry in process design and operation, I was totally rusty in academic subjects but my industrial experience and maturity were compensatory. I worked for J. C. Brier as a research assistant on contract research on the ignition of solid propellants, and devised a doctoral research project on heat transfer at extreme conditions using much of the same experimental equipment. Combustion and heat transfer have remained among my principal fields of research to this day. One day in 1950, G. G. Brown invited me to become an Instructor. I accepted without hesitation because that fostered by career goal, but it cost me more than a year in terms of the completion of my Ph.D. Another delaying factor was my decision to enroll in virtually every graduate course in physics, physical chemistry, and mathematical analysis. This supplemental background has been a great resource and has more than compensated for the temporary diversion from my doctoral research. Unfortunately, the present structure of contract research leads doctoral supervisors to discourage enrollment in such “non-relevant” courses.
On completion of my Ph.D. in 1952, I was offered an Assistant Professorship at the U of M, which was literally a dream come true. As an aside, hiring their own graduates was a common practice at U of M and MIT at that time because there were few other schools with strong graduate programs. By the time that I became Chairman many strong programs had emerged and perhaps ironically I determined that we should no longer do so.
In my first semester as an Assistant Professor, I had two academic experiences with permanent impacts on my career. A visiting professor, Myron Tribus, invited J. K. Knudsen and me to join him in conducting a graduate seminar on the theoretical structure of heat transfer. This opened my eyes to a whole new world, and for many years afterward I conducted such a seminar in which the objective of each student was to make an original contribution to the literature. Many succeeded and thereby proved to themselves that they could do theoretical work at the frontier of science and engineering. Many of my most lasting publications arose from those seminars because we had no constraints on topicality.
The following semester, Donald L. Katz asked Knudsen and me to join him in teaching the regular graduate course in fluid mechanics and heat transfer with the responsibility of introducing new material. This experience led me to introduce 20% or more new material each time I re-taught a course, with obvious benefit to myself as well as to the students.
Soon thereafter, Robert R. White, one of my colleagues, invited me to participate with him in an analysis of the processing or rate data and the evaluation of the associated uncertainties. This work culminated many years later in my first book on chemical engineering itself, namely, The Rate Process Concept. The Interpretation and Use of Rate Data. White had by then left academia, and declined to be a coauthor, but I am grateful for the insights provided by our collaboration.
At the time that I began my academic career, most of the graduate students in chemical engineering at the U of M were supported by industrial fellowships with their experimental expenses funded by research grants or contracts. This had the advantage of allowing the students a free choice of topics for their doctoral research, something that does not exist today. I took advantage of this freedom to undertake research on many unrelated topics, which prompted D. L. Katz to warn me that I might not attain tenure if I did not focus my efforts more narrowly. I did not heed his advice, and one persisting characteristic of my research has been its breadth, one element of which has been the encouragement of students to abandon their initial plans in order to explore the consequences of an unexpected observation.
The period when I began research was that in which electronic digital computers became available. One of our exploratory excursions was of their use to solve the differential and integral equations of conservation numerically, something I am still doing today. As another aspect of those times, most of the grants and contracts early in my career were from the military, but none of them imposed any serious restrictions related to secrecy and publication.
I was promoted to Associate Professor in 1955, to Professor in 1957, and was chosen as Chairman of Chemical and Metallurgical Engineering in 1962. The latter position was truly beyond my expectations. One feature of my tenure as Chairman was a large turnover in faculty prompted by retirements, the emergence of new fields such as biological engineering, and the elimination of courses such as metals processing. It took only five years as Chairman to convince me that I preferred teaching and research to academic management. At that point in time, the University of Pennsylvania offered me the first chair in chemical engineering, the Carl V. S. Patterson Professorship, with the proviso of freedom from academic management and related responsibilities. That promise was honored in the main. Although I was forced to become Emeritus in 1990 at the age of 70, I have continued to teach and do research with only minimal administrative chores to this day.
Participation in AIChE
During early years of my academic career, I participated in many AIChE activities including accreditation, the Local Section, and the Heat Transfer Division. In 1962 I was nominated and elected to AIChE Council and in 1965 as Vice President. Since W. B. Franklin, my predecessor, had a heart attack early in his term, I effectively served two terms as President. The AIChE position on environmental pollution, portable pensions, and the requirements for the several classes of membership were divisive issues during my time as a Council Member and Officer. During that period the AIChE took the leadership among the engineering societies in opposing successfully a plan by the “Goals” Committee of the ASEE to revise engineering education radically, including, notably, the elimination of the bachelor’s degree. It was a great privilege and responsibility to serve as AIChE President, and I have observed that all former Presidents assume an active and supporting role during the rest of their careers. I found the same dedication to the AIChE at the University of Pennsylvania, where S. P. Sandtler was President (the first) in 1908-1909 and Arthur E. Humphrey in 1991. I served as Student Chapter Advisor at the University of Pennsylvania for over 20 years.
Chemical engineers have rarely had difficulty in finding professional employment over the past century because they are unique in being able to deal with thermodynamics, fluid mechanics, heat transfer, and reaction kinetics – a combination that occurs in most processes and products involving one or more chemical conversions. Processes, products, and even industries come and go, but not the need for this combination of skill. The only dark cloud at the moment is the uncertainty of long-term employment, a condition that places a premium on networking through professional organizations such as the AIChE.
Research Interests
I have had the fulfilling experience, in conjunction with my students and colleagues, of contributing through research and professional consultation to many societal needs. These investigations and discoveries include the retrograde phase-behavior of ethylene and acetylene; the attenuation of thermal radiation from nuclear weapons; the ignition of solid-state propellants; the safe handling of H2 and O2 in rockets; the development of an icing detector for aircraft; the use of an air-stream to extract geothermal energy from underground rivers; the reduction of jet-engine noise; the prevention of H2-O2 detonations in nuclear reactors; the safe-handling of liquefied natural gas; the identification of the cause of fires associated with kerosene heaters; the characterization of radiative transfer through thermal insulations, packed beds, and fluidized beds; the purification of river water by bubbling air; the development of a novel burner for almost all fuels that produces essentially no pollutants and can also be used to incinerate refractory molecules such as dioxin; thermal transport in space vehicles; heat transfer in solar water-heaters; natural convection in living spaces; Czochralski crystallization; the use of a shock tube to carry out reactions at high temperature; the use of a plasma to produce pure aluminum; the development of a double-spiral heat exchanger/catalytic reactor for the elimination of cigarette smoke, micro-organisms, nitrous oxide, and other pollutants in the air of working and living spaces; the discovery of an optimal rate of flow in such a device; the removal of dispersed water droplets from gasoline; extraction in two-phase co-current flow; modeling of the extrusion of Plexiglas; the in-situ retorting of shale-oil, the use of a combined annular and central-jet reactor to avoid corrosion; the enhancement of heat exchange by turbulizers, turbulent-laminar-turbulent transition, and energetic chemical reactions; the enhancement of cooking and curing by off-on heating; the enhancement of water migration through porous media of capillary dimensions; and the first accurate measurements of thermoacoustic convection (which is the cause of thunder).
The theoretical findings of a fundamental nature that have emerged from my research are not so readily described in a single phrase and therefore must be slighted here, but they include the first numerical solutions of the partial differential equations of conservation for natural convection as well as formulation of numerical algorithms for buoyant behavior of extended scope; a computer program for dimensional analysis of partial differential models that identifies and invokes similarity transformations; a generalized form of algebraic correlation in terms of asymptotes that has become the standard for flow and heat transfer; an algebraic model for turbulent transport that is almost exact; and the first exact model for thermoacoustic convection and thereby an explanation of the failure of the transient Fourier equation at short times.
The focus on topics with a practical identification, together with my insistence on a combination of experimental and theoretical work, has undoubtedly been a factor in the decision of doctoral students to work with me or not. At the same time, I have never encountered any difficulty in persuading them to abandon the initial objective to explore the consequences of an anomalous observation. Such side-tracks have produced the most important of our discoveries, whereas the synergetic combination of experiment and theory has had many payoffs, not only in terms of testing the validity of experimental measurements but also in terms of exploitation of the anomalies.
Chemical engineering has had a major role in my life even apart from technology. Most of my personal friends are colleagues or former students, and one, Warren D. Seider, is both. My wife Renate was formerly Editor of International Chemical Engineering, a journal of translations published by the AIChE. My grandson, Stefan C. Zajic, studied chemical engineering at the University of Pennsylvania and we have four joint publications based on his research as an undergraduate. I have many interests other than chemical engineering, but it is the key element of my life.