National Academy of Engineering Memorial Tributes: National Academy of Engineering, Volume 10
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Memorial Tributes: National Academy of Engineering, Volume 10

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             HOYT C.HOTTEL                                            141
                              HOYT C.HOTTEL
                TO THOSE WHO KNEW HIM, HOYT C.HOTTEL will be remembered
            for his intensity, intellect, and integrity. He would shut out the world as he
            pursued his activities, and his concentration on the problem at hand would often
            be mistaken for absentmindedness or aloofness. Few problems could long
            withstand the sustained assault of his undivided attention. His career in the
            Department of Chemical Engineering at the Massachusetts Institute of
            Technology, from 1928 until his death at the age of ninety-five on August 18,
            1998, was filled with remarkable accomplishments. His final technical
            contribution was his narration of the history of the Combustion Institute, of which
            he was a cofounder, videotaped at his home on July 29, less than three weeks
            before his death.
                He was born to Louis Weaver Hottel and Myrtle Clarke on January 15,
            1903, in Salem, Indiana. His family moved shortly thereafter to St. Louis. He
            liked to recount, as a measure of his longevity, memories of becoming separated
            from his parents at the 1905 World’s Fair and of watching Halley’s Comet from
            his backyard in a St. Louis suburb. Having moved to Chicago at the age of ten, he
            graduated from the Hyde Park High School in 1918. He subsequently attended
            Indiana University, from which he graduated with a B.A. degree in chemistry in
                He went directly from Indiana to MIT for graduate studies in chemical
            engineering and enrolled in the School of Chemical
             HOYT C.HOTTEL                                            142
             Engineering Practice. One of the field stations of the Practice School that he
             attended, first as student then as an assistant director, was the Lackawanna plant
             of the Bethlehem Steel Company, where he developed his lifelong interest in
             furnaces and combustion. He returned to MIT to work on a doctoral thesis on
             flame propagation under Robert T.Haslam. When Haslam asked him to write up
             his thesis, Hottel requested that he concentrate instead on the publication of some
             radiation calculations that he considered to be more important. The paper he
             published in Industrial and Engineering Chemistry, and then more elaborately in
             American Institute of Chemical Engineers (AIChE) Transactions, in 1927
             established the basis for the quantitative treatment of radiative heat transfer in
             furnaces and provided the transition for the treatment of radiation in furnaces from
             an art to a science. This paper was the first of many digressions from writing his
             never-to-be-completed doctoral thesis.
                Probably the most lasting of his contributions was the development of the
             gas emissivity charts for quantifying heat transfer in furnaces. The sophistication
             of his equipment, mostly home built, was extraordinary for any time. He designed
             and constructed the first infrared spectrometer at MIT and developed such a
             sensitive radiometer for measuring energy fluxes that the galvanometer would go
             off scale from the adiabatic temperature rise resulting from the pressure increase
             when the laboratory door was closed. Measurements could only be made in the
             still of the early morning on days so calm that the wind would not raise the
             institute flag. To eliminate interference from the radiation of confining windows,
             he developed an aerodynamic confinement of the radiating hot gas mixtures. The
             data that he generated in the 1930s yielded results that provided standards until
             the present. In addition to measuring gas emissivity, he established the
             mathematical framework for the quantitative treatment of furnaces and the zone
             method for furnace heat transfer. He was working on a paper on his one-zone
             method of analysis of furnaces at the time of his death.
                Professor Hottel’s other achievements include early series of studies (1932
             to 1936) of heterogeneous combustion, which first identified quantitatively the
             roles of diffusion and chemical re
             HOYT C.HOTTEL                                            143
             action in the combustion of solid carbon. This research again reflected the
             sophistication of his experimental design, his meticulous attention to precision in
             gathering data, and his application of scientific reasoning to the interpretation of
             the results. One paper was reprinted fifty years later by International
             Communications in Heat and Mass Transfer as a classic contribution to the field.
             Some of the work was expanded by Frank Kamenetsky in his Russian book
             Diffusion and Heat Transfer in Chemical Kinetics(English publication, 1969).
             His ability to translate fundamentals to practice was illustrated by his application
             in 1941 of incorporating his single-particle models in a treatment of pulverized
             coal flames, which anticipated the computational treatment of pulverized coal
             flames to be developed three decades later.
                His research on gaseous diffusion flames (1939 to 1949) provided a first
             quantitative treatment of the impact of transition from laminar to turbulent flows
             on the length of gaseous diffusion flames. As part of that research, he developed
             jointly with W.R.Hawthorne the concept of unmixedness. His research
             established the notion of the length of the flame being controlled by the mixing at a
             molecular level of fuel and air, and treated quantitatively the effect of
             unmixedness on the lengthening of the flames. These findings have become
             cornerstones to the understanding of turbulent flame structure.
                With funding from Godfrey L.Cabot in 1938, he organized the world’s first
             research center on the use of solar energy, a few years before the Russian
             heliocentric center at Tashkent. The studies led to the choice of the flat-plate
             collector as the most promising device for solar heating, development of the
             performance-predicting equations in use today for assessing such collectors and
             for testing new concepts, construction of the first solar-heated house and of three
             others that provided data for economic assessment of solar space-heating and hot
             water supply. Simultaneously, Professor Hottel maintained a balanced view of the
             significance of solar energy in national or world energy use, advocating the
             separation of emotional from logical inputs to the assessment of the prospects for
             economic use of the sun as an energy source.
                During World War II, he was chief of the National Defense
             HOYT C.HOTTEL                                            144
             Research Committee group that studied and developed incendiaries. After the
             war, he chaired the Armed Forces Special Weapons Panel on Thermal Radiation
             from 1949 to 1956. Noting that war necessitates the development of technology
             for ugly purposes, he turned his attention in peacetime to maximizing the
             contribution of the engineer and scientist to fire prevention and suppression. He
             was involved in organizing and chaired, for its first eleven years, the National
             Research Council’s Commission on Physical Sciences, Mathematics, and
            Resources Panel for Fire Research. He was responsible for stimulating research
            on the reduction and suppression of peacetime fires and aided the U.S. Bureau of
            Standards (now the National Institute of Standards and Technology), through
            congressional testimony, in its successful drive to set up a fire research center.
                Professor Hottel was co-founder, with Bernard Lewis and A. J.Nerad, of the
            Combustion Institute (International), and cofounder, with R.A.Sherman, and
            chairman for its first twenty-one years, of the American Flame Research
            Committee, subsidiary to the International Flame Foundation. Professor Hottel
            was elected a member of the National Academy of Sciences (1963), the National
            Academy of Engineering (NAE) (1974), and the American Academy of Arts and
            Sciences. His professional awards include the United States Medal of Merit;
            King’s Medal for Service in the Cause of Freedom, Great Britain; Founders
            Award, NAE; Founders Award, AIChE; Fritz Medal, United Engineers Trustees;
            Sir Alfred Egerton Gold Medal, the Combustion Institute; William H.Walker
            Award, AIChE; Max Jakob Award, American Society of Mechanical Engineers
            and AIChE; ESSO Energy Award, Royal Society, London; and Melchett Medal,
            Institute of Fuel, Great Britain.
                He was an inspiring teacher and mentor to students for more than six
            decades. On the principles of teaching, he said: “Beware that a student’s spirit be
            not done to death by a formula, by teaching with answers cast in concrete. Be less
            concerned with technical content and timeliness of what you teach and less
            concerned with the completeness of coverage of your subject than with stretching
            the student’s mind and stimulating him to self-teaching, hopefully stretched
            throughout life.” He would often
             HOYT C.HOTTEL                                            145
             take students home to continue discussions of thesis research, and his wife,
             Nellie, and his four children gracefully accepted these intrusions. As one of his
             students recollected, he would look suddenly at his watch and exclaim, “My
             heavens, it’s half-past six and Nellie will be wondering where I am; you’d better
             come home with me.” Later in the evening, “My heavens, it’s half past eleven.
             You’d better stay here tonight.”
                Away from academia, Professor Hottel took great pride in his extensive
             vegetable and flower gardens. He was a prodigious and skilled woodworker who
             built some beautiful hardwood coffee tables and crafted his own Christmas
             decorations over the years. He also built kayaks for his daughters. One of his
             proudest achievements was climbing Mount Teton in Wyoming with several
             younger MIT colleagues when he was fifty years old. He had a strong interest in
             classical music, and he enjoyed the Boston Symphony regularly for many years
             with his wife, a singer. He had a nearly perfect ear and could sing any song, using
             the diatonic scale. He once determined the frequency range of the sound from a
             research combustor at MIT by telephoning his young daughter at home and
             asking her to play for him the piano keys sequentially over the telephone.
                He was survived by four children: Lois Hottel Wood of Lebanon, New
             Hampshire; H.Clarke Hottel, Jr., since deceased, of Mattapoisett, Massachusetts;
             Barbara Hottel Willis of Severna Park, Maryland; and Elizabeth Hottel Barrett of
             Annapolis, Maryland; ten grandchildren, and eighteen great grandchildren. He
             was a giant of twentieth century chemical engineering and leaves a rich legacy in
             his research output and the large number of students and colleagues, whom he
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