Robert Moffat, expert on heat transfer and beloved teacher, dies at 96

Robert Moffat, a professor emeritus of mechanical engineering whose research on heat transfer led to improved methods for cooling electronic components and gas turbine engines, died May 10 in Los Altos. He was 96.

One of the foremost experts on experimental methods in the thermal sciences, Moffat was also distinguished for his work on a portable incubator for ill and premature newborns. He developed the incubator with Alvin Hackel, a professor of anesthesiology and of pediatrics at the Stanford School of Medicine. The battery-powered incubator could fit in a helicopter or ambulance and was used to transport tens of thousands of sick infants. (Hackel died in 2023.)

Moffat joined the faculty of the Department of Mechanical Engineering in 1967 and served as chairman of its Thermosciences Division from 1973 to 1986. (The division was later split into two units: the Thermofluids, Energy, and Propulsion Systems Group and the Flow Physics and Computational Engineering Group.)

He retired in 1993 but continued to conduct research, consult for companies, and co-author papers through the 2010s. With engineer and retired Kyoto University professor Roy Henk, Moffat also co-authored Planning and Executing Credible Experiments: A Guidebook for Engineering, Science, Industrial Processes, Agriculture, and Business (Wiley, 2020).

“Retirement didn’t slow him down in the slightest,” said his wife, Karina Nilsen.

Moffat was a beloved teacher, said Alfonso Ortega, who was Moffat’s PhD advisee at Stanford. “He was funny. He clearly liked teaching. He made his students laugh and enjoy class,” said Ortega, now a professor of engineering at Villanova University. “I was always really proud to be called Bob’s protégé.”

Moffat once told the Stanford News Service that his award for excellence in undergraduate teaching from Stanford’s chapter of Tau Beta Pi, an engineering honor society, was more important to him than his PhD.

In a 2003 article in Stanford magazine, alumna Shelly Williams Trainor recalled how, in the mid-1970s, she was three years into her mechanical engineering studies – “not really sure I was very good at anything” – when she enrolled in a thermosciences course taught by Moffat.

“In his class I discovered I could actually be good at engineering – good enough to get my first A+,” she wrote. “I had finally found something I loved doing and someone who encouraged me to do it. Professor Moffat – one of the few engineering professors who did not seem put off by having women in his class – became my friend and mentor that last year. I left Stanford with a clear sense of my abilities and the strength to survive in a male-dominated field.”

General Motors to Stanford

Robert John Moffat was born Nov. 29, 1927, in Grosse Pointe, Michigan. He enrolled at the University of Michigan but at the end of his first semester was drafted into the Army.

After being discharged, he re-enrolled at Michigan, earning a bachelor’s degree in mechanical engineering in 1952 and then taking a job as a research engineer in applied thermometry, the discipline of measuring temperature, at General Motors. He was promoted a few year later and assumed responsibility for testing periodic-flow heat exchangers for regenerative-gas turbines.

In 1961, while still a GM employee, he earned a master’s degree in mechanical engineering from Wayne State University. He earned a PhD in mechanical engineering from Stanford in 1967.

As a member of the Stanford School of Engineering faculty, he worked on convective heat transfer in engineering systems, with an initial focus on gas turbine blades and vanes. The overarching goal was to figure out ways to dissipate the immense heat – temperatures as high as 3,000 F – generated by jet engines. Much of his research was sponsored by industry, and he was a sought-after consultant for jet-engine manufacturers, said John Eaton, professor emeritus of mechanical engineering and the Charles Lee Powell Foundation Professor, Emeritus.

Building a prototype of a gas turbine engine can cost upward of $2 billion, so companies are often interested in first gathering evidence that the design will work, Eaton said. They want to determine, for example, whether high temperatures will melt certain components and if the cooling mechanism works. Moffat was skilled at setting up experiments to accurately obtain this kind of information, Eaton said. He also developed deep expertise in the use of thermochromic liquid crystals for measuring temperature on surfaces.

Around 1980, Moffat turned his expertise in thermometry to understanding the complex flow and transport phenomena in forced air cooling of electronic components. His research group at Stanford was the first to use the superposition principle to understand heat transfer from arrays of objects that weren’t uniformly heated. (The principle states that the effects of two or more stimuli in a linear system can be determined by adding them up.)

“Using concepts adapted from heat transfer in gas turbine cooling applications, Bob and his team introduced the concept of the adiabatic heat transfer coefficient,” Ortega said. “The concept was revolutionary and paved the way to understanding how to handle any situation in which heat transfer takes place from discrete, isolated heat sources that may interact with each other” – such as microchips on printed circuit boards.

He added, “It is rare that a researcher can introduce a truly unique concept to a field, but without a doubt, the concept of adiabatic heat transfer coefficient was unique and is illustrative of the innovative nature of Bob’s research.”

In 1989, Moffat received the Heat Transfer Memorial Award from the American Society of Mechanical Engineers. ASME also awarded him the prestigious Holley Medal in 1988 for “pioneering work in the invention, analysis, design, testing and prototype construction of the proven standard of infant incubator-transporter which has saved the lives of thousands of critically ill neonates.” And he was awarded ASME’s Melville Medal in 1986 for best original research.

The Instrument Society of America (now International Society of Automation) presented him with the Robert Abernethy Award in 1989, the Mills Dean Award in 1985, and the Donald P. Eckman Award in 1977. Moffat was a fellow of both the ASME and the ISA.

The Semiconductor Thermal Measurement, Modeling and Management Symposium, held annually in Silicon Valley, inducted Moffat into its Thermal Hall of Fame in 2017 for his lifetime achievements and contributions to the field of electronics thermal management.

Moffat co-authored more than 250 papers and served as the primary adviser or co-adviser for 36 PhD students and four engineer’s degree students.

Renaissance man and trout psychologist

Friends and colleagues considered Moffat a Renaissance man. “Bob’s curiosity about the world was legendary, and not just in engineering,” Ortega said. “One year he decided to learn to grow orchids in his apartment. Another year he decided to learn Japanese. In yet another year he took up calligraphy and tried to convert me into a calligrapher.”

Moffat especially enjoyed fly fishing in Ketchum, Idaho, where he owned a second home. “He was deeply immersed in trout psychology, and trudged across stubble fields to wade the rivers and forget his obligations for a while,” Nilsen said. He also enjoyed biking, traveling, wine tasting, and building a wine collection, she said.

In addition to Nilsen, who lives in Los Altos, Moffat is survived by a son, John Moffat of Seattle, from an earlier marriage.