Professor Bao Yang: Engineering a Cooler World

Bao Yang in front of Glenn L. Martin Hall; the background shows the buildings red bricks and while columns

Mechanical engineering Professor Bao Yang has been tackling one of the central challenges in quantum computing: how to cool quantum systems efficiently to temperatures approaching absolute zero.

“If we want to see the quantum effects, the temperature needs to be very, very low,” says Yang, a faculty member with the University of Maryland Center for Environmental Energy Engineering (CEEE). With funding from a now-completed National Science Foundation project, he investigated whether thermoelectric devices — which use electricity to pump heat from one location to another — could offer an energy-efficient alternative for ultra-low temperature refrigeration.

His research team explored advanced thermoelectric materials, working toward the ultimate goal of developing devices capable of cooling to 4 K. Early results have been promising, pointing to the technology’s potential. The project recently wrapped up, but there's still work to be done, and Yang hopes to secure support to carry it forward.

Innovating eco-friendly cooling methods is nothing new for Yang, who joined the University of Maryland in 2003, after serving as a visiting researcher at Massachusetts Institute of Technology. He holds two doctorate degrees: a Ph.D. in Physics from the University of Science and Technology in China and a Ph.D. in Mechanical Engineering from the University of California, Los Angeles (UCLA).

Yang still remembers his first visit to College Park. He was immediately impressed by the chair of the search committee, CEEE founding director Reinhard Radermacher (1952–2025).

“I received several job offers, but I chose Maryland for one important reason — the people here,” Yang says. He was struck by the caliber of their research, encouraged by their spirit of collaboration and intrigued by their industry partnerships. Maryland offered an opportunity to grow as a researcher, providing the perfect marriage of fundamental and applied research. He soon began collaborating with Radermacher and CEEE co-founder Michael Ohadi.

Since joining UMD, Yang has built an internationally recognized research program in thermal management. He published 112 journal papers, 33 refereed conference papers, seven book chapters and two books: Thermoelectric Microcoolers and Energy Consumption, Conversion, Storage, and Efficiency. He received two non-provisional international patents (both of them with Radermacher), four non-provisional U.S. patents and 16 provisional patents. He consistently ranks among the top 2% of researchers worldwide based on the number of citations of his work, according to a ranking developed by Stanford University.

His research focuses on two primary areas: 1) thermoelectric devices and systems for electronic cooling applications and 2) advanced nanomaterials for thermal management applications.

The power of electricity

In the search for sustainable cooling solutions, thermoelectric cooling checks many of the boxes. “It’s solid state cooling,” Yang explains. “It doesn't need any chemical refrigerants. It doesn't have any moving parts. It can operate quietly.” In other words, it offers a highly reliable technology, with no direct global warming potential. The technology has been used extensively in portable coolers and mini refrigerators.

"I received several job offers, but I chose Maryland for one important reason — the people here."

Professor Bao Yang

“The issue is the efficiency is not as high as vapor compression-based refrigeration,” he says. But what if the two approaches were combined? In the early 2000s, he teamed up with Radermacher to develop a thermoelectric-assisted vapor-compression refrigeration system. The hybrid solution offered improved performance, he says, but further research would be needed to make the price competitive with a vapor-compression-only system.

Yang's thermoelectric work has been particularly impactful in the area of electronics cooling, where the challenge is to remove large amounts of heat from very small, localized areas. In collaboration with the Research Triangle Institute, his team engineered thermoelectric superlattice micro-coolers capable of delivering a power density of 235 W/cm² — a record for thermoelectric technology.

His group also developed mini-contact enhanced thermoelectric cooling — using thermoelectric cooling elements that are only a millimeter long — to significantly increase heat removal from localized hotspots. Yang’s ongoing research continues to push the limits of thermoelectric cooling, with a focus on developing increasingly efficient materials and devices for applications ranging from electronics cooling to quantum computing.

Small materials, large impact

Yang is also recognized for his work developing advanced nanomaterials for thermal management applications — leveraging materials so small that they are measured in nanometers.

His team pioneered a microemulsion-based approach to improve absorption chillers — refrigeration systems that use heat instead of an electric compressor to produce cooling. In conventional absorption chillers, water must be vaporized or boiled during the desorption process, which requires substantial energy. Yang’s method releases the absorbed water as liquid instead.

“This desorption process requires about one-tenth of the energy compared to conventional processes,” he says. The approach could substantially improve the theoretical coefficient of performance (COP) of absorption chillers, increasing overall system efficiency by as much as threefold compared with existing systems. But further research is needed to enhance its temperature lift and cooling capacity.

“Achieving these improvements will require interdisciplinary collaboration among experts in materials science, mechanical engineering and systems engineering,” Yang says.

Yang’s group has also developed new ways to improve heat-transfer fluids, including the use of thermally conductive phase-change-material (PCM) micro- and nanoparticles. These materials can absorb and release large amounts of heat during phase changes — like from solid to liquid — helping systems manage temperatures more efficiently.

Next-gen motivation

For Yang, some of the most rewarding moments of his career come from watching his students grow. He takes pride in guiding the next generation of scientists and engineers. Breakthroughs like his team’s work with microemulsions take years of collaboration and countless late nights of lab work. “We become like family,” he says. “I’m so proud of my students. They graduate and get good jobs with companies like Nvidia, ASML, Google and Qualcomm.”

When he’s not in the lab, Yang enjoys spending time with his two sons — one in high school, one in college. His family and his students are what drive him to build a sustainable, energy-efficient future. "We live on Earth," he says. "I want the next generation to have a better future."

Published November 12, 2026