ECE’s Bermel publishes paper on radiative cooling
Having a simple and effective way to provide passive cooling – an approach that focuses on reducing temperatures without consuming energy - could help make renewable energy more widely achievable and available.
With this goal in mind, Peter Bermel, associate professor of electrical and computer engineering, set out to learn whether radiative cooling could provide a substantial amount of extra passive cooling for concentrating photovoltaics (CPV). CPV systems generate electricity from sunlight that is focused by lenses or mirrors onto small, efficient photovoltaic cells or modules.
By consulting prior literature, creating a detailed model, and conducting a series of experiments, he determined that enhanced radiative cooling for CPV is a cheap, lightweight add-on requiring no input power, making it a viable option. It can reject significantly more waste heat than convection and conduction at high temperatures by sending it directly into space. As a passive and compact cooling mechanism, radiative cooling does not require or consume input power, making it promising for thermal management in outdoor systems generating low-grade heat.
Bermel and his team at the Birck Nanotechnology Center recently published a paper outlining their major findings in Joule.
“We found that our approach can cool off CPV by 36 degrees Celsius compared to controls under certain circumstances, which can also increase the open circuit-voltage of a photovoltaics cell by 27% relative,” Bermel said. “We expect it to greatly increase the lifetime and decrease the failure rate of CPV in the field over extended time periods.”
Historically, CPV have been limited in performance and reliability by typically relatively high operating temperatures, Bermel explained. “Providing a simple way to run them much cooler may increase their feasibility to be deployed more widely. Our approach may also benefit related electronics technologies that operate more effectively or efficiently at lower temperatures.”
He said the group’s results should be of interest to companies creating high-performance coatings to reduce the operating temperature of CPV and sensitive electronics, “as well as policymakers deciding where to prioritize investment of research dollars in energy and electronics technologies.”
Bermel, who also serves as the associate director of graduate admissions for ECE, came to Purdue in 2012 “because of the University’s outstanding colleagues, students, and facilities in which to conduct research in the interface of nanophotonics and electronics.” At Purdue, he has been able to extend his previous research that began while he was a PhD student at MIT.
He provided the overall direction of this project and guided students during specific experiments and simulations. In addition, he helped interpret and describe the results and took the lead in the paper’s submission, including the review process.
His team is in the process of filing a patent on this technology. Furthermore, they aim to develop additional approaches to apply radiative cooling to related applications. Funding for this research was provided by the National Science Foundation, U.S. Department of Energy and the Office of Naval Research.