Professor of Mechanical Engineering Deyu Li has been awarded an inaugural National Science Foundation TRAILBLAZER Engineering Impact Award to extend Max Planck’s theory of thermal radiation from equilibrium thermal sources to a regime where non-equilibrium energy carriers can lead to significantly enhanced radiative heat dissipation.
The resulting super-efficient radiative cooling approaches could revolutionize a wide range of engineering practices including energy conversion, data center and microelectronic device thermal management, and passive cooling of buildings.
Li’s $3 million TRAILBLAZER Award for Super-Planckian Far Field Radiation via Non-equilibrium Polaritons is one of six three-year projects led by a single investigator announced on July 23, 2024 by the NSF Engineering Directorate. The new $18-million program enables researchers who have a track record of innovative breakthroughs and unconventional hypotheses to pursue groundbreaking engineering ideas.
“Professor Li’s trailblazing research explores the frontiers of energy and materials technology at the nanoscale, pushing the limits of scientific fields,” said Krish Roy, Bruce and Bridgitt Evans Dean of Engineering and University Distinguished Professor. “This new project proposes transformative contributions to extend fundamental physical laws at the interface of thermal science, atomic scale physics, materials and energy technologies, and provides opportunities for path-breaking new discoveries.”
Li will pursue approaches using phonon polaritons, energy carriers resulting from coupling between infrared light and atomic vibrations, to achieve super-efficient radiative cooling beyond the blackbody limit. An ideal body that can completely absorb incoming radiation of all frequencies is called a blackbody, which also emits at a maximum efficiency under a thermal equilibrium condition that is called the blackbody radiation limit.
“Efficient heat dissipation is a bottleneck for a broad spectrum of technologies,” Li said. “This project could shift the paradigm of thermal radiation and transform thermal engineering. The National Science Foundation’s support will be instrumental in bringing this visionary concept from a hypothesis to reality and push the boundaries of energy technologies.”
Radiative heat transfer over large distances, or far field radiation, has an upper bound known as the blackbody limit. Li observed in a recent study published in Nature that heat conduction along silicon carbide (SiC) nanowires with a short segment of gold coating at the end of the wires can reach a level that is well beyond the Landauer limit, indicating stimulations of non-equilibrium energy carriers propagating along the wire. This seminal discovery leads to the hypothesis that these thermally triggered non-equilibrium polaritons could also enable far-field radiation at a rate beyond the blackbody limit.
Experiments will demonstrate super-Planckian far field radiation from individual polar nanowires with a short segment of gold coating at the end of the wire. Large-area metal surfaces with partially embedded polar nanowire arrays will be built to demonstrate an emissivity that is greater than unity, the value for a blackbody—and cooling effectiveness when attached to solar panels and light emitting devices (LEDs).
This grant proposal was supported by Vanderbilt University Research Development and Support, which offers proposal development assistance for private (foundation) and federally funded opportunities. RDS is housed within the Office of the Vice Provost for Research and Innovation.