Events

Abstract

High-temperature thermal transport is important for a multitude of energy conversion and storage processes, such as power generation, thermochemical, solar-thermal, thermophotovoltaic, thermoelectric, and thermal energy storage. Heat transfer physics at high temperature is also markedly different from its counterpart at room- and low- temperatures, including higher degree of anharmonity of lattice dynamics resulting in stronger phonon-phonon scattering and the more prominent or even dominant role of radiation heat transfer. On the other hand, high temperature poses tremendous challenges on thermal, chemical, and phase stability of materials. We have been working on several fronts related to high temperature thermal transport materials and physics over the past few years, including basic studies of conduction-radiation coupled phenomena in nanostructures and metamaterials and the development of materials and devices for engineering applications such as solar energy harvesting, thermal insulation, thermal storage, heat exchangers, selective emitters. In this talk, I will specifically present two recent examples of our work in this area. First, we experimentally probed the contribution of surface phonon polariton (SPhP) in polar dielectric (e.g., SiO₂) nanostructures to radiation and conduction heat transfer from room to high temperature. We found that SPhP could be a significant energy carrier for heat conduction at high temperatures. Second, we measured thermal transport properties of ceramic particles as granular media, which are being investigated as alternative high-temperature heat transfer and thermal energy storage medium (e.g., to replace molten salts). Due to the discrete nature of the granular media, we found important roles of flow-dependent particle-wall thermal resistance and thermal conductivity of particle beds on the heat transfer coefficient of particle bed heat exchangers. This will shed light on the design of future particle-based heat exchangers for high-temperature thermal energy conversion and storage systems.

About the Speaker

Renkun Chen is a Professor in the Department of Mechanical and Aerospace Engineering and Program in Materials Science and Engineering at the University of California, San Diego. He received his B.S. degree in Engineering Thermo-physics from Tsinghua University in 2004, and Ph.D. degree in Mechanical Engineering from the University of California, Berkeley in 2008. He was a postdoctoral researcher at Lawrence Berkeley National Laboratory in 2009 and joined the faculty of UC San Diego in the Department of Mechanical and Aerospace Engineering in Nov. 2009. His research group is interested in fundamental micro- and nano- scale heat transfer and its applications in energy and biological systems.  He has received a R&D 100 award and a Hellman Fellowship.