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ME-EM Graduate Seminar Speaker Series
Dr. Keunhan Park
University of Utah
Abstract: In 2014, Unites States consumed more than 97 quadrillion BTU of energy. This is equivalent to the amount of energy in 3.5 billion tons of coal or 776 billion gallons (US) of gasoline. However, almost 59% of such energy consumption is being lost as waste heat in the form of hot exhaust gas, cooling water, and heat lost from hot equipment surfaces and heated products. It is thus imperative to find an innovative way of recycling energy from a waste heat source as an emission-free and less-costly energy resource. This presentation aims to introduce the recent efforts of the Micro/Nanoscale Energy Transport and Conversion Laboratory to utilize the near-field enhancement of thermal radiation for renewable energy recycling. Particularly, near-field thermophotovoltaic (NTPV) and near-field enhanced thermionic energy conversion (NETEC) technologies will be discussed. Previous studies have found that thermal radiation can exceed the blackbody limit by several orders of magnitudes when objects are separated by a sub-wavelength vacuum gap distance. In the near field, thermally excited evanescent electromagnetic waves on both sides of the gap are strongly coupled to transfer a significant amount of radiative energy across the vacuum gap. Both NTPV and NETEC systems make use of such near-field enhancement of thermal radiation to boost photoexcitation of electrons in a low-bandgap semiconductor, one for direct photovoltaic power generation and the other for the enhancement of thermionic electron emission. I will discuss the fundamental physics of these novel energy conversion systems and their performance analysis schemes, followed by the recent experimental efforts to verify near-field thermal radiation for energy conversion.
Bio: Keunhan (Kay) Park earned his BS and MS degrees in mechanical engineering at Seoul National University in 1997 and 1999, respectively, and achieve his PhD in mechanical engineering at the Georgia Institute of Technology in 2007. During 2007- 2008, he was in the Beckman Institute for Advanced Science and Technology at the University of Illinois at Urbana-Champaign as a postdoc researcher. From 2008-2013 he held an assistant professor position in the Department of Mechanical, Industrial and Systems Engineering at the University of Rhode Island. He is currently an assistant professor in the Department of Mechanical Engineering at the University of Utah. His research interests are micro/nanoscale energy transport and its engineering applications, focusing on (1) tip-based nanoengineering for imaging and analysis of nanoscale photonic, electronic, and thermal energy interactions; (2) near-field based energy recycling technologies; and (3) nanoscale manufacturing.
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