Tuesday, December 06, 2011
4:00 PM -
5:00 PM
Spalding Laboratory 106 (Hartley Memorial Seminar Room)
Applied Physics Seminar
Series: Applied Physics Seminar Series
Thermionic and photon-enhanced emission for solar thermal energy conversion
Nick Melosh,
Department of Materials Science and Engineering,
Stanford University,
Speaker's Bio:
Professor Melosh received his B.S. degree in Chemistry from Harvey Mudd College in 1996, then went on to do a Ph.D. in Materials Science at UC Santa Barbara working with Brad Chmelka, Galen Stucky, and Glenn Fredrickson. He then went to UCLA/Caltech to work with Professor Jim Heath as a post-doc from 2001-2003, and became an Assistant Professor of Materials Science and Engineering at Stanford University in 2003. Professor Melosh's interests include molecular electronics, electron emission, energy conversion, and interfacing electronics with biology. He is a Terman Fellow and Reid and Polly Anderson Faculty Scholar at Stanford University.
Professor Melosh received his B.S. degree in Chemistry from Harvey Mudd College in 1996, then went on to do a Ph.D. in Materials Science at UC Santa Barbara working with Brad Chmelka, Galen Stucky, and Glenn Fredrickson. He then went to UCLA/Caltech to work with Professor Jim Heath as a post-doc from 2001-2003, and became an Assistant Professor of Materials Science and Engineering at Stanford University in 2003. Professor Melosh's interests include molecular electronics, electron emission, energy conversion, and interfacing electronics with biology. He is a Terman Fellow and Reid and Polly Anderson Faculty Scholar at Stanford University.
Thermionic emission has long been an attractive idea for thermal energy conversion for its potentially high-efficiency conversion with no moving parts and simple device geometry. However, previous generations of convertors have had relatively poor actual performance due space charge effects and low output voltages, which has severely restricted their implementation and research. Here we discuss why modern microfabrication techniques and a new idea that combines both photovoltaic and thermionic effects together may reverse the fortunes of this technology, and lead to highly efficient conversion devices. We show that both theoretical and experimental data on MEMs thermionic devices show higher maximum currents than previously possible. Solar thermal applications also have a considerable quantity of light present, and we describe a new mechanism, photon-enhanced thermionic emission (PETE), that can benefit from both photon illumination and thermal energy. This process enables thermionic emission at much lower temperatures (~400ºC) than conventional thermionic emission, and may have higher overall efficiency. We will discuss experimental demonstrations of this process and the critical barriers to making lab prototypes into realistic conversion systems.
Event Sponsors:
For more information, please contact Christy Jenstad by phone at 8124 or by email at [email protected].