Woodruff School of Mechanical Engineering
Mechanical Engineering Seminar
Reversing Joule Heating with Phonon-Absorbing Heterobarrier
Dr. Massoud Kaviany
University of Michigan
Friday, April 11, 2014 at 11:00:00 AM
MRDC Building, Room 4211
Dr. Satish Kumar
Using graded heterobarrier placed along the electron channel, the phonons emitted in joule heating are recycled in-situ by increasing the entropy of phonon absorbing electrons. The asymmetric electric potential distribution created by alloy grading separates the phonon absorption and emission regions, and emission in the larger effective mass region causes momentum relaxation with smaller electron kinetic energy loss. These lead to smaller overall phonon emission rate resulting in simultaneous potential-gain and self-cooling effects. This potential gain increases with lower current and higher optical phonon temperature, tending toward the reversible limit with diminishing current and small barrier height. Phonon recycling remains significant at finite currents and for GaAs:Al electron channel the results are presented under ideal and nonideal thermal isolation with the surroundings.
Massoud Kaviany (Ph.D. UC-Berkeley 1979) is a Professor in the Department of Mechanical Engineering and in Applied Physics Program, University of Michigan, since 1986. His interest is in heat transfer education and research. He has authored Heat Transfer Physics 2008 and Essentials of Heat Transfer 2011, by Cambridge University Press. He was Chair of ASME Committee on Theory and Fundamental Research in Heat Transfer (1995-1998), is ASME Fellow (1992) and APS Fellow (2011), and has received University of Michigan Engineering 2003 Education Excellence Award, 2002 ASME Heat Transfer Memorial Award (Science), and 2010 ASME Harry Potter Gold Medal (Thermodynamics Science).
Refreshments will be served.