Invitation and Sponsorship: Promod Vohra, Dean
Northern Illinois University (NIU)
Seminar Lecture at Northern Illinois University
NIU Engineering Building - EB Event Room 354
at Noon on Friday 9 March 2012
Refreshment at 11:30 AM * No registration required * [PDF Seminar Flier] [Handouts]*
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* UPDATED Info at: www.kostic.niu.edu/Seminars/Zhang2012NIU.htm
MICRO/NANOSCALE HEAT TRANSFER:
Interfacial Effects Dominate the Heat Transfer
Xing Zhang, Director and Professor
Institute of Engineering Thermophysics
Department of Engineering Mechanics
, Beijing, China
Chair, Executive Committee for the Beijing2018_IHTC-16
President, Chinese Heat and mass Transfer Society (Also 与会学者合影[前排左起)
The effects of size on heat conduction in nanofilms, convective heat transfer in micro/nanochannels, and near-field radiation in nanogaps are described. As the size is reduced, the ratio of the surface area to the volume increases; therefore, the relative importance of the interfacial effects also increases. The physical mechanisms for these size effects have been classified into two categories. When the scale is reduced to the order of micrometers (except for gases), the interfaces only affect the macro parameters and the continuum assumption still holds, but the relative importance of the various forces (inertia force, viscous force, buoyancy, etc.) and effects (interfacial effect, axial heat conduction in the tube wall, etc.) changes, resulting in changes in the heat transfer characteristics from normal conditions. As the size is further reduced to the order of submicrometers or nanometers, the interface affects not only the macro parameters but also the micro parameters (mean free path, relaxation time, etc.) so the continuum assumption breaks down and Newton’s viscosity law and Fourier’s heat conduction law are no longer applicable. Thus, the major characteristic of micro/nanoscale heat transfer is that the interfacial effects dominate the heat transfer.
Biography: Professor Xing Zhang is the Director of the Institute of Engineering Thermophysics at Tsinghua University and the Chairman of the Heat and Mass Transfer Society of China. He received his Ph.D. degree from Tsinghua University in 1988 and worked as a Lecturer at Southeast University after his graduation. From 1990 to 2006, he worked as a Research Associate, an Assistant Professor and an Associate Professor at Kyushu University in Japan. He, as a Professor, returned to Tsinghua University in 2006. His current research interests include micro/nanoscale heat transfer, thermophysical properties of nanostructured materials, and efficient use of wind/solar/hydrogen energy etc. He has published over three hundred papers, and has delivered more than 40 Keynote, Plenary, and Invited Lectures at major technical Conferences and Institutions. He is currently the Editor of Experimental Thermal and Fluid Science, an Assembly Member of International Heat Transfer Conference and an Executive Committee Member of International Center for Heat and Mass Transfer.
During his U.S. visit Professor Zhang also attended and presented a Keynote at The ASME 2012 3rd Micro/Nanoscale Heat & Mass Transfer International Conference in Atlanta, GA, on March 3-6, 2012, and visited UIUC and NIU.
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UPDATED Info at: www.kostic.niu.edu/Seminars/Zhang2012NIU.htm