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2015 年 05 月 21 日
Seminar - Recent Advances in Condensation Heat Transfer By Prof. Ping Cheng

Date: 21 May 2015 (Thursday)

Time: 11:00 am – 12:30 pm

Venue: EF305, The Hong Kong Polytechnic University

Abstract:

This talk will include two parts. In the first part the development of innovative
methods for characterizing the mechanical properties of nanowires, nanobelts and
ultrathin films will be introduced. In the second part the fundamental understanding of
deformation mechanisms of a thin film multilayered structure under mechanical loading
and its removal characteristics involved in abrasive machining will be discussed.

Classical theories of film condensation and dropwise condensation will be briefly reviewed. Deficiencies of previous theoretical analyses on onset of droplet nucleation and dropwise condensation heat transfer will be identified. An improved theory on the critical radius for onset of droplet nucleation, taking into consideration wettability of the subcooled surface and the thermal properties of the coating will be presented. Based on this critical nucleation radius, the predicted nucleation droplet density and condensation heat flux are shown in good agreement with experimental data. Effects of temperature and humidity of air, as well as temperature and wettability of the wall on onset of droplet condensation are analyzed and its application to anti freezing will be illustrated. Theoretical and experimental investigation on enhanced dropwise condensation heat transfer by an externally imposed electric field will be presented. The newly developed phase-change lattice Boltzmann method is used to simulate film condensation and dropwise condensation as well as self-propelled jumping of droplets after coalescence on a superhydrophobic surface. Experimental investigations on flow condensation in microchannels are carried out, and the surface wettability is shown to have a significant impact on the flow pattern, pressure drop and condensation heat transfer characteristics.

Bio-sketch:

Prof. Ping Cheng, a member of Chinese Academy of Sciences, is a Distinguished Professor of Mechanical Engineering Department at The Hong Kong Polytechnic University. He is also an Honorary Director of Institute of Engineering Thermophysics and a Chair Professor in School of Mechanical Engineering at Shanghai Jiaotong University.

Prof. Cheng received his B.S. degree in Mechanical Engineering from Oklahoma State University, his M.S. degree in Mechanical Engineering from MIT, and his Ph.D. in Aeronautics and Astronautics from Stanford University. Prior to his present position, he served as Chairman of Mechanical Department at University of Hawaii (1989-1994) and as the 2nd Head of Mechanical Engineering Department at Hong Kong University of Science and Technology (1995-2002).

Prof. Cheng has done seminal research work in porous-media heat transfer, microscale heat transfer, radiative gasdynamics, and most recently in meso-scale simulations of boiling and condensation heat transfer phenomena. He has published over 200 SCI journal papers, and was listed by Thomson Reuters as one of the world’s “Highly Cited Researchers” in 2014. A Fellow of both American Society of Mechanical Engineers (ASME) and American Institute of Aeronautics and Astronautics (AIAA), Prof. Cheng has received many international honors including: 2005 ASME/AIChE Max Jakob Memorial Award (the most prestigious international award in the field of heat transfer), 1996 ASME Heat Transfer Memorial Award, 2003 AIAA Thermophysics Award, and 2006 ASME Heat Transfer Classic Paper Award. He was also a recipient of 2006 Shanghai Science & Technology award (1st prize category) and 2007 Natural Science Award of China (2nd prize category) for his pioneering work in microscale heat transfer with applications to cooling of electronic chips and high heat flux devices.

Prof. Cheng is presently serving as Editor for International J. of Heat & Mass Transfer and Editor for International Communication on Heat & Mass Transfer, and is on the editorial boards of 14 other international heat transfer and energy journals. He will be the Chair of the 16th International Heat Transfer Conference to be held in Beijing on Aug.10-18, 2018.