Journal of Nanomedicine & Nanotechnology

Nanostructures on surface wettability and roughness manipulation for heat transfer applications

2^nd International Conference on Nanotek and Expo

December 3-5, 2012 DoubleTree by Hilton Philadelphia Center City, USA

Hyung Hee Cho

Scientific Tracks Abstracts: J Nanomed Nanotechol

Abstract:

Nanotechnology has been expanding its application fields based on ever-progressing compatibility and availability. Materialization of nanoscale structures provides simple tools for the manipulation of surface wettability and morphology, which are principal factors for the performance of boiling heat transfer accompanying phase-change phenomena of coolant. Surface wettability is related to the accessibility of liquid-type working fluid toward a heat transfer surface. In addition, it affects the physics of vaporized bubble behaviors that is nucleation, development and detachment from the hot spot surface. As an effective and powerful technique to manipulate heat transfer performance, silicon nanowire arrays (SiNWs) via metal assisted chemical etching process can be employed to meet the requirements for both superhydrophilic and superhydrophobic conditions. Extreme surface roughness by SiNWs with high aspect ratio reinforces hydrophilicity or hydrophobicity according to surface energy characteristics. The wettability control technique proved by theoretical/experimental approaches is applied to effective heat dissipation under boiling heat transfer. Local wall temperature, heat transfer coefficient, and heat power for allowable limit are evaluated according to manipulating SiNWs and surface free energy. It can be shown that the bubble dynamics, which is a crucial factor to characterizing local heat transfer, is dominated by the preconditions of nanoscale structures.

Biography :

Hyung Hee Cho received the Ph.D. degree in mechanical engineering from University of Minnesota, Minneapolis, in 1992. Since 1995, he has been with the Department of Mechanical Engineering, Yonsei University, Seoul, Korea, where he is currently a Full Professor in the School of Mechanical Engineering. He is currently a Director of the Yonsei Institute of Green Technology. He has published for over 100 scientific papers in renowned journals and serving as Associate Editor of the International Journal of Fluid Machinery and Systems. He is a Fellow of the American Society of Mechanical Engineers.