Gangtao Liang

School of energy and power engineering, Dalian University of Technology, China.

E-mail:gtliang@dlut.edu.cn

Professor Gangtao Liang received his B.Eng. in 2009 and Ph.D. in 2014 from Dalian University of Technology. He undertook his postdoctoral research from 2015 to 2017 at Purdue University Boiling and Two-Phase Flow Laboratory (PU-BTPFL), where he was dedicated to experimental investigation and theoretical modeling of two-phase flow and heat transfer. His primary research interests are two-phase flow and heat transfer, covering droplets impingement, spray cooling, micro-channel flow boiling and condensation, horizontal-tube falling film evaporation, and boiling enhancement. He has published over 60 archival journal papers in Int. J. Heat Mass Transfer, Int. Commun. Heat Mass Transfer, Ind. Eng. Chem. Res, and other recognized journals in the thermal science field. He is currently a member of American Society of Mechanical Engineers (ASME), a member of World Society of Sustainable Energy Technologies (WSSET), Advisory Board Member of Heat Transfer Division in Cambridge Scholars Publishing, International Advisory Board Member of Thermal Science Journal, and Editorial Board Member of Fluid Dynamics & Materials Processing. He also serves as an outstanding reviewer for many international journals.  

Title：Boiling Heat Transfer on Hybrid-Wettability Surface

Abstract: Aggressive miniaturization accompanied by high integration of electronic components have posed challenges for more effective thermal management solutions This significantly motivates researchers in thermal field to shift their attention toward two-phase cooling, to seek new thermal control techniques to tackle a great amount of heat dissipation in high- and ultra-high-heat-flux devices. The two-phase cooling is based on boiling, which is superior to single-phase cooling as it can utilize far greater liquid/vapor phase-change latent heat along with temperature-rise sensible heat rather than sensible heat alone for the latter. We studied boiling heat transfer on the hybrid-wettability surfaces, i.e., hydrophobic dot/stripe patterns fabricated on a superhydrophilic substrate. It is shown that the nucleate boiling heat transfer coefficient for the hybrid surface is improved compared to both the substrate and plain copper reference, but the critical heat flux (CHF) on the enhanced surface is very complex. The pattern-to-substrate contact angle difference is also concerned: CHF for the hybrid surface increases remarkably with increasing the contact angle difference, but the nucleate boiling heat transfer coefficient declines. Combining the results for both dot and stripe patterns, it is revealed that CHF on the hybrid surfaces is closely associated with the pattern-to-surface area ratio and the pattern-to-pattern spacing: it declines generally with increasing the area ratio; its dependence on the pattern spacing is minor at large area ratios; however, at small area ratios, the pattern spacing plays an increasingly important role because it dominates both vapor-liquid instabilities and surface rewetting, and the optimal pattern spacing for maximal pool boiling heat transfer enhancement can be estimated using the capillary length. A modified theoretical model is proposed to predicting CHF on both homogenous- and hybrid-wettability surfaces.