Experimental Study on Pool Boiling on Hydrophilic Micro/Nanotextured Surfaces with Hydrophobic Patterns

Over the past decades, pool boiling on various wetting surfaces has been intensively investigated to enhance boiling heat transfer and critical heat flux. In this study, to enhance the two thermal performances simultaneously, we developed hydrophilic micro/nanotextured surfaces with hydrophobic patterns. Using a silicon substrate, well-arrayed microtextures and randomly arrayed nanotextures were fabricated hierarchically using micro/nanoelectromechanical system processes. The top of the microtextures was coated locally with hydrophobic characteristics using specific self-assembled monolayer coating methods. Based on experimental data, we postulate that the critical heat flux was enhanced by the capillary-induced flow between microtextures and that nanotextures with superhydrophilicity contribute to the delay of the critical heat flux by better wetting the dried area. Owing to the hydrophobicity at the top of the micropillars, the nucleate site density and boiling heat transfer increased.