Controlled bubble departure diameter on biphilic surfaces for enhanced pool boiling heat transfer performance

To elucidate the boiling heat transfer on a biphilic surface, the bubble departure diameter and the bubble location were controlled through the variation of the size and pitch of hydrophobic patterns on the biphilic surface. We postulated that if the average bubble departure diameter can be reduced, both the critical heat flux (CHF) and heat transfer coefficient (HTC) can be enhanced owing to the reduced dry spot area and increased active bubble cycle. The bubble dynamics and boiling performance were evaluated by adjusting the hydrophobic pattern size and the pitch of the biphilic surface using a porous super-hydrophobic material with high adhesion to vapor, 14.5% of CHF and 34.1% of HTC in S2P4N64 biphilic surface were enhanced over the bare surface. The bubble departure diameter decreased as the pattern size and pitch decreased, and the CHF was enhanced in inverse proportion to bubble departure diameter. This study indicates that the bubble departure diameter on biphilic surfaces can be controlled according to the intentions of the designer. (C) 2020 Elsevier Ltd. All rights reserved.