A preliminary study on biphilic surface for enhanced pool boiling performance

Abstract

A biphilic surface having hydrophobic patterns on the hydrophilic surface has been considered as one of the promising strategies for enhancing the BHT because it could control the bubble dynamics by wettability gradient. In this study, the pool boiling experiment of the square patterned biphilic surface was conducted to evaluate the effect of the biphilic patterns on the BHT as preliminary work. The biphilic surface had the hydrophobic square patterns on SiO2 hydrophilic surface. The pattern geometry was designed based on the bubble departure diameter, and the hydrophobic coating was applied using a spray coating method. The BHT performance of four biphilic surfaces and two uniform wettability surfaces was evaluated at the saturated pool boiling condition using DI water. In addition, for the comprehensive understanding of the boiling mechanism, bubble dynamics and temperature distribution were observed by using high-speed video and IR thermometry. The maximum enhancement of a heat transfer coefficient (HTC) of 40.0 % was obtained for S3P25 surface with a size of 3 mm and pattern number of 25 at a heat flux of 600 kW/m2 without the deterioration of critical heat flux (CHF). However, there was no significant enhancement of CHF such that maximum enhancement was 4.8 % in S2P36 surface.