Pool boiling heat transfer on superhydrophobic, superhydrophilic, and superbiphilic surfaces at atmospheric and sub-atmospheric pressures

Surface wettability is one of the key parameters in the manipulation of the boiling phenomenon. Al-though there are a number of studies on the effect of surface wettability on boiling heat transfer, there are few research efforts to explain the boiling phenomenon on superbiphilic surfaces at sub-atmospheric pressures. In this study, pool boiling experiments were conducted to investigate the boiling heat trans-fer performance of surfaces with uniform (superhydrophobic and superhydrophilic) and mixed (super-biphilic) wettability. This study presents the results obtained from four different surfaces for both atmo-spheric (103.7 kPa) and sub-atmospheric (28.3 kPa) pressures and aims to provide an understanding of the wettability effect using saturated deionized water as the working fluid in the heat flux range of 7 -290 kW/m2. The experimental results show that the superbiphilic surface (superhydrophobic spots with a pitch size of 3 mm and diameter of 0.7 mm) offers improvements in boiling heat transfer at both atmo-spheric and sub-atmospheric pressures up to 98% and 54%, respectively. Due to bubble coalescence being more likely to occur at sub-atmospheric pressure, the enhancement effect of superbiphilicity on boiling heat transfer is more significant for atmospheric pressure.(c) 2022 Elsevier Ltd. All rights reserved.