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

Official URL: https://dx.doi.org/10.1016/j.ijheatmasstransfer.2022.123582

Surface wettability is one of the key parameters in the manipulation of the boiling phenomenon. Although 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 transfer performance of surfaces with uniform (superhydrophobic and superhydrophilic) and mixed (superbiphilic) wettability. This study presents the results obtained from four different surfaces for both atmospheric (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 atmospheric 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.