Pool boiling enhancement on biphilic micropillar arrays: Control on the thin film evaporation and rewetting flow

Abstract

In the present article, a new surface treatment is proposed for pool boiling enhancement. For this purpose, a combination of hydrophilic–hydrophobic micropillar arrays with hydrophilic insulation strips between them is used to control and manage the thin film evaporation, surface rewetting, and bubble dynamics. The distance between hydrophobic sections of micropillars acts as permanent active nucleation site for pool boiling, which liquid thin films are established at the hydrophilic–hydrophobic interface. The hydrophilic section of micropillars is used for surface rewetting based on the wicking mechanism. The bubble dynamics is controlled by insulation strips to avoid the merging of departure bubbles and also vapor jets and columns. The effect of micropillar array dimensions on the pool boiling is investigated for the case of water on the hybrid silicon micropillar array. The maximum heat flux is 377.5 W/cm2 at 10 K wall superheat. Moreover, the variation of boiling heat flux is almost linear with respect to the wall superheat due to the permanent active nucleation sites. It leads to significant pool boiling enhancement at low superheat temperatures.