Bubble dynamics and pool boiling performance on biphilic patterned surfaces

Boiling heat transfer is effective cooling mechanism accompanying phase change phenomena, and it is used in various high heat flux generated systems such as power plant and integrated electronic devices. Bubble dynamics is one of main factors to decide boiling performance such as heat transfer coefficient (HTC) and critical heat flux (CHF). Surface wettability control is an effective method to change bubble dynamics for enhanced boiling heat transfer. In this study, we fabricated various biphilic surfaces which have both hydrophilicity and hydrophobicity. Our strategy is that biphilic patterned surface can activate nucleation, enhance HTC and maximize CHF by preventing bubble merging through ensuring enough pitch between individual bubbles. Dot sizes were strictly controlled from few micrometers to milimeters by photolithography method and hydrophobic chemical coating. Bubble base and departure diameters, activate nucleate sites and frequency were analyzed by 2000 fps high speed camera images. We carried out pool boiling experiments on biphilic multi dots arrays which were designed based on single bubble characteristics. This study demonstrates that the biphilic patterned surface could enhance boiling performance by controlled bubble dynamics. Moreover, we expect that this study provides the strategy for further improvement of high heat flux cooling technology using wettability control.