Enhanced capillary and heat transfer performance of asymmetric micropost wicks

Abstract

We developed asymmetric capillary wicks composed of slanted microposts using inclined photolithography. Then we investigated the effects of inclination angle and wicking direction on the capillary and the heat transfer performances. The working fluid accelerates when it flows in the slope direction of the structure (forward direction, FD) and decelerates when it flows in the opposite slope direction (rear direction, RD). We applied the scaling law to the capillary rise experiment data to verify that the inclination angle and the wicking direction affect the capillary performance. The capillary performance parameter was improved by up to similar to 39% with FD case and decreased by 21.3% with RD. The heat transfer performance test showed that the wick-CHF (the enhanced critical heat flux due to the formation of the wick) of the asymmetric FD case was increased by 43.3% compared to symmetric ones while maintaining the heat transfer coefficient. This work shows that asymmetric evaporator wicks can enhance the critical heat flux without sacrificing the heat transfer coefficient, which can help develop high-performance thermal management solutions.