Permeability of dual-height micro-post wicks for heat pipes

Abstract

Micro-post wick is a promising candidate for liquid-based thermal management of future electronics and energy systems. In this study, the permeability of the dual-height micro-post wicks is investigated numerically with taking into account the shape of meniscus. The meniscus shape of liquid in dual-height micro-post wicks is estimated based on surface energy minimization algorithm. The estimated meniscus shape is then imported into a CFD study for predicting the permeability using the Darcy’s law. The effects of contact angle, primary and secondary post heights, and post diameter on the permeability of the dual-height heat sink are investigated in this study. The results indicate that there exists a finite range for the secondary height of the post according to the given primary post height. This range is shown to be enlarged as the contact angle decreases and hardly affected by the post height. The dual-height configuration is shown to bring about enhanced permeability compared with single height configuration with same mean post height, due to the increased effective liquid height. The permeability of the dual height micro-post wick is shown to increase monotonically as either the primary height or the secondary height increases. The permeability increases as the contact angle increases and the nondimensional post diameter decreases. Unlike the permeability, the dual-height configuration is shown to reduce the capillary pressure of the micro-post wick. Based on the numerical results a correlation for predicting the dual-height micro-post wick is proposed.