Wicking Performance of Two-Dimensional Bi-Porous Wicks

Abstract

Micro-post wick is a promising candidate for high-heat-flux applications due to its compatibility, high conductivity and permeability. In this study, the capillary performances of micro-post wicks of various configurations are investigated. Five types of micro-post wicks which have dual-scale pore structure (parallel, quadratic, hexagonal, diamond, and periodic) are considered and the capillary performance is compared with micro-post wicks of uniform array. The capillary performance of wicks is characterized using capillary rate of rise experiments and numerical simulations that accounts for the finite curvatures of liquid menisci. From the experimental and numerical studies, it is shown that the capillary performance of multi-scale wicks is higher than that of mono-scale wicks significantly (by 35% for parallel array, 31% for quadratic array). The capillary performance parameter is shown to be primarily a function of solid fraction and decreases approximately linearly with solid fraction, regardless of the array type. The experiment, associated with visual observation, indicates that the capillary performance is degraded when the pore size is too large or the solid fraction is too small.