Study on evaporation heat transfer performance of composite porous wicks with spherical-dendritic powders based on orthogonal experiment

Abstract

Based on our previous research on the composite porous wick with spherical-dendritic powders, this paper further adopts the orthogonal experiment to study the effect of the combination and the mixing ratio of the spherical and dendritic powders, and the particle size and volume ratio of the pore former. In order to obtain the optimal prepared parameters of the composite porous wick with spherical-dendritic powders, nine porous samples are prepared based on the orthogonal experiment, and their thermal physical properties are measured and analyzed. Five types of operating curves for temperature and evaporating mass are observed in the evaporation heat transfer experiment. The metal powder materials have significant effects on all the considered physical properties in this paper, but the mixing ratio of metal powders only has a significant effect on the critical heat load and the evaporator wall temperature. The particle size and volume ratio of the pore former also have certain influence on these indexes, except that its particle size has no influence on porosity. The highest critical heat load is 530W and occurs in the composite porous wick with the spherical nickel and the dendritic copper powders with the volume ratio of 3:7, and the particle size of 30-45 μm and the volume ratio of 40% for the pore former, which are not the conditions for the lowest effective thermal conductivity. Low evaporator wall temperature and high critical heat load are required for the excellent performance of composite porous wick. High volume ratio of dendritic copper powders is beneficial to increase the quantity of small pores with high evaporating rate, so as to increase the critical heat load and reduce the evaporator wall temperature. This study can guide the parameter design of the composite porous wick with spherical-dendritic powders to improve its performance.