Thermofluid Characteristics in Microporous Structure With Different Flow Channels for Loop Heat Pipe

Abstract

The use of two-phase heat transfer devices using capillary action in a microscale porous structure such as a loop heat pipe (LHP) is a promising heat transport technology. It is because they have characteristics of higher heat transfer power and longer heat transport distances with no electrical power compared with conventional heat pipes. The thermal performance of an LHP is governed by the thermo-fluid behavior in a microscale porous structure called the wick. In this research, high-performance wicks made of polymer has been developed, and its pore distribution and permeability were evaluated. The effects of the vapor channel's shape on the loop's thermal performance have been investigated by calculation and experiment to enhance evaporator performance. A mathematical model of the evaporator considering super heat in the channel, pressure drop across the wick, and two-phase pressure loss on the boundary face between the wick and the evaporator case was newly developed. The experiment was also conducted as a function of the groove shapes. From calculation and test results, it was found that in order to increase the maximum heat transport capability and decrease the operating temperature, the groove should be well distributed.