A Lightweight, High-Performance Porous Wick for Loop Heat Pipe: Polyethersulfone Film Wick

Abstract

Loop heat pipe, which features of high heat flux heat dissipation and light weight, is a promising heat dissipation technology for the aerospace electronic devices with high integration and high power. The optimized design of porous wick in loop heat pipe has become the key for increasing the heat transfer capacity and decreasing the weight. However, the commonly used metallic mesh porous wick and sintered metal powder porous wick cannot realize collaborative optimization of liquid-absorbing capacity, permeability, weight, and manufacturing cost. To solve this problem, in this study, a lightweight polymer material-polyethersulfone (PES) film with high capillary force and high permeability characteristics was chosen as porous wick in the loop heat pipe. The parameters of the surface structure, pore size, permeability, and porosity of the PES film porous wick were given in details. Results show that the PES wick has a special dual pore size structure, which achieves a synergistic enhancement of capillary force and permeability. By comparing the heat transfer performances of the traditional copper mesh porous wick, sintered nickel powder porous wick and PES wick, we conclude that the PES film porous wick which has the advantage of simple preparation and low cost easily achieve the heat transfer effect of sintered nickel powder wick and is much higher than copper mesh porous wick, showing great development potential and application prospects in the field of loop heat pipes. It was found that the weight of the PES wick was only 1/13 th of the sintered nickel powder wick and 1/5 th of the copper mesh wick, which greatly reduced the weight of the porous wick. For the PES wick, under the conditions of 55% optimal filling ratio and 300 W heat load, the temperature of heating surface is 61.695°C. The entire thermal resistance of the loop heat pipe and evaporator thermal resistance are 0.161°C/W and 0.056°C/W (24.3% lower than that of the sintered nickel powder wick), respectively.

Keywords: Polyethersulfone film, Enhanced heat transfer, Light weight, Loop heat pipe, Porous wick, Thermal resistance