Operational characteristics of flat type loop heat pipe with biporous wick

Abstract

Loop heat pipes (LHPs) are two-phase heat transfer devices that utilize the evaporation and condensation of working liquid to transfer heat. In present paper, experimental researches are conducted for a new type of flat type LHP, in which biporous porous media and stainless steel mesh are adopted as primary wick and secondary wick respectively, and this innovative structure can support the primary wick and assist it pumping working liquid. The loop is made of copper with sintered nickel powder as primary wick and methanol as the working fluid. Both start-up test and performance test are conducted to validate the reliability and performance of the loop. From the test results, it is found that, in the horizontal position, the loop is able to start-up with a heat load rang between 20 W and 160 W(heat flux of 16.8 W/cm2) with evaporator wall temperature below 85 °C. At heat load between 30 W and 80 W, temperature oscillations are observed throughout the loop, however, the effect of this oscillation on the performance of the loop is not significant. During a random loading test, the loop can stand a load jump as high as 100 W without an operation failure. The thermal resistance of the LHP lies between 0.46 °C/W to 2.28 °C/W.