Design, Fabrication and Testing of an Ultra-Thin Multi-evaporator Loop Heat Pipe

"A Loop Heat Pipe (LHP) is a two-phase heat transfer device that utilizes the evaporation and condensation of a working fluid to transfer heat, and the capillary forces developed in fine porous wicks to circulate the fluid. Since the LHP can transport large amount of heat with no electric power under various gravity environment, the LHP is attracting attention as thermal management device for both space and terrestrial applications, and various studies on LHP have been conducted. Recently, with the miniaturization and high performance of devices, the integration of equipment is remarkably advanced, and thermal management for multiple heat sources is urgently required. In this study, an ultra-thin LHP with two evaporators (UTMLHP) which can applied to small electric device and/or micro satellite has been proposed. First, the UTMLHP was designed by using a steady-state MLHP model. Based on the thermal requirement, the size of UTMLHP was determined. Secondly, the UTMLHP was fabricated. The case and the wick of UTMLHP was made of copper and pure water was used as a working fluid. The size of each evaporator is 15×15×t0.6mm. The heat transport length is about 380mm. Next, the comprehensive test was conducted under atmospheric condition by changing orientation (horizontal, top-heat, bottom-heat, and sideways), charge amount of the working fluid, heating pattern on the evaporators (both sides, and one side only). The stable operation of the MLHP up to 12W was demonstrated. Finally, the test results are compared with the mathematical model of UTMLHP. The effects of test conditions on thermal performance is discussed with these results. The details of the UTMLHP specification and test results will be presented in the full paper."