Development of biporous wicks for flat-plate loop heat pipe

Two different methods, cold pressing sintering and loose powder sintering, are adopted to fabricate the biporous nickel wicks for loop heat pipes (LHPs) in the present study. Porosity of the wicks is measured by Archimedes method and radius and distribution of pores is observed by Scanning Electronic Microscope (SEM), and permeability of wicks is calculated by empirical equation. The effect of different sintering method, proportion of pore former, and sintering temperature on the wicks is investigated experimentally. Result shows that wicks are successfully fabricated, the optimal wicks are found to be sintered at 700 °C, using cold pressing sintering method, with pore former content 30% by volume; these wicks could reach the porosity of 77.40%, the permeability of 3.15 × 10−13 m2, and have sufficient mechanical strength to meet the machining requirements. The effect of lathing and wire electro discharge machining on surface pores of wick is analyzed by SEM. In order to verify the performance of the biporous wick, a flat plate type of LHP is designed, fabricated and tested in this paper, and the results presents that the LHP can startup and run reliably under different heat loads.