Effect of the number of grooves on a wick's surface on the heat transfer performance of loop heat pipe

This study investigated the effects of increasing the number of grooves on a wick's surface, thereby increasing the evaporation surface area, on the performance of loop heat pipe (LHP). In this paper, wicks were manufactured, and the effect of increasing evaporation area (from 0% (8 grooves) to 100% (16 grooves)) on LHP heat transfer performance was examined. Results indicated that heat transfer performance increases with the number of grooves and the wick evaporation area; when the evaporation area was increased by 75% (14 grooves), the optimal heat load of 500 W was achieved, with lowest thermal resistance of 0.14 degrees C/W. Compared with results from literature (using wicks with 0% increase in evaporation area), the heat transfer performance was increased by about 60%. The wick parameters in this study were as follows: permeability 13-3.25 m(2) x 10(-13), largest effective pore radius 1.9-2.5 mu m, and porosity 63-67%. Taking into consideration the manufacturing process and the resulting structural strength and durability of the wick, 50% increase (12 grooves) in evaporation area yielded the best overall results. Therefore, this paper suggests 12 grooves for the wick; a relationship between LHP performance enhancement and evaporation area was suggested based on empirical results, which can be used to guide future wick designs. (C) 2014 Elsevier Ltd. All rights reserved.