Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4991569 | Applied Thermal Engineering | 2017 | 17 Pages |
Abstract
A loop heat pipe (LHP) with composite multiscale porous wicks was designed and investigated. The focus was on heat transfer and start-up characteristics. Three layers of wick were used to form the composite wicks. The primary layer was sintered on the evaporator wall using copper powder with different average particle diameters (dp = 13, 37, 88, and 149 μm) to form a groove multiscale wick. The second layer was laid on top of the first one by a second sintering. The third layer was made of absorbent wool with excellent thermal insulation. A series of experiments were performed to study the effects of various parameters, including wick structures, tilt angles (θ = â90°, 0°, and 90°), liquid filling ratios (38.5-64.1%), liquid line lengths, and heating power. Compared with conventional monoporous wicks, the composite multiscale porous wicks shortened the start-up time, decreased the wall temperature, and suppressed the temperature instability of the LHP. At a heat load of 200 W, the LHP with composite wicks could reach a heat flux of 40 W/cm2 for the anti-gravity operation, under which the wall temperature was only 63 °C. Some reasons that accounted for performance improvement were as follows: the porous groove wall increased the surface area and multiscale structures realized a successful synergy between vapor release and liquid supply, large pores for vapor release, and small pores for liquid suction. In addition, a synergy between thermal conductivity and insulation was achieved, which ensured a high thermal conductivity for the primary layer wick and a good thermal insulation for the entire wick. This greatly reduced the heat leakage from the evaporator to the compensation chamber.
Keywords
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Fluid Flow and Transfer Processes
Authors
Xianbing Ji, Ye Wang, Jinliang Xu, Yanping Huang,