No abstract

This study used aluminum (Al) powder as a raw material to fabricate a wick for loop heat pipes (LHPs) by the powder metallurgy method and took advantage of the excellent corrosion resistance, low density and low cost of Al. The average pore diameter, porosity and permeability of the Al wicks were 9 ?m, 47.65%, and 2.1?10-13 m-2, respectively. Then, to verify the feasibility of the Al wick, it was installed into a LHP to test the heat transfer performance. The experimental results showed that the LHP could transport a heating load of 130 W with a thermal resistance of 0.04 KW-1 under horizontal condition. A steady-state LHP mathematical model was developed, and the numerical results were compared with the experimental data. The results show that the model data are consistent with the experimental data, which means that Al wicks are suitable for use in the case of a high heating load and light weight.

In this paper, a thin film evaporation model that includes expressions for energy, mass and momentum conservation was established through the augmented Young-Laplace model. Based on this model, the effects of pore size and superheating on heat transfer during thin film evaporation were analyzed. The influence of the wick diameter of the loop heat pipe (LHP) on the critical heat flux of the evaporator is analyzed theoretically. The results show that pore size and superheating mainly influence evaporation through changes in the length of the transition film and intrinsic meniscus. The contribution of the transition film area is mainly reflected in the heat transfer coefficient, and the contribution of the intrinsic meniscus area is mainly apparent in the quantity of heat that is transferred. When an LHP evaporator is operating in a state of surface evaporation, a higher heat transfer coefficient can be achieved using a smaller pore size.