Effect of fabricating parameters on properties of sintered porous wicks for loop heat pipe

The aim of this study is to investigate the effect of forming pressure and microcrystalline cellulose addition on porosity and pore size distribution of the sintered porous wick and combined with a porosity control method developed in this study so that pore properties of sintered porous wick can be well controlled to meet the requirements of loop heat pipe application during its preparation. The porous wicks are prepared by powder metallurgy method with microcrystalline cellulose as space-holder. The result shows that porosity increases about 6.32% when forming pressure decreases 10 MPa and increases about 6.64% when microcrystalline cellulose addition increases 10 wt.%. The pore size distribution ranges become wider and the mean pore diameters increase as the increasing space-holder addition. The error of porosity was less than 6% in the case study that used the porosity control method to fabricate porous wicks with the expected porosity of 75%. The capillary pumping performances were different while both thermal conductivities and porosities of the porous wicks prepared by the porosity control method were the same. Capillary pumping performance can be considered as the balance of the capillary force and the flow property and it is better than permeability in evaluating the performance of porous wick for loop heat pipe. It is suggested that low forming pressure (low space-holder addition) should be used in order to get good capillary pumping performances when fabricating porous wicks with the same porosity for loop heat pipe.