Effects of multiple sintering parameters on the thermal performance of bi-porous nickel wicks in Loop Heat Pipes

The thermal performances of a bi-porous nickel wicks in Loop Heat Pipe (LHP) including porosity, permeability, capillary pumping head and effective thermal conductivity (ETC) have been examined theoretically and experimentally, based on five key sintering parameters including the content of pore forming agent, compacting pressure, sintering holding time, sintering temperature and the particle size of pore forming agent. Firstly, a total number of 16 orthogonal tests are carried out with five key sintering factors and four levels of each factor. The optimal level of five sintering factors is obtained from the point of acquiring the most desirable overall performance of bi-porous nickel wicks, which can be used as the reference sintering process for bi-porous nickel wicks. Then, the experimental values of ETC were compared with eleven theoretical models. The results showed that the Alexander model and the Maxwell model overestimated and underestimated the experimental results of bi-porous nickel wicks, respectively. In the porosity range of 0.5–0.7, an average of the Chernysheva and Maydanik model and the Chaudhary and Bhandari model was found to be the best fit to the experimental data, providing an accurate method to predict ETC values of bi-porous nickel wicks of LHP.