Permeability of a Capillary Structure of Sintered Copper Powder Used in Heat Pipes

A heat pipe is a passive device that has a high thermal conductivity, which uses a closed biphasic cycle and the latent heat of the working fluid vaporization to carry out the heat transfer. The capillary structure directly influences the thermal performance of the heat pipe, because it promotes capillary pumping and the flow path to conduct the working fluid inside the heat pipe. Among the main properties of a capillary structure, there are the critical pore radius, porosity, permeability, and thermal conductivity. Thus, in this research, the experimental evaluation of the permeability of a sintered copper powder structure was performed for use as a capillary structure in heat pipes. For this, a Capillary Extrusion Test, based on MPFI Standard 39, was used. The experimental results showed that the average permeability of the copper powder capillary structure was 7.81 x 10-13 ± 0.38 x 10-13 m2.