For several thermally challenging space applications, an effective and reliable heat transport device for thermal management of electronic components is demanded. One such device used for transporting large heat over long distances with a small temperature difference is loop heat pipe (LHP). LHP is a highly efficient, passive device that uses evaporation and condensation of working fluid. One of the key components of LHP is sintered porous nickel wick which aids in the circulation of working fluid in the loop by capillary forces developed in the wicking structure. Three major wick parameters like permeability, porosity, and maximum pore radius greatly influence the performance of the wick and affect the performance of LHP.
This paper addresses the techniques employed for measuring various wick parameters, describes the experimentation setup developed for measurements and presents the results. One of the key features that determine the heat transport capacity of the wick is the maximum attainable capillary pressure which is dependent on the wick pore radius. The liquid pressure drop through the wick, a fraction of the total pressure drop in the loop, is dependent on the permeability of the wick which in turn is dependent on porosity. The measurements are carried out on the cylindrical sintered porous Nickel wick. The measured maximum pore radius of the wick is 5.3 µm. The liquid permeability is around 1×10^-13 m² and porosity is 0.61.