Effect of Porosity of the regenerator on the performance of a miniature Stirling cryocooler

The performance of a miniature Stirling cryocooler depends primarily on the porosity of wire-meshes used in the regenerator. A low porosity regenerator requires higher input power to get the same pressure ratio to compress the working fluid due to a higher pressure drop compared to that of a high porosity regenerator. On the other hand, a high porosity regenerator requires less power input. However, the thermal performance of the regenerator decreases as the porosity increases. In the present experimental study, uniform porosity and non-uniform porosity matrices were considered to obtain an optimum porous matrix of the regenerator for the cooling capacity of 0.5 W @80 K with Helium as the working fluid. In the parametric study, for the regenerator with the uniform porosity, the wire-mesh number of 200, 300, 400 and 500 are considered. Based on the cool-down time and power input, wire-mesh number 400 is considered to be optimum. For the reduction of cool-down time and power consumption, non-uniform porous matrix regenerators were considered with different combinations of wire meshes for a miniature Stirling cryocooler. Present study shows that non-uniform porous matrices reduce the power consumption or cool-down time considerably compared to the uniform porous matrix of the miniature Stirling cryocooler.