Effect of length scale on miniature Stirling cycle cryocooler

Miniature cryogenic coolers operating on the reversed Stirling cycle are used for cooling IR detectors in satellites, imaging cameras in battle tanks and super conductor filters. These coolers should be of low weight, compact size, trouble free operation high reliability and high endurance limit. The performance of the Stirling cooler depends on the effectiveness of the regenerator used in the system. In the present study, the influence of length scale on each individual loss associated with the regenerator is investigated. For fixed cycle parameters and regenerator length scale the system produces net refrigeration for a specific range of hydraulic diameters only. There is an optimum value for hydraulic diameter which gives maximum net refrigeration. It was also found that the optimum value of ratio between hydraulic diameter and regenerator length decreases when the regenerator length increases. Among the different regenerator materials investigated, material with minimum thermal conductivity gives maximum net refrigeration.