Theoretical and experimental investigations on the three-stage Stirling-type pulse tube cryocooler using cryogenic phase-shifting approach and mixed regenerator matrices

Theoretical analyses and experimental verification for a three-stage Stirling-type pulse tube cryocooler (SPTC) expected to operate at 5-12 K are conducted. Cryogenic phase-shifting and mixed regenerator matrices are employed to improve the performance at the third stage. Simulations of the phase relationship, dynamic pressure and mass flow rate are presented with third-stage phase-shifters at 40 K, 50 K and 293 K, respectively. Mixed regenerator matrices of conventional stainless steel meshes and rare-earth materials such as Er3Ni, HoCu2 and Er0.6Pr0.4 are optimized theoretically. Different ratios and combinations are analyzed and compared, and the quantitative analyses by the entropy analysis are made. A three-stage SPTC without external precooling is developed based on the theoretical analyses, and experiments were conducted. The results show a good agreement between simulations and experiments. With an overall input electric power of 370 W, the three-stage SPTC has experimentally reached a no-load temperature of 6.82 K and achieved a cooling capacity of 112 mW at 10 K.