Performance of cryogenic regenerator with 3He as working fluid

Almost all experimental and theoretical studies on regenerative cryocoolers at temperatures below 20 K mention the use of ⁴He as working fluid. A preliminary qualitative evaluation indicates that because of the superfluid phase transition, a working fluid of ³He would overcome the cooling temperature limitation set by ⁴He. Starting with a comparison of the thermophysical properties of 3He and ⁴He, cryogenic regenerator simulations applied to the third/last stage of a pulse tube refrigerator, with ³He and ⁴He separately, were implemented to quantitatively analyze performance differences of the regenerator with respect to regenerator loss, cooling power and COP. Results conclude that ³He could significantly improve the performance of a regenerative cryocooler.