A cascade pulse tube cooler capable of energy recovery

A pulse tube cryocooler (PTC) cannot work with Carnot efficiency due basically to the expansion work that has to be dissipated thermally at the warm end of the pulse tube, this dissipation is especially phenomenal with high cooling capacity or at high temperatures which reduces the COP and limits the application of PTC above 120K. Therefore, how to recover this amount of dissipated work becomes a critical issue in a high efficient PTC. Here, we proposed a cascade PTC with a built-in transmission tube between stages for energy recovery. The key point of this new configuration is that the acoustic power at the outlet of the primary stage can be recovered through the transmission tube which provides proper phase angle to drive the secondary stage. This idea is verified both theoretically and experimentally. The cooling efficiency can be improved by 33% when the machine works at 233K.