Thermodynamic analysis and experimental verfication on a novel looped pulse tube cryocooler

Compared with the Stirling cryocooler, the pulse tube cryocooler has obvious advantage in reliability. The reservoir is usually needed to help the inertance tube to obtain larger phase shifting ability, which makes the pulse tube cryocooler not to be as compact as the Stirling cryocoolers. To improve compactness, a looped pulse tube cryocooler without the reservoir was proposed in the paper. The inertance-tube is directly connected to the backside of a linear compressor and the reservoir is removed. To compare its cooling performance with that of the inertance-tube pulse tube cryocooler with a reservoir, the theoretical model including a linear compressor, main hot-end exchanger, regenerator, cold-end exchanger, pulse tube, and secondary hot-end exchanger are described for the both cryocoolers. The simulation results show that the looped cryocooler can achieve a similar or even better cooling performance, comparing with the traditional inertance-tube cryocooler. In the experiment, the performances of both cryocoolers driven by a same linear compressor were extensively tested. A lowest cold-head temperature of 40 K is acquired and the maximum cooling power reached 9.4 W at 77 K for the novel looped pulse tube cooler, corresponding to about 15% relative Carnot efficiency