Advances on a cryogen-free Vuilleumier type pulse tube cryocooler

•The experimental setup of the Vuilleumier type pulse tube cryocooler is introduced.•A minimum no-load temperature of 15.1K has been obtained in experiment with a pressure ratio near 1.18.•Numerical simulation gives a lowest temperature similar to that of experimental results under same condition.•The simulation shows that relationship between pressure ratio and lowest temperature is quite weak.•This result gives us design guidelines to improve the system performance. This paper presents experimental results and numerical evaluation of a Vuilleumier (VM) type pulse tube cryocooler. The cryocooler consists of three main subsystems: a thermal compressor, a low temperature pulse tube cryocooler, and a Stirling type precooler. The thermal compressor, similar to that in a Vuilleumier cryocooler, is used to drive the low temperature stage pulse tube cryocooler. The Stirling type precooler is used to establish a temperature difference for the thermal compressor to generate pressure wave. A lowest no-load temperature of 15.1K is obtained with a pressure ratio of 1.18, a working frequency of 3Hz and an average pressure of 2.45MPa. Numerical simulations have been performed to help the understanding of the system performance. With given experimental conditions, the simulation predicts a lowest temperature in reasonable agreement with the experimental result. Analyses show that there is a large discrepancy in the pre-cooling power between experiments and calculation, which requires further investigation.