Numerical simulation and exergy analysis of a single-stage GM cryocooler.

Improving the efficiency of the GM cryocoolers is of great importance for energy saving and CO emission reduction due to the large amount of cryocoolers installed in the emerging fields of semiconductor manufacture and High Temperature Superconductors (HTS) cooling. Previous studies mainly focused on the losses analysis and optimization on the part of cold head, but the details of losses distribution in the parts of compressor and rotary valve were seldom carried out. In this paper, a numerical model of a single stage GM cryocooler including compressor, rotary valve and expander is built, and the feasibility of the model is verified by the experimental results. The losses characteristics of the whole cryocooler are studied based on the exergy analysis method with the help of the numerical model. The results indicate that the main losses are occurred in compressor and rotary valve, the value of exergy loss in compressor decrease with the cooling temperature, and accounts for more than 60% at all cooling temperature. The loss in rotary valve accounts for about 20% of the input electric power, and it does not significantly vary at different cooling temperatures. Pressure drop dominates the loss in the compressor and rotary valve. The insufficient heat exchange between the working gas and regenerative material is the main loss in regenerator, and the losses in regenerator increase significantly with the decrease of cooling temperature when the compressor and rotary valve are fixed. This study provides useful guides for the optimization of GM-type cryocoolers.