The effects of the clearance in the cold finger on the performance of the Stirling refrigerator

Publisher Summary This chapter investigates the influences of the radial clearance on the performance of Stirling refrigerator by numerical simulation. The Stirling refrigerator has the clearance in the compressor and cold finger. Its cooling capacity comes from the relation of the pressure in the expansion space and motion of displacer. In the radial clearance of the cold finger, the parasitic dynamic losses from the leakage flow and shuttle heat losses are inevitably occurred. Therefore, to get the maximum performance of the refrigerator, the radial clearance should be optimized. The SAGE is used to investigate the effects of the operating frequency, the stroke of the displacer and the radial clearance between the seal rings and the expander on the cooling performance. The calculation results show that the enthalpy flow through the refrigerator is a dominant heat loss. The leakage flow through the clearance has the effects on the cooling capacity through the gross refrigeration, the enthalpy flow, and the shuttle heat loss. The enthalpy flow through the clearance depends on the operating frequency and the radial clearance of the cold end, whereas the shuttle loss depends on the stroke of the displacer.