Theoretical analysis of refrigeration and losses in a pulse tube

Based on thermal analysis of hot end of pulse tube, a group of formula is deduced to calculate the theoretical refrigeration, which reveals that refrigeration is mainly determined by parameters of the pulse tube hot end. Then three important losses in the pulse tube that may reduce refrigeration are analyzed. They are jet flow loss due to gas out of and into the reservoir, surface heat pumping loss or shuttle loss due to heat transfer between tube wall and gas in tube, and gas mixing due to cyclic flow or density difference. The gas mixing loss always exists and is difficult to eliminate; but jet flow loss may be reduced. Jet flow loss is verified by experiment. Analysis of surface heat pumping shows that the ratio of high and low temperature is one key parameter. In the basic pulse tube refrigerator, the amplitude of surface heat pumping decreases till zero with temperature ratio increasing, while for the orifice version and low temperature, this heat pump effect is from high temperature to low temperature evidently. This paper concludes: refrigeration is mainly determined by hot part of pulse tube, while the pulse tube is one key loss source though it is an irreplaceable part in the refrigerator.