A new tapered regenerator used for pulse tube refrigerator and its optimization

The results of numerical simulation and theoretical analysis of the local heat transfer coefficient and the average remaining gas mass with the length of a uniform cross-sectional regenerator are presented in this paper. It was found that there are some serious thermodynamic limitations in the uniform cross-sectional regenerator and thus the efficiency of the regenerator can not fully exert. In order to further reduce the loss of the regenerator and improve the heat transfer of the cold end, the authors bring forward a design principle: the variation trend of the cross-section of the regenerator will be consistent with the direction of the temperature gradient, and introduce two kinds of tapered regenerators including convergent and divergent in order to improve the performance of the pulse tube refrigerator. Two models were introduced with governing equations to simulate two kinds of pulse tube refrigerators with tapered regenerator. The simulation results showed that there exist an optimum cone angle for tapered regenerator. When the cone angle is close to a certain value, the pulse tube refrigerator with convergent type regenerator can improve the performance which means increasing the cooling power, decreasing the working power, and eliminating the DC-flow rate. But the divergent type regenerator deteriorates the performance. In order to further validate the feasibility of this structural design, based on the enthalpy flow theory, the mechanism of the improvement of the performance of a PTR with tapered regenerator is systemically analyzed.