高频脉冲管制冷机的蓄冷器源汇模型、流动模拟和参数优化

蓄冷器是脉冲管制冷机的一个关键部件,其工作性能将直接影响整机性能.针对工质在蓄冷器内交变流动的特性,提出了一个新的源/汇项模型来模拟蓄冷器内的流动与换热,同时模型也考虑了气固间的非热平衡.对于蓄冷器和换热器内的固体填料,在一些假定条件的基础上推导得到了固体物质的温度分布的解析解.该模型不需要建立固体的能量方程,减小了计算的工作量,避免了达西定律在高频下不适用的限制条件,并针对交变流动情况下对流换热系数的取值提出了解决方法.新模型的计算结果与实验结果符合良好,验证了模型的可靠性.进一步应用此模型分析了蓄冷器内部的热交换和制冷机理,并进行了蓄冷器的优化设计,对于不同目数,不同丝径,不同材料的丝网,进行了各种情况下蓄冷器的换热性能优化分析.

NEW SOURCE/SINK MODEL,FLOW SIMULATION AND PARAMETER OPTIMIZATION OF THE REGENERATOR FOR HIGH FREQUENCY PULSE TUBE REFRIGERATOR

The regenerator filled with solid matrix is one of the major components in the PTC (pulse tube cryocooler). In this paper, a new source/sink model instead of porous medium assumption, which is merely applicable for low frequency apparatus, is established to simulate the flow and transport in the regenerator. The new model also is a non-thermal equilibrium model. Based on some assumptions, the analytic solution of the filled solid temperature can be obtained. The new model can reduce the computational workload because the model does not require the establishment of the energy equation of solid. We also propose a method to calculate the value of convective heat transfer coefficient under the alternating flow conditions. According to the comparison with the experimental data, the new model is verified. Then the model is used to analyze the heat transfer mechanism between the working fluids and the solid fillers in the regenerator. The regenerator heat transfer performance are optimized under different mesh screen geometries and properties with numerical simulation.