20~30 K两级脉管制冷机相位特性对比研究

Comparative study on phase characteristics of 20−30 K two-stage pulse tube refrigerator

液氢温区热耦合两级脉管制冷机中,低温级的相位调节是性能优化的关键之一,为此,采用主动相位调节方式对低温级脉管相位特性进行研究,分析对比调相活塞相对压缩机活塞运动相位差变化时,冷指内相位分布的变化以及对制冷性能的影响。研究结果表明:当活塞行程一定时,随着活塞相位差增加,在低温段回热器两端,压力波相对于质量流的相位差(PU相位差)均增大,制冷量与制冷效率呈现出先增大后减小的趋势;随着制冷温度从20 K提高至30 K,最大制冷量与最佳制冷效率时低温段回热器两端PU相位差的差值减小;实验验证了20 K和30 K时制冷性能随活塞相位差的变化规律,可为液氢温区两级脉管制冷机设计中的相位调节提供参考。

The phase adjustment of the lower temperature stage is one of the keys to optimize the performance of the thermally coupled two−stage pulse tube refrigerator in liquid hydrogen temperature zone,the phase characteristics of the lower temperature stage were investigated by active phase control method,the phase distribution inside the pulse tube and its effect on cooling performance were analyzed when the phase difference between the compressor piston and the warm displacer changed.The results show that when the piston stroke is constant,the phase difference between pressure wave and mass flow(θ_(PU))at both ends of the lower temperature part of the regenerator(RegⅡ)increases with the increase of piston phase difference,and the cooling capacity and cooling efficiency show a trend of first increasing and then decreasing.As the cooling temperature increases from 20 K to 30 K,the difference inθ_(PU) between the two ends of the RegⅡdecreases when the maximum cooling capacity and the optimal cooling efficiency are obtained.The relationship between the cooling performance and the piston phase difference is experimental verified at 20 K and 30 K,which provides reference for the phase adjustment method in the design of the two-stage pulse tube refrigerator in the liquid hydrogen temperature zone.