VM型脉冲管制冷机数值模拟与实验研究

The Numerical Simulation and Experimental Study on a VM Type Pulse Tube Cryocooler

本文介绍了由VM型热压缩机驱动的脉冲管制冷机基本结构、数值模拟与实验研究。热压缩机借鉴VM制冷机产生压力波动的方式,即依靠室温与冷源之间的温度差产生压力波动,驱动低温级脉冲管制冷机。利用液氮温区制冷机为热压缩机提供所需要的冷量,避免使用低温液体带来的不便。低温级脉冲管制冷机的回热器与脉管采用U型布置,调相机构采用小孔气库加双向进气方式。这种结构不使用有阀压缩机,可以产生低频压力波动,保证回热器在低温区高效工作。在原有结构的基础上,改造热压缩机回热器尺寸与填料,使用Sage软件进行了整机模拟,对调相机构进行优化,考察其在不同的运行频率、平均压力、排出器位移下的制冷性能。对改造后的脉冲管制冷机进行了初步的实验研究,获得14.4K无负荷制冷温度。

This paper mainly introduces the structure,numerical simulation and experimental study on a VM type thermally-driven pulse tube cryocooler.The thermal compressor,similar to that in VM cryocooler,utilizes temperature difference between room temperature and cold heat sink to generate pressure wave.Two cryocoolers working at liquid nitrogen temperature are thermally coupled with the cold end of this thermal compressor to provide the required precooling power,preventing the inconvenience from cryogenic fluid.Low temperature stage regenerator and pulse tube are arranged with U type structure,and the orifice and the double-inlet are used as phase shifters.This cryocooler consists of a thermal compressor instead of valved compressor and operates with a low frequency,which is beneficial to improving regenerator performance at low temperature.Based on the previous study,the regenerator for thermal compressor is modified,and numerical simulations on the pulse tube cryocooler are performed.The dependence of system performance on frequency,average pressure and displacer displacement amplitude are investigated in the simulation.Finally,preliminary experimental study were performed and a lowest no-load temperature of 14.4 K were achieved.