百毫瓦液氦温区节流制冷机换热器的仿真设计及实验验证

Simulation Design and Experimental Verification of Heat Exchanger of Throttle Cryocooler in Hundred Milliwatt Liquid Helium Temperature Region

摘要: 本文基于在液氦温区取得百毫瓦级冷量的制冷目标，设计计算了节流制冷机多级换热器。分析了换热器与预冷机组以及压缩机组的负载之间的关系，给出了节流制冷机一二级预冷温度、高压工况、流量等设计边界参数。通过Matlab建立换热器一维仿真计算模型，以各级换热器低压侧沿程压降作为目标函数，对各级换热器的管径和管长组合做出了寻优，计算得到了三级换热器的最优尺寸参数组合。最后通过实验验证了计算模型的准确度，实验测得换热器换热效率与计算值偏差为0.31%~1.04%，测得低压侧沿程压降偏差值为5.5%~11.9%，并成功在4.3 K取得了97 mW的制冷量。

Abstract: Based on the refrigeration goal of obtaining a refrigeration capacity of hundreds of milliwatts at liquid helium temperature, the multi-stage heat exchangers of a throttling cryocooler have been designed and calculated in this paper. The relationship between the heat exchangers and the load of the pre-cooling and the compressor unit is analyzed. Besides, the design boundary parameters such as the primary and secondary pre-cooling temperature, high-pressure working condition and flow rate of the throttling cryocooler are given. A one-dimensional simulation calculation model of the heat exchangers is established by Matlab. Taking the pressure drop along the low-pressure side of the heat exchangers as the objective function, the optimization of the tube diameter and length combination of the heat exchangers were made. So the optimal size parameter combination of the three-stage heat exchangers is calculated. Finally, the accuracy of the calculation model was verified through multiple open experiments. The experimental results show that the deviation between the heat transfer efficiency of the heat exchanger and the calculated value is 0.31% to 1.04%. The deviation of pressure drop along the low pressure side is 5.5% to 11.9%, and the cooling capacity of 97 mW was successfully obtained at 4.3 K.