微型同轴脉管制冷机系统运行参数的优化及氢氦混合工质应用的试验研究

进行了微型同轴脉管制冷机系统运行参数的优化及氢氦混合工质应用的试验研究。系统运行参数的优化试验结果表明，不同的氢氦配比下，微型同轴脉管制冷机系统的最佳运转频率为15.5～17.2 Hz。随着系统平均压力的提高，最低制冷温度也随之下降，但变化幅度越来越小。气库小孔阀和双向进气阀均存在最佳开度，在试验系统中气库小孔阀最佳开度为70°，双向进气阀最佳开度为30°。同时，氢氦混合工质的试验结果表明，在其他运行参数不变的情况下，随着氢气摩尔分数的减少，系统最低制冷温度逐渐降低，当氢气摩尔分数小于20%时，系统最低制冷温度接近纯氦水平。在100～120 K温区，氢氦混合工质能提高系统的制冷量，当氢气摩尔分数为20%时，系统制冷量比纯氦时提高了13.5%～16.5%。

OPTIMIZATION OF OPERATIONAL PARAMETERS AND EXPERIMENTAL STUDY WITH HELIUM-HYDROGEN MIXTURE ON MINIATURE CO-AXIAL PULSE TUBE REFRIGERATOR

The optimization of the operational parameters and the experimental study with helium-hydrogen mixture on the miniature co-axial pulse tube refrigerator are carried out. The experimental optimization results show that the optimum frequency of the compressor is about 15.5～17.2 Hz for different hydrogen-helium mixture. When the mean pressure of the compressor increases, the lowest refrigerating temperature decreases, with the increases of mean pressure its effect gradually becomes weaker and weaker. The optimum jaw opening of the orifice is 70o and 30o for the double-inlet valve. The hydrogen-helium mixture experimental results show that with the decrease of the mole fraction of hydrogen in the hydrogen-helium mixture, the lowest refrigerating temperature decreases, and when the mole fraction of hydrogen is below 20%, the lowest refrigerating temperature is close to that using pure helium. The cooling capacity of the miniature co-axial pulse tube refrigerator in 100～120 K temperature region can be improved with hydrogen-helium mixture. When the mole fraction of hydrogen is 20% in the mixture, the cooling capacity is 13.5%～16.5% higher than that using pure helium.