进气压力及流量对自调型J-T制冷器性能的影响

Influence of inlet pressure and flow rate on the performance of self-adjusting J-T cryocooler

针对因高压流体进气压力及流量变化造成制冷器运行不稳定的问题,基于热平衡方程法,建立制冷器内换热器及自调机构的理论模型,分析不同高压流体进气压力及流量对自调型J-T制冷器运行性能的影响规律。结果表明:节流前高压流体的总压降及节流后低压流体的干度随进气压力增加而减小,随流量增加而增大;随着进气压力及流量变化,制冷器制冷量存在峰值;当高压流体进气压力增加或流量减小,制冷器冷段区域范围逐渐减小;当换热器结构一定,随着进口压力及流量改变,阀针插入深度及其锥角具有最优值。对于本文研究的制冷器结构,当质量流量小于0.1 g/s时,可忽略高压流体入口压力变化(20~30 MPa)对阀针插入深度范围的影响。

Aiming at the unstable operation of the cryocooler self-adjusting mechanism caused by the change of inlet pressure and flow rate of high pressure fluid,the theoretical model of the heat exchanger and self-adjusting mechanism in the cooler is established based on the heat balance equation method.The influence of high-pressure fluid with various inlet pressure and flow rate on the performance of self-adjusting J-T cryocooler is analyzed.The results show that the total pressure drop of high pressure fluid before throttling and the dryness of low pressure fluid after throttling decrease with the increase of inlet pressure but increase with raising flow rate;with the change of inlet pressure and flow rate,there is a peak value of refrigerating capacity;under the increase of inlet pressure and the decrease of flow rate of high-pressure fluid,the cold zone of cooler gradually narrows;for the fixed heat exchanger structure in this study,with the change of inlet pressure and flow rate,the needle insertion depth and cone angle have the optimal value.For the cryocooler structure studied in this paper,when the flow rate is less than 0.1g/s,the influence of high-pressure fluid inlet pressure(20~30 MPa)on changing the range of needle insertion depth can be ignored.