氦液化器内纯化器实验与模拟研究

Experimental and numerical investigation on internal purifier of helium liquefier

利用内纯化器实验平台,对氦氮混合气体及氦氧混合气体进行了纯化实验,根据实验结果计算出换热器UA随着压力及气体组分的变化,分析冷凝液膜的变化及对内纯化器换热性能的影响;建立全尺寸冷凝换热器模型,增加氦气-空气混合气体,进行模拟计算,得到管内外流体温度场分布,计算UA值的变化并与实验结果对比,进一步计算了管外流体Nu数、Pr数及Re数的变化,并和利用传热科伯因子法计算得到的Nu数相比较,发现在内纯化器冷凝换热器设计中存在的问题及改进的方向。

Purification experiments were carried out on the experimental platform of internal purifier. According to the experimental results,the UA value of heat exchanger was calculated and the change of condensate film and its influence on heat transfer performance were analyzed. A full-scale condensation heat exchanger model was established. The temperature distribution of the fluid was calculated,and the change of the UA value was compared with the experimental results. The changes of Nusselt number,Prandtl number and Reynolds number of the fluid outside the tube were further calculated. The problems existing in the design of the condensation heat exchanger of the internal purifier and the direction of improvement were found.