逆布雷顿空气制冷机动态降温特性数值研究

Numerical study on dynamic cooling performance of reverse Brayton cycle air cryocooler

建立了逆布雷顿空气制冷机系统时间相关数学模型,对系统动态降温过程进行了数值分析。详细阐述了系统主要部件板翅式换热器及透平膨胀机动态回热及降温数学模型。以该模型为基础,分析了逆布雷顿空气制冷系统不同入口压力、温度、流量及不同换热面积和膨胀机效率下的动态温降特性曲线,讨论了部分参数对系统动态降温性能的影响。结果表明:对于确定的入口流量,提高系统入口压力可以加快系统降温速度和最大温降;此外,系统设计时采用较大的回热换热器面积和提高膨胀机效率也是实现更大温降的有效手段。

In order to study the dynamic cooling process performance of a reverse Brayton cycle air cryocooler, a system time-dependent numerical model was set up and described, including the dynamic thermal performance model of a plate-fin heat exchanger and a turbo expander. The dynamic cooling process of the air cryocooler was discussed under different system inlet parameters, including pressure, tempera- ture, volume flowrate, different heat exchange area and different turbo expander efficiency. The theoretical results shown that the higher the system inlet pressure the faster the system temperature decreases in case of low system inlet temperature and small system inlet flowrate, the increase of heat exchange area and turbo expander thermal efficiency can promote the system cooling performance.