传热不可逆回热式布雷顿制冷机分析

Analysis of Heat Transfer Irreversible Regenerated Brayton Refrigerator

用有限时间热力学方法分析实际稳态制冷装置性能，导出了恒温和变温热源条件下实际闭式回热式布雷顿制冷循环制冷率与压力比和制冷系数与压力比之间的解析关系。考虑的不可逆性包括高、低温侧换热器和回热器的不可逆传热损失，压缩机和膨胀机中的非等熵压缩和膨胀损失，以及管路系统中的压力损失。通过优化两个换热器和回热器之间的热导率分配或传热面积分配可得循环最优性能。由数值算例给出了各项损失对循环制冷率和制冷系数的影响。

The performance of a real steady refrigeration plant is analyzed by using a method of finite time thermodynamics.The analytical relations between cooling load and pressure ratio,as well as between coefficient of performance (COP) and pressure ratio of real closed regenerated Brayton refrigeration cycles coupled to constant and variable temperature heat reservoirs are derived.The irreversibilities considered in the analysis include that the heat transfer irreversible losses in the hot and cold side heat exchangers and the regenerator,that the nonisentropic expansion and compression losses in the compressor and expander as well as that the pressure drop losses in the pipe system.The optimal performance can be obtained by optimizing the distribution of heat conductances or heat transfer surface areas among the two heat exchangers and the regenerator.The effects of various loss factors on the performance of the cycle are examined by detailed numerical examples.