空气制冷循环最优性能解析

通过建立单级空气制冷循环的量纲为一的热力学模型，推导出对应最优性能系数的压比公式，以及最优压比下的循环性能参数解析表达式.在此基础上针对不同的运行工况和转动部件效率，对循环性能进行数值分析，发现：高低温热源温差的增大，最优压比升高，最优性能系数下降，单位制冷量升高.提高转动部件效率，最优压比小幅降低，最优性能系数大幅升高以及单位制冷量大幅下降.同比之下，膨胀机效率对系统最优性能的影响更大.这些都有助于实际空气制冷系统的优化设计.
A dimensionless thermodynamic model of single stage air refrigeration cycle was developed. Based on the model, analytical solution of the optimal pressure ratio at the maximum ε (coefficient of performance) was derived. So did the cycle key performance indices. Furthermore, numerical analysis using the analytical solutions was conducted to reveal the impact of operating conditions and component efficiencies on the cycle performance. The results show that bigger heat source temperature difference leads to higher optimal pressure ratio, higher cooling capacity, but lower ε. On the other hand, higher compressor/expander efficiencies result in less lower optimal pressure ratio, much higher ε and cooling capacity. Under the same conditions, the expander efficiency has more significant influence on the cycle performance than the compressor efficiency. The analytical solutions and corresponding conclusions are helpful in optimal design of air cycle refrigeration systems