CO_2跨临界两级压缩制冷循环热力学分析

Thermodynamic Analysis on CO_2 Transcritical Two-Stage Compression Refrigerating Cycle

采用热力学方法对 CO2 跨临界两级制冷循环性能进行了分析 ,并与单级系统进行了对比 .结果表明 ,采用两级压缩可提高 CO2 循环的 COP,相同工作条件下 ,两级压缩与单级压缩系统相比 ,其 COP可提高 5 %左右 ;一定的蒸发温度下 ,CO2 循环的最佳冷却压力在 9.0 MPa左右 ;采用回热器在循环最佳冷却压力以下可大幅度提高系统性能 ,超过最佳冷却压力以后 ,对系统的改善很小 ;相同压缩终了压力下 ,两级压缩的排气温度可比单级压缩低 1 8

This paper analyzed the performance of CO2 transcritical two-stage compression cycle, and contrasted it with one-stage system. The results indicate that the two-stage compression cycle can increase the COP by about 5% compared with the one-stage compression system in the same condition. The optimum heat rejection pressure is 9.0 MP at certain evaporating temperature. The internal heat exchanger can improve the performance greatly below the optimum heat rejection pressure, while little above the optimum heat rejection pressure. The exhaust temperature of the two-stage system is decreased by about 18°C in the same conditions.