通过用分析方法对CO2 跨临界制冷循环带节流阀和带膨胀机系统进行分析 ,发现节流阀的损失较大 ,用膨胀机代替节流阀后 ,可使这部分损失降低 ,提高系统效率。在带膨胀机的系统中 ,主要损失发生在气体冷却器、压缩机和膨胀机 ,其中高压侧压力、气体冷却器出口温度以及蒸发温度对各部件的损失和效率都有不同程度的影响 ,在优化系统设计时应综合考虑这些参数。用分析方法对系统性能进行评价 ,可为系统的改进提供理论依据 Through the analysis of CO2 transcritical refrigeration cycle with throttle valve and expander system by using the analytical method, it is found that the throttle valve loss is relatively large. When the expander is used instead of the throttle valve, the loss can be reduced and increased System  efficiency. In systems with expanders, major losses occur in gas coolers, compressors and expanders, with high-pressure side pressure, gas cooler exit temperature, and evaporating temperature varying to varying degrees Impact, these parameters should be considered when optimizing system design. Use  analytical method to evaluate the performance of the system can provide a theoretical basis for system improvement