中文摘要：

建立了带膨胀机CO2跨临界热泵系统的数学模型，将模拟计算结果与实验测量结果进行了比较，验证了模型的准确性。利用数学模型分析了冷却水进口温度和质量流量、冷冻水进口温度和质量流量对带膨胀机CO2跨临界热泵系统的制冷性能系数及最佳高压侧压力的影响。降低冷却水进口温度和提高其质量流量不仅有利于提高制冷性能系数，而且能降低最佳高压侧压力。提高冷冻水进口温度及质量流量有利于提高制冷性能系数，对最佳高压侧压力影响不大。

英文摘要：

The mathematical model for transcritical CO2 heat pump system with expander is established, the simulative calculation results are compared with the experimental measurement results, and the accuracy of the model is verified. The influence of the inlet temperature and mass flow of cooling water and the inlet temperature and mass flow of refrigerant water on refrigerant performance coefficient and optimal pressure at high pressure side of the transcritical CO2 heat pump system with expander is analyzed using the mathematical model. Reducing the inlet temperature of cooling water and increasing its mass flow are favorable to increase refrigerant performance coefficient, and can decrease optimal pressure at high pressure side. Increasing the inlet temperature and mass flow of refrigerant water is also favorable to increase refrigerant performance coefficient, but has no great influence on optimal pressure at high pressure side.