中文摘要：

为了分析带膨胀机CO2跨临界热泵系统的性能和运行特性,对该系统建立数学模型,将模拟计算结果与实验数据进行了比较,它们的最大偏差不超过25%.然后,利用所建模型分析了冷却水进口温度和流量,以及冷冻水进口温度和流量对系统性能系数的影响.结果表明,对冷却水来说,降低进口温度和增加其流量不仅有利于提高系统的性能系数,而且能够降低最佳高压侧压力,使系统能够在更加安全高效的工况下运行.对冷冻水来说,增加冷冻水的进口温度和流量对提高系统的性能系数非常有利,而对最佳高压侧压力的影响并不是太大.通过对系统的性能进行模拟计算,可为系统的优化设计和操作运行提供理论依据和指导.

英文摘要：

To analyze the performance and operating characteristics of the transcritical CO2 heat pump system with expander, the mathematical model for the system was developed. The performance of the system was simulated and compared with the experimental results, and the maximum error was less than 25%. Then the verified model was adopted to analyze the effect of the inlet temperature of cooling water and its mass flow rate and the inlet temperature of chilling water and its mass flow rate on the system coefficient of performance. The results show that for the cooling water, decreasing its inlet temperature and increasing its mass flow rate can not only increase the system performance but also reduce the optimal heat rejection pressure, which keeps the system operating at safe and high efficiency condition. For the chilling water, increasing its inlet temperature and mass flow rate is favorable for increasing the system performance, while the optimal heat rejection pressure is not variable. The result can provide theoretical base and instruction for the system optimization design and operation by simulating the performance of the system.