【摘要】 最优排气压力是影响跨临界CO₂热泵性能最重要的因素。为研究最优排气压力存在原因及其影响参数，并揭示各参数对最优排气压力的影响机理，基于传热夹点理论对最优排气压力进行了理论分析。利用AMESim软件搭建了考虑气体冷却器内部传热夹点的跨临界CO₂热泵模型进行仿真计算，在进水温度为10～40℃、出水温度为60～90℃、环境温度为-30～25℃的宽工况内定量研究了进水温度、出水温度、环境温度及回热率对热泵系统最优排气压力的影响。研究结果表明：进水温度越低、出水温度越低、环境温度越低，均会导致传热夹点向气体冷却器出口移动，从而使系统的最优排气压力减小；同时，采用回热方式也能够将传热夹点进一步向气体冷却器出口推移，从而减小最优排气压力。研究结果证实传热夹点的位置对于系统最优排气压力的取值具有重要影响，因此基于传热夹点的分析与设计方法具有更强的适用性，可为热泵供暖、车辆热管理等用途中CO₂热泵系统的设计和性能优化提供理论与工程基础。更多还原

【Abstract】 Optimal discharge pressure is the most important factor affecting the performance of a transcritical CO₂ heat pump. In this study, the reasons for the optimal discharge pressure were theoretically analyzed based on the heat transfer pinch point. The factors influencing the optimal discharge pressure and their influence mechanism were determined by constructing a transcritical CO₂ heat pump simulation model using the AMESim software. The model took into consideration the internal heat transfer pinch point of the gas cooler. Under inlet water temperature of 10 ℃-40 ℃, outlet water temperature of 60 ℃-90 ℃, and ambient temperature-30 ℃-25 ℃, the influence of inlet temperature, outlet temperature, ambient temperature, and heat recovery rate on the optimal discharge pressure was studied quantitatively. The results showed that the lower the inlet, outlet, and ambient temperatures, the lower the optimal discharge pressure of the system. Moreover, the optimal discharge pressure could be reduced by using an internal heat exchanger. The influence mechanism of each factor on the optimal discharge pressure was found to be closely related to the heat transfer pinch point and the physical properties of CO₂ near the critical point and supercritical zone. The research results can provide a reference for the design and performance optimization of CO₂ heat pump systems.更多还原