CO_(2)/HCs跨临界热泵系统仿真模拟与优化

Simulation and optimization of CO_(2)/HCs transcritical heat pump system

为了研究CO_(2)/HCs混合工质跨临界单级带节流阀系统的性能,针对CO_(2)/R1270和CO_(2)/R290这2种混合工质建立系统模型,并通过试验对其进行了验证。模拟分析了蒸发器入口温度、气冷器出口温度、高压压力、冷却水温度和流量对系统性能的影响;对系统进行优化计算,分析了气冷器内管管径、外管管径和管长对换热系数和换热量的影响。结果表明:当蒸发器入口温度升高,气冷器出口温度和冷却水入口温度降低,冷却水流量升高时,COP_(c)增大;CO_(2)/R1270的最优制冷高压压力在9 MPa左右,比纯CO_(2)降低了3%,CO_(2)/R290的最优制冷高压压力在8.5 MPa左右,比纯CO_(2)降低了8%;适当增大气冷器的内管管径或减小其外管管径,可以有效提高其换热性能。研究结果可为CO_(2)/HCs混合工质跨临界系统的优化设计提供参考。

In order to study the performance of a transcritical CO_(2)/HCs mixed refrigerant single stage heat pump system with throttle valve,a system model was established for the CO_(2)/R1270 and CO_(2)/R290 mixed refrigerants,and it was verified through experiments.The effects of evaporator inlet temperature,gas cooler outlet temperature,high-pressure pressure,cooling water temperature and flow rate on system performance were analyzed.And the system optimization is carried out by analyzing the effects of inner pipe diameter,outer pipe diameter,and pipe length of the gas cooler on heat transfer coefficient and heat transfer capacity.The results show that when the inlet temperature of the evaporator increases,the outlet temperature of the air cooler and the inlet temperature of the cooling water decrease,and the cooling water flow rate increases,COP_(c) increases.The optimal refrigeration high-side pressure for CO_(2)/R1270and CO_(2)/R290 system is around 9 MPa and 8.5 MPa,which is 3% and 8% lower than that of pure CO_(2),respectively.Properly increasing the inner pipe diameter or reducing the outer pipe diameter of gas cooler can effectively improve its heat transfer capacity.The research results can provide reference for the optimization and design of a transcritical CO_(2)/HCs mixed refrigerant systems.