低环境温度空气源热泵适用环保工质研究

Study on the Application Environmental Refrigerant for Air Source Heat Pumps in Cold Areas

空气源热泵因其节能、环保、应用灵活等优点,在过去一段时间成为我国华北农村地区清洁采暖的主要选择。但供暖用空气源热泵在我国华北地区依旧面临低温工况下制热能力衰减、室外换热器结霜和总体能效降低等问题,空气源热泵系统循环工质的臭氧消耗潜值(Ozone Destruction Potential,ODP)和全球变暖潜能值(Global Warming Potential,GWP)亦对环境产生不利影响。在蒙特利尔协定和我国双碳战略背景下,高效环保制冷剂的研究是优化空气源热泵节能环保运行的重点之一。本文首先通过空气源热泵系统工质的热力学循环过程,建立了工质循环性能数学模型。而后搭建实验台对充注R22、R417A共2种典型工质的空气源热泵运行性能进行了实验测试,并对所建立的数学模型进行了优化和验证。在此基础上,利用优化和验证后的数学模型,根据制冷剂的选用原则混合了4种环保工质,并计算了不同工况下混合工质的各项热物性参数和循环性能,得出适用于我国华北地区供暖用空气源热泵的环保工质,确定了混合比例为0.9/0.1的R161/CF3I的压缩比最低,排气温度低于R22系统,在室外温度较低时与R22系统COP差值非常小,适合替代R22制冷剂作为北京地区空气源热泵供热工质,为优化空气源热泵系统节能环保性能提供参考。

Air source heat pumps for heating still face problems such as heat production capacity attenuation under low temperature conditions,outdoor heat exchanger frosting and overall energy efficiency reduction in North China.The Ozone Destruction Potential(ODP)and Global Warming Potential(GWP)of the circulating working medium of air source heat pump system also have adverse effects on the environment.Under the background of the Montreal Agreement and our carbon peak and carbon neutrality strategy,the research of high efficiency and environmental protection refrigerant is one of the key points to optimize the energy-saving and environmental protection operation of air source heat pumps.In this paper,the thermodynamic cycle process of air source heat pump system was used to establish a mathematical model of working medium cycle performance.Then a test bed was built to test the operation performance of the air source heat pump charged with two typical working medium of R22 and R417A,and the mathematical model was optimized and verified.On this basis,using the optimized and verified mathematical model,according to the principle of refrigerant selection,four environmental protection working fluids were mixed,and the thermal and physical parameters and cycle performance of the mixed working fluid under different working conditions were calculated,and the environmental protection working fluid suitable for heating air source heat pump in North China was obtained.The compression ratio of R161/CF3I with a mixing ratio of 0.9/0.1 was identified as the lowest,the exhaust temperature was lower than that of the R22 system,and the COP difference with the R22 system was very small when the outdoor temperature was low.It is suitable for replacing R22 refrigerant as the working fluid of air source heat pump heating in Beijing,which provides a reference for optimizing the energy saving and environmental protection performance of air source heat pump system.