Study on the Application Environmental Refrigerant for Air Source Heat Pumps in Cold Areas
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.
mixture refrigerantsair source heat pumpODPGWPlow ambient temperature
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