Experimental Study On The Performance Of Heat Pump Using Low GWP Mixtures R1234yf/R32 As Refrigerant

With the acceleration of our country's economic and social development and urbanization process,heat pump technology has attracted wide attention from industry personnel for its energy-saving,high-efficiency,and green environmental protection.At the same time,research of new low-greenhouse effect refrigerants and the performance of high-efficiency heat pump systems have also become the hot topics of heat pump and air conditioner field.This paper use simulation software,based on two-stage tandem annular tubes heat pump system that has set up,comparing and analysing the thermodynamic cycle characteristics of a new type of mixed working medium in the two-stage tandem annular tubes heat pump system.The main research contents are:(1)Based on the previous research work,the physical characteristics of the selected refrigerants(R1234yf,R32,R125,R134a)were analyzed,under the nominal working condition of heat pump water heater,by using the EES simulation software,the heat pump circulation characteristics of three groups of mixed refrigerants(R1234yf/R32,R1234yf/R125,R1234yf/R134a)under the thermodynamic model were simulated and calculated,the results indicate that the optimal ratio of R1234yf/R32 mixture is 10%/90%,and the optimal thermal coefficient of performance of R1234yf/R32 system is 4.25,and the COP_h value of R1234yf/R32 system increased by 27.2%compared with that of R1234yf/R125,and the R1234yf/R32 system's condensing pressure dropped by 20%,exhaust temperature dropped by12.21?,compression ratio decreased by 1.2%and rose 9.1%of heating capacity compared with the pure R32 system,pointed out that R1234yf/R32 mixture is the most promising alternative refrigerant.(2)Based on the pure refrigerant R32,the optimal charging capacity test was carried out.Under the setting conditions,it is found that the system's thermal coefficient of performance reaches the optimal value of 2.95 when the R32 filling quantity is 1.9kg.It provides a reference for the performance test of the new mixed heat pump.(3)In order to verify the circular characteristics of R1234yf/R32 system and explore its actual heat pump cycle performance,through the experimental research and analysis,the optimal COP_h values of the five groups'charge quantity were all found in the ratio 10%/90%,the system's heating coefficient of performance under the optimal charge quantity and ratio compared with other filling quantity(1.7 kg,1.8 kg,2.0 kg,2.1 kg)increased by 8.1%,4.1%,3%and 8.9%respectively,and increased by 8.1%compared with pure R32 heat pump system under the optimal charge quantity,and its'power consumption decreased by 1.6%,exhaust temperature decreased by 7.6?and pressure ratio decreased by 3%compared with pure R32heat pump system.