| R1234yf is a kind of new refrigerant,which is becoming refrigerant research focus with low GWP and ODP in recent years.Performance of evaporator in R1234 yf heat pump system was researched through structural design,numerical simulation and experimental testing.Heat transfer,pipe diameter and pipe ranges of tube-in-tube evaporator were designed in reasonable calculation according to heat exchanger design manual and national standard in the relevant provisions.It is determined that the length of each tube is 1m.The tube process is 7.The inside of the casing is the structure of three heat transfer tubes.Partition grid of tube-in-tube evaporator's model with ICEM,and the boundary conditions are stipulated according to actual working conditions,the mixed model was selected as a multi flow model.Refrigerant flux,density of heat flow,chilled water flow and pipe size are changed with FLUENT.Combined with the basic theory of gas-liquid two phase flow,the heat transfer of evaporator was analyzed with the increase of heat flux,refrigerant flow and chilled water flow rate,the heat transfer coefficient increases.The heat transfer coefficient increases first and then decreases with the increase of tube diameter.The influence of evaporation temperature,the inlet and outlet temperature and the flow rate of frozen water on performance of the heat pump system was studied on R1234 yf heat pump test bench.Theoretical analysis and experimental error analysis show that with steady flow,the error between five temperature points on tube inlet and simulation results decreases gradually,and temperature point error is reduced to 7%.The research results can provide basis for the design of R1234 yf heat pump system and the development of related products. |
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