Based on the Chinese National Standards involving heat pump water heater and space heating system, performances of the R744/R290 subcritical heat pump system have been discussed and compared with those of the R22 system, which is widely used in heat pump systems in China nowadays. It can be indicated that R744/R290 mixture can work efficiently as a refrigerant for heat pumps with a large heat-sink temperature rise. When mass fraction of R290 is increased, discharge pressure is reduced. Under the nominal working condition, there is an optimum mixture mass fraction of 20/80 for R744/R290 under conventional condensation pressure. Both the heating COP hs (coefficient of performance) and volumetric heating capacity are increased by about 12.62% and 34.24% respectively compared with those of R22 based system. But for the heat sink with a small temperature rise, R744/R290 system has poorer performances than R22 system. When heat transfer pinch point in evaporator and condensation processes is considered, the degree of superheat has a negative influence upon system performances under the given conditions.
Abstract-An experimental setup about solar ejector refrigeration is designed and built using HFC134a as working fluid in this paper. Based on Zhengzhou meteorological parameters, the hourly coefficient of performance(COP), energy efficient ratio(EER), cooling capacity and other parameter about the ejector refrigeration system have been researched with the solar radiation changed, The experimental data show that the hourly COP and EER of the system change constantly, and it has been influenced by the solar radiation, the ambient temperature, generator temperature, and condenser temperature et al., and the cooling capacity, heat transfer capacity about the exchanger, and generator temperature appear rise and fall in the research range. The average daily COP is 0.18 at the July 26, the average EER can up to 3.5.
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