Comparison analysis of different refrigerants in solar-air hybrid heat source heat pump water heater

An original collector/evaporator that gathering solar and air energy is a promising device to reduce energy consumption. And the performances of self-designed heat pump with hybrid heat source using different refrigerants were simulated in the present work. Based on lumped parameter method, the steady state models, including collector/evaporator, compressor and gas cooler, were established. The effects of R22, R134a and R744 were analyzed in terms of power consumption, coefficient of performance (COP), solar energy input ratio and so on. The results showed that three refrigerants performed an analogous operating performance. R22 and R134a had a little difference considering different evaluation factors. By contrast, CO2 had a poor COP, but it had a good low temperature performance.