Abstract: A novel dual-temperature condensation heat pump with the intermediate discharge of refrigerant (DTHP-IDR) is proposed to supply heat at two temperature levels. The system model was set up. in which R1234yf was used as the refrigerant. The results show that as the intermediate exhaust ratio increases, the compressor consumption decreases, and the heating performance coefficient increases. As the evaporation temperature increases, the mass flow rate of the compressor, the compressor consumption, and the heating performance coefficient all increase. As the middle-temperature condensation temperature increases, the compressor consumption increase, while the heating performance coefficient decrease. As the high-temperature condensation temperature increases, the compressor consumption and the heating performance coefficient of DTHP-IDR increase and decrease respectively too. It is found that when the evaporation temperature is 5 ℃, the middle and high-temperature condensation temperatures are 40 ℃ and 65 ℃, respectively. When the exhaust ratio is 28%, the heating performance coefficient of DTHP-IDR is improved by around 11% compared with the traditional single condensing heat pump system.

Key words: rotary compressor, intermediate refrigerant discharge, dual temperature condensation, heat pump