A double-heat source high-temperature heat pump system with an intermediate heat exchanger

To improve the thermal performance of industrial heat pumps and realize the high-efficiency recovery of industrial low-temperature residual heat, a double-heat source high-temperature heat pump system with an intermediate heat exchanger is proposed in this paper and the cold water is heated to high temperatures by two stages for industrial application. First, it is heated to the intermediate temperature by CO₂ which absorbs heat from the air, and then, the water is further heated to a high temperature by R152a, taking waste water as the heat source. In the intermediate heat exchanger, the heat of R152a after condensation is recovered by heating CO₂ to the superheated state after evaporation. Thermodynamic analysis was conducted and it was indicated that there exists a highest superheated temperature for CO₂ when the temperature drop of R152a is given in the intermediate heat exchanger, which shows the best performance of this heat pump system. Compared with the single-heat source heat pump by recovering the residual heat of waste water of 50℃, the hot water supply is more than double of it; the average power consumption per kg of hot water decreases about 43.2%; and the COP and energy efficiency increase about 41.9% and 23.9% respectively.