Experimental study on energy, exergy, and exergoeconomic analyses of a novel compression/ejector transcritical CO2 heat pump system with dual heat sources

Abstract

A novel compression/ejection transcritical CO2 heat pump system with dual heat sources (CHP) was proposed in our previous research. This paper experimentally investigates the feasibility and performance of the novel system and compares it with the conventional transcritical CO2 heat pump system (THP). The experimental results show that the maximum heating capacity and outlet water temperature can reach 50.49 kW and 85.8℃; The maximum exergy destruction of the novel system at 20 Hz to 30 Hz occurs in the gas cooler, which varies from 701.05 W to 1335.47 W, but the maximum exergy destruction at 35 Hz is the compressor, which is 1824.21 W; The total exergy cost rate of the throttle valve plays a dominant role in the system operation. In addition, the coefficient of performance (COP) and the exergy efficiency (ηEX) of the CHP are higher than that of the THP; The COP, ηEX, and IREX improvements of the CHP over the THP at the optimum discharge pressure, and the maximum improvements accordingly are 14.83 %, 38.14 %, 10.26 %, respectively. It can be concluded that the novel system is feasible and superior to the THP system. The research results will help to further promote the research and application of air source heat pumps integrating solar energy or geothermal energy due to the addition of the water source evaporator.