Simulation and Experimental Study for Transcritical CO_2 Heat Pump System with Expander

To analyze the performance and operating characteristics of the transcritical CO2 heat pump system with expander,the mathematical model for the system was developed.The performance of the system was simulated and compared with the experimental results,and the maximum error was less than 25%.Then the verified model was adopted to analyze the effect of the inlet temperature of cooling water and its mass flow rate and the inlet temperature of chilling water and its mass flow rate on the system coefficient of performance.The results show that for the cooling water,decreasing its inlet temperature and increasing its mass flow rate can not only increase the system performance but also reduce the optimal heat rejection pressure,which keeps the system operating at safe and high efficiency condition.For the chilling water,increasing its inlet temperature and mass flow rate is favorable for increasing the system performance,while the optimal heat rejection pressure is not variable.The result can provide theoretical base and instruction for the system optimization design and operation by simulating the performance of the system.