Modeling and Simulation of Transcritical CO2 Heat Pump System with Throttle Valve

In order to analyze the characteristics of the transcritical CO₂ heat pump system with throttle valve, it is necessary to simulate and further to optimize control the system operation. Therefore, the mathematical model for this system is developed in this paper. The simulation values are validated by the test data. The results show that the average error for cooling coefficient of performance (COP) and heating coefficient of performance (COPh) between simulation and experiment values is 10% or so. Then with the validated model, system performance is simulated for various operating parameters. Decreasing the inlet temperature and increasing the mass flow rate of cooling water both can increase the system performance. Whereas, increasing the inlet temperature and mass flow rate of the chilling water is slightly favorable. Compared to other parameters, the effect of water temperature at the inlet to the gas cooler on system performance is more significant. At last, the high pressure control strategy is introduced since there is an optimum high pressure corresponding to the maximum COP.