Modeling and simulation of a transcritical R744 heat pump system

To analyze the performance of a carbon dioxide heat pump system, a steady state simulation model has been developed. The effects for different operating parameters such as compressor speed and water inlet temperature of the gas cooler were studied. It was shown that there was an optimum compressor speed for a certain system, and the maximum COP decreased and the optimum discharge pressure increased with the increasement of water inlet temperature of the gas cooler. The maximum COP and optimum pressure were correlated as functions of water inlet temperature of the gas cooler, and it is expected to offer useful guidelines for CO2 heat pump design and development.