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This work evaluates through numerical modeling, the efficiency of an air-to-water heat pump that operates using a transcritical CO2 cycle assisted by an indirect dedicated mechanical subcooling (IDMS) cycle, with R1234ze(E) as the refrigerant. The research aims to analyze how the size of the heat exchangers used as the evaporator and the condenser for the IDMS cycle affects the overall efficiency of the system. A numerical model previously developed in Matlab® is used to modify the refrigerant and compressor of the IDMS cycle and to determine the optimal number of evaporator and condenser plates that maximize the efficiency of the whole system. The compressor model is derived from manufacturer correlations, whereas the models for the heat exchangers are obtained through a parametric study developed using IMST-ART® to characterize their operating parameters based on their number of plates and the inlet conditions of water and refrigerant. Once the models are developed, they are integrated into the model of the overall system to find the heat exchanger sizes that maximize the efficiency of the system.
Obono et al. (Thu,) studied this question.