Dynamic modeling and co-optimization of configuration and operation for a solar-assisted ejector heat pump with energy storages

To improve the heat pump coefficient of performance, an integrated solar phase change energy storage heat pump system is proposed. This system utilizes solar thermal energy to raise the evaporation temperature and employs phase change energy storage to improve the coefficient of performance. Firstly, a dynamic model of the integrated system is established. Then, the simulation results of the coupled system are analyzed. By comparing the simulation results of CHHPTES system and SEHPTES system, it is observed that the use of PV/T (photovoltaic/thermal) technology significantly improves the coefficient of performance. The operation variables such as compressor frequency, heating and cooling volume flow rates, and ejector throat area are analyzed. In addition, a multi-objective nonlinear dynamic optimization is carried out for both the configuration and operational parameters of the system. The optimal configuration and operational parameters are determined. Instantaneous coefficient of performance and instantaneous heating capacity are used as objective functions, with compressor frequency, heating and cooling flow rates, and ejector throat area considered as independent variables in the optimization process. After optimization, the overall coefficient of performance increases by 17.20 % and the charging time decreases by 21.50 %. This study provides a configuration and operation cooptimization strategy for solar heat pump energy storage systems, enabling them to have a good coefficient of performance and shorter charging time.