Abstract:
The coupling of heat pumps with packed bed latent heat thermal energy storage (PBTES) systems offers an effective solution to mitigate the spatiotemporal mismatch between heat supply and demand. However, existing research remains insufficient regarding the dynamic thermodynamic characteristics and coordinated optimization of integrated photovoltaic/thermal (PV/T)-heat pump-PBTES systems. Three heating system configurations were developed and compared: An air-source heat pump (ASHP) direct heating system, an ASHP coupled with PBTES heating system, and a composite heating system integrating an ASHP, a PV/T heat pump, and a PBTES unit. Using a representative severe winter day in Xi'an as the calculation condition, a cyclic heat storage model and a transient heat release simulation program dynamically coupled with a hydronic radiator were established for the PBTES system. A dynamic flow control optimization strategy for the heat release process was proposed, and the thermodynamic performance and operational economics of the three systems were systematically compared. The results indicate that under a constant ASHP heating power of 20 kW and a flow rate of 8 m
3/h, the PBTES system completes heat storage within the 8 h valley electricity period, achieving a total heat storage capacity of 101.65 MJ and an exergy storage capacity of 54.00 MJ, with the exergy storage power peaking at approximately 3.0 kW during the PCM phase change stage. Regarding heat release optimization, the parabolic increasing flow strategy extends the effective heat release duration to 2.54 h, representing a 172.5% improvement over the constant flow baseline. In terms of system performance comparison, the ASHP+PV/T heat pump+PBTES composite system achieves the best overall performance, with a system COP(Coefficient of Performance) of 3.73 and a daily operational cost of 92.58 CNY, representing a 41.83% improvement in COP and a 41.53% reduction in operational cost compared to the ASHP direct heating system, and a 37.64% improvement in COP and a 37.04% reduction in cost compared to the ASHP+PBTES system. Additional analyses conducted under typical cloudy conditions demonstrate that the performance rankings of the three systems remain consistent across different operating conditions. This study provides a theoretical basis and practical reference for the engineering design and operational optimization of solar thermal-heat pump-phase change storage integrated heating systems.