Evaluation of control strategies for a dual-source heat pump

A dual-source heat pump is coupled with two heat sources/sinks, such as the ground and the air. Such solutions allow to decrease the installation costs and balance the thermal load to the ground, shifting part of the heating or cooling thermal load to the finned coil heat exchanger and preventing the possible degradation of the long-term ground-source heat pump performance. The strategy to switch between the two heat sources and sinks is crucial to ensure good heat pump performance in the short and long-term system’s operation. This work investigates a control strategy to choose the value of switch temperature, which establishes the most favorable heat source or sink to be used by the heat pump. A dynamic TRNSYS model was used to simulate an existing commercial building, where a dual-source heat pump is installed and whose operation data are monitored. The model allowed the thermal and electrical behavior of double-source heat pumps to be studied and predicted. A sensitivity analysis was performed to investigate the effect of the dynamic switch temperature selector parameters on the heat pump long-term energy use and the model was applied to scenarios with different heating and cooling loads and number of borehole heat exchangers.