Parallel loop configuration for hybrid heat pump – gas fired water heater system with smart control strategy

Abstract

Air source heat pumps suffer from reduced thermal delivery in cold climate conditions. In this study, the parallel loop hybrid system with the combination of heat pump and gas fired water heater in one device is provided as the sustainable alternative to alleviate such issues. An economic-based new control strategy has been proposed for the hybrid system to investigate the system thermal performance and reveal the economic benefits for residential space heating application. The climate conditions, fuel source price ratio and gas heater thermal efficiency have been included in the analysis of the hybrid performance. Under the operating map, the control strategy can lead to a ∼10% to ∼60% system operating economic benefits for space heating application for −12 °C to 20 °C ambient. Raising the price ratio can decrease the ratio of the heat delivered by the heat pump on the overall heat loading, especially for higher final water target temperatures. Lowering the price ratio can improve the energy process saving potential (% gas heater heating mode baseline). In addition, several typical cities have also been investigated as a part of studies for hybrid performances and environmental impacts.