Air-Source Heat Pump with Integrated Latent Heat Storage for Residential Buildings: Concept Development and Design Evaluation

Heat pumps effectively support electrification and reduce energy consumption associated with building heating and cooling. Air-source heat pumps (ASHP) use the ambient air as a thermal source or sink for the heat pump (HP). ASHPs are the most common form of HP system in Canadian residential buildings due to their simplicity and lower initial cost. While the technology is recognized to play a key role in the path to building decarbonization, its widespread adoption will significantly increase peak demand for electricity grids, especially in regions where fossil fuel-based systems are to be replaced. Thermal storage technology can support the increased adoption of ASHPs in those regions by providing a more energy-flexible link between the building's thermal demand and the electrical grid. This study investigates a new method of integrating and applying a phase change material (PCM) as latent heat storage in an ASHP system for residential buildings. The approach employs direct heat exchange between the refrigerant and the PCM and indirect discharge of thermal energy into the room. This research describes the concept and evaluates its advantages. It also explores two suggested design configurations to integrate the storage unit into current ASHP systems. This research further evaluates the effect of those configurations on the storage unit's charging process via a numerical model developed to simulate heat transfer in the storage medium.