Paper No 331 – A Review of Recent Residential Heat Pump Systems and Applications in Cold Climates – 14th IEA Heat Pump Conference, Chicago, USA
The heat pump (HP) system is one of the environmentally friendly solutions to reduce the carbon footprint of buildings due to its high efficiency and low added initial cost from the cooling-only systems. This paper presents a literature review of the recent advances in HP systems applied in cold climate regions categorizing the systems into two major types depending on energy source types. The first type is the systems with an air source without additional energy sources, i.e., Air Source HP (ASHP) systems, which use various working fluids and configurations. However, several issues impede their widespread applications. When the systems are used for space or water heating in cold climates, ASHP systems suffer a high discharge temperature and pressure ratio at low ambient temperature, which leads to low efficiency and heating capacity. Furthermore, some researchers reported that the defrost penalty reduced the energy efficiency by up to 30%, leading to a degradation of heating capacity by 43%. The second type is the systems with additional energy sources, like solar-assisted HP systems, which can partly improve energy performance but have difficulties in coupling different sub-systems to achieve increased operational time and are limited to locations with enough solar radiation. This study identifies the future research directions as (1) developing multi-source heat pumps with efficient control; (2) utilizing waste heat for defrosting; and (3) optimizing HP configurations and minimizing refrigerant charge while achieving higher efficiency.