Research development in direct-expansion solar-assisted heat pump technology

Outlines basic configurations of the direct-expansion solar-assisted heat pump (DX-SAHP) system. Reviews development of the research on the DX-SAHP. Summaries the research development of several aspects of DX-SAHP heating systems, including the thermal performance, effects of refrigerant on the system performance, effects of variable compressor capacity on the system performance, as well as the DX-SAHP with photovoltaic and photo-thermal hybrid panels. Presents simply the research development of the water heating system in DX-SAHP air conditioning system.