Heating and power generation characteristics of the vapor injected photovoltaic-thermal heat pump system

The vapor injection compression cycle has been proved that can effectively improve the heating performance of the photovoltaic-thermal (PVT) heat pump system. In this paper, a simulation model of the vapor injected PVT heat pump system (VI-PVTHP) has been established and verified experimentally. The influence law of environmental parameters on the heating and power generation performance of the VI-PVTHP have been clarified. Results show that the coefficient of performance (COP) of the system would increase by about 0.035 under the water heating condition when the ambient temperature increases by 1 °C, and would increase by about 0.041 under the space heating condition. The COP of the system would increase by 0.12 and 0.15 with an average increase of 100W/m2 of solar irradiance under the water heating condition and space heating condition respectively. Additionally, the heating performance of the VI-PVTHP and the conventional PVT heat pump (employing single stage compression cycle) has been compared. Results show that the heating capacity and COP improvement of the vapor injected PVT heat pump system could be higher than 30% and 15% respectively. And the harsher the ambient condition is, the more obvious the heating performance advantage of the vapor injected PVT heat pump system is.