Experimental study of a photovoltaic solar-assisted heat pump/gravity-assisted heat pipe hybrid system

In the present study, a hybrid PV/T collector/evaporator was designed and manufactured. On this basis, a hybrid system named photovoltaic solar-assisted heat pump/gravity-assisted heat pipe system (PV-SAHP/GHP) was proposed. The proposed hybrid system can alternatively operate in GHP-PV/T mode and PV-SAHP mode. An experimental test platform was then constructed and a series of outdoor experiments were conducted to reveal and contrast the operating characteristics in different modes. Net yields and energy-saving factors were additionally employed to reveal the priority of different operating modes. The results indicated that the daily average energy efficiency and exergy efficiency of the GHP-PV/T mode were 36.87% and 7.09%, while that of the PVSAHP mode were 51.39% and -6.34%. The fitting results of the thermal efficiency and overall efficiency of the PV-SAHP mode were higher than that of the GHP-PV/T mode. The GHP-PV/T mode though achieved a satisfactory energy-saving effect, its water temperature cannot meet the demand; while the PV-SAHP mode though met the temperature demand, and its energy conservation effect was unsatisfactory. Therefore, it is recommended to operate the GHP-PV/T mode during intense radiation and operate the PV-SAHP mode otherwise to balance the thermal performance and energy-saving benefits of the hybrid system.