Experimental research on the vapor injected photovoltaic-thermal heat pump for heating, power generation and refrigeration

Abstract

This paper presents a vapor injected photovoltaic-thermal heat pump system (VI-PVTHP), which can take advantages of the vapor injection (VI) heat pump cycle, significantly increase the heating performance of the system. Not only that, but the VI-PVTHP can also be used for refrigeration by effectively use the PVT modules as condenser of the system. As a result, the system can realize three functions of heating, power generation and refrigeration, and can be used to meet building’s heating, electricity and cooling demands. Then a prototype of the VI-PVTHP was established. Based on the test data of the prototype, the performance and operation characteristics of the VI-PVTHP were analyzed. Results show that the system has good operation reliability and considerable heating, power generation and refrigeration performance during the three working conditions of hot water production, winter space heating and summer night refrigeration. Even on cloudy winter days with ambient air temperatures as low as −8.1 °C, the system can produce domestic hot water of 50 °C with an average COP of 2.59. The VI-PVTHP prototype can continuously and stably produce hot water at the temperature of 40 °C which required for space heating, with an average COP of 2.65. The average EER of the VI-PVTHP prototype was 2.12 during the refrigeration test in summer night. The PVT modules can make good use of night sky radiation and air convection for heat dissipation and is suitable for serving as condenser for heat pump. Radiative heat dissipation to sky is the main way of heat dissipation. During the tests, the heat dissipation flux of the PVT module has reached to ∼650 W/m2.