| The efficient utilization of the solar energy is one of the effective ways to reduce the energy shortage and the environmental pressures, the solar photovoltaic/thermal system(PVT) can provide domestic hot water when use solar power for generating electricity, it has advantages of high overall efficiency, low cost of the system and less installation area.A solar photovoltaic/thermal integrated heat pump/heat pipe system which combining heat pipe technology and solar assisted heat pump was studied in this paper, the refrigerant of the system evaporates directly in the collector tubes of photovoltaic panels'back, cooling the photovoltaic cells for high efficient electricity output; The heat that refrigerant absorbes through heat pipe or heat pump passes to the tank to provide domestic hot water, thereby reaching efficient photovoltaic and thermal utilization. The photovoltaic/thermal performance, the strategy of variable volume operation and the composite heat pipe-heat pump mode were theoretically and experimentally researched in this paper.Monocrystalline-silicon PVT collector was produced through the calculation of system components selection, a domestic hot water experiment system with R22 as the working medium was built. Besides, in this PVT heat pump system, the inverter compressor and the electronic expansion valve were applied to regulate the circulating mass of refrigerant according to the ambient parameter changes, which guaranting the capacity matching between PVT collector and heat pump for system's high efficient and steady operation.In order to further study the PVT heat pipe/heat pump system operation rule and the overall coefficient, each component's mathematical model and the simulation program of PVT heat pump and heat pipe system were coded by Visual C++. The simulation results agreed well with experimental values, so the accuracy of the model was verified,which providing the studying basis for variable volume control operation of the PVT heat pump system and the operation of heat pipe-heat pump composite mode.Under two similar ambient conditions in Nanjing, the heating performance and the electric output performance of the PVT heat pump domestic hot water system was tested under the condition of different compressor operation frequency, the operation rules of the system variable volume were studied, and the modulation regimen was made using the simulation model, the specific regulation strategy of every month throughout the year and performance characteristic of the variable volume PVT heat pump system was obtained. The results revealed that the PVT heat pump system could maintain run efficiently all year round beyond the heat pump coefficient 4.0, and save up to 30.8% of its electricity than the rated capacity system.The solar photovoltaic/thermal integrated heat pipe model was experimentally tested under the ambient condition, and the operation performance has been analyzed. The combined heat pipe-heat pump operation system has been analyzed through theoretical model, thus the heat pipe mode ran firstly, and then heat pipe mode was switched to heat pump when the water reach to a certain temperature in the cooling water tank. Reasonable switching strategy has been worked out according to the energy consumption and heating time, and the system annual operation performance of the composite mode has been analyzed. The results revealed that heat pipe-heat pump switch mode power consumption is 0.853 kWh, and saved 40.6% more power consumption than independent heat pump mode in spring and autumn typical sunny day. The combined heat pipe - heat pump mode should be used in preference in spring and autumn typical sunny day; In the winter, with the less solar radiation and lower ambient temperature, PVT heat pipe mode was difficult to run continuously, the PVT heat pump mode should be used only. |
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