Research On Performance Of Solar Photovoltaic Loop Heat Pipe Water Heating System

A new type of solar photovoltaic loop heat pipe water heating system was proposed in this paper which combined the PV/T technology with the heat pipe technology.The system can overcome the problems of anti-freezing in winter,leakage of working fluid and low heat collection efficiency in the traditional PV/T system.The working temperature of the photovoltaic module of the system can be further reduced,and the photovoltaic power generation efficiency can be improved,the comprehensive utilization efficiency of the solar energy can be effectively improved too.In addition,the system has many characteristics,such as layout flexibility,high heat transfer efficiency and easy integration with buildings,etc.It can provide domestic hot water and electric energy for buildings,which is a conducive to reduce building energy consumption,and in line with the development trend of China's low carbon economy.This paper mainly used theoretical analysis and mathematical modeling to compare the operating characteristics of the built system and forced circulation PV/T water heating system.Moreover,analyzed the impact of different climatic conditions on the operational performance of the target system,and studies the social and economic benefits of the system.Providing theoretical basis and design reference for the engineering application of the system.The research of the paper contains the following aspects:(1)Analyzed the operating principle of the target system;based on the first law of thermodynamics,the heat transfer model of the system was established.And then the simulation program of the system was established by using Visual Basic 6.0.Selected the forced circulation PV/T water heating system as the benchmark system,through TRNSYS software,a simulation model was constructed.Above works paved the way for further simulation of the two systems.(2)Based on the established models,the variation of the typical operating conditions and long-term performance of the systems in cold area was discussed.The results show that the cooling effect of the target system on the PV layer is more obvious than that of the reference system.The temperature of the PV layer is reduced by 15.43 °C.The integrated performance of the photosystem is more prominent.The integrated efficiency ofphotoelectric photothermal of the target system is increased 3.12%.(3)Based on the principle of latitude correction,the optimal installation inclination and orientation of the system in Beijing,Shanghai and Guangzhou were determined.From the perspective of energy efficiency,the integrated efficiency of photoelectric photothermal in the Guangzhou area reached 56.00%,which is 8.19% and 5.58% higher than that in Beijing and Shanghai respectively,which confirmed that the system has good climate adaptability and is most suitable for hot summer and warm winter areas.(4)Based on the optimization results,This paper elected the electric water heater system as the reference system to further explored the social and economic benefits of the target system.The results showed that the target system has good energy-saving,environmental and economic benefits.The system has good energy-saving benefits and environmental benefits in Guangzhou,and has good economic benefits in Beijing.The specific application of the system is related to the sequential relationship of the three benefits.