Thermal And Electrical Performance Stady Of A Concentrating Photovoltaic-Thermoelectric Generation Integrated System

Due to the limited fossil energy resources and the increasingly serious environmental pollution problems,solar energy has received worldwide attention as a renewable energy gradually.The solar energy industry has been vigorously developed in China in recent years as China is rich in solar energy resources.Photovoltaic-thermal technology has been widely studied as an efficient way to improve photovoltaic conversion efficiency and generate thermal energy at the same time.Other technologies are gradually combined with photovoltaic-thermal technology,like concentrators,phase change materials,thermoelectric power generation.In order to improve the comprehensive utilization efficiency of photovoltaic-thermal system,a new heat pipe based low concentrating photovoltaic-thermal-thermoelectric power generation system(HP-LCPV/T-TEG)is proposed,which combines the thermoelectric generation technology suitable for medium-low temperature thermal utilization with photovoltaic-thermal system.The basic technologies involved in new systems are introduced,included the optimized CPC concentrator,and heat pipe based photovoltaic-thermal technology and thermoelectric power generation technology.The overall structure and operation principle of the system are described in detail.The theoretical modeling and analysis of the system are carried out,and the experimental platform is built to study the experimental performances of the system.The whole-day performance study of the experimental system shows that the PV power increases first and then decreases,the changes of TEG power and thermal power are not obvious throughout the day.The daily average electric power and daily average thermal power of the system are 76.1W and 279.4W,respectively.The highest PV efficiency of the experimental system reaches 12.8%,and the lowest is 9.2%at 11:30 a.m.,the electrical efficiency of TEG relative to the system is only less than 1%,which provides 1-2W power.The thermal efficiency of the system decreases first and then increases during the whole day,with an average thermal efficiency of 45%.The interrelation between environmental parameters and performance parameters of the system has been studied by correlation analysis,the results show that there is a strong correlation between system efficiency and irradiation intensity.The correlation coefficients between PV efficiency,TEG efficiency,thermal efficiency and irradiation intensity are higher than that between these parameters and ambient temperature and inlet water temperature,which are-0.64,-0.93,-0.97,respectively..The experimental results under different cooling water flow show that the electrical efficiency of the system increases with the increase of flow rate in a certain flow range.