Research On Key Technologies Of Reflective High Concentration Photovoltaic Thermoelectricity System

In the energy crisis and environmental destruction of the moment,solar energy as the most promising new energy and is widely concerned by society.Reflectively high concentration photovoltaic/thermal system,as one of the forms of solar energy utilization,has been greatly developed.However,non-uniformity of the receiver surface energy flux-density,the characteristics of Ga As battery and the cooled system can affect the photoelectric conversion efficiency of the photovoltaic cell.Base on the above questions.In the dissertation,the uniformity,the characteristics of Ga As battery and the cooled system,in the reflective concentrator photovoltaic system,are studied,and the main study contents are as follows:1.The uniformity was studied by using a plane mirror array,a two-stage concentrators and a “light funnel”.(1)The uniformitys of dish condenser and trough condenser were studied by using a plane mirror array,and a new algorithm is put forward about plane mirror array,MATLAB is used to write the corresponding program accoding to the algorithm,and the calculation data is put into TRACEPRO to simulation,the results are as follows:Dish concentrator: the uniformity is greater than 99.00%,the experimental result(96.91%)is in agreement with the simulation results.the relationships of the effective area of the photoelectric conversion,the average irradiance,the maximum irradiance and the focal length are studied and show: in the case of theoretical concentration ratio is unchanged,the effective area of the photoelectric conversion is unchanged with the focal length,the relationship of the maximum irradiance with the focal length is proportional and logarithmic function,and the relationship of the average irradiance with focal length is also proportional and logarithmic function.Trough concentrator: the simulation result of energy flux-density uniformity is greater than 99.00%,when the theoretical concentration ratio is 29.40,the effective area rate of the photoelectric conversion is 71.44%,the relationships of the maximum irradiance,the average irradiance with the focal length are also proportional and logarithmic function.(2)A two-stage concentrators is used to achieve the uniformity of energy flux density,TRACEPRO is used to build a model of two-stage concentrators for simulation,the results show that the uniformity is greater than 99.00%;the effective area of the photoelectric conversion,the maximum irradiance and the average irradiance are not affected by the focal length,the relationship of the effective area ratio of the photoelectric conversion and the theoretical concentration ratio is proportional and logarithmic,the relationships of the maximum irradiance,the average irradiance and the theoretical concentration ratio are positive proportional and primary function.(3)the "light funnel" is added between the concentrator and the receiver to realize the uniformity of energy density on receive's surface.According to the ray tracing method and the rays of(R+r)/2 can vertically irradiate on the concendesor,which the light funnel is designed.The opening diameter of the concentrator is 3200 mm and the focal distance is 1700 mm.The Tracepro simulation results show that the uniformity of the energy density of the receiver surface is 92.23%,the experiment shows that the uniformity is 94.64%,and the simulation value is similar to the experimental value.According to the maximum output efficiency of Ga As battery,the layout range of the battery is determined.The simulation results show that the battery is arranged in the radius of 58 mm,which is similar to the experimental value(60mm).the relationship of the photoelectric conversion efficiency and the temperature of Ga As battery's surface is inverse proportional and primary function,and the total efficiency is 83%.2.The performance and layout mode of Ga As cell are studied.The experimental results show: the efficiency of Ga As cell can reach 39.73%,and the short-circuit current of Ga As battery component is proportional to the concentration.When the opening of the condenser is square,and the form of the battery assembly is also square.The utilization effective of the spot is higher than the opening of the condenser.3.DC plate radiator is used to dissipate heat of the Ga As cell surface.Design a double loop cooled system,and use flow control method to achieve Ga As battery surface temperature constant,ensure maximum output power.Experimental results shown: the flow control method is a little effected by the random change of the solar direct normal irradiance(DNI),and flow control method can achieve the purpose of constant temperature.When the concentration ratio is 1200 and the changes of the solar direct normal irradiance DNI from 750w/m2 to 850w/m2,and the flow is controlled between 8.50L/min and 10.00L/min.