Design And Performance Research Of Biplan Compound Concentrator

The utilization of solar energy as the main clean energy is more and more extensive,solar concentrating technology is an effective way to improve the high-quality conversion of solar energy.At present,there are many problems in the common concentrators,such as complex system,poor uniformity of light and low efficiency.In view of this,this paper proposes the concept of biplane compound concentrator,and designs the biplane compound concentrator according to the principle of mirror imaging and edge light.According to the geometric characteristic formula of biplane compound concentrator,The geometric characteristics of the concentrator are related to1? and2?,and there is an optimal value of sum,which makes the geometric spotlight ratio of the biplane composite concentrator maximum.On this basis,the parameters of three receiving half angles(15°,20°,36°)with the largest geometric spotlight ratio are selected to analyze the performance of biplane composite concentrator.The calculation results show that the optical efficiency of the concentrator increases with the increase of the receiving half angle,and the maximum solar incidence angle that the concentrator can receive also increases.The incidence angle corresponding to the inflection point of the optical efficiency of the concentrator is the same as that of the receiving half angle;When the incident angle is less than the half angle of the receiver,increasing the reflectivity can effectively increase the optical efficiency of the concentrator,but when the incident angle is greater than the half angle of the receiver,the effect is weakened;in the comparison of the optical efficiency with various kinds of concentrators,the performance of the biplane composite concentrator is better.In terms of the annual lighting quantity,the more the dip angle adjustment times of the biplane composite concentrator are,the more the annual lighting quantity is received.Under the two dip angle adjustment,the lighting quantity in summer and winter increases obviously,and under the three dip angle adjustment,the annual lighting quantity increases evenly.The influence of azimuth on the daylighting of biplane composite concentrator is greater than that of fixed inclination in two and three angles.Under the condition that the annual daylighting loss is 1%,the range of fixed inclination is within 12 ° to the south,while the two and three angles are within 9 °.The theoretical calculation results from five representative cities show that with the increase of the number of planes of the concentrator,the annual daylighting received by the concentrator is also increasing,while the increase of the number of planes also brings the increase of the height of the concentrator and the decrease of the optical efficiency,and the increase of the number of planes makes the processing more difficult.In addition,the double plane composite concentrator is suitable for the sun The area with abundant irradiation will bring more effect.Compared with the compound parabolic concentrator under the same receiving half angle and geometric spotlight ratio,the result shows that the light received by the concentrator is close to CPC at high reflectivity,especially at fixed inclination.Based on the average solar radiation received on the absorber,the change of the uniformity of the light on the absorber is reflected by the ratio of the solar radiation received at each position on the unit length of the absorber to the average value.The results show that with the increase of the number of flat mirrors,the light uniformity of the condenser is also decreasing,and the higher the reflectivity is,the smaller the receiving half angle is,the worse the light uniformity is.Therefore,under the condition of light uniformity,optical efficiency,annual lighting amount and processing complexity,the biplane composite concentrator has better performance and can effectively achieve the purpose of simple and efficient.On the basis of theoretical calculation and simulation analysis,in order to better explore the application characteristics of biplane compound concentrator,the output power,current and voltage of photovoltaic cells under different conditions are tested,the results show that the output power,current and instantaneous radiation of the non focused and focused photovoltaic cells are almost the same with the change of solar time angle,and the voltage change is relatively stable.Compared with the output power of the non concentrating photovoltaic cells,the output power of the concentrating photovoltaic cells increases by more than 23% at a fixed tilt angle;the output power of the concentrating photovoltaic cells at a two tilt angle under cloudy conditions increases by more than 47% at a maximum compared with the non concentrating photovoltaic cells,by more than one time compared with the fixed tilt angle;the maximum output power of PV cells under sunny conditions is still 47% higher than that of non PV cells,but the output power of PV cells under sunny conditions is stable,with an average output power increase of about 40%;the output power of PV cells under biaxial tracking is 57% higher than that of non PV cells under cloudy weather,and In sunny days,the output power is more than 49%,but from the measured average output power,the output power increases nearly 45% in sunny days,while only 35% in cloudy days;compared with the output power of the concentrating photovoltaic module under the condition of two dip angles,the output power increases slowly under the condition of two axis tracking,and only increases 5.8% under the condition of two dip angles.The results show that the effect of biplane composite concentrator is good in photovoltaic application,especially in the condition of two inclination angle,it can achieve the goal of simple and efficient application of concentrated photovoltaic.