Study On The Performance Of Flat Absorber Surface-to-body Separation Non-imaging Concentrato

To address the problem that the concentrating surface of the standard compound parabolic concentrator(S-CPC)is prone to thermal deformation and that the absorber is separated from the concentrating surface but the sunlight escapes from the gap.In this paper,a composite parabolic concentrator with the separation of concentrator surface and plane absorber but no light escape(SCSA-CPC)is designed.The optical property of concentrators with different geometrical structure parameters are analyzed based on Monte Carlo ray tracing.Based on the theory of direct dispersion radiation separation,the mathematical model of an annual collection of concentrators with the axial northsouth horizontal arrangement and axial east-west inclined arrangement is constructed.Based on the data of typical meteorological years in Kunming area,the radiation collection performance of the concentrator was simulated and analyzed with C++.A test platform of concentrated photovoltaic system was built to compare and analyze the photoelectric conversion performance of the system.The main work and conclusions of this paper are as follows:(1)Based on the principle of non-imaging optics,the parametric equation of SCSACPC plate absorber is derived by differential geometry.The optical concentration performance of SCSA-CPC was verified by visual laser experiments,which proves the accuracy of the mathematical model of SCSA-CPC constructed theoretically.The effect of the gap height on the structure of SCSA-CPC was analyzed,where the concentration ratio and the aspect ratio of SCSA-CPC were found to decrease with increasing gap height.The material consumption of SCSA-CPC increases with the increase of gap height in face type processing and manufacturing,but the consumable ratio of SCSACPC with a gap height of 3 mm only increases by 0.285% compared with S-CPC,which has less impact on the manufacturing cost of the spotlighting system.(2)The effects of reflectance and gap height on the optical efficiency of S-CPC and SCSA-CPC were analyzed by optical simulation software.Due to the unique concentrating structure of SCSA-CPC,the incident light is reflected less on its concentrating surface,and the instantaneous optical efficiency and average optical efficiency under different reflectance are both improved compared with S-CPC.In addition,the optical efficiency of Separation of Concentrator Surface and Absorber CPC with gap height of 3mm is more significantly improved under the same reflectivity.Considering the influence on optical efficiency,manufacturing and cost analysis of the reflector,the reflector with reflectance of 0.87 is more suitable as the concentrator surface.Compared with S-CPC,SCSA-CPC can reduce the energy peak on the absorber surface while maintaining high optical efficiency.Considering the optical efficiency,manufacturing cost and energy distribution of the concentrator,the SCSA-CPC 3 has a better optical structure.(3)According to the numerical results of the procedure,the effective working time of the concentrators with an obliquity of the local latitude is significantly improved over that of the concentrators with a horizontal arrangement,by 176.83%,48.21%,163.34%and 113.36%,respectively,in each season.Compared with the radiation collection performance of S-CPC,the annual radiation collection amount of SCSA-CPC3 with two layout modes is significantly improved.Based on the surface structure parameters of SCSA-CPC3,the design method of the concentrator array arrangement with the axial tilt to the east and west is studied.Through the geometric model of the array,the optimal distance between the front and back is 326.39 mm.(4)The outdoor experimental results show that the SCSA-CPV system with the axial east-west tilt arrangement has the highest electric power of 11.4 W in clear weather and light wind,which is 23.9%,48.1% and 93.2% higher than the SCSA-CPV with the axial north-south horizontal arrangement,the PV system with the axial east-west tilt arrangement and the axial north-south horizontal arrangement,respectively.However,the conversion efficiency of SCSA-CPV system is lower than that of photovoltaic panels due to the increase of temperature inside the photovoltaic cell caused by the concentrated light of the concentrator,which reduces 19.68% and 34.34% respectively.Based on typical local meteorological year data,the SCSA-CPV system with an axial east-west tilt arrangement per unit area was calculated to have the highest annual generation at406.6 KWh.