| In order to solve the problem of conventional fossil energy shortage and further improve the utilization rate of solar energy,compound parabolic concentrator（CPC）is more and more popular.However,the conventional compound parabolic concentrator（S-CPC）has a limited effect on collecting solar radiation energy at the end of the concentrator surface,and the large surface structure is not conducive to its wide application in practical engineering.Based on the principle of edge ray,this dissertation proposes and designs a critical truncated compound parabolic concentrator（CT-CPC）using the critical point calculation method,and obtains the specific position of the critical point through the V/C++program.On this basis,the optical model of CT-CPC is constructed,and its optical performance is explored.At the same time,the theoretical heat transfer model of CT-CPC is also constructed.The numerical solution of the theoretical model is obtained based on the V/C++program,and the outdoor photo-thermal conversion experimental platform is built to verify and analyze the performance of the CT-CPC heat collection system.The main research contents and conclusions are as follows:（1）The parameter equation of vacuum tube absorber S-CPC is established by using the geometric model method,and the specific position of the critical point is calculated by the V/C++program.Subsequently,the geometric model of CT-CPC was designed and constructed,and the physical model of CT-CPC was printed through additive manufacturing technology.The energy accumulation characteristics of CT-CPC were analyzed and verified by using the adjustable laser experimental platform and the outdoor experimental platform of photothermal conversion.（2）In terms of optical performance,first of all,the average optical efficiency of CT-CPC is 7.20%higher than that of S-CPC,and the instantaneous optical efficiency is 3.40%higher than the maximum when the incident angle is 0°.This shows that CT-CPC can effectively reduce the reflection times of solar rays on the upper concentrated surface,especially the solar rays when it is vertically incident.Secondly,the energy flux distribution on the surface of the absorber is more uniform,and the peak value of the energy flux distribution is only 48.90%of that of S-CPC when the incident angle is30°.In addition,the allowable half angle of CT-CPC is increased by 50.00%compared with S-CPC,and the average effective working time is increased by 56.42%.Finally,based on typical meteorological year data,it can be seen that the annual radiation collection of CT-CPC has increased by 11.20%,which further indicates that CT-CPC has more significant advantages in radiation collection.（3）In terms of economy,CT-CPC saves 28.60%of consumables compared with S-CPC,and the annual radiation collection per unit concentrating area of CT-CPC is also increased by 55.80%compared with S-CPC.The comprehensive research results show that CT-CPC has better performance than S-CPC in terms of optical performance and economy,and it also has better engineering application potential.（4）In terms of heat collection performance,based on the law of conservation of energy,the photo-thermal conversion performance of the CT-CPC system is analyzed and evaluated.The results show that the average outlet temperature of the solar vacuum tube is 331.65 K,and the maximum outlet temperature is 336.35 K.The average relative error is 8.51%,and the ratio k RMSE is 6.16%.The maximal photo-thermal conversion efficiency of the CT-CPC is 63.78%,the average photo-thermal conversion efficiency is 60.81%,the ratio k RMSE is 6.03%,and the maximum uncertainty is 9.62%.The consistency of outlet temperature and photo-thermal conversion efficiency verifies the reliability of the theoretical model. |
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