Study On Photothermal Performance And Structural Design Of Cylindrical CPC Concentrator

Two important factors restricting the application of compound parabolic concentrator(CPC)in low and medium temperature fields are the cost and efficiency of CPC.In order to realize the low cost and high efficiency utilization of the CPC concentrating system in the range of medium and low temperature,this paper carries out the optimization design of the CPC structure.The function relationship between the CPC structure parameters and the concentrating ratio,arc length,the number of CPC receivers in the same area and the total arc length is given.The influence of the CPC structure parameters on the optical efficiency is explored.At the same time,the CPC concentrating heat collection system is built,and the heat collection efficiency of CPC under different working conditions is compared and analyzed.It provides theoretical support,simulation and practical basis for the effective use of CPC.The main research work is as follows:(1)According to the parametric equation of CPC,the functional relationship between CPC structural parameters and CPC related parameters is deduced theoretically.The effects of receiving half-angle,interception ratio and receiver radius on the total arc length of CPC and the number of receivers in the same area are investigated.The results show that the curve arc length of CPC is significantly reduced by intercepting the CPC of each structure,and the interception ratio in the range of 0.2 to 0.4 should be emphasized.Combined with the calculation formula of the total cost of each CPC structure in the same area given in this paper,it will provide the relevant theoretical basis for the effective utilization of CPC.(2)A three-dimensional physical model of CPC is established.Based on Tracepro software,according to the changing characteristics of solar altitude angle and azimuth angle at each moment,the two-dimensional tracking of CPC is realized by replacing the sunlight with the light emitted by the simulated light source.Then the optical efficiency of CPC with different structures is simulated and calculated,which is beneficial to the realization of high-efficiency light-gathering and heat-gathering of CPC.(3)A one-dimensional steady-state heat transfer model of vacuum tube is established.The maximum error between experimental temperature difference and theoretical temperature difference is 8.43% and the relative error is 3.89%.The reliability of optical efficiency simulation is verified.It shows that the two-dimensional ray tracing method for CPC based on Tracepro software is accurate.CPC collector system was built to investigate the effects of inlet temperature,ambient temperature and effective irradiation intensity on the efficiency of CPC collector.