Optimization Of Optical Performance And Tracking Mode Of External CPC Heat Pipe Vacuum Tube Collector

Compound Parabolic Concentrator(CPC)is a kind of low focusing non imaging concentrator,which has a broad application prospect in the field of solar energy medium and low temperature heat utilization.This paper takes the heat pipe vacuum tube compound parabolic condenser as the research object,through the experiment,explores the heat transfer performance of the heat pipe type vacuum tube receiver under different working conditions,determines the structure optimization measurement standard of CPC condenser;then establishes the light tracing model for CPC concentrator,analyzes the optical performance of CPC under different structural parameters and determines the composite thermal tube vacuum tube composite heat pipe performance through programming The tracking method of parabolic condenser in actual operation.The main work of this paper is summarized as follows:Firstly,the heat transfer performance of the receiver of the vacuum tube is studied experimentally under the condition of non-uniform heating.The size of the receiver has been determined in the early stage of the project group.Therefore,according to the experimental scheme of the receiver,an experimental system for heat transfer performance is built.The results show that the heat efficiency of the heat pipe is the highest under uniform heating condition,the lower half surface is heated next,the upper half surface is the lowest;under the same heating mode,the heat efficiency of the heat pipe decreases with the increase of inclination angle.Secondly,the structure and structure equation of CPC concentrator with circular tube as receiver are introduced.The factors affecting the optical performance of the condenser are analyzed,including the maximum receiving width,radius of the tube,the width of the gap between the receiver and the tip.In order to consider the influence of the shape error of the sun on the reflection path of the light in the concentrator,the concept of the shape of the sun is introduced and the formula derivation process is given.Thirdly,the formula derivation of the relationship between the incident and reflection of CPC concentrator with circular tube as receiver is given,and the ray tracing model of CPC concentrator is established.The program of ray tracing is developed by MATLAB software,and optical simulation of optical performance of the optical concentrator under different parameters is carried out.In order to verify the accuracy of the MATLAB ray tracing program,the calculation results are compared with those ofsoltrace optical software.The distribution trend of heat flux density of circular tube receiver calculated by the two software is basically the same,and the peak value of heat flux density is slightly different,but the error is small.Fourthly,the influence of the maximum acceptance width,gap width and intercept ratio on the optical performance of CPC concentrator is simulated by using the program of ray tracing.The main measure of the optimization of the structure of the condenser is the product of optical efficiency and concentration ratio,and the structure of the condenser is optimized.The optimization results show that when the receiver outer diameter is 42 mm,the maximum receiving width of the concentrator is 35 °,the width of the gap is 2.1mm and the interception ratio is 0.5.Finally,the equation of reflection light when there is a bias angle between the incident light and the opening plane of CPC concentrator is derived.The corresponding ray tracing program is compiled,and the influence of the angle of incident light on the optical performance of the concentrator is calculated.The results show that the change of the heat flux density of the receiver is small when the incident angle is small;with the increasing of the incident angle of light,the asymmetry of the distribution of the circumferential heat flux density increases gradually,and the peak difference of the heat flux density on both sides of the receiver increases gradually;the optical efficiency of CPC concentrator will drop suddenly when the incidence angle is more than 35°.According to the optical simulation results of the angle of incident light,the optimal tracking mode of the summer solstice CPC concentrator is determined to be adjusted once at noon.