Research On Performance And Structure Optimization Of Cavity Receivers In Solar Power Tower System

The technology of solar power tower is currently a solar thermal power technology with a broad application prospect in large-scale power generation.The solar power tower system mainly includes a concentrating subsystem,a heat collecting subsystem,a heat storage subsystem,an auxiliary energy subsystem,and a power generation subsystem.In the solar power tower system,the receiver is an important component in the heat collection subsystem,and plays an important role in the process of solar-to-thermal conversion,therefore,the performance of the receiver has a significant impact on the performance of the entire system.So this thesis is devoted to research on the performance and structural optimization of cavity receivers based on solar power tower systems.The main research are summarized as following.(1)According to the irradiation conditions of Delingha at noon on the summer solstice day,design the heliostat layout of the solar power tower system by the tracking model of heliostat and choose reasonable light source settings and heat transfer media for the system.(2)Design cavity receivers in four different shapes(spherical,cylindrical,conical,and flattopped cone),use SolidWorks to create three-dimensional models,and study receivers with different structural parameters through TracePro.Their optical performance are investigated in the given solar power tower system.The results indicate that in the given solar power tower system,the receivers with the same aperture size but different area ratios(aperture area/total interior area of receiver)have optical efficiencies above 90%,in which the conical and spherical cavity receivers have a better absorption capability of incident irradiation and the distribution of the energy flux density on the interior surface of spherical and conical receivers is more uniform than the receivers of the other two shapes..(3)Based on the simulation results of the optical performance,this thesis chooses the spherical cavity receiver with an area ratio of 0.2 for further analysis.The size of the spherical cavity receiver is designed,and its optical performance and thermal efficiency are studied.The results show that the uniformity of the energy flux density distribution on the interior surface of the spherical cavity receiver with the same area ratio is more uniform with increase of the aperture size,and varies greatly with the increase of it.The reflecting loss increases with the increase of the aperture size,but the optical efficiency slightly decreases because the reflecting loss accounts for a small proportion of the total luminous flux.The overall thermal efficiency of the spherical cavity receiver decreases as the aperture size increases,and the heat loss increases.The spherical cavity receiver with an aperture radius of 0.6 meters has the least heat loss and the highest thermal efficiency which reaches 79%.Among the radiation loss,convection loss and reflection loss,the convection loss is most affected by the size of the aperture,followed by radiation loss,and since the area ratio is fixed,the reflection loss is independent of the aperture size.