Research On Tower Light Concentrating Heat Flux Testing And Spot Quality Analysis System

The heliostat is a very important component in the tower solor power system.It is an energy gathering device that gathers solar radiation onto the heat absorber at the top of the tower.The shape and concentration performance of the heliostat will determine the position of the reflected sunlight and the shape of the light spot,so it is very important to evaluate the surface shape and light concentrating performance of the heliostat.Existing methods for evaluating the shape and light concentrating performance of heliostats have various problems and have not been applied on a large scale.Therefore,there is an urgent need for a cost-effective method to evaluate the shape and light-concentration of heliostats performance.The energy flow density distribution of the heliostat's reflected light spot is a direct reflection of the heliostat's surface shape and light gathering performance,so this paper proposes a method for evaluate the heliostat's surface shape and light concentrating performance by comparing the theoretical and measured light spot energy flow density distribution.First of all,based on the existing calculation method of spot energy flux density,we introduces the cause of the formation of solar divergence and the shape model of the sun,and we established the heliostat's spot imaging and energy flow density distribution model on the receiving target surface when the solar light was non-parallel light;Then,based on the existing measurement methods,a comprehensive measurement system of CCD camera combined with heat flow sensor is proposed and experimented.The CCD camera is used to obtain the brightness distribution information of the spot.The heat flux sensor designed by the working principle of the battery obtains the reference value of the spot energy flow density,and processes the two results to obtain the measured energy flow density distribution of the spot;finally,compare and analyze the measured energy flow density distribution of the spot with the theoretically calculated energy flow density distribution model,the results show that the accuracy of the measurement system is within the required range,that is to say,the method can be used to evaluate the surface shape and light-collecting performance of the heliostat.Evaluating the surface shape and light-concentrating performance of the heliostat can provide a certain basis for correcting the heliostat and lay the foundation for the subsequent optimization of the aiming point of the heliostat.It is believed that this research will play a certain role in promoting the development of tower CSP stations in China.