Modeling Simulation and Experimental Verification of Focal Length Optimization in Linear Fresnel Collector

ObjectivesIn order to improve the concentrated light interception rate of linear Fresnel collector (LFC), increase the error control threshold of the tracking system, and enhance the system’s photothermal conversion efficiency, it is necessary to study the variation patterns of light spot width on the primary reflector. Therefore, the reflected light spot width of the LFC micro-arc mirror is modeled, simulated and experimentally studied.MethodsBased on the structural characteristics of the LFC, a light concentrating model of the micro-arc primary reflector is developed. Through MATLAB simulation analysis, the variation patterns of light spot width under the boundary conditions of the micro-arc primary reflector are obtained. A light spot test platform is developed, which simulates solar incidence angles of different seasons and times of the day by changing the angle of the test platform and adjusting the position of the receiver board, to verify the accuracy and effectiveness of the simulation results.ResultsDue to the presence of the solar angle, the reflected light spot width increases by 75.8% compared to the parallel light condition. The experimental results of rotating test platform show that the variation patterns of the measured light spot width are consistent with the simulation results. Under the influence of the solar angle, the maximum tracking error control margin of the LFC is 0.173° in winter and 0.207° in summer.ConclusionsThe tracking control accuracy of the LFC system in winter should be 16.4% higher than that in summer. Therefore, the focal length of the LFC micro-arc reflector should be designed based on the tracking control margin of the light spot width in winter.