Optimized Design of Heliostat Field Efficiency Based on Finite Element Analysis Method

In this paper, the optical efficiency model of tower solar fixed-sun mirror field is established by using the finite element differential method, and various parameters of the fixed-sun mirror field are investigated. First of all, according to the spatial geometric relationship, we establish the mapping model of solar altitude angle and solar azimuth angle with the incident light direction vector under the mirror field coordinate system (referred to as the field system), which can be calculated at each moment of the solar incident light vector, and solved by using the matlab software, so as to get the solar incident light vector model. Then, the shadow shading efficiency calculation model was established by using finite element analysis. We construct the mirror coordinate system (referred to as the mirror system) in the fixed-sun mirror, establish the coordinate mapping model of the mirror system coordinates to the field system coordinates, do the finite element discretization of the mirror, so that each finite element has a corresponding coordinate in the mirror system. We use the coordinate mapping model of the mirror system coordinates to the field system coordinates to get the field coordinates of each finite element, using the finite element's field coordinates, the incident and reflected light line vectors of each mirror, it can be obtained that the equations of the incident reflected rays of each finite element in the field system. We calculate the intersection point of the incident and reflected light rays in the field system with the plane where the surrounding 4 mirrors are located, convert the field system coordinates of this intersection point into the corresponding mirror system coordinates, determine whether this coordinate is in this mirror, and determine the loss of shadow occlusion of this mirror by cyclically traversing whether the light rays of each finite element are in the shadow occlusion region. Based on the HFCAL truncation efficiency model in Ref. and through geometric reasoning, it is concluded that the truncation efficiency in an isotropic heliostat field is a function of the distance between the heliostat and the absorber tower, the truncation efficiency of the heliostat at distances from the absorber tower is calculated to be 100m, 150m, 200m, 250m, 300m, and 350m, and the relationship between truncation efficiency and the circumferential radius of the circle where the heliostat is located is established by fitting the function. The relationship between the truncation efficiency and the radius of the circle where the heliostat is located is established by fitting the function, and the model of the truncation efficiency of the heliostat field is established.