Finite Element Modeling of Parabolic Trough Mirror Shape in Different Mirror Angles

Deviations from the ideal shape of reflector panels for parabolic trough solar power plants can have relevant impact on field efficiency and thus on the performance of the whole power plant. Analyzing the gravity-induced deformation of mirror shape for different mirror angles is relevant for performance calculation of solar parabolic trough collectors and identifying optimization potential of the mirror panels. Two mirror model cases (stiff and elastic supports) are evaluated in four angles: in horizontal laboratory angle (mirrors facing upward with mounting points horizontally aligned), and in 0 deg, 45 deg, and 90 deg collector angle. The resulting slope maps are calculated in a separate postprocessing. In order to evaluate the effect of gravity load on mirror shape, the deformed mirror in each evaluated angle is compared to the nondeformed mirror shape, and to the shapes in 0 deg (zenith) collector angle, respectively. The resulting slope deviation maps show the mirror deformation in different mirror angles. Stiffness of the mounting to the support structure has a relevant impact. Mirror deformation on elastic brackets (SDx up to 1.6 mrad) is much more pronounced than on an ideal stiff support structure (SDx up to 1.0 mrad).