Effect of different errors on deformation and thermal stress of absorber tube in solar parabolic trough collector

Abstract

Solar parabolic trough collector (PTC) always operates under non-designed conditions in actual situation. Some errors such as slope error, tracking error and installation error strongly affect the absorber tube's deformation and thermal stress performance. Based on the optical-thermal-stress coupling principle, a numerical analysis on the influence of different errors on deformation and thermal stress of absorber tube was carried out by coupling MCRT-FVM-FEM. The results show that the maximum deflection always occurs in the middle of absorber tube, and lower slope error and higher positive y-direction (vertical direction) installation error can greatly increase the deflection of absorber tube. Tracking error and x-direction (horizontal direction) installation error have little impact on the maximum deflection, but can remarkably increase the maximum equivalent stress as slope error is 0 mrad. Due to the occurrence of tracking error and x-direction installation error, the absorber tube's bending direction changes and it's equivalent stress distribution becomes asymmetric. The maximum equivalent stress descends with enlarged tracking error when slope error is greater than 3 mrad. While slope error is more than 6 mrad, the maximum equivalent stress is hardly affected by x-direction installation error. Under the condition of slope error, increasing y-direction installation error from 0 mm to 15 mm elevates the maximum equivalent stress.