Thermal performance of parabolic trough collector with absorber tube misalignment and slope error

摘要

In this work, thermal performance of a parabolic trough collector with absorber tube misalignment and reflector slope error has been evaluated. Finite volume method has been used for the thermal analysis. Variable local heat flux, on the absorber tube, obtained from ray tracing simulations has been incorporated in finite volume method. Analytical study has been conducted for a parabolic trough having aperture width 6.868 m and rim angle of 81.3. Two different diameters of the absorber tube, 70 mm and 80 mm are taken. Simulations have been done for slope error and volumetric flow rate in the range of 0 to 3 mrad and 5.65 to 33.9 m(3) h(-1) respectively. The absorber tube misalignment up to 15 mm each in two directions i.e. along optical axis and lateral direction has been considered. The intercept factor, circumferential temperature gradients in the absorber tube and overall collector efficiency of the PTC have been evaluated. It is found from the results that collector performance is affected by absorber tube misalignment, mirror slope error and absorber tube diameter. It has been studied that intercept factor decreases by up to 11% under influence of both absorber tube misalignment and slope error for 70 mm diameter absorber tube. Results also indicate that overall collector efficiency decreases by up to 11% for 70 mm diameter tube with absorber tube dislocation in presence of slope error.