DETERMINING THE OPTIMUM FOCAL HEIGHT OF A PARABOLIC TROUGH CONCENTRATOR USING AN OPTICAL METHOD
M. P. S. Viraj1, P. D. C. Kumara2*, and H. H. E. Jayaweera3
2 Institute of Technology University of Moratuwa, Sri Lanka, 1,2,3 Centre for Instrument Development, Department of Physics, University of Colombo, Sri Lanka, 1Department of Physics, University of Bologna, Italy
Session: Technical Session B
Abstract
This study investigates the optimal focal height of a Parabolic Trough Concentrator (PTC) solar thermal plant, a key parameter affecting its overall performance. The dimensions of the PTC module are 4.5 m × 4.8 m with an aperture area of 20.3 m2. Unlike diffuse solar systems, the effectiveness of a concentrated solar thermal plant is highly dependent on factors such as the parabola's concentration ratio and geometrical parameters. This paper presents an optical/photographic approach to determine the optimum focal height of the PTC while harnessing solar thermal energy. The findings highlight the importance of maintaining accurate geometric parameters over time due to structural deformations, environmental conditions, and aging effects. The theoretical focal height of the PTC module was calculated as 1700 mm at the design stage. A laser scanning mechanism revealed that the actual focal height of the PTC module was 1830 mm after manufacturing, when the parabolic reflective mirror was rotated to point towards the ground, and the laser pointers were fired vertically upwards to ensure they were perpendicular to the focal plane. A digital single-lens reflex (DSLR) camera was used to capture the focused solar concentrated beam on the target board. The findings verified that the optimum focal height of the PTC module is 1675 mm while harnessing solar thermal energy.
Keywords: optical methods, optimum focal height, parabolic trough concentrator, solar thermal energy, thermal distribution measurement
DOI: 10.64752/WWAA5191