Construction and performance analysis of a three dimensional compound parabolic concentrator for a spherical absorber

Abstract

Three-dimensional compound parabolic concentrator (3-D CPC) was found to be more efficient than 2-D CPC because of higher concentration ratio. A 3-D CPC was fabricated with a half acceptance angle of 4° for a spherical absorber (radius 100 mm). UV stabilized aluminized polyester foil having high reflectivity was pasted on the reflector for a total height of 441 mm and an aperture width of 540 mm. Theoretical value (0.645) of optical efficiency compared well with experimental value (0.626). Experimental values of optical and thermal efficiencies were in good agreement with theoretical values. Optical efficiency from 3-D CPC was found significantly higher than that of 2-D CPC of similar dimensions. Time constant of 3-D CPC (431 sec) was fairly high as compared with 2-D CPC (110 sec). An attempt was made to generate low-pressure steam in in-situ steam generation mode, which was one of the possible applications of 3-D CPC module.