Scheffler paraboloidal concentrator image Analysis

Erick Alfred Dib¹; Flávio Augusto Sanzovo Fiorelli¹

¹ Escola Politécnica da USP

doi:10.20906/CPS/COB-2015-0893

Resumo

The purpose of this work is to help the design of receivers for Scheffler concentrators in order to avoid losses of energy at the entrance of thermal radiation absorbers. The Scheffler concentrator is a paraboloidal solar concentrator that works in a two axes track system and, thus, maintains the focal image fixed in its stopped absorber with the variation of the solar declination and azimuth. The image formed by Scheffler concentrator is presented. The reflector geometry is defined by a lateral section of a paraboloid and its reflector has elliptical profile. Rim angles at equinox, are approximately 49.6 and 109.6 degrees from the paraboloid axis. However the tracking system for adjusting to the variation in solar declination causes a change in these rim angles. An analysis of the effect of these variations over the image of the focus, the aperture area to the Sun, and the concentration ratio is performed. The effect of the variation of rim angles was found to cause variations in the size of the focal image of Scheffler reflectors in two axes, and these variations differ among them. It were also verified that the aperture area and the concentration ratio can vary respectively two times and once during the year.

Palavras-chave: Solar Energy; Scheffler Paraboloidal Concentrator; Focus Image