Analysis of the image produced by Scheffler paraboloidal concentrator

Our purpose is to help projects 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. At equinox, these rim angles 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 variations 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 these axes. Were also found that the aperture area can vary twice, and, the concentration ratio, once during the year.