Design and realization of a novel sun tracking system with absorber displacement for parabolic trough collectors

Algeria has an important solar irradiation potential especially in the southern area. Technically, the hard climate of the region makes exploitation of this energy very difficult; thus, looking for adequate and innovative solutions is a necessity. In this paper, we propose and describe a new single axis sun tracking system that has a moveable absorber which can be adjusted in order to minimize the optical losses caused by the cosine effect in parabolic trough concentrators (PTC). This new system was tested in the region of Ghardaia (32.48 degrees, -3.66 degrees, 502 m), which is 640 km to the south of Algiers. First, a theoretical study and simulations were carried out using TRNSYS software. After simulations and design calculations, the different parts of the prototype, the mechanical structure and the electronic cards, were implemented. For the data collection system and the control system, many sensors were installed for those purposes. A complete evaluation of the PTC was made according to the ASHRAE 93-1986 (RA 91). The obtained experimental results are in a good agreement with those obtained by simulation using TRNSYS software [S. A. Klein et al., see http://sel.me.wisc.edu/trnsys for TRNSYS version 16, Solar Energy Laboratory, University of Wisconsin-Madison, 2004]. The efficiency of the proposed sun tracking system lies between the efficiencies of a single axis and a two axes sun tracking systems. Efficiencies close to 50% were obtained. (C) 2013 AIP Publishing LLC.