Parametric analysis of the curved slats fixed mirror solar concentrator for medium temperature applications Ramon Pujol-Nadal ⇑ , Víctor Martínez-Moll Departament de Física, Universitat de les Illes Balears, Spain article info Article history: Received 8 August 2013 Accepted 22 November 2013 Available online 18 December 2013 Keywords: Solar concentrator CSFMSC Ray-tracing Heating process Moving receiver abstract The Curved Slats Fixed Mirror Solar Concentrator (CSFMSC) is a solar concentrator with a static reflector and a moving receiver. An optical analysis using ray-tracing tools was presented in a previous study in function of three design parameters: the number of mirrors N, the ratio of focal length and reflector width F/W, and the aperture concentration C a . However, less is known about the thermal behavior of this geometry. In this communication, the integrated thermal output of the CSFMSC has been deter- mined in order to find the optimal values for the design parameters at a working temperature of 200 °C. The results were obtained for three different climates and two axial orientations (North–South, and East–West). The results show that CSFMSC can produce heat at 200 °C with an annual thermal effi- ciency of 41, 47, and 51%, dependent of the location considered (Munich, Palma de Mallorca, and Cairo). The best FMSC geometries in function of the design parameters are exhibited for medium temperature applications. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction The Curved Slats Fixed Mirror Solar Concentrator (CSFMSC) is a solar concentrator with static reflector and moving receiver that can produce thermal energy in medium temperature range [1]. The CSFMSC is made up of a set of curved mirrors arranged with their respective central lines positioned along a circular path (called a generating circle) and oriented such that the rays re- flected by the curved mirrors intersect upon a small area on the same base circle. The CSFMSC geometry is an evolution of the Fixed Mirror Solar Concentrator (FMSC) that emerged in the seventies [2–4] where flat mirrors are replaced by curved mirrors (for more details on the optical behavior of the FMSC, see the study pre- sented by the authors in 2012 [5]). Therefore, the CSFMSC has the same sun tracking properties as FMSC, so receiver sun tracking can be done simply by positioning the receiver at a certain angle over the circle path without moving the reflector. Fig. 1 gives an example of each geometry: Fig. 1(a) for the diagram of the FMSC with focal length and reflector width ratio F/W = 1.5, and Fig. 1(b) for the diagram of the CSFMSC with focal length and reflector width ratio F/W = 1. These geometries have several advantages when compared to other designs, namely it is one of the best geometries for collector integration onto building roofs. The main exponent of this technol- ogy [6] is the Concentrating Collector with Stationary Reflector (CCStaR) prototype, developed by Tecnologia Solar Concentradora S.L. (www.tsc-concentra.com) in close collaboration with the Uni- versity of the Balearic Islands [7–9]. The CCStaR collector is a CSFMSC with one parabolic mirror (N = 1). An optical study of CSFMSC geometry was presented in [10,11] for the number of curved mirrors: 1, 3, 5, and 7, that form the reflector. The optical efficiencies were analyzed in function of three design parameters: the number of mirrors N, the ratio of focal length and reflector width F/W, and the aperture concentration C a (in order to represent different receiver widths). The results show that the CSFMSC has better optical behavior than the FMSC, which results in a solar concentrator with fewer reflector segments for the same concentration and optical efficiency [11]. A standard evacuated tube with a flat fin was used as a receiver; see Fig. 2 for the receiver configuration. The receiver tube design considered was based on a commercial evacuated tube collector tested at TÜV [12]. In the optical analysis [11] the practical interest of the geometry was shown, and a set of candidate parameters with high optical efficiencies was determined. Nevertheless, in practical applica- tions, the best optical efficiency does not necessarily produce the highest thermal efficiencies, since other factors like the concentra- tion factor also have a large influence on the collector output, espe- cially at high working temperatures. Therefore, to find the more practical parameters, a thermal analysis has been conducted using 0196-8904/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.enconman.2013.11.032 ⇑ Corresponding author. Address: Ctra de Valldemossa km 7,5, 07122 Palma de Mallorca, Illes Balears, Spain. Tel.: +34 971259542; fax: +34 971173426. E-mail address: ramon.pujol@uib.es (R. Pujol-Nadal). Energy Conversion and Management 78 (2014) 676–683 Contents lists available at ScienceDirect Energy Conversion and Management journal homepage: www.elsevier.com/locate/enconman