Fabrication and Characterization of a Prototype Parabolic Trough Solar Concentrators for Steam Production

Abstract

In this paper, the potential for a solar-thermal system to produce steam has been studied. Three parabolic trough solar concentrators (PTSCs) for roof tops of similar dimension were designed, fabricated, characterized and their efficiencies compared when closed and when open. The PTSCs´ were made of appropriate materials and were manually tracked. They were designed with principal focus at 0.4 m so that the receiver heat loss was minimized by covering the collectors with glass which was 0.0025 m in thickness. The dimensions of the collector were aperture width: 1.2m, Collector length 5.8 m, aperture area: 6.95 m

2 . The absorber pipe was a copper tube which carried water as the heat transfer fluid. The concentration ratio of the solar concentrators was 128. The concentrator testing was carried out for each of the concentrators. The maximum temperature of steam obtained was 248.3 oC while average temperature of steam was produced was 150o C. When closed their efficiencies were: Aluminium sheet reflector PTSC; 55.52 %, Car solar reflector PTSC; 54.65 % and Aluminium foil reflector PTSC; 51.29 %. The open solar concentrator efficiencies were 32.38 %, 34.45 % and 27.74 % respectively. The results obtained show that production of power using the sun flux is a viable undertaking. The concentrators can be used to provide power to remote areas which are away from the gridlines. This will make power readily available to the marginalized rural poor people. Improvement of the tracking system and optical efficiency can improve the efficiencies of the fabricated concentrator systems.