Abstract:
In this work, the potential for a solar-thermal concentrator to produce steam has
been studied. Three parabolic trough solar concentrators (PTSCs) of dimensions: -
aperture width of 1.2 m, Collector length of 5.8 m and aperture area of 6.95 m2
were investigated. The absorber pipe was a copper tube which carried water as
the heat transfer fluid, 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 is minimized by covering the
collectors with glass which was 0.0025 m in thickness. 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 248.3oC
while average temperature of steam was produced was 150oC. 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
efficiency of car solar reflector when open was higher than for aluminium sheet
since it was less prone to thermal degradation when exposed to weather
elements. 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 far away from the power transmission gridlines. This will make
power readily available to the marginalized rural people. Improvement of the tracking system and optical efficiency can improve the efficiencies of the fabricated concentrator systems.
