Abstract
A laboratory-scale passive solar grain dryer was developed and its performance evaluated in Makurdi
metropolis, Benue State, Nigeria. The dryer consist of a solar collector panel, a thermal storage unit and
a drying chamber. The top of the collector is made of one layer of 4 mm thickness of colourless glass
sheet as glazing. The absorber material used was corrugated 0.5 mm thick zinc roofing sheet painted
black. The thermal storage unit and the drying chamber were built of wood because of its good
insulation properties. The dryer was evaluated using 10 kg of freshly harvested maize at 32.8%wb. The
performance evaluation results obtained showed that the mean drying rate of the dryer was 0.7 kg/day
per every 10 kg of corn whereas sun-drying rate was 0.3125 kg/day comparatively. The solar dryer has
considerable advantages over the traditional sun drying method in terms of faster drying rate, less fear
of spoilage by micro-organisms when crop is harvested at high moisture content and handling
convenience. Savings in time was achieved by using the solar grain dryer as against the traditional sun
drying. It took 4-days to dry the corn to moisture content of 13.1%wb using the passive solar dryer
while it took 8-days to dry to 13.4%wb under sun drying. Commercial sizes of the solar dryer can be
amplified and produced for community level cooperative use and for prospective investors to fast track
agricultural development in the rural areas.
Key words: Passive, solar, grain dryer, development, performance, laboratory-scale
