Abstract

Akanbi Alani, Ibrahim Kawu and Iya Adeleke

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.