Design of a Forced-Air Drying System for Maize Post-Harvest Management in Kwara State

This study involves the design and performance evaluation of a forced-air drying system for maize post-harvest management in Kwara State, North Central Nigeria. Maize harvested during the rainy season in Kwara State frequently has moisture content of 22 to 28 percent, well above the safe storage moisture content of 13 percent. Traditional sun drying on open ground or roof surfaces takes 7 to 14 days, exposing grain to contamination, animal damage, and aflatoxin risk under humid drying conditions. This study designs a forced-air batch dryer with a perforated plenum floor, centrifugal fan, diesel burner, and 1-tonne batch capacity. The dryer is modelled using thin-layer drying equations to predict drying rates and energy consumption. Prototype testing is conducted at the University of Ilorin agricultural engineering research field, using freshly harvested TZPB maize at 26 percent initial moisture content. Drying time, specific energy consumption, grain damage, and aflatoxin levels are measured at 60, 80, and 100 degrees Celsius inlet air temperatures. Findings reveal that 80 degree Celsius inlet temperature achieves target moisture content in 6 hours with acceptable grain quality and specific energy consumption of 4.2 megajoules per kilogram of water evaporated. Aflatoxin contamination is below detectable limits in all forced-air dried samples, compared to detectable levels in sun-dried controls. The study concludes that forced-air drying is an effective post-harvest solution for Kwara State maize producers.

Keywords: maize drying, forced-air dryer, post-harvest management, Kwara State, aflatoxin.