Design of a Small-scale Maize Dryer
Abstract
Maize is the most widely grown cereal crop in Zimbabwe. At harvest, the content of moisture in maize is usually above 25% which is undesirable for safe storage throughout the year. The acceptable moisture content for prolonged storage of maize is about 12.5 %. Most farmers in Zimbabwe use the traditional way of drying maize by exposing it to the sun for a prolonged period. The drying period can span up to three months using these traditional methods. This delays the delivery of the grain to the market as well as the quality of the product resulting in post-harvest losses. This paper is a documentation of the project that was supported and sponsored by the Southern African Solar Thermal Demonstration Initiative (SOLTRAIN) to design a small-scale solar grain dryer for maize in Zimbabwe. Drying experiments were conducted in the laboratory to determine the drying parameters that were used in the design. An optimum drying temperature of 60 °C was determined against a drying time of 6 hours in order to reach the acceptable moisture levels using a drying vessel of a capacity of 1.5 tonnes and a collector area of 45 m2 using flat plate air collectors. The control system of the dryer was also developed