Agriculture and Food Sciences Research

Forced convection grain dryers are more efficient and achieve greater drying rates than natural convection dryers. However, it is necessary to dry an appropriate grain layer thickness in such a dryer for the drying process to occur efficiently and at an appropriate rate. A well sized fan is also essential if the drying process is to proceed effectively. An oversize fan will be unnecessarily expensive to buy and operate due to high fan power, while an undersized one will not be able to supply adequate air flow. The solar collector must be properly sized if it is to heat the air to the required temperature. All these factors need to be addressed during the design of a grain dryer. Lengthy and expensive trial and error processes can be avoided by applying simulation in the design process. This study developed an experimental grain dryer, addressing the above mentioned issues in the process. Simulation of air flow within an initial model of the dryer was done and the results used to size the fan and drying cabinet. The solar collector was also sized. The experimental grain dryer developed consisted of a drying cabinet of dimensions 0.5 m x 0.5 m x 1.0 m and was equipped with a 0.039 kW centrifugal fan. The solar collector area was of dimensions 1.2 m x 1.8 m.