Conceptual Design and Simulation of African Oil Bean Seed Dehuller

Abstract

Dehulling is a unit operation preceding oil extraction of most agricultural products. While it is common to dehull the African oil bean seed manually, the mechanical operation of the process has not been reported. Thus, this study was undertaken to design and simulate African oil bean seed dehulling machine. The design was based on previous investigation of the physical and mechanical properties of the seed at 15 % moisture content (db), including average breaking force of the seed (1.12 kN). Computational fluid dynamic method was used to carry out machine simulation and the effect of time of machine operation on motor torque; angular velocity and linear displacement were investigated. The design results show that a 3 HP, single phase electric motor was required to power 25 mm shaft diameter of the machine. The simulation results show that the angular velocity was high as soon as the machine commences operation, but this progressively decreases with an increase in the time of operation. The reason for this may be due to a decrease in the viscous effect of the internal wall which causes the air stream flow to slow down with a resultant drop in the relative angular velocity to the surface. This implies that the machine is practicable with performance likely to decrease with time of machine operation.