National Agricultural Extension and Research Liaison Services,

Cleanliness is an important quality characteristic for market acceptance of food products. One of the most important valuable additions is reduction of the contaminant to the barest minimum. This research work was carried out between 9/12/2003 and 15/01/2004 with the aim of developing a prediction equation describing the cleaning process in a stationary sorghum thresher using a mathematical model based on physical-aerodynamic properties of sorghum and machine characteristics. Dimensional analysis was used to obtain a functional relationship between the cleaning efficiency and independent variables such as grain moisture content, straw moisture content, grain bulk density, straw bulk density, feed rate, sieve oscillation frequency, threshing cylinder speed, diameter of sieve hole, air velocity and particle density. The developed cleaning efficiency model was verified by comparing the predicted cleaning efficiency with measured experimental data from the sorghum thresher-testing rig. The cleaning efficiency model showed a good agreement between the predicted and experimental result at 5 % level of significance