Abstract

This study determined the effect of cylinder speed, feed rate and tray angle on the dehulling efficiency and the effect of fan speed, feed rate and tray angle on the cleaning efficiency and grain loss from an acha (Digitaria exilis) dehulling machine in a 3 × 3 factorial experimental design in three replicates. The cylinder speeds were 1500, 2000 and 2500 rpm and the fan speeds were 160, 185 and 213 rpm. The feed rates were 20, 30 and 40 g min-1 and tray angles of 22.5°, 45°, and 67.5°. The results were analyzed using the analysis of variance at p ≤ 0.05 to determine if the speeds and tray angle inclinations had a significant effect on the dehulling efficiency, cleaning efficiency and grain loss at the various feed rates. The Duncan’s New Multiple Range Test was used to separate the means where there was significant difference. The feed rate had no significant effect on the dehulling and cleaning efficiencies and grain loss. The speeds and tray angles had a significant effect on the dehulling and cleaning efficiencies and grain loss. The dehulling efficiency was higher at higher tray angles. The cleaning efficiency was higher at the higher fan speeds and tray angles. The grain loss from the machine was higher at the higher fan speeds and lower at the higher tray angles.

Key words: Acha, dehulling machine, cleaning, grain loss, feed rate, tray angle