DEVELOPMENT AND PERFORMANCE EVALUATION OF MELON SHELLING AND SEPARATING MACHINE

Melon shelling machine was designed, constructed and evaluated. Shelling efficiency and cleaning efficiency were evaluated for on the machine. The design adopted the method of shelling by attrition. The major machine elements of the shelling machine are the hopper, shelling chamber and the separating chamber. The hopper is made up of welded galvanized sheet slanted at 23⁰ which is the coefficient of static friction of melon on galvanized sheet. The shelling chamber has an impeller which consists of two circular disks with 24 vanes positions in between the disks. The vanes are inclined at an angle of 45⁰ to the horizontal axis. The minimum power required for the impeller was calculated to be 598.2W and the terminal velocity was calculated to be 7.6 m/s. Evaluation was carried out for the machine shelling efficiency and cleaning efficiency using three levels of moisture content (3.79% d.b., 6.61% d.b. and 9.53% d.b.) and three levels of impeller speeds (800, 1000, and 1200 rpm). The results showed that the moisture content had a significant effect (at P<0.05) on the shelling efficiency and cleaning efficiency. However, the impeller speed has a significant effect only on shelling efficiency. The optimal values of the shelling efficiency and cleaning efficiency were 39.1% and 70.3% respectively with machine loss of 4.5% at 3.79% d.b. and 1200 rpm