Design and performance evaluation of centrifugal cashew nut sheller

Abstract

Cashew nut centrifugal shelling machine was designed and constructed. Shelling efficiency and whole kernel recovery was evaluated for hot-oil roasted nuts on the machine. The design was based on the principle of the optimum kinetic energy that could break the cashew nut shell. The deformation energy used was 4.8763 Joules. The angular velocity of the impeller calculated from the energy was 376.12 rad/s which was equal 3592 rpm. The motor power used was more than 917.34 Watts, the minimum power requirement. The prototype of cashew nut sheller was constructed and evaluated for its shelling efficiency and whole kernel recovery using three levels of moisture content (7.00%w.b., 8.46%w.b. and 9.83% w.b.), three levels of impeller speeds and three grades (large, medium and small) of nut sizes. The results showed that moisture content has significant effect (at P < 0.05) on the shelling efficiency and whole kernel recovery for all the grades of the nut. However, the impeller speed has significant effect on the whole kernel recovery of medium and small nuts. The predicted optimal values of the whole kernel recovery and shelling efficiency for large nut were 65.4% and 96.8% respectively at 3110rpm and 9.06w.b. For medium nut, they were 51.62% and 93.24% respectively at 3487rpm and 8.92w.b. For small nut, they were 37.95% and 92.56% respectively at 3487rpm and 9.83w.b.