Design modifications and performance evaluation of a centrifugal impact palm nuts cracker

This study presented a modified centrifugal impact palm nuts cracker that will enhance cracking efficiency of the existing prototypes in traditional and small-scale oil palm mills in Southwestern Nigeria. This study focused on the effect of modified centrifugal impact blades and cracking ring at higher speed on physical properties, cultivar differences and drying period of the palm nuts. The physical properties of Dura and Tenera cultivars palm nuts were investigated prior to machine design. The modified prototype was developed and evaluated using palm nuts of three categories of geometrical mean diameters (GMD) at steady condition of 80 C and drying periods of 15, 18 and 21 hrs. The results of the physical properties such as length, breadth, thickness, mass, GMD and sphericity were in the range 25.19-35.84 (mm), 18.69-26.44 (mm), 15.0521.71 (mm), 4.60-11.57 (g), 19.10-27.58 (mm) and 0.75-0.77 (%); 26.90-33.97 (mm), 17.89-24.57 (mm), 14.32-20.44 (mm), 3.28-8.84 (g), 18.50-25.84 (mm) and 0.71-0.75 (%) for Dura and Tenera palm nuts cultivars, respectively. The optimum throughput at 15, 18 and 21 hrs drying periods were: 200 and 180, 240 and 218, 235 and 230 (kg/hr) for Dura and Tenera cultivars, respectively. The optimum cracking efficiency of 88% was obtained across all level of GMD, while the predicted value above threshold of 94% for Dura cultivar only. The damaged percentage and recovery efficiency have threshold of 8% and 6% for both cultivars, respectively. Hence, the determination of physical properties and drying condition prior to development and evaluation of this machine enhances its performance efficiently.