Design, fabrication and performance evaluation of centrifugal sunflower dehuller for small-scale enterprises in developing countries

Sunflower is grown by small-scale farmers in many developing countries like Tanzania. Lack of effective machines for dehulling sunflower seeds has resulted in high oil losses during extraction, especially for small- and medium-scale enterprise. This paper reports on the design, fabrication and performance evaluation (in terms of throughput capacity, dehulling efficiency and kernel breakage efficiency) of a centrifugal machine for dehulling sunflower seeds. The purpose was to improve the dehulling efficiency and to reduce kernel breakage of the dehulled seeds. The machine consists of a frame, feeding hopper, power shaft, bearings system, dehulling chamber and power unit. The results showed that the higher the impeller speed, the higher the throughput capacity and dehulling efficiency. The highest dehulling efficiency was 94.3% which is significantly higher than that of existing abrasive dehullers (17%). However, high speed also resulted in increased kernel breakage (5-20.9%) hence reducing the quality of the dehulled seeds. Thus an impeller speed of 1445 rpm was selected for the operation of the machine. The results suggest that the designed centrifugal dehuller can be used by small- and medium-scale sunflower oil enterprises for improving oil extraction.