DESIGN, FABRICATION AND EVALUATION OF A MANUALLY OPERATED HYDRAULIC OIL EXTRACTOR FOR GROUNDNUT

Abstract

Functional processing of agricultural produce requires easily operated equipment. A manually operated hydraulic press was developed for extracting oil from decorticated groundnut seeds. It is made up of a piston, cylinder, collector, hydraulic jack and frame. The total weight of the press is 32.7 kg with height and breath of 72.4 and 30.9 cm respectively. The pressing by a 3 ton hydraulic jack. The components of the machine were fabricated using locally available materials such as mild and stainless steel, which are sourced from the local market. The extractor unit-was tested using press cage with pore sizes of3, 4 and 5 mm and cage diameter of 5.2, 7.9 and 10 cm. Whole and ground groundnut seeds were used for the machine testing. The Kampala variety (Sam nut-10) of groundnut was used for the evaluation of the machine performance. Oil yield, extraction efficiency and machine capacity of the machine were evaluated. The physco-chemical properties of the groundnut oil extracted were determined. Results obtained showed that pore size of 3 mm gave the least oil yields of21.2 and 23.6 %, for whole and ground seed at cage diameters of7.9 cm. the pore size 4mm gave an oil yield of 23.0 and 26.9 % while that of 5 mm gave 23.0 and 26.2 %; for whole and ground seed respectively with no significant difference. Similar trend was observed for the extraction efficiency and machine capacity where the values increased sharply as pore size increased from3 to 4 mm but decreased with a further increase from 4 to 5 mm. The increase in cage diameter from 7.9 to 10 cm resulted in a decrease in oil yields from 23.02and 26.87 %to 21.74 and 24.08; for whole and ground sample respectively. Maximum extraction efficiency of79.02 and 84.22 % was recorded for diameter 5.2 cm at pore size of 4 mm for whole and ground seed respectively, while cage diameter of 10 cm gave the lowest value of 39.80 and 44.09 % for whole and ground seeds respectively. The highest machine capacity of 0.978; 1.084 kg /hr (whole and ground seeds respectively) was obtained at cage diameter of 10 cm. Analysis of variance showed that cage diameter made a significant effect (p~0.05) on all the parameters evaluated. For all pore size and cage diameter except cage diameter of 7.9 cm, material type (whole and ground seed) do not have significance effect on oil yield, extraction efficiency and machine capacity. Regression analysis was conducted using stepwise regression Models of the form Y = ax2+ bx + c were best fitted to predict the oil yield (YI), extraction efficiency (Y2} and machine capacity (Y3) with pore size (Xr) cage diameter and (X2) as the independent variables. The combined effect of pore size and cage diameter for oil yield, extraction efficiency and machine capacity showed that, pore size has a positive relationship with the machine performance and negative relationship cage diameter. While machine capacity accounts for 29 %of the variation observed in machine capacity for whole seed and 37 % for ground seed.