Mathematical modeling of mechanical horizontal screw oil extractor

Abstract

A theory using mechanical expression was proposed from the physics of oil expression in a screw press to characterize a mathematical model. The general oil expression equation was solved for three machine parameters (choke clearances, screw shaft clearances and screw shaft speeds) which simulate the machine parameters effects in the overall screw expeller process. The mathematical model was validated by the experimental data obtained from pressing fish oil with a screw press, using regression analysis. The experimental oil extraction data was fitted to the model and the quality of fit evaluated. A good fit was indicated by correlation coefficient of 0.9983, coefficient of determination of 0.9967, absolute average percentage deviation of 4.8 %, coefficient of variation of 3.4 % and chi-square goodness of fit of 1.8. Good agreement was obtained between experimental and predicted data. The optimum oil yield (22.5 %) is equal to the maximum oil yield (22.5 %) obtained in the experimental study. The mathematical model was also used to satisfactorily predict the performance of commercial screw expellers. This theory however provided an alternative to the costly and time-consuming empirical studies in obtaining information on the performance of a press.