Model of extrusion pressed oils from rapeseed

Abstract

This paper presents a hydrodynamic model for rapeseed oil extrusion-pressing, which is based on the laws of conservation of momentum, mass and energy. We examine a raw material that is a plastically deformed, porous oil-saturated medium. A boundary-value problem that includes such independent variables as medium pressure, oil pressure, medium velocity and temperature distribution is formulated. An approximate analytical solution to the problem is found for constant viscosity and filtration coefficients. The solution describes pressure growth and an increase in the oil extraction rate along the extracting box as monotonic, and this does not coincide with the experimental data. Based on the experimental data for rheological and filtration dependencies, a numerical algorithm is developed using a finite element method. Pressure fields for medium and oil, medium velocity and filtration flow velocity in the extruder channel equipped with extracting box are obtained. It has been found that the increase of pressure in the raw material reduces oil extraction rate, and the distribution of oil extraction rate along the extracting box exhibits a maximum, which coincides with the experimental data. Our model can form the basis for determining optimum extrusion-pressing conditions.