Modelling and Design of a Prototype Machine for De-hulling Jatrophacurcas L. Fruit

Overview

Jatrophacurcas L. is plant oil that can be used as alternative fuel. An integrated production process of Jatropha has become more and more important in order to fulfil the increasing demands of biofuel production. The first important post harvesting processing step is separation of fruit seed from the hull. The process is handled manually since a proper de-hulling machine for Jatropha fruit has never been manufactured. At Universität Hohenheim a prototype machine was designed and constructed for de-hulling Jatropha fruits, a framework research project founded by BMBF. The aim of the study was to model and construct a prototype de-hulling machine which integrates many areas of knowledge by using prototyping platforms such as computer aided design (CAD), discrete element method (DEM) and finite element analysis (FEA). CAD was used to determine physical and mechanical properties of rigid components such as mass, inertia and dimension. DEM was applied to predict the mechanical behaviour of Jatropha fruit under cracking conditions. The loads of flexible elements were approached by using FEA, which calculates maximum stress and adaptability effects of the elements to achieve more realistic outcomes. After the construction of 3D CAD geometry, the performance of the machine was tested with Jatropha fruits to enable improvement and adaptation of the existing parts. To support the kinematic mechanisms, two AC motors are used to drive the system. The machine consists of three major parts; de-huller which cracks fruits into seeds and hulls, primary separation made of a perforated cylinder to separate hulls and seeds, and secondary separation made of four layers of sieves with different holes diameter to separate the seeds based on the size.

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