A Complete Dynamic Model for Twin Screw Extruders

Abstract

A one-dimensional physically motivated dynamic model of a twin-screw extruder for reactive extrusion has been developed. This model can predict extruder behaviour such as pressure, filling ratio, temperature and molar conversion as well profiles as residence time distribution under various operating conditions such as feed rate, screw speed, monomer/initiator ratio and heat flux supplied to the barrel. The model consists of a cascade of perfectly stirred reactors which can be either fully or partially filled with backflow. We consider the mass balance coupled with the momentum balance for the calculation of the pressure profile and the flows between the different reactors. At each reactor is associated the concentration in monomer, the temperature of the matter, the temperatures of the associated piece of screw and barrel. The final model consists of a set of differential algebraic equations. The experimental validation is only made on flow aspects of the model by using experimental RTD's.