Modeling and Simulation of Modular Corotating Twin Screw Extruder for Processing Polymers

Twin screw extruders are being widely used in polymers and food reactive or nonreactive extrusions. Typical operations include solids conveying, pressurization, spontaneous heating, softening, melting, mixing, and pressure relief. For efficiently representing the coupled extrusion of multielements and multiphase transformations, we established a modular model to predict profiles of temperature and pressure in a corotating twin screw extruder with conveying section, kneading block, reverse element and expanding conveying section. Our model explicitly accounts for voidage‐dependent heat transfer between the barrel wall, entrained air and the processed polymer particles in the conveying section by introducing voidage. Meanwhile we quantitatively analyzed individual contributions of plastic energy dissipation (PED), frictional energy dissipation (FED) and viscous energy dissipation (VED) to the temperature and pressure increases during the melting process in the kneading block. Furthermore the model simulated pressure relief in a reverse element following the kneading block and a subsequent expanding conveying section, and examined the effects of feed rate, screw speed and barrel temperature on axile profiles of temperature and pressure, which are consistent with industrial polymer processing practice. The proposed model is simple and efficient for the design and diagnosis of such twin screw extruders.