An Integrated MODEL-OPTI-SCALE Computer System for Modeling, Optimization, and Scaling-Up of Plastic Extrusion.

An integrated Model-Opti-Scale (MOPS) computer system for the modeling, optimization, and scaling-up of plastic extrusion has been built. This enabled simulations of single-screw extrusion with conventional, gravitational feeding of the extruder and single-screw extrusion with metered feeding. This system enables predictions of the behavior of these processes using material, geometry, and operating data and contains numerous original and unique models and algorithmic solutions. The system co-operates with specially developed optimization and scaling procedures based on Genetic Algorithms, allowing process optimization/scaling-up. A unique, holistic approach to modeling flood-fed/starve-fed processes, with a possibility of transfer between these feed methods, is presented. The problem of optimizing the operating/geometry parameters of single-screw extrusion for maximizing process efficiency and minimizing specific energy use has been solved. Optimization has been achieved in a unique way, allowing the coupling of both methods of feeding. It has also been observed that an optimal solution may be obtained upon flood feeding or starve feeding, depending on the assumed weights of the optimization criteria. This optimized process was scaled up to increase process efficiency by enlarging the extruder diameter while keeping the length/diameter ratio constant. Scaling-up has been achieved using criteria comprising single parameters, including specific energy consumption, material temperature, and the plasticization rate, as well as criteria comprising functional parameters, such as temperature distribution and the material plasticization profile.