Dynamic modeling and simulation of mass, momentum, and energy transport in a single-screw plastic extrusion process

This study presents a novel semi-physical phenomenological model that addresses a significant gap in the literature by incorporating dynamic 1D mass, momentum, and energy balances across all zones of a single-screw extruder. The model was implemented for a conventional screw geometry with a smooth feed section. The methodology involved spatial discretization using upwind finite difference schemes, resulting in a system of differential-algebraic equations (DAE). This system was solved numerically and validated with experimental data from an industrial extruder processing polypropylene. Simulation results demonstrate that the model accurately predicts plastification profiles, melt temperatures, and pressure distributions with low prediction errors. Mean Absolute Error (MAE) values of 7.45 × 10⁻⁶ m² for the solid flow area, between 0.51 and 8.96 bar for pressure, and 1.66°C for the melt temperature were obtained. A key feature is its computational efficiency, with simulations requiring a maximum time of 875 seconds. As far as we know, this work presents the first dynamic 1D model that unifies all key extrusion zones in a fully coupled manner. The key novelty of this work is that its rapid and accurate predictive capabilities make it a valuable tool for screw geometry optimization, sensitivity studies, and integration into digital-twin frameworks to support decision-making in industrial operations.