Modeling melt conveying and power consumption of co-rotating twin-screw extruder kneading blocks: Part A. Data generation

Mathematical models of polymer melt flow in co-rotating twin-screw extruders are crucial to screw design and predict processing characteristics, such as pressure distribution, back-pressure lengths, degree of filling, melt-temperature increase, and drive power. Twin-screw modeling focuses predominantly on conveying elements, and kneading blocks are commonly represented with fictitious continuous flights, which significantly simplifies geometry and ignores considerable leakage flow. This work (Part A) presents a comprehensive analysis of the conveying characteristics and power demands of fully intermeshing co-rotating twin-screw extruder kneading blocks that considers the complex three-dimensional geometry without geometrical simplifications. This analysis comprises the following steps: (1) dimensionless description of the geometry, (2) simplification of the governing equations, (3) formulation of novel dimensionless conveying and power parameters, and (4) a parametric design study with the novel approach of using the characteristic angular screw position, which avoids complex numerical algorithms and drastically reduces the computation required. Our comprehensive parametric design study included 1536 independent design points—a vast amount of data that revealed various effects that are highlighted in this work, including new findings on the interactions between geometry and conveying and power parameters. The obtained results serve, for example, as the basis for screw design, optimizations, scale-up, and soft sensors.