scholarly journals A Network-Theory-Based Comparative Study of Melt-Conveying Models in Single-Screw Extrusion: A. Isothermal Flow

Polymers ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 929 ◽  
Author(s):  
Christian Marschik ◽  
Wolfgang Roland ◽  
Jürgen Miethlinger
Keyword(s):  
Comparative Study ◽  
Network Theory ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Polymer Melt ◽  
Pressure Profile ◽  
Single Screw ◽  
Single Screw Extrusion ◽  
Power Law Fluids ◽  
Flow Theories

In many extrusion processes, the metering section is the rate-controlling part of the screw. In this functional zone, the polymer melt is pressurized and readied to be pumped through the die. We have recently proposed a set of heuristic models for predicting the flow behavior of power-law fluids in two- and three-dimensional metering channels. These novel theories remove the need for numerical simulations and can be implemented easily in practice. Here we present a comparative study designed to validate these new methods against experimental data. Extensive experiments were performed on a well-instrumented laboratory single-screw extruder, using various materials, screw designs, and processing conditions. A network-theory-based simulation routine was written in MATLAB to replicate the flow in the metering zones in silico. The predictions of the three-dimensional heuristic melt-conveying model for the axial pressure profile along the screw are in excellent agreement with the experimental extrusion data. To demonstrate the usefulness of the novel melt-flow theories, we additionally compared the models to a modified Newtonian pumping model known from the literature.

scholarly journals Application of Network Analysis to Flow Systems with Alternating Wave Channels: Part B. (Superimposed Drag-Pressure Flows in Extrusion)

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1900
Author(s):  
Christian Marschik ◽  
Wolfgang Roland ◽  
Marius Dörner ◽  
Sarah Schaufler ◽  
Volker Schöppner ◽  
...  
Keyword(s):  
High Performance ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Wave Dispersion ◽  
Pressure Profile ◽  
Design And Optimization ◽  
Single Screw ◽  
Modeling Approach ◽  
Single Screw Extrusion ◽  
Pressure Flows

Due to progress in the development of screw designs over recent decades, numerous high-performance screws have become commercially available in single-screw extrusion. While some of these advanced designs have been studied intensively, others have received comparatively less attention. We developed and validated a semi-numerical network-theory-based modeling approach to predicting flows of shear-thinning polymer melts in wave-dispersion screws. In the first part (Part A), we systematically reduced the complexity of the flow analysis by omitting the influence of the screw rotation on the conveying behavior of the wave zone. In this part (Part B), we extended the original theory by considering the drag flow imposed by the screw. Two- and three-dimensional melt-conveying models were combined to predict locally the conveying characteristics of the wave channels in a discretized flow network. Extensive experiments were performed on a laboratory single-screw extruder, using various barrel designs and wave-dispersion screws. The predictions of our semi-numerical modeling approach for the axial pressure profile along the wave-dispersion zone accurately reproduce the experimental data. Removing the need for time-consuming numerical simulations, this modeling approach enables fast analyses of the conveying behavior of wave-dispersion zones, thereby offering a useful tool for design and optimization studies and process troubleshooting.

scholarly journals A Novel Modeling Approach for Plastics Melting within a CFD-DEM Framework

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 227
Author(s):  
Alptekin Celik ◽  
Christian Bonten ◽  
Riccardo Togni ◽  
Christoph Kloss ◽  
Christoph Goniva
Keyword(s):  
Three Dimensional ◽  
Melting Rate ◽  
Experimental Results ◽  
Single Screw ◽  
Modeling Approach ◽  
Single Screw Extrusion ◽  
Three Dimensional Modeling ◽  
Solids Transport ◽  
Joint Consideration ◽  
Liquid States

Existing three-dimensional modeling approaches to single-screw extrusion can be classified according to the process sections. The discrete element method (DEM) allows describing solids transport in the feed section. The melt flow in the melt section can be calculated by means of computational fluid dynamics (CFD). However, the current state of the art only allows a separate consideration of the respective sections. A joint examination of the process sections still remains challenging. In this study, a novel modeling approach is presented, allowing a joint consideration of solids and melt transport and, beyond that, the formation of melt. For this purpose, the phase transition from the solid to liquid states is modeled for the first time within the framework CFDEMCoupling®, combining CFD and DEM by a novel melting model implemented in this study. In addition, a melting apparatus for the validation of the novel melting model is set up and put into operation. CFD-DEM simulations are carried out in order to calculate the melting rate and are compared to experimental results. A good agreement between the simulation and experimental results is found. From the findings, it can be assumed that the CFD-DEM simulation of single-screw extruder with a joint consideration of the feed and melt section is feasible.

A Generalized 2D Output Model of Polymer Melt Flow in Single-Screw Extrusion

2017 ◽  
Vol 32 (2) ◽  
pp. 209-216 ◽  
Author(s):  
S. Pachner ◽  
B. Löw-Baselli ◽  
M. Affenzeller ◽  
J. Miethlinger
Keyword(s):  
Polymer Melt ◽  
Melt Flow ◽  
Single Screw ◽  
Single Screw Extrusion ◽  
Screw Extrusion
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