Extruder simulation model

The groundwork for all this was laid by F. Laenger at HANDLE GmbH and made public in a number of articles dealing with an extruder-simulation model [17]. 

In principle there are two possibilities to get the informations over the material parameters. First we have a theoretic model modified from the model over high filled polymere melts. This model allows to meassure and evaluate the rheological parameters. On the other hand we have a rheological computer model called ESM (extruder simulation model), developed by the author, which brings us in the position to simulate the material parameters. 

The extruder simulation model (ESM) was developed by Handle GmbH. The theoretical fundamental principles and examples for application of the ESM are described in detail in various articles published by Laenger [17]. This model is based on measurements obtained from a special laboratory version measuring extruder of 80 mm barrel diameter. 

Table 2 Variables and target values of the Extruder-Simulation-model [17 part 4a]...

The following steps are concerned with the design of the compounding step. They are supported by the flow diagram editor and the simulation tool MOREX. The extruder simulation expert models the compounding process as a part of the overall chemical process with the help of the flow diagram editor. The respective part of the flow diagram is used to derive a model for ID simulation in MOREX. 

The tertiary goals of extruder simulation as introduced in Subsect. 4.1.4, and some other categorizations, are modeled as categorization schemes in the descriptive area. Each of the schemes is composed of a set of categories (which are not shown in Fig. 4.7). This allows to integrate the TRAMP functionality of annotating weakly structured (multimedia) documents. 

Topaz was used to calculate the time response of the model to step changes in the heater output values. One of the advantages of mathematical simulation over experimentation is the ease of starting the experiment from an initial steady state. The parameter estimation routines to follow require a value for the initial state of the system, and it is often difficult to hold the extruder conditions constant long enough to approach steady state and be assured that the temperature gradients within the barrel are known. The values from the Topaz simulation, were used as data for fitting a reduced order model of the dynamic system. 

Experimental and simulation results presented below will demonstrate that barrel rotation, the physics used in most texts and the classical extrusion literature, is not equivalent to screw rotation, the physics involved in actual extruders and used as the basis for modeling and simulation in this book. By changing the physics of the problem the dissipation and thus adiabatic temperature increase can be 50% in error for Newtonian fluids. For example, the temperature increase for screw and barrel rotation experiments for a polypropylene glycol fluid is shown in Fig. 7.30. As shown in this figure, the barrel rotation experiments caused the temperature to increase to a higher level as compared to the screw rotation experiments. The analysis presented here focuses on screw rotation analysis, in contrast to the historical analysis using barrel rotation [15-17]. It was pointed out recently by Campbell et al. [59] that the theory for barrel and screw rotation predicts different adiabatic melt temperature increases. 

Tronconi et al. [46] developed a fully transient two-phase 1D + 1D mathematical model of an SCR honeycomb monolith reactor, where the intrinsic kinetics determined over the powdered SCR catalyst were incorporated, and which also accounts for intra-porous diffusion within the catalyst substrate. Accordingly, the model is able to simulate both coated and bulk extruded catalysts. The model was validated successfully against laboratory data obtained over SCR monolith catalyst samples during transients associated with start-up (ammonia injection), shut-down (ammonia... 

Today, the most widely used model simplification in polymer processing simulation is the Hele-Shaw model [5], It applies to flows in "narrow" gaps such as injection mold filling, compression molding, some extrusion dies, extruders, bearings, etc. The major assumptions for the lubrication approximation are that the gap is small, such that h < . L, and that the gaps vary slowly such that... 

We have therefore a rigorous model for pressure build-up in an extruder section. However, we also need dimensionless parameters A, and A2 for the screw geometry used (for full details see Section 6.7.1 and Chapter 7). These are either measured beforehand (Fig. 2.24, Chapter 2) and/or, if possible, calculated by means of a comprehensive flow simulation (Section 6.8.3). Thus, all three aspects of Fig. 6.2 contribute towards the description of the... 

This paper describes a finite element formulation designed to simulate polymer melt flows in which both conductive and convective heat transfer may be important, and illustrates the numerical model by means of computer experiments using Newtonian extruder drag flow and entry flow as trial problems. Fluid incompressibility is enforced by a penalty treatment of the element pressures, and the thermal convective transport is modeled by conventional Galerkin and optimal upwind treatments. 

Although relatively unexplored, an alternative approach is to determine frictional yield properties by high-pressure shear and triaxial cells, and to incorporate these properties into soils or plasticity models for finite element simulations of flow within the extruder body, as has been done for compaction (cf. Fig. 21-141). 

Fig. 13 Computational model for U-Profile die design (A) preland, die land, and free surface as computational domain (B) finite element mesh (symmetry exploited to reduce computational requirements) (C) boundary conditions for simulation of polymer fiow through die and extrudate free surface and (D) relevant profiles (1) preland inlet (2) die land (uniform along flow length) (3) final free surface (target extrudate profile) and (4) symmetry plane.

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