Experimental and Numerical Study of Rhomboidal Mixing Sections

Rios, Antoine C.; Gramann, Paul J.; Osswald, Tim A.; Noriega, María del Pilar; Estrada, Omar

doi:10.3139/217.1578

Cited by 18 publications

(8 citation statements)

References 6 publications

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“…12.37. Rios et al [95] investigated several different configurations of the rhomboid mixing section by changing the two helix angles that define the mixing section. The different sections analyzed are shown in Fig.…”

Section: 434rhomboidal Mixers and Fluted Mixers (Leroy/maddock)mentioning

confidence: 99%

“…This device must be well designed for the number of rhomboids in the axial and circumferential directions, length, pitch, and channel depth to create the optimal mixing environment. Using the boundary element method along with experiments Gramann et al [94] and Rios et al [95] studied the rhomboid mixing section. Gramann et al [94] showed with both simulation and a flow visualization experiment that multiple stagnant regions may occur on the sides of the rhomboid depending on its shape.…”

Section: 434rhomboidal Mixers and Fluted Mixers (Leroy/maddock)mentioning

confidence: 99%

“…Geometries of rhomboidal mixing sections analyzed by [95] The geometries were compared according to mixing efficiency, pressure, and energy consumption. The experiments for this study were performed on three of the mixing sections shown in Fig.…”

Section: Figure 1239mentioning

confidence: 99%

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Modeling and Simulation of the Extrusion Process

Gramann¹,

Davis²,

Osswald³

2014

Polymer Extrusion

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In most polymer processes, the quality of the final part is greatly dependent on the melting, flow and mixing of the polymer. The optimization of the equipment and manufacturing process, as done today, is time consuming and expensive. It is often necessary to build complex flow visualization equipment, i. e., model extruders with transparent barrels, to qualify the flow during processes. Quantifying flow and heat transfer is an even more intimidating task. Furthermore, reproducing the properties of a particular blend from batch to batch can be extremely difficult. Obviously, these barriers make numerical simulation a viable alternative when optimizing and analyzing the extrusion process.Traditionally, when simulating polymer processes, the main concern of the engineer has been to accurately represent the material behavior using complex models. Although many problems still exist regarding polymer material models and will continue to be a field of research, today one can easily deal with the shear thinning behavior, temperature dependence and to some degree the viscoelasticity of polymers. In fact, to date a large number of processes have been realistically simulated in polymer processing ranging from mold filling with fiber orientation, shrinkage and warpage, to extrusion with viscoelastic effects. However, only a few fully threedimensional models of realistic processes have been solved. Simulating a fully three-dimensional process involves intensive labor, trying to accurately represent the geometry of the device and also requires large amounts of computation time and data storage. Obviously, computational demands have been reduced by the enormous increase in computational power available to the engineer at the desktop. However, the labor intensity and requirements of computer performance are multiplied by the added complexity of moving boundaries. Two types of moving boundaries are very common in polymer processing: moving free boundaries and moving solid boundaries.* Moving free boundary problems are encountered in such areas as mold filling, extrudate swell, coating problems, inside the extruder at the screw, to name a few. Solid moving boundaries are those where the actual cavity that con-* The name "moving solid boundary problems" for this category of problems was introduced by Prof . C . L .

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Section: 434rhomboidal Mixers and Fluted Mixers (Leroy/maddock)mentioning

confidence: 99%

Section: 434rhomboidal Mixers and Fluted Mixers (Leroy/maddock)mentioning

confidence: 99%

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Modeling and Simulation of the Extrusion Process

Gramann¹,

Davis²,

Osswald³

2014

Polymer Extrusion

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“…Rios et al use the boundary element method to compare several different designs of rhomboidal mixing sections with regard to pressure loss and residence time distribution, with a subset of the designs also being subjected to laboratory trials including an analysis of colorant distribution and thermal homogeneity [ 23 , 24 ]. However, the simulation is somewhat simplified and thermal mixing is not considered during design and only measured ‘after the fact’.…”

Section: Introductionmentioning

confidence: 99%

A Method for the Validation of Simulated Mixing Characteristics of Two Dynamic Mixers in Single-Screw Extrusion

et al. 2020

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The field of simulation and optimisation of dynamic mixing elements (‘mixers’) is lacking good methods for spatially resolved validation and flow visualisation. For this reason, the authors present an experimental setup that gives better insight into the thermal, distributive and dispersive mixing process by measuring melt temperatures upstream of the mixer and injecting a secondary, visually distinguishable stream of melt upstream. Running extrusion trials for a polyethylene on both a rhomboidal and a Maddock mixer, temperatures, gray scale distribution of images of extrudates and size of dispersed domains in incompatible polystyrene were measured. It was found that temperatures upstream and downstream of the mixer can be quantified. This was used to validate a simulation of thermal mixing. In distributive mixing, good agreement with simulation and an excellent spatial resolution were observed, thereby identifying an area of the rhomboidal mixer in need of geometric improvement. For dispersive mixing, a trend coherent with extrusion theory was found.

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“…Additionally, multiple processing steps increase energy usage, manufacturing costs, coordination steps, and time. However, single screw extrusion with new mixing element designs offers several advantages over twin screw extrusion, which has changed the function of single screw extrusion from only plasticating to both plasticating and mixing . For homogeneity, dispersive mixing followed by distributive mixing is optimal…”

Section: Introductionmentioning

confidence: 99%

High shear melt‐processing of fiberglass‐reinforced poly(trimethylene) terephthalate composites

Lynch

2015

J of Applied Polymer Sci

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As the demand for polymer-matrix composites (PMC) expands in order to replace traditional materials, processing of the PMC is increasingly vital, as the morphology and properties are processing dependent. Typically, thermoplastic PMCs are processed in at least two heat-intensive steps, including a pre-compounding step in order to achieve good mixing followed by a part fabrication step. The key aim of this study is to prepare a fiberglass-reinforced poly (trimethylene terephthalate) (FG-PTT) composite using a one-step, high shear melt-processing method that achieves both compounding and part fabrication. The morphology, thermal properties, and mechanical properties are characterized to determine the effect of FG reinforcement on this renewable biopolymer. This novel method produces a FG-PTT composite with superior mixing and tensile strength, as well as enhanced toughness, in one processing step, reducing polymer degradation and fiber attrition, as well as, time, energy, and cost requirements.

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Experimental and Numerical Study of Rhomboidal Mixing Sections

Cited by 18 publications

References 6 publications

Modeling and Simulation of the Extrusion Process

Modeling and Simulation of the Extrusion Process

A Method for the Validation of Simulated Mixing Characteristics of Two Dynamic Mixers in Single-Screw Extrusion

High shear melt‐processing of fiberglass‐reinforced poly(trimethylene) terephthalate composites

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