Numerical simulation and experimental validation of mixing performance of kneading discs in a twin screw extruder

Zhang, Xianming; Li, Feng; Chen, Wenxing; Hu, Guohua

doi:10.1002/pen.21404

Cited by 121 publications

(106 citation statements)

References 38 publications

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“…The dispersive mixing efficiency of the flow field was assessed in terms of its elongational flow components and magnitude of shear stresses. Zhang et al (2009) uses a mesh superposition technique to solve intermeshing twin-screw extruders without remeshing. The procedure, incorporated into the Polyflow software, generates finite element meshes for the flow domain and each screw element, respectively, which are then superimposed.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional Numerical Study of the Mixing Behaviour of Twin-screw Elements

Ilinca

Hétu

2012

International Polymer Processing

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In this work the numerical modeling of the flow inside co-rotating twin-screw extruders is performed and solutions are analyzed to determine the mixing behavior of two screw elements:conveying and mixing elements. The flow around intermeshing screws is computed using an immersed boundary finite element method capable of dealing with complex moving solid boundaries. The flow is considered isothermal and the material behaves as a generalized nonNewtonian fluid. Because the viscosity depends on the shear rate, solutions will be shown for various rotation velocities of the screw. The 3D solutions are then analyzed in order to determine various parameters characterizing the flow mixing such as the residence time and the linear stretch. Residence time distribution inside the twin-screw extruder is first computed by using a particle tracking algorithm based on a fourth order Runge-Kutta method. A large number of particles are tracked inside the extruder and the resulting particle data is used to determine the distribution of the residence time and of the linear stretch. The spatial distribution of the residence time is also computed by solving a transport equation tracking the injection time of the polymer melt. The methodology shows important differences in the mixing behavior of the screw elements considered.3

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Section: Introductionmentioning

confidence: 99%

Three-dimensional Numerical Study of the Mixing Behaviour of Twin-screw Elements

Ilinca

Hétu

2012

International Polymer Processing

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“…The flow is assumed to be incompressible, and in a pseudo-steady state to screw rotation, as has often been assumed in polymer flow in twin-screw extruders. 11,15,18,20,22,[24][25][26] With these assumptions, the governing equations become…”

Section: Numerical Simulationmentioning

confidence: 99%

“…Among various types of mixing elements [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] , kneading disks (KD) are the most commonly used due to their mixing efficiency. In order to tune the mixing characteristics of conventional KD for application to various purposes, a modified type of KD has been proposed, called "pitched-tip kneading disks" (ptKD).…”

Section: Introductionmentioning

confidence: 99%

Effects of Pitched Tips of Novel Kneading Disks on Melt Mixing in Twin-Screw Extrusion

Nakayama

Nishihira

Kajiwara

et al. 2017

J. Soc. Rheol., Jpn

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In mixing highly viscous materials, like polymers, foods, and rubbers, the geometric structure of the mixing device is a determining factor for the quality of the mixing process. In pitched-tip kneading disks (ptKD), a novel type of mixing element, based on conventional kneading disks (KD), the tip angle is modified to change the channel geometry as well as the drag ability of KD. We discuss the effects of the tip angle in ptKD on mixing characteristics based on numerical simulation of the flow in the melt-mixing zone under different feed rates and a screw rotation speed. It turns out that the passage of fluid through the high-stress regions increases in ptKD compared to conventional KD regardless of the directions and sizes of the tip angle, while the fluctuation in residence time stays at the same level as the conventional KD. Furthermore, pitched tips of backward direction increase the mean applied stress on the fluid elements during its residence in the melt-mixing zone, suggesting the enhancement of dispersive mixing quality in ptKD. These understandings of the role of the tip angle on KD can give a basic guide in selecting and designing suitable angle parameters of ptKD for different mixing purposes.

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“…The Lagrangian average of the mixing efficiency can be used to distinguish flows with or without re-orientation (Ottino, 1989). The Lagrangian average of the mixing efficiency has also been used to quantify mixing in the pin-mixing section of a single-screw extruder (Yao et al, 2001) and mixing in the melt-mixing zone of a twin-screw extruder (Connelly and Kokini, 2007;Zhang et al, 2009).…”

Section: Distributive Mixing Indexmentioning

confidence: 99%

Capturing the Efficiency of a Melt-Mixing Process for Polymer Processing

Kajiwara

Nakayama

2011

J. Chem. Eng. Japan / JCEJ

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Numerical simulation and experimental validation of mixing performance of kneading discs in a twin screw extruder

Cited by 121 publications

References 38 publications

Three-dimensional Numerical Study of the Mixing Behaviour of Twin-screw Elements

Three-dimensional Numerical Study of the Mixing Behaviour of Twin-screw Elements

Effects of Pitched Tips of Novel Kneading Disks on Melt Mixing in Twin-Screw Extrusion

Capturing the Efficiency of a Melt-Mixing Process for Polymer Processing

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