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TECHNICAL PAPERS

Numerical Simulation and Mixing Study of Pseudoplastic Fluids in an Industrial Helical Static Mixer

[+] Author and Article Information
Ramin K. Rahmani

Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH 43606rkhrahmani@yahoo.com

Theo G. Keith

Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH 43606tkeith@eng.utoledo.edu

Anahita Ayasoufi

Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH 43606aayasoufi@yahoo.com

FLUENT is a registered trademark of Fluent Inc., Lebanon, NH.

J. Fluids Eng 128(3), 467-480 (Oct 03, 2005) (14 pages) doi:10.1115/1.2174058 History: Received November 30, 2004; Revised October 03, 2005

Static mixers are increasingly being used to perform a variety of mixing tasks in industries, ranging from simple blending to complex multiphase reaction systems. Use of static mixers to process non-Newtonian fluids is quite common. Data on the pressure drop of non-Newtonian fluids in static mixers and the degree of mixing of materials through the mixer are very useful in the design and engineering application of these tools. This paper extends a previous study by the authors on an industrial helical static mixer and illustrates how static mixing processes of single-phase viscous liquids can be simulated numerically. A further aim is to provide an improved understanding of the flow pattern of pseudoplastic liquids through the mixer. A three-dimensional finite volume simulation is used to study the performance of the mixer. The flow velocities, pressure drops, etc., are calculated for various flow rates, using the Carreau and the power law models for non-Newtonian fluids. The numerical predictions by these two models are compared to existing experimental data. Also, a comparison of the mixer performance for both Newtonian and pseudoplastic fluids is presented. The effects of the Reynolds number of the flow and also properties of pseudoplastic fluids on the static mixer performance have been studied. It is shown that for the materials studied here, the fluid type is not effective on the degree of mixing. It is also shown that the fluid type has a major impact on the pressure drop across the mixer.

Copyright © 2006 by American Society of Mechanical Engineers
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References

Figures

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Figure 1

A six-element static mixer

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Figure 2

Nondimensionalized difference between the viscosities predicted by the power law and the Carreau models

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Figure 3

Path line of one particle through the mixer

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Figure 4

Pressure drop through the six-element mixer

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Figure 5

Particles locations at second, fourth, and sixth element, respectively, from left to right. (CMC concentration level from top to bottom: 50ppm, 500ppm, and 5000ppm)

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Figure 6

Particles locations at second, fourth, and sixth element. From top to bottom Re′=0.1, 1, 10, 100, and 1000

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Figure 7

Structure radii for Re′=1 (CMC concentration level: 5000ppm)

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Figure 8

Structure radii at the end of each mixing element when Re=1 (Newtonian fluid)

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Figure 9

Structure radii at the end of the last mixing element (CMC concentration level: 5000ppm)

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Figure 10

Structure radii at the end of the last mixing element (Newtonian fluid)

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Figure 11

PDU values for a CMC solution

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Figure 12

Intensity of segregation at the sixth element

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Figure 13

Distribution function for CMC solutions flow in the six-element static mixer (Re′=1,dt*=0.01)

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Figure 14

Distribution function for flow in a six-element static mixer (dt*=0.01)

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Figure 15

Particle distributions for a Newtonian fluid at the end of the second, fourth, and sixth mixing elements (from top to bottom Re=0.1, 10, 100, and 1000)

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Figure 16

Distribution function for Newtonian fluid in a six-element static mixer (dt*=0.01)

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Figure 17

G values for a six-element mixer (1/s). CMC concentration level: 50ppm.

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Figure 18

G values for a six-element mixer (1/s). CMC concentration level: 500ppm.

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Figure 19

G values for a six-element mixer (1/s). CMC concentration level: 5000ppm

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