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Evaluation of the cavity transfer mixer (CTM) for dispersive mixing and polymer blending

Wang, Chicheng
http://rave.ohiolink.edu/etdc/view?acc_num=case1057758785

Abstract Details

1994, Doctor of Philosophy, Case Western Reserve University, Macromolecular Science.
The Cavity Transfer Mixer (CTM) was primarily designed as a distributive mixing device to be used as an add-on unit to existing extruders. In determining the CTM overall mixing efficiency as well as its potential use for various applications, the flow patterns/characteristics within this mixer must be well understood. In this work, a fluid dynamics analysis package – FIDAP – using the finite element method was employed to simulate the flow patterns in a prototype CTM with 3 rows and 6 cavities per row. A 3-D, isothermal flow analysis for a Newtonian fluid was carried out. The flow field was characterized in terms of characteristic profiles, average shear stresses and a parameter λ quantifying the elongational flow components. The last two parameters are the most important ones in analyzing dispersive mixing efficiency. The influence of processing variables on the flow characteristics was also discussed. The simulation results show good agreement with the experimental data. The flow patterns in a complete CTM with 6 rows and 4 cavities per row was simulated. A 3-D, isothermal flow analysis was carried out and the fluid of choice was a flexible polyvinylchloride whose rheological behavior is described by a power-law model fluid. The flow field was characterized in terms of velocity profiles, pressure distributions, shear rates/shear stresses generated and a parameter λ quantifying the elongational flow components. The results of the flow simulations were compared with experimental data. The potential use of cavity transfer mixers for dispersive mixing was discussed. The flow patterns and flow field characteristics within the CTM are of the fundamental importance for its proper design and for its potential use of this device for dispersive mixing. Due to the complex geometry and the transient characteristics of the flow, solving for the flow patterns in the CTM is not an easy task. However, some of the design features of the CTM can be reproduced in a simplified device which will allow more detailed experimental and numerical investigations. In this work such a simplified device was built and used to reveal some of the features of the flow patterns and the influence of one design parameter (cavity depth) on the mixing efficiency. The problem of time dependent flow boundaries was solved by selecting a number of sequential geometries to represent a complete mixing cycle. Based on the simulated flow field, massless particles were tracked for one complete cycle. The simulation and the experimental results show an excellent agreement. The efficiency of different cavity depths for dispersive mixing was evaluated from the simulation and the experiment on carbon black agglomerates in the flow medium – polydimethylsiloxane.
Ica Manas-Zloczower (Advisor)
167 p.
cavity transfer mixer (CTM); dispersive mixing; polymer blending

Recommended Citations

Citations

  • Wang, C. (1994). Evaluation of the cavity transfer mixer (CTM) for dispersive mixing and polymer blending [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1057758785

    APA Style (7th edition)

  • Wang, Chicheng. Evaluation of the cavity transfer mixer (CTM) for dispersive mixing and polymer blending. 1994. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1057758785.

    MLA Style (8th edition)

  • Wang, Chicheng. "Evaluation of the cavity transfer mixer (CTM) for dispersive mixing and polymer blending." Doctoral dissertation, Case Western Reserve University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=case1057758785

    Chicago Manual of Style (17th edition)

case1057758785
808
© 1994, all rights reserved.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.