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Technical Brief

On the Computational Modeling of Unfluidized and Fluidized Bed Dynamics

[+] Author and Article Information
Lindsey C. Teaters

Department of Mechanical Engineering,
Virginia Tech,
Blacksburg, VA 24061

Francine Battaglia

Department of Mechanical Engineering,
Virginia Tech,
Blacksburg, VA 24061
e-mail: fbattaglia@vt.edu

1Corresponding author.

Contributed by the Fluids Engineering Division of ASME for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received February 3, 2013; final manuscript received April 10, 2014; published online July 24, 2014. Assoc. Editor: D. Keith Walters.

J. Fluids Eng 136(10), 104501 (Jul 24, 2014) (7 pages) Paper No: FE-13-1071; doi: 10.1115/1.4027437 History: Received February 03, 2013; Revised April 10, 2014

Two factors of great importance when considering gas–solid fluidized bed dynamics are pressure drop and void fraction, which is the volume fraction of the gas phase. It is, of course, possible to obtain pressure drop and void fraction data through experiments, but this tends to be costly and time consuming. It is much preferable to be able to efficiently computationally model fluidized bed dynamics. In the present work, ANSYS Fluent® is used to simulate fluidized bed dynamics using an Eulerian–Eulerian multiphase flow model. By comparing the simulations using Fluent to experimental data as well as to data from other fluidized bed codes such as Multiphase Flow with Interphase eXchanges (MFIX), it is possible to show the strengths and limitations with respect to multiphase flow modeling. The simulations described herein will present modeling beds in the unfluidized regime, where the inlet gas velocity is less than the minimum fluidization velocity, and will deem to shed some light on the discrepancies between experimental data and simulations. In addition, this paper will also include comparisons between experiments and simulations in the fluidized regime using void fraction.

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Figures

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Fig. 1

Schematic of the fluidized bed domain

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Fig. 2

Relationship between pressure drop and inlet gas velocity

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Fig. 3

Time- and plane-averaged void fraction versus height normalized with bed height comparing experiments [20] with simulations

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Fig. 4

Time-averaged void fraction profiles comparing walnut shell bed simulations with experimental data [20] at (a) h/h0 = 0.25, (b) h/h0 = 0.5, (c) h/h0 = 0.75, and (d) h/h0 = 1

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Fig. 5

Pressure drop versus inlet gas velocity comparing experiments [20] with modeling approaches

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Fig. 6

Pressure drop versus inlet gas velocity using the MOD approach for the parametric study and compare with experiments [20]

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Fig. 7

Pressure drop versus inlet gas velocity using the porous media model as compared with experiments [20] and MFIX [22]

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