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Modeling the fluid dynamics of bubbl...

Chen, Peng.

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Modeling the fluid dynamics of bubble column flows.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Modeling the fluid dynamics of bubble column flows./
作者:	Chen, Peng.
面頁冊數:	192 p.
附註:	Source: Dissertation Abstracts International, Volume: 65-07, Section: B, page: 3574.
Contained By:	Dissertation Abstracts International65-07B.
標題:	Engineering, Chemical. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3140691
ISBN:	9780496878314

Modeling the fluid dynamics of bubble column flows.
Chen, Peng.

Modeling the fluid dynamics of bubble column flows. - 192 p.

Source: Dissertation Abstracts International, Volume: 65-07, Section: B, page: 3574.

Thesis (D.Sc.)--Washington University, 2004.

Bubble column and slurry bubble column reactors are used in numerous industrial applications. In these systems gas sparged through the liquid rises in forms of bubbles of various sizes and provides the energy via interfacial momentum transfer for vigorous mixing of the liquid. The Euler-Euler approach describes the motion of the two-phase mixture in a macroscopic sense, which is preferred for industrial applications. To model the drag force term, which is one of the key closures, most numerical simulations resort to a single particle model with a so-called "mean" bubble size. This assumption is physically unrealistic in churn-turbulent flow regime and results in poor gas holdup prediction and limited capability for interfacial area concentration prediction. Moreover, the determination of the assumed "mean" bubble size needs a trial-and-error procedure which significantly compromises the prediction capability of Computational Fluid Dynamics (CFD) approach. This research shows that bubble column flows could be better modeled by explicitly accounting for bubble breakup and coalescence with the implementation of Bubble Population Balance Equation (BPBE) into the CFD code. When the breakup rate is increased by an order of magnitude, compared to values predicted by models in the literature, the implementation of BPBE leads to better agreement of CFD prediction with all available data for gas holdup and liquid axial velocity distribution, compared to the simulation based on an estimated constant mean bubble diameter. The choice of currently available bubble breakup and coalescence closures has some but not a significant impact on the simulated results. Quantitative comparisons with the experimental data (Kumar, 1994; Degaleesan, 1997; Chen et al., 1999; Ong, 2003; Shaikh et al., 2003) demonstrate that CFD model coupled with BPBE provides satisfactory mean axial liquid velocity and gas holdup profile for columns operated over a wide range of superficial velocity, operating pressure, physical properties, and column diameter. The bubble Sauter mean diameter and interfacial area per unit volume are also reasonably predicted. For reactor modeling, convective and axial dispersion time scales are predicted correctly, improvement is needed for the radial dispersion time scale which is currently overpredicted.

ISBN: 9780496878314Subjects--Topical Terms:

1018531
Engineering, Chemical.

Modeling the fluid dynamics of bubble column flows.
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500 $a Director: Milorad P. Dudukovic.
502 $a Thesis (D.Sc.)--Washington University, 2004.
520 $a Bubble column and slurry bubble column reactors are used in numerous industrial applications. In these systems gas sparged through the liquid rises in forms of bubbles of various sizes and provides the energy via interfacial momentum transfer for vigorous mixing of the liquid. The Euler-Euler approach describes the motion of the two-phase mixture in a macroscopic sense, which is preferred for industrial applications. To model the drag force term, which is one of the key closures, most numerical simulations resort to a single particle model with a so-called "mean" bubble size. This assumption is physically unrealistic in churn-turbulent flow regime and results in poor gas holdup prediction and limited capability for interfacial area concentration prediction. Moreover, the determination of the assumed "mean" bubble size needs a trial-and-error procedure which significantly compromises the prediction capability of Computational Fluid Dynamics (CFD) approach. This research shows that bubble column flows could be better modeled by explicitly accounting for bubble breakup and coalescence with the implementation of Bubble Population Balance Equation (BPBE) into the CFD code. When the breakup rate is increased by an order of magnitude, compared to values predicted by models in the literature, the implementation of BPBE leads to better agreement of CFD prediction with all available data for gas holdup and liquid axial velocity distribution, compared to the simulation based on an estimated constant mean bubble diameter. The choice of currently available bubble breakup and coalescence closures has some but not a significant impact on the simulated results. Quantitative comparisons with the experimental data (Kumar, 1994; Degaleesan, 1997; Chen et al., 1999; Ong, 2003; Shaikh et al., 2003) demonstrate that CFD model coupled with BPBE provides satisfactory mean axial liquid velocity and gas holdup profile for columns operated over a wide range of superficial velocity, operating pressure, physical properties, and column diameter. The bubble Sauter mean diameter and interfacial area per unit volume are also reasonably predicted. For reactor modeling, convective and axial dispersion time scales are predicted correctly, improvement is needed for the radial dispersion time scale which is currently overpredicted.
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