New methods for flow regime identification in bubble columns and fluidized beds

Nedeltchev, Stoyan

doi:10.1016/j.ces.2015.06.054

Cited by 52 publications

(33 citation statements)

References 129 publications

(160 reference statements)

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“…However, in the literature, many authors consider only the first regime transition, without any reference to the second one, except for a limited number of studies (Nedeltchev, 2015;Nedeltchev and Shaikh, 2013). In the following, for the sake of clarify, we refer to "flow regime transition point" considering the first transition.…”

Section: Flow Regime Transitionmentioning

confidence: 99%

Comprehensive experimental investigation of counter-current bubble column hydrodynamics: Holdup, flow regime transition, bubble size distributions and local flow properties

Besagni

Inzoli

2016

Chemical Engineering Science

117

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Section: Flow Regime Transitionmentioning

confidence: 99%

Comprehensive experimental investigation of counter-current bubble column hydrodynamics: Holdup, flow regime transition, bubble size distributions and local flow properties

Besagni

Inzoli

2016

Chemical Engineering Science

117

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“…Many authors consider only the first flow regime transition, without any reference to the second one, except for a limited number of studies (Nedeltchev, 2015;Nedeltchev and Shaikh, 2013;Sharaf et al, 2015). In the following, for the sake of clarity, we refer to "flow regime transition point" considering the first flow regime transition.…”

Section: Flow Regime Transitionmentioning

confidence: 99%

“…The global and local fluid dynamic properties are strictly related to the prevailing flow regime: the homogeneous flow regime, the transition flow regime and the heterogeneous flow regime (if considering large-diameter bubble columns, see refs. (Nedeltchev, 2015;Nedeltchev and Schubert, 2015;Nedeltchev and Shaikh, 2013)). In the following, these flow regimes are described: (i) first, the general definitions are given; (ii) secondly, the literature concerning the flow regimes is summarized; (ii) finally, the definition of the flow regimes within this research is given.…”

Section: Bubble Column Fluid Dynamicsmentioning

confidence: 99%

The dual effect of viscosity on bubble column hydrodynamics

Besagni

Inzoli

Guido

et al. 2017

Chemical Engineering Science

112

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A B S T R A C TSome authors, in the last decades, have observed the dual effect of viscosity on gas holdup and flow regime transition in small-diameter and small-scale bubble columns. This work concerns the experimental investigation of the dual effect of viscosity on gas holdup and flow regime transition as well as bubble size distributions in a large-diameter and large-scale bubble column. The bubble column is 5.3 m in height, has an inner diameter of 0.24 m, and can be operated with gas superficial velocities in the range of 0.004-0.20 m/s. Air was used as the dispersed phase, and various water-monoethylene glycol solutions were employed as the liquid phase. The water-monoethylene glycol solutions that were tested correspond to a viscosity between 0.9 mPa s and 7.97 mPa s, a density between 997.086 kg/m 3 and 1094.801 kg/m 3 , a surface tension between 0.0715 N/m and 0.0502 N/m, and log 10 (Mo) between −10.77 and −6.55 (where Mo is the Morton number). Gas holdup measurements were used to investigate the global fluid dynamics and the flow regime transition between the homogeneous flow regime and the transition flow regime. An image analysis method was used to investigate the bubble size distributions and shapes for different gas superficial velocities, for different solutions of watermonoethylene glycol. In addition, based on the experimental data from the image analysis, a correlation between the bubble equivalent diameter and the bubble aspect ratio was proposed. The dual effect of viscosity, previously verified in smaller bubble columns, was confirmed not only with respect to the gas holdup and flow regime transition, but also for the bubble size distributions. Low viscosities stabilize the homogeneous flow regime and increase the gas holdup, and are characterized by a larger number of small bubbles. Conversely, higher viscosities destabilize the homogeneous flow regime and decrease the gas holdup, and the bubble size distribution moves toward large bubbles. The experimental results suggest that the stabilization/destabilization of the homogeneous regime is related to the changes in the bubble size distributions and a simple approach, based on the lift force, was proposed to explain this relationship. Finally, the experimental results were compared to the dual effect of organic compounds and inorganic compounds: future studies should propose a comprehensive theory to explain all the dual effects observed.

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“…Different methods have been presented over the last few decades, as discussed by Shaikh and Al-Dahhan [102], Nedeltchev and Shaikh [26] and Nedeltchev [27]. The most common methods employed are statistical methods (by interpretation of the ε G -U G curve), the swarm velocity [7,11,34,46,[51][52][53]75,76,89,91,229,315,316] and the drift flux [7,11,34,38,46,51,53,75,76,229,[316][317][318] approaches.…”

Section: The Flow Regimesmentioning

confidence: 99%

“…Kawase and Moo-Young [207] proposed the following empirical correlation (Equation (27)), where ν a is the apparent kinematic viscosity and the apparent dynamic viscosity is expressed in terms of the consistency index, K, as follows µ a = K (27) It is important to highlight that Kawase and Moo-Young [207] suggested that a more precise correlation should also account for the effect of the surface tension on the gas hold-up which they have not included. In addition, Kawase and Moo-Young [204] developed a theoretical model for gas hold-up in bubble columns with Newtonian and non-Newtonian fluids using the concept of a characteristic turbulent kinematic viscosity in bubble columns:…”

Section: Scheme Of Correlations By Lockett and Kirkpatrickmentioning

confidence: 99%

Two-Phase Bubble Columns: A Comprehensive Review

2018

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We present a comprehensive literature review on the two-phase bubble column; in this review we deeply analyze the flow regimes, the flow regime transitions, the local and global fluid dynamics parameters, and the mass transfer phenomena. First, we discuss the flow regimes, the flow regime transitions, the local and global fluid dynamics parameters, and the mass transfer. We also discuss how the operating parameters (i.e., pressure, temperature, and gas and liquid flow rates), the operating modes (i.e., the co-current, the counter-current and the batch modes), the liquid and gas phase properties, and the design parameters (i.e., gas sparger design, column diameter and aspect ratio) influence the flow regime transitions and the fluid dynamics parameters. Secondly, we present the experimental techniques for studying the global and local fluid dynamic properties. Finally, we present the modeling approaches to study the global and local bubble column fluid dynamics, and we outline the major issues to be solved in future studies.

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New methods for flow regime identification in bubble columns and fluidized beds

Cited by 52 publications

References 129 publications

Comprehensive experimental investigation of counter-current bubble column hydrodynamics: Holdup, flow regime transition, bubble size distributions and local flow properties

Comprehensive experimental investigation of counter-current bubble column hydrodynamics: Holdup, flow regime transition, bubble size distributions and local flow properties

The dual effect of viscosity on bubble column hydrodynamics

Two-Phase Bubble Columns: A Comprehensive Review

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