Experimental Analysis of the Mass Transfer Coefficient and Interfacial Area in an Aerated Coaxial Mixing System Comprising a Non-Newtonian Solution

Jamshidzadeh, Maryam; Ein‐Mozaffari, Farhad; Lohi, Ali

doi:10.1021/acs.iecr.0c03641

Cited by 18 publications

(21 citation statements)

References 59 publications

(133 reference statements)

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“…For example, Ogut and Hatch [111] showed that the gas flow rate significantly affects the volumetric mass transfer coefficient. From their results, the aeration had a direct effect on the volumetric mass transfer coefficient, which was also reported by other authors [18,21,37,108]. In this regard, the aeration increases the number of bubbles inside the vessel that leads to an increase in the mass transfer rate [40].…”

Section: Aeration Effectsupporting

confidence: 77%

“…The hydrodynamic effect of the central impeller was also investigated by Jamshidzadeh et al [37]. They observed that using a double down-pumping pitched blade turbine generated a higher volumetric mass transfer coefficient than using a double up-pumping pitched blade turbine or double Scaba impellers.…”

Section: Coaxial Mixersmentioning

confidence: 98%

“…It is worth mentioning, however, that small differences are expected when using different experimental methods to measure the volumetric mass transfer coefficient. Furthermore, Jamshidzadeh et al [37] proposed novel dimensional and dimensionless correlations for coaxial mixers. The parameters were fitted for an impeller configuration in co-rotation mode, and they found that the best correlation should include the effects of both apparent viscosity and speed ratio.…”

Section: Volumetric Mass Transfer Coefficientmentioning

confidence: 99%

“…However, the combination between aeration and agitation phenomena determines which variable controls the mass transfer. For instance, the stirrer agitation has a more significant influence at low aeration rate, whereas the mass transfer is controlled by the aeration at high gas flow rate [37].…”

Section: Aeration Effectmentioning

confidence: 99%

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Gas Dispersion in Non-Newtonian Fluids with Mechanically Agitated Systems: A Review

2022

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Gas dispersion in non-Newtonian fluids is encountered in a broad range of chemical, biochemical, and food industries. Mechanically agitated vessels are commonly employed in these processes because they promote high degree of contact between the phases. However, mixing non-Newtonian fluids is a challenging task that requires comprehensive knowledge of the mixing flow to accurately design stirred vessels. Therefore, this review presents the developments accomplished by researchers in this field. The present work describes mixing and mass transfer variables, namely volumetric mass transfer coefficient, power consumption, gas holdup, bubble diameter, and cavern size. It presents empirical correlations for the mixing variables and discusses the effects of operating and design parameters on the mixing and mass transfer process. Furthermore, this paper demonstrates the advantages of employing computational fluid dynamics tools to shed light on the hydrodynamics of this complex flow. The literature review shows that knowledge gaps remain for gas dispersion in yield stress fluids and non-Newtonian fluids with viscoelastic effects. In addition, comprehensive studies accounting for the scale-up of these mixing processes still need to be accomplished. Hence, further investigation of the flow patterns under different process and design conditions are valuable to have an appropriate insight into this complex system.

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Section: Aeration Effectsupporting

confidence: 77%

Section: Coaxial Mixersmentioning

confidence: 98%

Section: Volumetric Mass Transfer Coefficientmentioning

confidence: 99%

Section: Aeration Effectmentioning

confidence: 99%

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Gas Dispersion in Non-Newtonian Fluids with Mechanically Agitated Systems: A Review

2022

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“…The gas–liquid volumetric mass transfer coefficient is a key parameter describing the gas–liquid volumetric mass transfer and plays a vital role in the design and amplification of gas–liquid STRs 24,33 . The dynamic dissolved oxygen electrode technology is used to measure the gas–liquid volumetric mass transfer coefficient ( k L a ), and an appropriate gas–liquid mixing model is selected in accordance with the change in oxygen concentration in the liquid phase to fit the dissolved oxygen concentration time relationship curve 13,15,21 .…”

Section: The Experiments and Measurementmentioning

confidence: 99%

Circulating jet for enhancing the mass transfer in a gas–liquid stirred tank reactor

Wang

et al. 2021

AIChE Journal

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There are some problems in gas–liquid stirred tank reactor (STR), such as low mass transfer efficiency, high exhaust gas oxygen concentration, and low product conversion rate, due to limitations of stirring speed and input power. This article summarizes the effect of adding circulating jet internals on bubble size distribution, overall gas holdup, gas–liquid volumetric mass transfer coefficient, and power per unit volume of the STR. When circulating jet is added, the average bubble Sauter mean diameter in the STR is reduced to 1.26 mm, and the overall gas holdup is increased to 8.23%, which is an increase of 3.62 times of the original STR. The gas–liquid volumetric mass transfer coefficient is increased to 0.05556 s−1, which is 4.84 times of the original STR. The power per unit volume is increased by only 1.4 times. These data provide references for the design and scale‐up of new jet STRs.

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Exploiting the prediction of mass transfer performance in aerated coaxial mixers containing biopolymer solutions using empirical correlations and neural networks

Barros,

Ein‐Mozaffari,

Lohi

et al. 2023

Can J Chem Eng

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The volumetric mass transfer coefficient is commonly used to assess the mixing effectiveness of gas–liquid bioreactor systems. Analyzing mass transfer performance in non‐Newtonian fluids inside coaxial mixers can be challenging due to the complex interaction between process variables, which requires developing robust characterization and estimation approaches. This study aims to investigate the gas dispersion in shear‐thinning biopolymers with yield stress using coaxial mixers in order to evaluate the effects of aeration and agitation on the volumetric mass transfer coefficient. A mixing configuration comprising a pitched blade turbine and an anchor was employed to disperse air into xanthan gum solutions, and the mass transfer performance was obtained at different impeller speeds and biopolymer concentrations by measuring the dissolved oxygen concentration. A dimensionless empirical correlation was proposed, and the results showed that the mass transfer was positively influenced by aeration intensity and agitation mechanism, quantified by the gas flow number and Reynolds number, respectively. Additionally, a strategy using stacking‐ensemble artificial neural networks was developed to accurately estimate the volumetric mass transfer coefficient, with a correlation coefficient of 0.998. The proposed mass transfer characterization approach overcame the complexities of analyzing aerated coaxial mixer systems and provided a reliable design model for bioreactor systems containing non‐Newtonian fluids.

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Experimental Analysis of the Mass Transfer Coefficient and Interfacial Area in an Aerated Coaxial Mixing System Comprising a Non-Newtonian Solution

Cited by 18 publications

References 59 publications

Gas Dispersion in Non-Newtonian Fluids with Mechanically Agitated Systems: A Review

Gas Dispersion in Non-Newtonian Fluids with Mechanically Agitated Systems: A Review

Circulating jet for enhancing the mass transfer in a gas–liquid stirred tank reactor

Exploiting the prediction of mass transfer performance in aerated coaxial mixers containing biopolymer solutions using empirical correlations and neural networks

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