Experimental study on gas–liquid dispersion and mass transfer in shear-thinning system with coaxial mixer

Liu, Baoqing; Zheng, Yijun; Cheng, Ruijia; Xu, Zhe; Wang, Manman; Jin, Zhi-jiang

doi:10.1016/j.cjche.2018.02.009

Cited by 18 publications

(19 citation statements)

References 28 publications

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“…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. Similarly, Liu et al [18] studied different single central impeller types and observed that even though PBT exhibited the highest mass transfer coefficient, the BDT-6 impeller exhibited a better gas pumping capacity. Jegatheeswaran and Ein-Mozaffari [101], in turn, reported that a radial-axial impeller named ASI was the most energy-efficient impeller in dispersing the gas compared to Scaba, PBT, ASI Slanted, PBT Updown, and PBT-Rushton impellers.…”

Section: Coaxial Mixersmentioning

confidence: 94%

“…Since the viscosity varies depending on the local shear rate, poor mixing regions may exist, which can lead to process inefficiencies [17]. Thus, impeller configurations in aerated non-Newtonian applications are often designed to target the reduction of stagnant regions created by the shear rate gradient in the vessel and to enhance the mixing performance [18]. Some of the mixing configurations the power law model.…”

Section: Introductionmentioning

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: Coaxial Mixersmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

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 measured three times and the average value is taken, and the measurement error mainly comes from the fitting in the data processing. Given that the saturated oxygen concentration is related to temperature, the temperature of k L a should be corrected in accordance with the following equation 35 :

{(k_{normalL} a)}_{20} = \frac{{((), k_{L} a)}_{T}}{{1.022}^{T ‐ 20}}

where T is the temperature under the experimental conditions, °C.…”

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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“…Rudolph et al [16] and Ein-Mozaffari et al [17][18][19][20][21][22] have employed advanced measurement technologies such as electrical resistance tomography and computational fluid dynamics (CFD) to carry out more extensive research. Bao et al [23,24], Liu et al [25][26][27][28], and Huang et al [29] have also done considerable research on this topic.…”

Section: Introductionmentioning

confidence: 99%

“…Besides, there has been a change of research focus from single-phase to gas-liquid and solid-liquid two-phase systems. Tanguy et al [10] have done some initial investigations, and more detailed research has been done by Ein-Mozaffari et al [17,[19][20][21][22] and Liu et al [24][25][26][27][28], including the power consumption, gas holdup, mass transfer, solid suspension characteristics and micromixing performance. With respect to the gas holdup, Ein-Mozaffari et al [21,22] pointed out that the anchor-pitched blade turbine (PBT) coaxial mixing system operating in the downward-pumping co-rotation mode has the highest overall gas holdup, while Liu at al.…”

Section: Introductionmentioning

confidence: 99%

Synergistic Effects in Coaxial Mixers: The Controlling Strategy of the Flow and Shear

et al. 2021

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Synergistic effects implying that strong flow and high shear can be obtained simultaneously were found in coaxial mixers. The flow field, axial pumping rate Q zave , and shear strain rate were studied to characterize the synergistic effect quantitatively. The indicator of synergy S was proposed to judge the goodness of synergy. The influences of the fluid viscosity, speed ratio, and rotation mode were studied. The S value becomes larger and smaller with increasing fluid viscosity for helical ribbon and pitched blade turbine impellers, respectively. The variation trend is opposite to the increase of the speed ratio. The co-rotation mode has better mixing performance than that of the counter-rotation mode at constant specific power.

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Experimental study on gas–liquid dispersion and mass transfer in shear-thinning system with coaxial mixer

Cited by 18 publications

References 28 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

Synergistic Effects in Coaxial Mixers: The Controlling Strategy of the Flow and Shear

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