Local gas distribution and mass transfer characteristics in an annulus-rising airlift reactor with non-Newtonian fluid

Han, Mei; González, Gerardo; Vauhkonen, Marko; Лаари, Арто; Koiranen, Tuomas

doi:10.1016/j.cej.2016.09.102

Cited by 24 publications

(11 citation statements)

References 45 publications

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“…Gas holdup and bubble size distribution as well as bubble shape are the important parameters since they determine the gas‐liquid interfacial areas available for mass transfer . It has been reported that gas holdup and bubble size distribution of millimeter‐ or centimeter‐sized bubbles were significantly controlled by liquid viscosity .…”

Section: Introductionmentioning

confidence: 99%

Efficient Control of Microbubble Properties by Alcohol Shear Flows in Ceramic Membrane Channels

Liu

Han

et al. 2017

Chem Eng & Technol

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Efficient control of microbubbles is achieved by alcohol shear flows in ceramic membrane channels. The dependence of hydrodynamic and mass transfer properties of microbubbles on liquid viscosity was investigated in a bubble column. The multichannel ceramic membrane worked as the gas sparger, and the shear flow on the membrane surface controlled the microbubble generation. Oxygen gas and glycerin solutions with different viscosities served as gas phase and liquid phase, respectively. The microbubbles were massively generated at different liquid viscosities. With increasing viscosity, the bubble size first decreased and then increased. The dual effect of viscosity on bubble size was related to bubble coalescence. However, an impact of viscosity on gas holdup was not observed for microbubbles.

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Section: Introductionmentioning

confidence: 99%

Efficient Control of Microbubble Properties by Alcohol Shear Flows in Ceramic Membrane Channels

Liu

Han

et al. 2017

Chem Eng & Technol

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“…Meanwhile, bubble size and its behavior are affected by several factors, such as gas holdup, liquid velocity field and liquid physical property. Extensive studies [4][5][6][7][8] have shown that bubble size characteristics have significant effects on the hydrodynamics and mass transfer performance of ALR, especially for liquids with high viscosity. For example, Hwang and Cheng [5] found that gas holdup decreased with increasing Carboxyl Methyl Cellulose (CMC) concentration due to formation of large bubbles in highly viscous liquid.…”

Section: Introductionmentioning

confidence: 99%

CFD-PBM Coupled Simulation of an Airlift Reactor with Non-Newtonian Fluid

Han

Sha

Лаари

et al. 2017

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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-Hydrodynamics of an AirLift Reactor (ALR) with tap water and non-Newtonian fluid was studied experimentally and by numerical simulations. The Population Balance Model (PBM) with multiple breakup and coalescence mechanisms was used to describe bubble size characteristics in the ALR. The interphase forces for closing the two-fluid model were formulated by considering the effect of Bubble Size Distribution (BSD). The BSD in the ALR obtained from the coupled Computational Fluid Dynamics (CFD)-PBM model was validated against results from digital imaging measurements. The simulated velocity fields of both the gas and liquid phases were compared to measured fields obtained with Particle Image Velocimetry (PIV). The simulated results show different velocity field profile features at the top of the ALR between tap water and nonNewtonian fluid, which are in agreement with experiments. In addition, good agreement between simulations and experiments was obtained in terms of overall gas holdup and bubble Sauter mean diameter. NOMENCLATURE SymbolsVolume fraction of gas/liquid phase, 1 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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“…The volumetric mass transfer coefficient was determined using the dynamic oxygen absorption method . The evolution of the dissolved oxygen concentration with time was monitored and recorded using a MARVET BASIC 2000 Dissolved Oxygen Meter (Elke Sensor OÜ) with the oxygen sensor located 0.65 m above the bottom of the ALR.…”

Section: Methodsmentioning

confidence: 99%

“…The reactor can be equipped with an enlarged expansion, called a gas separator, at the top of the column in order to achieve good separation of the gas and liquid phases. Generally, the two categories of ALRs, the internal‐loop airlift reactor (IL‐ALR) and the external‐loop airlift reactor (EL‐ALR), are classified according to the arrangement of the riser and the downcomer . With the IL‐ALR, two aeration modes can be used, namely gas feed in the draft tube (a center‐rising airlift reactor, CR‐ALR) and gas feed in the annulus between the draft tube and the outer column (an annulus‐rising airlift reactor, AR‐ALR).…”

Section: Introductionmentioning

confidence: 99%

Effect of aeration mode on the performance of center‐ and annulus‐rising internal‐loop airlift bioreactors

2017

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Extensive experimental studies on internal-loop airlift reactors, including center-rising (CR-ALR) and annulus-rising airlift reactors (AR-ALR), have been reported in the literature. However, to the best of the authors' knowledge, the effects of the aeration mode on the local hydrodynamics remain an under-investigated area, especially for complex culture media. At present, it is difficult to select the best aeration mode for ALRs due to limited understanding of the pros and cons of the different modes. This study presents a detailed quantitative investigation of the overall gas holdup, local liquid velocity, liquid circulation time, shear rate distribution, and volumetric mass transfer coefficient in center-and annulus-rising airlift bioreactors to better understand the effect of aeration mode on airlift bioreactor performance. Particle image velocimetry is employed to conduct local measurements. The results show that the overall gas holdup, liquid circulation time, and volumetric mass transfer coefficient are larger in the AR-ALR than in the CR-ALR. The local liquid velocity circulating into the downcomer of the AR-ALR, which contributes to bubble entrainment and therefore to overall gas holdup, is higher than in the CR-ALR. It was observed that a large circulation loop formed in the CR-ALR, whereas two counter-looping circulation cells appeared in the AR-ALR. It was also found that the shear rate field was more uniform in the AR-ALR than the CR-ALR although the shear rates were similar in magnitude.

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Local gas distribution and mass transfer characteristics in an annulus-rising airlift reactor with non-Newtonian fluid

Cited by 24 publications

References 45 publications

Efficient Control of Microbubble Properties by Alcohol Shear Flows in Ceramic Membrane Channels

Efficient Control of Microbubble Properties by Alcohol Shear Flows in Ceramic Membrane Channels

CFD-PBM Coupled Simulation of an Airlift Reactor with Non-Newtonian Fluid

Effect of aeration mode on the performance of center‐ and annulus‐rising internal‐loop airlift bioreactors

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