Hydrodynamics and mass transfer performance of gas–liquid microflow in viscous liquids

Sheng, Lin; Chang, Yu Cheng; Deng, Jian; Luo, Guangsheng

doi:10.1016/j.cej.2022.140407

Cited by 8 publications

(10 citation statements)

References 70 publications

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“…To date, many dimensionless mathematic models have been proposed to calculate the mass transfer coefficient under the laminar flow, 15,25,26,31,40,50,51 and the dimensionless number mainly contains Reynolds number (Re), Schmidt number (Sc), and Sherwood number (Sh). In this study, the Reynolds number of the liquid and gas ranges in Figure 12 shows this equation can predict the results of the mass transfer coefficient well.…”

Section: Bubble Generation Characteristics In Step Tjunction Microdevicementioning

confidence: 99%

Remarkable improvement of gas–liquid mass transfer by modifying the structure of conventional T‐junction microchannel

et al. 2023

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Enhancing the mass transfer performance just by modifying the channel structure without external energy input is one of the most important topics for microchemical technology development. This work reports the high-performance gas-liquid mass transfer in a novel step T-junction microchannel. The liquid-side mass transfer coefficient in the step T-junction has been significantly improved by one order of magnitude when compared with the conventional T-junction, which is higher up to 60 Â 10 À4 m/s. To our knowledge, it might be the highest value obtained in the microchannel without external energy input. The parameters of bubble generation frequency and gas-liquid interface movement velocity in different microdevices are explored to reveal the mechanism behind the ultra-high mass transfer coefficient in the step T-junction. Finally, two models considering the gas absorption are developed for the bubble generation frequency and volume, and two models are proposed for the gas-liquid mass transfer coefficient.

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Section: Bubble Generation Characteristics In Step Tjunction Microdevicementioning

confidence: 99%

Remarkable improvement of gas–liquid mass transfer by modifying the structure of conventional T‐junction microchannel

et al. 2023

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“…The same as Figure 5, we also marked the liquid flow rate where the pressure drop region transfers from region II to region III in Figure 6 (see the pink circle), and it is evident that the transition point between region II and region III almost happens at the same gas holdup of 0.2. As Q L increases (or the gas holdup decreases), the bubble flow behavior goes through the process from gas–liquid two‐phase control to pure liquid control 21 . Thus, the pressure drop will increase with the liquid flow rate under a lower gas holdup, just as in a normal gas–liquid flow process.…”

Section: Resultsmentioning

confidence: 99%

“…As Q L increases (or the gas holdup decreases), the bubble flow behavior goes through the process from gas-liquid two-phase control to pure liquid control. 21 Thus, the pressure drop will increase with the liquid flow rate under a lower gas holdup, just as in a normal gasliquid flow process.…”

Section: Characteristic Parameters In N-shape Pressure Drop Curvementioning

confidence: 99%

“…The division between the Taylor flow pattern and the bubbly flow pattern is based on the relative size of bubble size and channel size 19 . At a given gas flow velocity, the bubble move velocity increases with the liquid flow velocity, 20 and this value is primarily controlled by the gas–liquid phases in the Taylor flow pattern but mainly controlled by the pure liquid phase in the bubbly flow pattern, 21 which indicates that the dispersion state (i.e., bubble size, liquid slug length) plays an important role in the hydrodynamics of the gas–liquid microflow. To the gas–liquid microflow pressure drop, both the homogeneous flow model (HFM) and the separated flow model (SFM) are widely accepted 22 .…”

Section: Introductionmentioning

confidence: 99%

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N‐shape pressure drop curve of gas–liquid microchannel reactor and modeling

et al. 2023

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Accurate prediction of gas–liquid pressure drop is essential to microreactors design; however, the understanding of general rules of pressure drop in a wide gas–liquid flow ratio, especially smaller than 1.0, remains insufficient, Accordingly, this work systematically studies the pressure drop rule within the gas–liquid flow ratio of 0.2–2.0. The results show that, under a given gas velocity, the pressure drop first increases and then decreases, and finally back increases with the liquid flow velocity, and the named N‐shape pressure drop curve could be clearly observed. Besides, the rules of gas–liquid unit length and gas‐phase holdup are explored to reveal the mechanism behind the N‐shape pressure drop curve. Finally, three semi‐empirical correlations based on the gas–liquid unit length and separated flow model are successfully proposed for the N‐shape pressure drop. This work provides some important fundamental information for the reliable design of gas–liquid microreactors.

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“…33 That is to say, a thinner liquid film is beneficial to reduce fluid leakage and increase the void fraction, and the liquid film thickens when the velocity increases. 34 Via the velocity field measurement technology, van Steijn et al 35 rates, 32 which means that the gas blocking degree will be decreased in T-junction-4 and more liquid phase will be leaked between the bubble body and channel wall. Therefore, a longer liquid slug or thicker liquid film will exist and the void fraction is decreased in T-junction-4.…”

Section: Void Fraction With Gas-liquid Flow Patternmentioning

confidence: 99%

General prediction models for void fraction and specific surface area of gas–liquid microflows

Sheng,

Zheng,

Chang

et al. 2023

AIChE Journal

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The flow characteristics of void fraction and specific surface area are important to predict the mass transfer and reaction performances in gas–liquid microreactors. However, the models and trends for the two parameters in different flow patterns remain ununified and insufficient. Accordingly, this work first time studies the void fraction and specific surface area in a very wide flow pattern range (Taylor, short bubble, bubbly, and bubble swarm flow). The results show that at the same gas–liquid flow rates, the void fraction decreases with bubble size in Taylor and short bubble flow but is totally opposite in bubbly and bubble swarm flow. Importantly, the variation of specific surface area with bubble size is independent of the flow pattern and decreases with bubble size. Finally, based on bubble size, two general models for the two parameters are developed. This work provides a new direction for the unification of flow characteristics.

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Hydrodynamics and mass transfer performance of gas–liquid microflow in viscous liquids

Cited by 8 publications

References 70 publications

Remarkable improvement of gas–liquid mass transfer by modifying the structure of conventional T‐junction microchannel

Remarkable improvement of gas–liquid mass transfer by modifying the structure of conventional T‐junction microchannel

N‐shape pressure drop curve of gas–liquid microchannel reactor and modeling

General prediction models for void fraction and specific surface area of gas–liquid microflows

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