Applicability of the axial dispersion model to coiled flow inverters containing single liquid phase and segmented liquid-liquid flows

Rojahn, Patrick; Hessel, Volker; Nigam, K.D.P.; Schael, Frank

doi:10.1016/j.ces.2018.02.031

Cited by 29 publications

(29 citation statements)

References 94 publications

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“…In the last years, CFIs have been characterized in terms of mixing and residence time distribution [3][4][5][6][7][8][9] and were applied for various processes such as liquid-liquid extraction [10][11][12], precipitation [13], crystallization [14][15][16], and gas-liquid reactions [17][18][19]. Here, increased mass transfer in a CFI was observed compared to straight and helically coiled capillaries as well as a more narrow residence time distribution.…”

Section: Introductionmentioning

confidence: 99%

Kinetic Study of Leuco‐Indigo Carmine Oxidation and Investigation of Taylor and Dean Flow Superposition in a Coiled Flow Inverter

et al. 2019

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In two‐phase capillary flow, Taylor and Dean vortices can enhance mass transfer according to recent studies. By utilizing a colorimetric method based on the consecutive oxidation of leuco‐indigo carmine it is possible to visualize the superposition of Taylor and Dean vortices in a gas‐liquid system. A kinetic study is performed in order to estimate the enhancement factor. Depending on the flow conditions, three different flow regimes are identified with different intensities of Taylor and Dean vortices affecting the oxygen distribution within the liquid phase. A dimensionless number is derived that describes this transition in flow regimes.

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Section: Introductionmentioning

confidence: 99%

Kinetic Study of Leuco‐Indigo Carmine Oxidation and Investigation of Taylor and Dean Flow Superposition in a Coiled Flow Inverter

et al. 2019

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“…The experimental data was fit to a deterministic axial dispersion (AD) model that is known to adequately represent the RTD of flow patterns showing slight deviations from plug flow, [ 28 ] as demonstrated by systems with co‐existing turbulent and laminar regions such as packed beds [ 29 ] and micromixers. [ 30 ] At flow rates of 35 and 55 g/min (Figure 4B,C), the modelled E θ curves line up impeccably with the experimental curves ( R 2 > 0.99). At 15 g/min (Figure 4A), they are also in good agreement with one another ( R 2 = 0.979), with slightly more scatter near the peak due to experimental background noise.…”

Section: Resultsmentioning

confidence: 60%

Computational fluid dynamics simulation of pressure drop and macromixing in LL microreactors

et al. 2021

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A computational fluid dynamics (CFD) model was developed to simulate single‐phase flow in LL microreactors using the open‐source software OpenFOAM. The k‐ω SSTLM turbulence model was implemented to account for the impact of small‐scale temporal and spatial fluctuations that emerge in the base LL mixing module (LLM) on the flow field and transport of a passive scalar. The CFD model was successfully validated based on excellent conformance to experimental pressure loss (R2 > 0.997) and residence time distribution (RTD) data (R2 > 0.97) at flow rates ranging from 10‐100 g/min. Streamlines, velocity, pressure, and turbulent viscosity profiles were mapped across the 3D domain of repeating reactor segments to analyze local fluid dynamics. In a continuous series of LLMs, the flow field becomes fully developed after the second module. A drastic change in flow behaviour in the LLM was identified at 30 g/min (Re = 643) based on the emergence of advective recirculation zones and significant turbulent dispersion. Recirculation zones in the LLM grow larger from 20‐50 g/min and are equal in size from 50‐100 g/min. Four LL reactor plates with differing configurations of spacing between LLMs were compared extensively by analyzing pressure drop and RTD. Plates with continuous or equally‐spaced LLMs demonstrated a near plug‐flow profile with minor dispersion (Pe > 100), albeit at a greater power dissipation. Plates with longer residence‐time channels between LLMs yielded a broader and right‐skewed RTD due to the intermittent attenuation of chaotic flow patterns.

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“…13 Considering an empty tube, a plug flow behavior can be obtained only if the tube is extremely long with respect to its diameter 15,16 and it possibly follows a coiled geometry. 17,18 Alternatively, active mixers such as ultrasonic micromixers and pulse-flow mixers can be employed, but their efficiency is hindered by their high cost, difficulty of maintenance, and high failure rate. 19 only the energy derived from the flow momentum itself.…”

Section: ■ Introductionmentioning

confidence: 99%

Influence of Buoyancy Effects on the Mixing Process and RTD in a Side-Injection Reactor Equipped with Static Mixers

Albertazzi

Florit

Busini

2021

Ind. Eng. Chem. Res.

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The mixing process and the residence time distribution (RT D) of molecules inside reactors is a well known topic in chemical engineering: good radial mixing and poor axial mixing of chemical species are the essential conditions in order to achieve a plug flow behaviour in a tubular reactor, which is often highly desirable. While the influence on mixing and RT D of viscosity and spatial velocities has been investigated in the literature, the influence of density differences between the streams to be mixed has been much less investigated, especially considering laminar regimes. Thus, the mixing and RT D of two miscible liquids with different densities and viscosities in a side-injection tubular reactor equipped with Sulzer Static Mixers were studied by RANS-based CFD simulations. The results obtained show that, if adequate configurations are used, it is possible to well approximate radial mixing and a plug-flow behaviour, even when large differences in densities are involved. Moreover, graphics for a fast estimation of the maximum mixing length involved as well as for the corresponding P e −1 value were obtained as a function of the Re number.

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Applicability of the axial dispersion model to coiled flow inverters containing single liquid phase and segmented liquid-liquid flows

Cited by 29 publications

References 94 publications

Kinetic Study of Leuco‐Indigo Carmine Oxidation and Investigation of Taylor and Dean Flow Superposition in a Coiled Flow Inverter

Kinetic Study of Leuco‐Indigo Carmine Oxidation and Investigation of Taylor and Dean Flow Superposition in a Coiled Flow Inverter

Computational fluid dynamics simulation of pressure drop and macromixing in LL microreactors

Influence of Buoyancy Effects on the Mixing Process and RTD in a Side-Injection Reactor Equipped with Static Mixers

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