Modelling of the residence time distribution in micromixers

Bošković, D.; Loebbecke, S.

doi:10.1016/j.cej.2007.07.058

Cited by 85 publications

(54 citation statements)

References 18 publications

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“…-Optical detection: although the material is expensive and fragile, optical detection (e.g. UV-vis spectrophotometry (Boskovic and Loebbecke, 2008;Adeosun and Lawal, 2009;Günther et al, 2004;Kurt et al, 2015), fluorescence techniques (Lohse et al, 2008)) is very often used in microreactors because the response time of the sensors is of some hundred milliseconds. Moreover, these methods can be non-intrusive as far as the detection zone is transparent.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…Therefore, to ensure a fast contact between reactants, these technologies are commonly designed according to complex geometries in order to intensify mixing despite laminar flow. It results in particular hydrodynamic behaviours (Amador et al, 2008;Boskovic and Loebbecke, 2008;Moreau et al, 2015) that need to be characterized in order to detect possible flow defaults. Global hydrodynamic characterization of reactors also gives information about the global hydrodynamic behaviour of a device (from the plug flow to the perfectly stirred tank character) for an adequate modelling of the reactor (Levenspiel, 1999).…”

Section: Introductionmentioning

confidence: 99%

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A new numerical method for axial dispersion characterization in microreactors

Moreau¹,

Raimondi²,

Sauze³

et al. 2017

Chemical Engineering Science

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new numerical method for axial dispersion characterization in microreactors.(2017) Chemical Engineering Science, vol. 168. pp. 178-188. ISSN 0009-2509 Open Archive TOULOUSE Archive Ouverte (OATAO) OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. h i g h l i g h t sAn innovative numerical method for axial dispersion characterization is proposed. The method is validated thanks to a RTD experiment in a microchannel. The method is applied to rectangular millimetric wavy channels. The impact of the channel geometry on the axial dispersion coefficient is studied. Keywords:Axial dispersion Numerical method CFD simulations Microreactor Wavy channel a s t r a c t Axial dispersion is a key phenomenon in reactor engineering that can affect yield and selectivity when reactions are carried out. Therefore its characterization is necessary for an adequate modelling of the reactor. The development of compact reactors to fit with process intensification expectations requires the use of characterization methods adapted to small-scale devices. An original method not-frequently used up to now for the estimation of axial dispersion coefficients is presented and applied to millimetric wavy channels. It is based on CFD simulations to calculate velocity and concentration fields from which axial dispersion coefficient can be estimated. This method is used to predict the impact of the wavy channel geometry and of the fluid velocity on axial dispersion in laminar flow regime. The investigated geometrical parameters are the hydraulic diameter (2-4 mm), the cross-sectional aspect ratio defined as the ratio between the channel width and its depth (0.25-1) and the internal curvature radius of the bends (2-3.4 mm). The range of Reynolds number considered is Re = 70-1 600. Axial dispersion coefficient increases with velocity, values range from 2.8 Á 10 À4 to 3.2 Á 10 À3 m 2 Ás À1. It appears that axial dispersion varies slightly in function of the channel hydraulic diameter. Square wavy channels generate less axial dispersion than rectangular wavy ones. Finally, axial dispersion coefficient increases with the internal curvature radius which shows the positive impact of sharp bends to reduce axial dispersion effect.

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Section: Experimental Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A new numerical method for axial dispersion characterization in microreactors

Moreau¹,

Raimondi²,

Sauze³

et al. 2017

Chemical Engineering Science

View full text Add to dashboard Cite

show abstract

“…These larger systems are more conducive for performing tracer measurements, and many reactor geometries have associated analytical solutions [13,14]. The application of RTD in microchemical processing technology has been investigated by various groups over the last 10 years [15][16][17][18][19][20], yet this remains a relatively new application and more work is necessary to understand the potential utility of this approach.…”

Section: Introductionmentioning

confidence: 99%

“…RTD in a retention reactor and coaxial heat exchanger in a commerical microreactor was investigated for improving processing time control [18]. Bošković and Loebbecke investigated the RTD in three different micromixers [19] and Bošković et al followed this work with an investigation of three microreactor designs that utilize different passive mixing structures: a 3-D serpentine structure, a split-and-recombine structure, and a staggered herringbone structure [20]. Adeosun and Lawal investigated laminar flow mixing behavior in a T-junction microchannel [21] and a MEMS-based mutilaminated/elongational flow micromixer using RTDs [22].…”

Section: Introductionmentioning

confidence: 99%

Characterization of Microchannel Hemodialyzers Using Residence Time Distribution Analysis

Coblyn¹,

Truszkowska²

2016

J Flow Chem

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Microchannel-based hemodialysis has a potential to improve survival rates and quality of life for end-stage renal disease patients compared to conventional hemodialysis technology. Characterization of hydrodynamic behavior in microchannel geometries is necessary for improving flow uniformity, a critical challenge in realizing a commercial device. A test loop was developed for measuring the impulse response of a tracer dye injected into a dialyzer test article for the purpose of developing residence time distributions (RTD) to characterize lamina design. RTD variance tended to lower for designs that are more dominated, volume-wise, by the microchannel array versus the headers. RTD results also emphasize how defect issues can significantly impact a microchannel device via discrepancies between conceptual and operational devices. A multisegmented CFD model, developed for pairing with the impulse response test loop and dialyzer, showed good agreement between visual observation of the tracer in simulations and experiments, and the shape and peak of the output profiles.

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“…Since micromixers are available in a great variety of geometries using different mixing principles, the selection of a suitable device for a given application becomes more challenging. Among various characteristics (like efficiency, energy loss) the knowledge of the RTD of a certain microfluidic device would be a useful help to identify the most appropriate one [12].…”

Section: Introductionmentioning

confidence: 99%

Computational Design and Experimental Validation of SAR Mixers

2016

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Abstract. In this study, two novel split and recombine (SAR) 'H-C' and 'Y-Y' micromixers along with a known SAR 'Chain' mixer are presented. The efficiency and pressure drop at Reynolds numbers (Re) up to 100 were investigated numerically as well as experimentally. Numerical and experimental values of mixing efficiency and pressure drop coincide considerably, which validate the numerical model. Results show that the mixing efficiency of the Chain mixer is good only at Re≥50 and the pressure drop is relatively high, whereas the H-C and the Y-Y mixers give a mixing efficiency higher than 90% over all the range of Reynolds numbers examined and their energy requirement is less than that of the Chain mixer. Furthermore, numerical residence time distribution (RTD) was explored, which successfully predicts the experimental results.

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Modelling of the residence time distribution in micromixers

Cited by 85 publications

References 18 publications

A new numerical method for axial dispersion characterization in microreactors

A new numerical method for axial dispersion characterization in microreactors

Characterization of Microchannel Hemodialyzers Using Residence Time Distribution Analysis

Computational Design and Experimental Validation of SAR Mixers

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