Computational fluid dynamics (CFD) software tools for microfluidic applications – A case study

Selective CO removal over Au/CeFe and CeCu catalysts in microreactors studied through kinetic analysis and CFD simulations, Chemical Engineering Journal (2010), doi:10.1016/j.cej.2010.08.083 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. E-mail address: lgandia@unavarra.es (L.M. Gandía) AbstractA kinetic study of the preferential oxidation of CO in H 2 rich streams (CO-PrOx) over a cerium-copper oxide (CeCu) and a gold catalyst supported on cerium-iron oxide (Au/CeFe) is presented. The gold catalyst is very active but the CeCu oxide is more selective. A kinetic model describing the CO-PrOx system with CO 2 and H 2 O in the feed has been formulated considering the oxidation of CO and H 2 and the reverse water-gas shift reaction. The rate equations have been implemented in computational fluid dynamics codes to study the influence of the operating variables on the CO-PrOx in microchannels and microslits. TheCeCu catalyst is the only one capable of achieving final CO contents below 10-100 ppmv.Due to the opposite effect of temperature on activity and selectivity there is an optimalPage 2 of 31 A c c e p t e d M a n u s c r i p t 2 temperature at which the CO content is minimal over CeCu. This temperature varies between 170 and 200 ºC as the GHSV increases from 10 000 to 50 000 h -1. Simulations have evidenced the very good heat transfer performance of the microdevices showing that the COPrOx temperature can be controlled using air as cooling fluid although the inlet temperature and flow rate should be carefully controlled to avoid reaction extinction. Both microchannels and microslits behaved similarly. The fact that the microslits are much easier to fabricate may be an interesting advantage in favor of that geometry in this case.

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“…This code has provided satisfactory results for a variety of microfluidic problems [17][18][19][20].…”

Section: Microreactor Models and Simulation Conditionsmentioning

confidence: 94%

Selective CO removal over Au/CeFe and CeCu catalysts in microreactors studied through kinetic analysis and CFD simulations

Arzamendi

Uriz

Diéguez

et al. 2011

Chemical Engineering Journal

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“…Yuan et al 11 applied a VOF method based on a piecewise linear interface construction (PLIC) to track the liquid-vapor interface in the simulation of natural convection film boiling and forced convection film boiling on a sphere at saturated conditions. Glatzel et al 12 evaluated the performance of commercial CFD codes based on VOF method when applied as and engineering tool for microfluidic applications. Surface tension effects and flow patterning of two fluids were studied in terms of computational speed and comparison with experimental data.…”

Section: Introductionmentioning

confidence: 99%

Volume‐of‐fluid‐based model for multiphase flow in high‐pressure trickle‐bed reactor: Optimization of numerical parameters

Lopes

Quinta‐Ferreira

2009

AIChE Journal

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Aiming to understand the effect of various parameters such as liquid velocity, surface tension, and wetting phenomena, a Volume-of-Fluid (VOF) model was developed to simulate the multiphase flow in high-pressure trickle-bed reactor (TBR). As the accuracy of the simulation is largely dependent on mesh density, different mesh sizes were compared for the hydrodynamic validation of the multiphase flow model. Several model solution parameters comprising different time steps, convergence criteria and discretization schemes were examined to establish model parametric independency results. High-order differencing schemes were found to agree better with the experimental data from the literature given that its formulation includes inherently the minimization of artificial numerical dissipation. The optimum values for the numerical solution parameters were then used to evaluate the hydrodynamic predictions at highpressure demonstrating the significant influence of the gas flow rate mainly on liquid holdup rather than on two-phase pressure drop and exhibiting hysteresis in both hydrodynamic parameters. Afterwards, the VOF model was applied to evaluate successive radial planes of liquid volume fraction at different packed bed cross-sections.

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“…The formulation of the models requires the consideration of transport phenomena, thermodynamic and kinetic aspects involved in the chemical and physical process during the reaction. In this regard, the simulation and modeling based on Computational Fluid Dynamics (CFD) have attracted increasing interest and have been successfully applied to the analysis and design of micro-flow devices [15] and catalytic microreactors [16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Preferential oxidation of CO (CO-PROX) over CuOx/CeO2 coated microchannel reactor

et al. 2012

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The general aspects of the synthesis and characterization results of a CuO x /CeO 2 catalyst were presented. In addition the principal steps for manufacturing a microchannel reactor and for the coating of the CuO x /CeO 2 catalyst onto the microchannels walls, were also summarized. The catalytic activity of this microchannel reactor during the preferential oxidation of CO (CO-PROX) was evaluated employing a feed-stream that simulates a reformate off-gas after the WGS unit. Two activation atmospheres were studied (H 2 /N 2 and O 2 /N 2 ). The reducing pretreatment improved the resistance to deactivation by formation of carbonaceous species over the catalyst surface at high temperatures. The presence of H 2 O and CO 2 in the feed-stream was also analyzed indicating that the adsorption of CO 2 inhibited the conversion of CO at lower temperatures because these compounds modified the active sites through the formation of carbonaceous species on the catalyst surface. Finally, the experimental results of the microreactor performance were compared with CFD simulations that were carried out using a kinetic for the CuO x /CeO 2 powder catalyst. The experimental results were reasonably well described by the model, thus confirming its validity.

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Computational fluid dynamics (CFD) software tools for microfluidic applications – A case study

Cited by 137 publications

References 37 publications

Selective CO removal over Au/CeFe and CeCu catalysts in microreactors studied through kinetic analysis and CFD simulations

Selective CO removal over Au/CeFe and CeCu catalysts in microreactors studied through kinetic analysis and CFD simulations

Volume‐of‐fluid‐based model for multiphase flow in high‐pressure trickle‐bed reactor: Optimization of numerical parameters

Preferential oxidation of CO (CO-PROX) over CuOx/CeO2 coated microchannel reactor

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