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Impact of the Diffusion Limitation in Microphotoreactors

Aillet, Tristan and Loubiere, Karine and Prat, Laurent E. and Dechy-Cabaret, Odile Impact of the Diffusion Limitation in Microphotoreactors. (2015) AIChE Journal, vol. 61 (n° 4). pp. 1284-1299. ISSN 0001-1541

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Official URL: http://dx.doi.org/10.1002/aic.14718

Abstract

This publication describes a model that aims (i) to predict the performances (conversion, photonic efficiency) of a photochemical reaction at the outlet of a microreactor, (ii) to quantify the effect of transverse diffusion limitations on the latter, and (iii) to propose some practical guidelines to avoid these limitations. To achieve this, a set of equations that couple mass transport, radiative transfer and kinetic equations is established and solved, considering (i) a two dimensional geometry, and (ii) a simple monomolecular photoreaction A→B, where the species A and B are in competition for absorbing incident photons. The model is expressed using classical dimensionless numbers, such as the Damköhler I and II numbers, and others describing the absorption properties of the medium (absorbance, competitive absorption factor). For that, the characteristic time of the photochemical reaction has to be defined consistently. The results show how and why, when competitive absorption exists, the occurrence of diffusion limitations (〖Da〗_II>1) can severely impact the conversion of the photochemical reaction and the photonic efficiency. Consequently, a diagram is proposed as a practical tool for selecting operating conditions (maximum photon flux received at the walls, residence time) subsequently avoiding these limitations (i.e. operation of the microreactor as a plug flow reactor).

Item Type:Article
Additional Information:Thanks to Wiley editor. The definitive version is available at http://onlinelibrary.wiley.com The original PDF of the article can be found at Wiley website : http://onlinelibrary.wiley.com/doi/10.1002/aic.14718/abstract
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UPS (FRANCE)
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Deposited By: Karine LOUBIERE
Deposited On:23 Jun 2015 13:59

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