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Modélisation des transferts radiatifs dans des milieux poreux non Beeriens au voisinage des parois : application aux procédés de vaporeformage de méthane

Abstract : The industrial goal of this work is to propose a radiative transfer model in a tubular reactor of steam methane reforming. During the reforming process, reactive gases are injected in the tubular reactor filled with catalytic pellets. The packed bed of pellets forms a porous medium, and a particular feature of it is that the characteristic pore size is large compared to the reactor inner dimension. In addition, the organization of the pellets in the near-wall region results in important porosity gradients which have a significant effect on the heat transfer, and more specifically on the radiative transfer. The scientific goal is to develop and validate a radiative transfer model applicable to strongly nonhomogeneous, anisotropic and non Beerian porous media. First, the radiative properties of the homogenised phase equivalent to the real porous medium are completely determined by the extinction cumulated distribution function, the phase function and the local porosity. These functions, previously introduced for statistically homogeneous and anisotropic porous media, are calculated very accurately by a Monte Carlo method. They have been extended to statistically non-homogeneous porous media. Similarly, the expression of the validity criterion of the Beer law is extended to statistically anisotropic and non homogeneous porous media : it is proven that for the considered porous media the Beer law is not valid in the homogenised phase, in particular in the vicinity of the walls. As a result, the Generalized Radiative Transfer Equation (GRTE) is needed and the emission source terms must be determined in a strongly nonhomogeneous non Beerian even at the optically thin limit : an absorption coefficient doesn’t have any physical meaning and correlations between emission and transmission appear due to the non Beerian behavior. The reciprocity principle and the properties of the extinction cumulated distribution functions allow the emission source terms in this kind of strongly non homogeneous and non Beerian media to be accurately determined. An emission-transmission correlation factor has been introduced. The GRTE has been solved by a Monte Carlo method. The complete model is applied, after validation, to the steam methane reformers in use by Air Liquide.
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Submitted on : Wednesday, July 13, 2016 - 11:59:37 AM
Last modification on : Thursday, October 14, 2021 - 9:17:04 AM


  • HAL Id : tel-01345204, version 1


Marie Zarrouati. Modélisation des transferts radiatifs dans des milieux poreux non Beeriens au voisinage des parois : application aux procédés de vaporeformage de méthane. Thermique [physics.class-ph]. Ecole Centrale Paris, 2015. Français. ⟨NNT : ⟩. ⟨tel-01345204⟩



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