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Molecular dynamics study of thermal diffusion in a binary mixture of alkanes trapped in a slit pore |
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| Authors: | Jean Colombani Guillaume Galliéro Bernard Duguay Jean-Paul Caltagirone François Montel Philippe A Bopp |
| Institution: | 1. Département de Physique des Matériaux (Unité Mixte de Recherche associée au CNRS 5586) , Université Claude Bernard Lyon 1 , 6 rue Ampère, Villeurbanne Cedex , F-69622 , France;2. Laboratoire MASTER , Ecole Nationale Supérieure de Chimie et Physique de Bordeaux , avenue Pey-Berland, Talence Cedex , F-33402 , France;3. Laboratoire de Physico-Chimie Moléculaire (Unité Mixte de Recherche associée au CNRS 5803) , Université Bordeaux 1 , cours de la Libération, Talence Cedex , F-33405 , France;4. Total-Fina-Elf Exploration Production , CSTJF , avenue Laribeau, Pau , F-64018 , France |
| Abstract: | We have used direct non-equilibrium molecular dynamics computer simulations to study the influence of an aluminosilicate slit pore on thermal diffusion in equimolar methane- n -decane. We have computed the Soret coefficient S T as a function of the pore width. The S T values deviate from those in a pore-free situation only for pores narrower than 35 Å. We have then investigated the possible causes for this deviation. We have noticed that the solid behaves as a thermal short circuit for the liquid but this has no consequence on the thermal and solutal profiles in the mixture. The main influence of the confinement of the liquid lies in the 'freezing' of the layer of molecules in contact with the pore walls. Outside this layer, the thermal diffusive behaviour of the mixture does not depart from that in the bulk fluid. This finding has enabled us to compute a 'corrected' Soret coefficient where the influence of the porous medium is eliminated. |
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