Publication de 12 numéros par an
ISSN Imprimer: 1091-028X
ISSN En ligne: 1934-0508
Indexed in
Ion Transport during Drying in a Porous Mediumunder High External Relative Humidity Conditions
RÉSUMÉ
Evaporation in a capillary porous medium in the presence of a dissolved salt (NaCl) is studied in relation to the problems of salt weathering, soil salinization, and drying. We concentrate on the situation where the relative humidity in the surrounding air is greater than the activity of a saturated NaCl-water solution, a situation where crystallization is not expected to occur. Combining a semianalytical model of convective drying with the numerical computation of ion transport, the impact of the presence of salt is investigated. Except for very small initial salt concentrations, it is shown that drying becomes extremely slow owing to the reduction of water activity with the NaCl concentration. In contrast, with pure water, a full drying cannot be expected. The saturation marking the end of drying is predicted from a simple mass balance. Two main situations are identified and analyzed depending on the initial salt concentration. When the initial salt concentration is above a certain critical concentration, which can be predicted from a mass balance, the liquid flux induced by capillary forces in the porous medium is always able to balance the external evaporation flux, and drying can be predicted by a relatively simple model. Below this critical concentration, prediction of drying is more involved and requires considering situations analogous to the classical falling rate period and possibly the receding front period.
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Eloukabi H., Sghaier N., Prat M., Ben Nassrallah S., Drying Experiments in a Hydrophobic Model Porous Medium in the Presence of a Dissolved Salt, Chemical Engineering & Technology, 34, 7, 2011. Crossref
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Prat M., Pore Network Models of Drying, Contact Angle, and Film Flows, Chemical Engineering & Technology, 34, 7, 2011. Crossref
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Espinosa-Marzal R. M., Scherer G. W., Mechanisms of damage by salt, Geological Society, London, Special Publications, 331, 1, 2010. Crossref