Study of the soil–atmosphere moisture exchanges through convective drying tests in non‐isothermal conditions |
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| Authors: | Pierre Gerard Angélique Léonard Jean‐Pierre Masekanya Robert Charlier Frédéric Collin |
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| Institution: | 1. Département ArGEnCo, Université de Liège, Chemin des Chevreuils, 1‐4000 Liège, Belgium;2. Département de Chimie Appliquée, Université de Liège, Belgium;3. Université du Burundi, Bujumbura, Burundi;4. FNRS Research Associate. |
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| Abstract: | This paper deals with the moisture exchanges occurring between soils and the surrounding atmosphere. Convective drying tests are performed on Awans silts at different drying temperatures and air relative humidities in order to reproduce the natural drying conditions. The experiments improve the understanding of the vapour transfers kinetics between the soil samples and the atmosphere. The experimental results are analysed assuming that the transfers take place in a boundary layer existing at the surface of the porous medium. The influence of the thermal conditions on the evaporation is also taken into account. In our model, coupled vapour and energy exchanges are controlled by mass and heat transfer coefficients characterizing the boundary layer. These coefficients are determined from the drying experiments. The modelling of the drying tests in non‐isothermal conditions is performed in order to validate the formulation of the vapour and heat exchanges. The numerical results present a good agreement with the kinetic of the materials desaturation determined during the tests. The analysis of the moisture transport mechanisms into the sample and at the boundary shows that at the beginning of the test, the drying is first achieved by the transport of moisture in its liquid form and its evaporation at the sample outer boundary in contact with the atmosphere. In a second step, vapour diffusion becomes predominant into the sample and it corresponds to the most important decrease of relative humidity. Copyright © 2009 John Wiley & Sons, Ltd. |
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| Keywords: | soil– atmosphere interaction vapour exchange convective drying test partially saturated modelling non‐isothermal |
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