Moisture Profiles Determination During Convective Drying Using X-Ray Microtomography

Authors

  • Angélique Léonard,

    Corresponding author
    1. Laboratory of Chemical Engineering, Department of Applied Chemistry, University of Liège, Building B6c-Sart Tilman, 4000 Liège, Belgium
    • Laboratory of Chemical Engineering, Department of Applied Chemistry, University of Liège, Building B6c-Sart Tilman, 4000 Liège, Belgium
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  • Silvia Blacher,

    1. Laboratory of Chemical Engineering, Department of Applied Chemistry, University of Liège, Building B6c-Sart Tilman, 4000 Liège, Belgium
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  • Pierre Marchot,

    1. Laboratory of Chemical Engineering, Department of Applied Chemistry, University of Liège, Building B6c-Sart Tilman, 4000 Liège, Belgium
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  • Jean-Paul Pirard,

    1. Laboratory of Chemical Engineering, Department of Applied Chemistry, University of Liège, Building B6c-Sart Tilman, 4000 Liège, Belgium
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  • Michel Crine

    1. Laboratory of Chemical Engineering, Department of Applied Chemistry, University of Liège, Building B6c-Sart Tilman, 4000 Liège, Belgium
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Abstract

The knowledge of internal moisture profiles which develop during drying is essential for model validation purposes, but they are difficult to determine experimentally. This paper shows that X-ray microtomography, together with image analysis, provides an accurate, non destructive and easy to use technique to determine moisture profiles. Results reported concern the drying of wastewater sludges whose management is becoming a real environmental challenge. An analysis of the development of moisture gradients at the sample external wall shows an influence of drying operating conditions. Finally, mass diffusion coefficients are estimated from the knowledge of both the moisture gradients and the drying flux.

Abstract

La connaissance des profils d'humidité internes se développant durant le séchage est essentielle pour la validation de modèles de simulation, mais ils sont difficilement accessibles expérimentalement. La microtomographie à rayons X, couplée à l'analyse d'images, permet de les mesurer d'une manière précise, aisée et non destructive. Ceci est illustré dans le cas du séchage de boues d'épuration, dont la gestion va devenir cruciale. Une relation entre les conditions opératoires et le développement de gradients à la paroi est mise en évidence. La connaissance du flux de séchage et des gradients à la paroi permet une estimation du coefficient de diffusion interne.

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