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Efflorescence fairy ring and salt centripetal colonization at the surface of a drying porous medium containing a salt solution. Impact on drying curve

Dueñas Velasco, Mauricio and Duru, Paul and Marcoux, Manuel and Prat, Marc Efflorescence fairy ring and salt centripetal colonization at the surface of a drying porous medium containing a salt solution. Impact on drying curve. (2013) In: 4th European Drying Conference (EuroDrying'2013), 2 October 2013 - 4 October 2013 (Paris, France). (Unpublished)

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Abstract

We study experimentally the drying of sintered glass porous pellets initially saturated with a sodium chloride solution. The objective is to develop a better understanding of the interplay between evaporation, ions transport and crystallization. The focus is on the characterization of the drying kinetic and its dependence on the development of salt crystals at the porous media surface. Together with analysis of the drying curves in relation with direct visualizations of the sample surface, quantitative pieces of information on the efflorescence growth and structure are obtained from X-ray computed tomography imaging. The study shows that markedly different results are obtained depending on the mean pore size of pellet. This is explained by the completely different efflorescence structure resulting from the drying process. A very thin salt crust is obtained for sufficiently small pores whereas cauliflower like efflorescence structures are obtained for sufficiently large pores. The salt crust tends to severely reduce the evaporation rate whereas the cauliflower like efflorescence does not affect the evaporation rate compared to pure water drying as long as the efflorescence is wet. In the case of the cauliflower type, the X-ray computed tomography images indicate a greater efflorescence growth at the periphery of the porous medium surface. The analysis of the data also suggests that the mean pore size in the efflorescence is significantly smaller than in the underlying porous medium.

Item Type:Conference or Workshop Item (Paper)
Audience (conference):International conference without published proceedings
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UPS (FRANCE)
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Deposited By: Mauricio DUEÑAS VELASCO
Deposited On:28 Feb 2014 13:33

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