Abstract
One-dimensional drying of a porous building material is modelled as a nonlinear diffusion process. The most difficult case of strong surface drying when an internal drying front is created is treated in particular. Simple analytical formulae for the drying front and moisture profiles during second stage drying are obtained when the hydraulic diffusivity is known. The analysis demonstrates the origin of the constant drying front speed observed elsewhere experimentally. Application of the formulae is illustrated for an exponential diffusivity and applied to the drying of a fired clay brick.
Résumé
Le séchage d'un matériau poreux est décrit par l'équation de diffusion non linéaire. Pour un coefficient de diffusion donné, des formules analytiques simples sont obtenues pour les profils hydriques et pour le front de séchage. Le cas, difficile à traiter, où la surface du matériau est éventuellement sèche, est considéré en détail. L'analyse montre l'origine de la vitesse constante du front de séchage, qui a été observée dans des études expérimentales indépendantes. L'application des formules au séchage d'une brique d'argile est illustrée pour un coefficient de diffusion qui dépend exponentiellement du contenu hydrique.
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Lockington, D.A., Parlange, J.Y., Barry, D.A. et al. Drying of porous building materials: hydraulic diffusivity and front propagation. Mat. Struct. 36, 448–452 (2003). https://doi.org/10.1007/BF02481524
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DOI: https://doi.org/10.1007/BF02481524