Experimental study and modelling of the water phase change kinetics in soils

Anne-Laure Lozano (1) , Fabien Cherblanc (1) , Bruno Cousin (2) , Jean-Claude Benet (2)

1 LMGC - Laboratoire de Mécanique et Génie Civil
2 CGB - Couplages en Géomécanique et Biomécanique

When dealing with porous media, the liquid-gas phase-change is generally considered instantaneous, while a retardation time is observed in the case of hygroscopic soils. So far, little research has been done to characterize the non-equilibrium behaviour of water phase change. Therefore, we propose a macroscopic model of the liquid-gas phase-change rate in porous media, based on the difference of chemical potentials between the liquid and its vapour, which is taken as the driving force. It introduces a phenomenological coefficient that must be determined experimentally. An original experiment able to create a macroscopic non-equilibrium between the liquid and its vapour is described. Analysing the return to equilibrium leads to the determination of the phenomenological phase-change coefficient. Depending on the range of partial vapour pressure, two different behaviours are observed: a linear domain close to equilibrium and a non-linear one far from equilibrium. The results emphasize the relation between water retention properties in hygroscopic porous media and this phase-change characteristics.

Domaines: Ingénierie de l'environnement; Milieux fluides et réactifs

Anne-Laure Lozano, Fabien Cherblanc, Bruno Cousin, Jean-Claude Benet. Experimental study and modelling of the water phase change kinetics in soils. European Journal of Soil Science, 2008, 59 (5), pp.939-949. ⟨10.1111/j.1365-2389.2008.01050.x⟩. ⟨hal-00449677⟩