MODELING AND EXPERIMENTAL INVESTIGATION ELF TRANSIENT, NONEQUILIBRIUMMASS-TRANSFER DURING STEAM STRIPPING OF A NONAQUEOUS PHASE LIQUID IN UNSATURATED POROUS-MEDIA

The present paper addresses the one-dimensional unsteady process of st eam stripping of the unsaturated zone of soils contaminated with nonaq ueous phase liquids (NAPLs). First, the volatilization mechanism and t he transport by steam are considered, taking the view that nonequilibr ium exists between liquid and vapor phases; second, the effect of evap oration on the specific area is taken into account. The governing equa tions are rendered dimensionless and solved in closed form. For variou s dimensionless numbers, solutions are presented, showing the role of the prevailing physical phenomena. Experiments have been performed usi ng two sand mixtures with water and NAPL saturations ranging from 24% to 44% and from 3.8% to 9.4%, respectively. The experimental results c onfirm the applicability of the theoretical model presented. Furthermo re, the analysis results in an empirical correlation for the Sherwood number valid for a broad range of Peclet numbers (2 < Pe < 60).