Abstract
Interphase mass transfer is an important process that dominates overall transport processes in multi-fluid system in porous media. This process plays a key role during the volatilization of non-aqueous phase liquids (NAPLs) in porous media that usually takes place during the remediation process of volatile organic compounds (VOCs) using soil vapor extraction (SVE) technique. Previously, interphase mass transfer coefficient was usually lumped together with interfacial area between air and liquid because of inaccessibility to quantify the interfacial area due to the heterogeneous nature of the pore structure of the media and the morphology of the fluid distribution. An effort was made to estimate the air-liquid interfacial area in three glass beads media using surfactant adsorption concept and was found decreasing with increasing liquid saturation. A series of one-dimensional NAPL volatilization experiments were carried out in a horizontal column for the same three-glass beads media using Toluene as the contaminant. Experiments were conducted for NAPL saturation range of 13.8∼71% and a pore gas velocity of 0.1∼2 cm/s and lumped mass transfer coefficients were evaluated. Actual vapor phase mass transfer coefficients were calculated using corresponding air-liquid interfacial area for a specific NAPL saturation and was characterized in dimensionless form for all the porous media used in the study. Results showed that the vapor phase mass transfer coefficient increases with increasing pore gas velocity and grain size but decreases with increasing NAPL saturation.
