Three-dimensional numerical model for soil vapor extraction.

Mass transfer limitations impact the effectiveness of soil vapor extraction (SVE) and cause tailing. In order to identify the governing mass transfer processes, a three-dimensional SVE numerical model was developed. The developed model was based on Comsol Multiphysics a finite element method that incorporates multi-phase flow, multi-component transport and non-equilibrium transient mass transfer. Model calibration was done against experimental data from previously completed lab-scale reactor experiments. The developed model, 3D-SVE, nicely simulates laboratory findings and allows for changes in the important governing mass transfer relationships. The modeling results showed that a single averaged mass transfer value is a poor representation of the entire SVE operation, and that a transient mass transfer coefficient is required to fully represent SVE tailing. Calibration of the lab scale model showed that the most important mass transfer occurs between the NAPL and vapor phase.