Heat and moisture migration in porous media during remediation using superheated steam injection: A coupled experimental and numerical study

Superheated steam injection has emerged as a promising technology for effective remediation of organic contaminants in the vadose zone. However, there is still a significant lack of comprehensive studies on the superheated steam front evolution during this process, which is essential for determining the remediation zone with enhanced efficiency. To elucidate the migration behavior of superheated steam front, this study systematically integrates an experimental approach with a non-isothermal compositional two-phase flow numerical model. Using the numerical model validated by experimental data, a quantitative sensitivity analysis was performed to identify the key parameters governing the heat and moisture transfer during the superheated steam injection. Observational data indicated that thermal infrared imaging was effective in delineating the progression of both the steam condensation and superheated steam fronts. It was notably observed that the superheated steam zone formed prior to the arrival of the steam condensation front at the extraction well. The simulation results corresponded well with the data obtained from both temperature sensors and thermal imaging, affirming the validity of the simulation model. Key parameters governing the heat and moisture migration during superheated steam injection included enthalpy flux of steam, heat capacity, porosity, and residual water saturation of soil. Furthermore, enthalpy flux of injected steam, heat capacity, porosity, and permeability of soil emerged as critical determinants in the evolution of the superheated steam front. The migration of condensation water had a minimal impact on the temperature profile during steam injection, which was predominantly influenced by capillary and gravitational forces.