NON-ISOTHERMAL MODELING OF SOIL VAPOR EXTRACTION SYSTEM INCLUDING SOIL TEMPERATURE EFFECT
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Abstract
Soil vapor extraction (SVE) is a proven effective in-situ technology for the removal of volatile
organic compounds (VOCs) from the subsurface. SVE process is highly sensitive to temperature.
Studying annual soil temperature variation with depth declares that there is a considerable temperature
variation in the upper few meters that may affect the overall efficiency of SVE process.
A numerical model was developed to aid in investigation of field-scale soil vapor extraction
process. The model is three-dimensional, time dependent that simulates nonisothermal vapor flow and
transport of multicomponent mixtures in soil and keeps track of the distribution of each compound in
the other three immobile phases (NAPL, aqueous, and sorbed). Rate limited interphase mass transfer
with linear driving force expressions were used to model volatilization of oil into gas phase. A local
equilibrium partitioning was assumed between gas, water, and solid phase. The model equations were
discretized using a standard Galerkin finite element method and solved using set iterative solution
algorithm.
Simulation of hypothetical field-scale problems was done. The physical domain described a threedimensional
system with flow to a single extraction well. A hypothetical soil temperature variation
with depth was incorporated with the model. The result of these simulations showed that this
temperature variation has a considerable effect on system efficiency and may play a role in optimum
system configuration.
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