http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Three dimensional semi-analytical simulation of multiple well soil vapor extraction
3-d semi-analytical simulation of multiple well soil vapor extraction
xiv, 204 leaves : illustrations ; 28 cm.
Volatile organic compounds are essential chemical agents in various industrial processes. As they are being used in many applications, improper disposal of these compounds create a serious environmental problem and a threat to public health. Soil vapor extraction is considered to be a cost-effective and less time-consuming technique for removal of VOCs from the subsurface. However, the design of the extraction system is still based on empirical rules of thumb and subjective professional engineering judgment. Expensive pilot test is often required to determine the feasibility of the technique and the optimum system operation parameters. Therefore, engineering design tools are needed to estimate the performance of SVE. In this dissertation, a mathematical formulation and a numerical simulation model for vapor extraction processes are developed. The contaminated domain is first discretized into small nonoverlapping control volumes. In order to improve the computation efficiency, the control volumes are discretized with variable size. More refined grids are used near the extraction wells to capture the rapid change in pressure within this area. Larger control volumes are used to cover the area that is further away from wells. The node is defined at the center of each control volume. The partial differential equation describing the pressure distribution induced by multiple well is solved by principle of superposition. It is based on the analytical solutions for a partially screened well. The differential equation describing the vapor transport within the unsaturated zone is solved numerically using the discretization method, in which the differential equation is integrated over the control volume. The subsurface environmental conditions and the physicochemical properties of the contaminants are used as input parameters and the model can estimate the required engineering properties. Validity of the numerical scheme is evaluated by comparing the solutions with special cases of contaminant transport with known solutions. The model can thus provide the essential tools to understand the principle of transport behavior of VOCs in porous medium and removal mechanisms of VOCs from the subsurface. Sensitivity analyses provide a deeper insight into the factors affecting the effectiveness of the operation. As a result, feasibility of the technique can be assessed for various environmental conditions and different contaminants.
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