Fundamental Changes in In Situ Air Sparging How Patterns |
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| Authors: | Michael C Brooks William R Wise Michael D Annable |
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| Institution: | Michael C. Brooks is a Ph.D. student in the Department of Environmental Engineering Sciences at the University of Florida (A.P. Black Hall, P.O. Box 116450, Gainesville, FL 32611-6450). He is a registered professional engineer in the state of Florida, and has worked in the environmental consulting industry for approximately five years. He is currently involved with several research projects related to ground water remediation.;William R. Wise is an associate professor in the Department of Environmental Engineering Sciences at the University of Florida. He holds M.S.E. and Ph.D. degrees in civil engineering from The University of Texas at Austin and a B.A. degree in chemical physics and environmental science from Rice University. Dr. Wise's research interests include the study of pore-scale phenomena and how they influence hydrologic processes.;Michael D. Annable has been a faculty member in the Department of Environmental Engineering Sciences at the University of Florida for five years. He received his Ph.D. from Michigan State University working on soil vapor extraction of multi-component nonaqueous phase liquids. His current interests are in physical-chemical processes related to field-scale application of innovative technologies for subsurface remediation. He is currently involved in a number of interdisciplinary research and education efforts in hydrologic sciences at the University of Florida. |
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| Abstract: | Two types of gas-phase flow patterns have been discussed and observed in the in situ air sparging (ISAS) literature: bubble flow and air channels. A critical factor affecting the flow pattern at a given location is the grain size of the porous medium. Visualization experiments reported in the literature indicate that a change in the flow pattern occurs around 1 to 2 mm grain diameters, with air channels occurring below the transition size and bubbles above. Analysis of capillary and buoyancy forces suggests that for a given gas-liquid-solid system, there is a critical size that dictates the dominant force, and the dominant force will in turn dictate the flow pattern. The dominant forces, and consequently the two-phase flow patterns, were characterized using a Bond number modified with the porous media aspect ratio (pore throat to pore body ratio). Laboratory experiments were conducted to observe flow patterns as a function of porous media size and air flow rate. The experimental results and the modified Bond number analysis support the relationship of flow patterns to grain size reported in the literature. |
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