Analysis of gas differential diffusion through porous media using prompt gamma activation analysis
| dc.contributor.advisor | Deinert, Mark | |
| dc.creator | Rios-Perez, Carlos Alfredo, 1981- | en |
| dc.date.accessioned | 2014-03-03T16:40:10Z | en |
| dc.date.issued | 2013-12 | en |
| dc.date.submitted | December 2013 | en |
| dc.date.updated | 2014-03-03T16:40:11Z | en |
| dc.description | text | en |
| dc.description.abstract | Accurate estimates for the molecular transport coefficients are critical to predicting the movement of gases in geological media. Here I present a novel methodology for using prompt gamma activation analysis to measure the effective diffusivity of noble gases in a porous medium. I also present a model to estimate the connectivity parameter of a soil from measurements of its saturated conductivity, macro porosity, and pore volume and pore surface fractal dimensions. Experiments with argon or xenon diffusing through a nitrogen saturated geological media were conducted. The noble gas concentration variations at its source were measured using prompt gamma activation analysis and later compared to a numerical diffusion model to estimate the effective diffusion coefficient. Numerical simulations using the estimated diffusivity and the experimental argon data produced results with a correlation parameter R² = 0.98. However, neglecting transport mechanisms other than diffusion largely under-predicted the xenon depletion rates observed during the first hours of experiment. To explain these results, a second model was developed which included the effect of pressure gradients and bulk convection that might arise from the faster molecular migration of the light species in a non-equimolar system and gravitational currents. Finally, the fractal model developed for this dissertation was used to estimate the connectivity parameters and walking fractal dimension of a group of geological samples that were previously characterized. This model successfully predicted positive connectivity factors and walking fractal dimensions between two and three for every sample analyzed. | en |
| dc.description.department | Mechanical Engineering | en |
| dc.embargo.lift | 12/1/2014 | en |
| dc.embargo.terms | 12/1/2014 | en |
| dc.format.mimetype | application/pdf | en |
| dc.identifier.uri | http://hdl.handle.net/2152/23383 | en |
| dc.subject | Prompt gamma activation analysis | en |
| dc.subject | Differential diffusion | en |
| dc.subject | Fractals | en |
| dc.subject | Connectivity parameter | en |
| dc.title | Analysis of gas differential diffusion through porous media using prompt gamma activation analysis | en |
| dc.type | Thesis | en |
| thesis.degree.department | Mechanical Engineering | en |
| thesis.degree.discipline | Mechanical Engineering | en |
| thesis.degree.grantor | The University of Texas at Austin | en |
| thesis.degree.level | Doctoral | en |
| thesis.degree.name | Doctor of Philosophy | en |
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