Speaker
Description
Dissolution and exsolution processes are key mechanisms to constrain when partially-soluble fluids exist together within the confined architecture of a porous medium. This scenario is prevalent in engineered and natural processes; e.g. air-water flows in the vadose zone, remediation of non-aqueous phase liquids (NAPLs) in groundwater and soil environments, storage of hydrogen and carbon dioxide gases in water-filled subsurface reservoirs, geologic hydrogen generation, and gas production in electrolyzers. In these examples, the primary objective is to understand the flow and fate of the non-aqueous phase, which is also often the non-wetting phase. Mass transfer of NAPLs and gases is complex, reliant on the phase distributions and aqueous flow fields that ultimately determine the local (pore-scale) concentration fields driving mass redistribution; these dynamic features are difficult to observe experimentally, especially within visually opaque media such as soils and rocks.
We present experimental results quantifying mass transfer kinetics between gas and water within porous media via multiple imaging methods: X-ray microcomputed tomography (X-ray $\mu$CT), planar laser-induced fluorescence (PLIF), and visible-range (conventional color-change) pH/concentration indicators. We highlight advantages and drawbacks of different approaches with emphasis on appropriate experimental conditions, and the array of information obtainable via various methodologies and analytical pipelines. We demonstrate how these techniques enable new observations of couplings between mass transfer processes and multiphase flow physics, focusing on (1) dissolution-induced ganglia destabilization and redistribution, and (2) how NAPL invasion into heterogeneities is affected by partial solubility.
| Country | United States |
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