Magnetic Resonance Imaging Measurements of Mass and Energy Transport: Oxygen transport in microbially impacted porous media and energy transport by forced and natural convection in packed beds

Abstract:

Magnetic resonance imaging (MRI) methods are well established for determining porous media pore fluid velocity and hydrodynamic dispersion. Recently the use of dual frequency ¹H/¹⁹F MRI has been demonstrated to allow simultaneous characterization of pore fluid dynamics and scalar transport to the particulate packed bed phase. Oxygen transport imaging in microbially impacted porous media composed of alginate gel particles with dispersed fluorinated (¹⁹F) hydrocarbons show the interplay of pore fluid water (¹H) velocity and microbial growth. The change in oxygen transport with chemical challenges of the microbes is visualized. MRI of energy transport is achieved using core shell particles of alkane phase change materials (PCM’s) to construct packed beds. The flow of fluorinated (¹⁹F) pore fluids in a range of thermodynamic phases, from liquid (fluorinert oil) to gas, near-critical and supercritical (C₂F₆), allows the study of forced and natural convection energy transport. Of particular interest is the broad range of natural convection flow conditions obtainable in near-critical fluids where compressibility becomes important and energy transport mechanisms vary.