Theses and Dissertations at Montana State University (MSU)

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An experimental study of drying in porous media in novel 2D micromodels with dual porosity
(Montana State University - Bozeman, College of Engineering, 2024) Habib, Md Ahsan; Chairperson, Graduate Committee: Yaofa Li
Drying of porous media is pervasive in numerous natural and engineering processes, such as oil recovery, CO 2 storage, and critical zone science. Drying is essentially a multiphase flow process, where the liquid phase evaporates and is displaced/replaced by the gaseous phases, as vapor diffuses out of the porous structure. In terms of pore structure and other physical characteristics like porosity and permeability, many porous matrices exhibit multi-scale heterogeneity. For instance, in critical zone, soil is often viewed as a hierarchical organization: primary particles form aggregates, which in turn form macroaggregates, effectively leading to a dual-porosity medium. Numerous activities, including gases and water transport, are known to be controlled by the resultant multiscale flow dynamics and inter-/intra-aggregate interaction during drying. However, the fundamental physics underlying drying of porous media with dual porosity is not well understood from a fluid mechanics perspective. In this work, a novel 2D microfluidic device fabrication technique has been developed. To study the multi-phase flow of air and water, emphasizing the multi-scale interaction, pore structure, and role of film flows, three distinct types of microfluidic devices have been fabricated, which bear the innovative three-layer glass-silicon- glass architecture, providing precise structural control and excellent optical access from both top and bottom. An innovative dual-magnification imaging technique has been introduced adapted for micro-PIV and epi-fluorescent microscopy which offers insightful information about the flow dynamics at both the micro- and macro-scales concurrently. In this thesis, two distinct types of experiments are outlined, focusing on diffusion-driven drying and flow-through drying, utilizing three diverse micromodels characterized by varying porous structures and distributions. The experimental results have presented the overall drying dynamics observed in different micromodels, each featuring unique porous configurations. The impact of porous geometry and external flow conditions on drying rate and associated pore-scale physics is thoroughly examined. The findings encompass a comprehensive overview of micro-macro pore interactions, as evidenced by separated saturation distribution, displacement rates, and other pertinent flow parameters. The findings have reflected the influence of pore geometry, distribution, hydraulic connectivity, and film flow on the observed effects.
NMR characterization of unfrozen brine vein distribution and structure in frozen systems
(Montana State University - Bozeman, College of Engineering, 2022) Lei, Peng; Chairperson, Graduate Committee: Sarah L. Codd; This is a manuscript style paper that includes co-authored chapters.
The liquid vein network (LVN) that forms in the interface of ice crystals or particles exists in frozen porous media due to the freezing point depression. The distribution and structure of the LVNs are dynamic due to the ice recrystallization phenomenon. In ice alone, the LVNs formed by the ice crystal interfaces can be characterized as a porous medium in terms of surface to volume ratio (SV /) and the tortuosity (alpha).The presence of solid particles or ice-binding proteins (IBPs) make the frozen system much more complex. The research presented uses nuclear magnetic resonance (NMR) experimental techniques, including magnetic resonance imaging (MRI), relaxation and self-diffusion measurements, to study the development of the LVNs in complex frozen systems containing solid particles or IBPs. Poly-methyl methacrylate (PMMA) particles of diameters 0.4, 9.9, and 102.2 microns are used with brine solution concentrations of 15, 30, and 60 mM Magnesium chloride (MgCl 2) to simulate complex frozen systems. The dynamic rearrangement with time of LVNs can be studied as a function of temperature, MgCl 2 concentration, and PMMA particle size. The results indicate that small solid particles dominate the structure dynamics while in larger solid particle packed beds the solute effect dominates. This behavior is quantified by determination of SV / and alpha from NMR relaxation and diffusion data. Additionally, IBP produced from the V3519-10 organism isolated from the Vostok ice core in Antarctica is added to ice samples frozen from 30, 60 and 120 mM MgCl 2 solution to investigate its influence on LVNs over months of aging. The interplay of the solute and biological effects is complicated but it appears the biological effect is more pronounced at lower salt concentrations. The data provide a basis for eventual combination of salt, IBP and solid particulate studies. The result of MRI, relaxation and self-diffusion measurements indicate the inhibition of ice recrystallization as a function of particle size, MgCl 2 concentration and the presence of IBP. The non-invasive data presented along with calibration of the relaxation experiments with self-diffusion experiments, demonstrate the continued extension of NMR techniques developed from porous media to frozen porous media and ice LVN structure.
Experimental characterization of pore-scale capillary pressure and corner film flow in 2D porous micromodels
(Montana State University - Bozeman, College of Engineering, 2023) Molla, Razin Sazzad; Chairperson, Graduate Committee: Yaofa Li
Multiphase flow in porous media is ubiquitous in natural and engineering processes. A better understanding of the underlying pore-scale physics is crucial to effectively guiding, predicting and improving these applications. Traditional models describe multiphase flows in porous media based on empirical constitutive relations (e.g., capillary pressure vs. saturation), which, however, are known to be hysteretic. It has been theoretically shown that the hysteresis can be mitigated by adding new variables in the functional form. However, experiments are still needed to validate and further develop the theories. In particular, our understanding of capillary pressure characterization and numerous pore-scale mechanisms is still limited. For instance, during capillary pressure measurement, fluid phases become disconnected, making the bulk pressure an inaccurate measure for the actual capillary pressure. In a strongly wetting medium, wetting phase always remains connected by corner films, through which trapped water continues to drain until a capillary equilibrium is reached, but the effects of corner film flow are minimally characterized. In this thesis, two different experiments are presented. In the first experiment, we focused on the capillary pressure characterization and the effect of measurement resolution. Microscopic capillary pressure along with other geometric measures are characterized during drainage and imbibition. By strategically varying the pressure at the boundary, different equilibrium states were achieved and imaged at four different magnifications (i.e., 2, 1.25, 0.5, 0.25 micron/pixel). In the second experiment, we for the first time characterized the corner film flow again during drainage and imbibition condition employing particle image velocimetry. Overall, our results suggest that the calculated macroscale pressure P c and the bulk pressure drop agree reasonably well when only interfaces associated with the connected phases are considered. A spatial resolution of 2 micron/pixel seems to sufficiently resolve the interface, and further increasing the resolution does not have a significant impact on the results. Additionally, corner film flow was found to be an active transport mechanism. During drainage, trapped water is continuously drained over time via thin film, whereas during imbibition snap-off events are enhanced by wetting films. These observations call for future studies to carefully treat corner film flows when developing new predictive models.
A structural analysis of zeolite-templated carbons
(Montana State University - Bozeman, College of Letters & Science, 2022) Taylor, Erin Elizabeth; Chairperson, Graduate Committee: Nicholas P. Stadie
Zeolite-templated carbons (ZTCs) are a distinct class of porous framework materials comprised of a three-dimensional pore network contained between atomically thin, polycyclic hydrocarbon walls. This class of materials arose from the goal to develop carbon- based frameworks with ordered, homogeneous microporosity (see Chapter 1), as opposed to activated carbons where the pore network is random. It has more recently been suggested that zeolite-templating may be a viable synthetic route to carbon schwarzites, an elusive class of theoretical materials, which follow triply periodic minimal surfaces and are predicted to have many fundamentally interesting properties. Herein we show that while experimentally synthesized ZTCs (see Chapters 2 and 3) are too amorphous to be considered schwarzites, understanding the current structural features of ZTCs may be the key to finally isolating a schwarzite via zeolite-templating. The experimentally relevant open- blade model developed in our work predicts paramagnetism of ZTC materials (see Chapter 5); superconducting quantum interference device measurements on archetypical ZTC materials confirms this prediction, highlighting the unique nature of spin polarization in porous carbon materials. While the current ZTC structure resembles an open-blade, generating a closed- tube schwarzite-like ZTC variant may be accessible by tuning the catalytic activity of the zeolite template pore walls. In Chapter 6, alkali metal exchange is explored as a route to strengthen cation-? interactions between the growing ZTC framework and zeolite template in an attempt to achieve a more schwarzite-like ZTC. LiY-templated ZTCs show beginning signs of conversion to a closed-tube structure. Lastly, recent benchmark computational studies suggest that nitrogen-doping of open-blade porous carbon surfaces has a significant, beneficial effect on the binding energy toward methane: a strengthening by up to 3 kJ mol -1 over pure carbon. The work presented in Chapter 7 identifies optimal conditions to achieve nitrogen-doped ZTCs with N-contents ranging from 0-9 at%. Therein, we show that indeed high-pressure (100 bar) methane adsorption characterization of nitrogen-doped ZTCs exhibit an increased methane binding energy of 1.3 kJ mol -1, validating the theoretical predictions.
Design and fabrication of membrane-based pressure sensor for capillary pressure measurement in micromodels
(Montana State University - Bozeman, College of Engineering, 2021) Raventhiran, Nishagar; Chairperson, Graduate Committee: Yaofa Li
Pressure is a fundamental quantity in virtually all problems in fluid dynamics from macro-scale to micro/nano scale flows. Although technologies are well developed for its measurement at the macro-scale, pressure quantification at the microscale is still not trivial. Yet, precise pressure mapping at microscale such as in microfluidics is imperative in a variety of applications, including porous media flows and biomedical engineering. In particular, pore-scale capillary pressure is a defining variable in multiphase flow in porous media and has rarely been directly measured. To that end, this study aims to design and fabricate an on-chip sensor that enables quantification of capillary pressure in microfluidic porous media, called micromodels. The micromodel is fabricated in polydimethylsiloxane (PDMS) using soft lithography with a thin membrane incorporated that deflects with pressure variations in the fluid flow. Employing a microscope coupled with a high-speed camera and the astigmatism particle tracking principle, precise pressure measurement is achieved with an accuracy of ~ 60Pa. This sensor is then applied to characterize the viscous pressure drop in single phase flows, and the capillary pressure in a water-air multiphase in microchannels, and good agreement is obtained between the sensor measurement, theoretical values and measurements employing a commercial pressure transducer. This thesis provides a novel method for in-situ quantification of local pressure and potentially 2D pressure field in microfluidics and thus opens the door to a renewed understanding of pore-scale physics of multiphase flow in porous media.
A study of bio-mineralization for the application of reducing leakage potential of geologically stored CO 2
(Montana State University - Bozeman, College of Engineering, 2019) Daily, Ryanne Leigh; Chairperson, Graduate Committee: Adrienne Phillips
A primary concern of carbon capture and storage (CCS) is leakage of the stored carbon dioxide (CO 2) from the subsurface back to the surface. To ensure long term storage of the CO 2, mitigation strategies are being developed to seal high permeability regions, such as fractures present in the caprock or the near wellbore environment. Ureolysis induced calcium carbonate precipitation (UICP) is a widely investigated technology utilizing the enzymatically driven process of ureolysis to alter the properties of porous media. The advantage of this technology over traditional fracture sealing methods, such as well cement, is the use of low-viscosity aqueous fluids enabling access to smaller fractures. However, CCS reservoirs provide a problematic environment for microbial activity due to the acidity of dissolved CO 2, high pressures, and elevated temperatures. A flow-through pressurized reactor experiment and batch high-pressure ureolysis rate experiments were conducted to investigate the application of UICP technology to mitigate CO 2 migration. First, UICP was induced in two composite rock cores in an environment simulating a CCS reservoir, using a high-pressure axial flow reactor, with an initial and final exposure of the rock cores to a carbonated brine. As a result of UICP, the apparent permeability of the rock cores were reduced by 5-orders of magnitude. The CO 2 challenge increased apparent permeability by 4-orders of magnitude, likely due to a preferential flow path created through the calcium carbonate (CaCO 3) seal, which was found with X-ray microcomputed tomography (micro-CT) imaging. The porosity of the composite rock cores was assessed throughout the experiment with two non-invasive technologies, micro-CT and nuclear magnetic resonance (NMR), both reported a significant decrease in porosity due to UICP and a slight increase after the CO 2 exposure. Second, ureolysis kinetics were assessed in the presence of a pressurized carbonated brine at pressures between 0 and 4 MPa. The kinetic studies were performed in a high-pressure batch reactor connected to high-pressure pH and conductivity probes. Samples could not be taken from the batch reactor without losing pressure; thus, conductivity was used as a surrogate measurement for urea concentration. It was found that, for the pressures tested, JBM urease was capable of hydrolyzing urea in the presence of a pressurized carbonated brine. It was also hypothesized that the rate observed at each experimental pressure may have been dependent on the buffered pH of the system. The combination of these studies suggests that, if the challenge of dissolution could be overcome, bio-mineralization may be used to enhance CCS by reducing the permeability of CO 2 leakage pathways.
Nuclear magnetic resonance studies to characterize phase transitions in porous systems
(Montana State University - Bozeman, College of Engineering, 2018) Thrane, Linn Winsnes; Chairperson, Graduate Committee: Sarah L. Codd; Emily A. Berglund, James N. Wilking, David Vodak and Joseph D. Seymour were co-authors of the article, 'NMR relaxometry to characterize drug structural phase in a porous construct' in the journal 'Molecular pharmaceutics' which is contained within this thesis.; Sarah L. Codd and Joseph D. Seymour were co-authors of the article, 'Probing molecular dynamics during hydrate formation by high field NMR relaxometry and diffusometry' submitted to the journal 'Journal of magnetic resonance' which is contained within this thesis.; Ryanne L. Daily, Abby Thane, Catherine M. Kirkland, Evan R. McCarney, Robin Dykstra, Sarah L. Codd and Adrienne J. Phillips were co-authors of the article, 'Detecting microbially induced calcite precipitation in porous systems using low-field nuclear magnetic resonance relaxometry' submitted to the journal 'Environmental science & technology' which is contained within this thesis.
Nuclear magnetic resonance (NMR) allows for in-situ non-invasive studies of a wide range of systems at microscopic time and length scales. NMR relaxometry and diffusometry techniques along with magnetic resonance imaging (MRI) are applied to explore and characterize various phase transitions in complex systems. NMR techniques are highly sensitive to the thermodynamic phase of the system as well as restrictions on molecular motion, and the ability to detect and monitor phase transitions non-invasively is of great interest for various industrial applications NMR frequency spectra and 1D T 2 relaxation measurements are used to characterize the presence of an amorphous drug and its liquid-solid phase transition. T 1- T 2 magnetic relaxation correlation experiments monitor the impact of long-time storage at high relative humidity on the drug in a porous silica tablet. The results indicate the ability of non-solid-state NMR to characterize crystalline and amorphous solid structural phases, and the potential for drug quality control by NMR methods. High resolution MRI along with T 1-T 2 magnetic relaxation correlation experiments and pulsed gradient stimulated echo (PGStE) NMR methods are demonstrated to characterize hydrate formation. MRI monitors the spatial heterogeneity of the system as well as local hydrate growth rates. Using T 1-T 2 correlation NMR and spectrally resolved diffusometry, the transition from mobile to restricted dynamics is observed simultaneously for both water and cyclopentane throughout the hydrate formation process. The combination of these MR techniques allows for exploration of the complex molecular dynamics involved in hydrate formation processes. Using a low-field NMR system, microbially induced calcite precipitation (MICP) processes in granular media are explored by means of 1D T 2 relaxation measurements. The 1D T 2 distributions allowed for in-situ monitoring of the mineral precipitation progress and indicates decrease in total pore volume and a significant change in the surface mineralogy of the granular media. The results confirm the potential for detailed characterization of MICP progression in engineering applications. Ultimately, NMR is demonstrated as an effective method for detecting, characterizing, and monitoring several distinct phase transitions at various time- and length-scales.
Crystal pressure of pharmaceuticals in nanoscale pores
(Montana State University - Bozeman, College of Engineering, 2017) Berglund, Emily Anne; Chairperson, Graduate Committee: James Wilking
Many pharmaceutical compounds are poorly soluble in water. This is problematic because most pharmaceuticals are delivered orally and must dissolve in the gastrointestinal fluid to be absorbed by the body. Drug dissolution rate is proportional to surface area, so a common formulation strategy is to structure drugs as small as possible to maximize surface area. A simple approach to create very small particles is to structure the compounds within the nanoscale pore space of a colloidal packing. The resulting composite undergoes rapid disintegration in water and the exposed drug exhibits dramatically improved dissolution rates. We hypothesize that composite breakup is driven by the growth of nanoscale crystals, which exert a pressure on the walls of the confining pores. To test this hypothesis, we systematically vary the amount of water permitted into the composite and use calorimetry to monitor the evolution of the crystal size distribution as a function of water content. To exert sufficient pressure to overcome the tensile yield stress of the composite, the crystals must be fed by a supersaturated phase. Our results suggest that differences in crystal curvature due to crystal confinement and crystal size polydispersity generate the necessary supersaturation. These results are relevant not just for drug formulations, but for understanding physical processes such as salt damage to buildings and road damage due to frost heave.
The interstitial fluid pressure response during stress-relaxation of articular cartilage due to viscosity and porous media effects: a computational study
(Montana State University - Bozeman, College of Engineering, 2018) Paschke, Brandon James; Chairperson, Graduate Committee: Erick Johnson
Articular cartilage is a complex material made of several fluid and solid components. A model that fully describes the responses of cartilage is required to accurately create a cartilage replacement that can be used in cases of injury or disease. Modeling of articular cartilage has proven difficult and currently no constitutive law fully describes its solid and fluid responses. Many of the current models describe the interstitial fluid as inviscid, even though it is known that proteoglycan migration within cartilage causes a viscous response within interstitial fluid. The goal of this research was to create a viscous fluid porous media model that better captures the compressive resistance of cartilage created by migration of interstitial fluid during cartilage compression. Through the creation of this model it was possible to capture the experimental magnitudes of fluid pressure within cartilage during unconfined slow compression simulations. As part of this model, a porous media approximation was used, which demonstrates that small variations in the solid matrix, comprised of collagen fibers, can cause large variations in system response. Magnitudes of mean pressure values, after 150 seconds of compression, for the viscous fluid porous media model bound the values found in experimental testing. Limitations of the fluid model are that system relaxation isn't captured and the slope increase of pressures during compression for experiments don't match those of the fluid model. A main conclusion drawn from the model is that viscosity of interstitial fluid plays a large role in creating compressive resistance within articular cartilage. Another takeaway is that the porous media approximation greatly impacts the magnitude of fluid pressurization, which creates a need to accurately represent the solid matrix within cartilage.
Magnetic resonance studies of fluid transport in porous systems and medical devices
(Montana State University - Bozeman, College of Engineering, 2017) Nybo, Elmira; Chairperson, Graduate Committee: Sarah L. Codd; Joseph D. Seymour (co-chair)
This research describes the application of nuclear magnetic resonance (NMR) techniques for non-invasive investigation of fluid transport and hydrodynamics in porous systems and medical devices. NMR microscopy is used to obtain information about internal structures and transport properties in porous materials and opaque systems. Controlling dispersion within restricted pore spaces is of importance in a variety of applications including soil consolidation and dewatering and electromigration of solutes. NMR pulsed gradient stimulated echo (PGSTE) techniques combined with electroosmotic flow (EOF) are used to study diffusion and dispersion coefficients in model glass bead packs. The results show that significant EOF-induced backflow can cause structural changes and alter the flow. Understanding the transport of liquids in porous materials during the application of electrical field holds promise for solving problems involving the delivery of binding agents to infill the pore space in rigid cement-based structures via electroosmosis. NMR PGSTE techniques and micro-CT scan imaging were used to study fluid transport and structural changes in a hydrating cement paste in a closed cell. It is shown that EOF in closed cement paste samples caused a significant increase in macroscopic void volume compared to closed samples with no flow. Needleless connectors (NCs) are commonly used medical devices with complicated internal design that leads to flow complexity that may cause undesirable bacterial deposition and biofilm formation. Magnetic resonance imaging (MRI) is applied to acquire spatial velocity maps of fluid flow at various positions within the devices. MRI velocimetry is demonstrated as an effective method to quantify flow patterns and fluid dynamic dependence on structural features of NCs. Alginate and alginate-based materials find an increasing interest in environmental engineering as adsorbents for heavy metal recovery from aqueous solutions. A Ca 2+ and Cu 2+ containing fluid flow through calcium-based alginate gel has been visualized using NMR velocimetry. NMR indicated velocity changes in gel capillaries caused by ion exchange processes and followed gel structural changes. NMR microscopy is shown as an effective method to describe fluid transport and internal structural features in opaque porous systems and medical devices.

Theses and Dissertations at Montana State University (MSU)

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