The dissolution and microfluidic mass transfer of carbon dioxide in water at high-pressure conditions are crucial for a myriad of technological applications, including microreactors, extractions, and carbon capture, utilization, and sequestration (CCUS) processes. In this experimental work, we use a high-pressure microfluidic method to elucidate the mass transfer process of CO2 in water at high pressure. An intriguing multiphase CO2 flow and dispersions are observed when operating at the pressure-temperature ($P$-$T$) condition close to the CO2 gas-liquid phase boundary ($P=6.5$ MPa and $T=23.5\pm 0.5~^{\circ}$C). We propose a series of strategies to unravel this complex multi-phase dynamics by calculating each phase's volume and mass change in a gas-liquid coexistent CO2 dispersion, estimating the possible CO2 concentration change in water, and comparing with the CO2 solubility data. Finally, we quantify the CO2 mass transfer by directly calculating the CO2 dissolution rate in water and estimating the volumetric mass transfer coefficient ($k_{L}a$). The results show that the mass transfer may be influenced by the specific area ($a$), CO2 concentration gradient in the water slug, and the traveling speed of a dispersion.
We show, using a model coupling mass transport and liquid theory calculations for a charge-stabilized colloidal dispersion, that diffusion significantly limits measurement times of its Equation Of State (EOS), osmotic pressure vs composition, using the osmotic compression technique. Following this result, we present a microfluidic chip allowing one to measure the entire EOS of a charged dispersion at the nanoliter scale in a few hours. We also show that time-resolved analyses of relaxation to equilibrium in this microfluidic experiment lead to direct estimates of the collective diffusion coeff…
Transport in multiphase flow through porous media plays a central role in many biological, geological, and engineered systems. Here, we use numerical simulations of transport in immiscible two-phase flow to investigate dispersion in multiphase porous media flow. While dispersion in the main flow direction is similar to that of a single-phase flow and is governed by the porous media structure, we find that transverse dispersion exhibits fundamentally different dynamics. The repeated activation and deactivation of different flow pathways under the effect of capillary forces lead to intermittent …
We consider Taylor dispersion for tracer particles in micro-fluidic planar channels with strong confinement. In this context, the channel walls modify the local diffusivity tensor and also interactions between the tracer particles and the walls become important. We provide a simple and general formula for the effective diffusion constant along the channel as well as the first non-trivial finite time correction for arbitrary flows along the channel, arbitrary interaction potentials with the walls and arbitrary expressions for the diffusion tensor. The formula are in particular amenable to a str…
Chaotic flows drive mixing and efficient transport in fluids, as well as the associated beautiful complex patterns familiar to us from our every day life experience. Generating such flows at small scales where viscosity takes over is highly challenging from both the theoretical and engineering perspectives. This can be overcome by introducing a minuscule amount of long flexible polymers, resulting in a chaotic flow dubbed \textit{elastic turbulence}. At the basis of the theoretical frameworks for its study lie the assumptions of a spatially smooth and random-in-time velocity field. Previous me…
We formulate a model for the dynamic growth of a membrane developing in a flow as the result of a precipitation reaction, a situation inspired by recent microfluidic experiments. The precipitating solid introduces additional forces on the fluid and eventually forms a membrane that is fixed in the flow due to adhesion with a substrate. A key challenge is that the location of the immobile membrane is unknown $\textit{a priori}$. To model this situation, we use a multiphase framework with fluid and membrane phases; the aqueous chemicals exist as scalar fields that react within the fluid to induce…
Mineral dissolution in porous media coupled with single- or multi-phase flows is pervasive in natural and engineering systems including carbon capture and sequestration (CCS) and acid stimulation in reservoir engineering. Dissolution of minerals occurs as chemicals in the solid phase is transformed into ions in the aqueous phase, effectively modifying the physical, hydrological and geochemical properties of the solid matrix, and thus leading to the strong coupling between local dissolution rate and pore-scale flow. However, our fundamental understanding of this coupling effect at the pore leve…
University of Cambridge（剑桥大学）；Univ. Bordeaux, CNRS, LOMA（波尔多大学，法国国家科学研究中心，LOMA实验室）；Gulliver UMR 7083 CNRS, ESPCI–PSL（法国国家科学研究中心Gulliver联合研究单位7083，巴黎高等物理化工学院-巴黎文理研究大学）
Solute dispersion in magnetically influenced multiphase flow through a porous tube: axial transport and microrotational effects
Cooch Behar Panchanan Barma University（古奇比哈尔潘查南·巴尔马大学）；SRM Institute of Science and Technology（SRM科学技术研究所）；University of Galway（高威大学）；Indian Institute of Technology Hyderabad（印度理工学院海得拉巴分校）
Microfluidics technology offers high efficiency of heat and mass transfer and low safety hazards compared to conventional multiphase processes. The multiphase flow in the microchannels is usually characterized as Taylor flow that includes elongated microbubbles , separated by liquid slugs. In the current study, we employ OpenFOAM CFD package to investigate the effect of the surface tension and the contact angle on the interfacial surface area and transport yield in microscale systems. The results show that contact angle can significantly affect the surface area and the bubble size while the su…
In this work, we study the role of viscoelastic instability in the mechanical dispersion of fluid flow through porous media at high Peclet numbers. Using microfluidic experiments and numerical simulations, we show that viscoelastic instability in flow through a hexagonally ordered (staggered) medium strongly enhances dispersion transverse to the mean flow direction with increasing Weissenberg number (Wi). In contrast, preferential flow paths can quench the elastic instability in disordered media, which has two important consequences for transport: First, the lack of chaotic velocity fluctuatio…
Viscous and gravitational fingering refer to flow instabilities in porous media that are triggered by adverse mobility or density ratios, respectively. These instabilities have been studied extensively in the past for 1) single-phase flow (e.g., contaminant transport in groundwater, first-contact-miscible displacement of oil by gas in hydrocarbon production), and 2) multi-phase immiscible and incompressible flow (e.g., water-alternating-gas (WAG) injection in oil reservoirs). Fingering in multiphase compositional and compressible flow has received much less attention, perhaps due to its high c…
Revealing mesoscale bubble and particle dynamics in ultrasound-driven multiphase fluids by ultrafast synchrotron X-ray radiography and hybrid modelling
The accurate representation of surface tension driven flows in multiphase systems is considered a challenging problem to resolve numerically. Although there have been extensive works in the past that have presented approaches to resolve these so called Marangoni flows at the phase boundaries, the question of how to efficiently resolve the interface in a universal and conservative manner remains largely open in comparison. Such problems are of high practical relevance in many manufacturing processes, especially in the microfluidic regime where capillary effects dominate the local force equilibr…
Using thermodynamic and variational principles we examine a basic phase field model for a mixture of two incompressible fluids in strongly perforated domains. With the help of the multiple scale method with drift and our recently introduced splitting strategy for Ginzburg-Landau/Cahn-Hilliard-type equations [Schmuck et al., Proc. R. Soc. A 468:3705-3724, 2012.], we rigorously derive an effective macroscopic phase field formulation under the assumption of periodic flow and a sufficiently large Péclet number. As for classical convection-diffusion problems, we obtain systematically diffusion-disp…
Speed of sound is a key parameter for the compressibility effects in multiphase flow. We present a new approach to do direct numerical simulations on the speed of sound in compressible two-phase flow, based on the stratified multiphase flow model (Chang & Liou, JCP 2007). In this method, each face is divided into gas-gas, gas-liquid, and liquid-liquid parts via reconstruction of volume fraction, and the corresponding fluxes are calculated by Riemann solvers. Viscosity and heat transfer models are included. The effects of frequency (below the natural frequency of bubbles), volume fraction, visc…
Idaho National Laboratory（爱达荷国家实验室）；Massachusetts Institute of Technology（麻省理工学院）；North Carolina State University（北卡罗来纳州立大学）
Multiphase flow phenomena have been widely observed in the industrial applications, yet it remains a challenging unsolved problem. Three-dimensional computational fluid dynamics (CFD) approaches resolve of the flow fields on finer spatial and temporal scales, which can complement dedicated experimental study. However, closures must be introduced to reflect the underlying physics in multiphase flow. Among them, the interfacial forces, including drag, lift, turbulent-dispersion and wall-lubrication forces, play an important role in bubble distribution and migration in liquid-vapor two-phase flow…
The multiphase flow mechanism in miscible displacement through porous media is an important topic in various applications, such as petroleum engineering, low Reynolds number suspension flows, dusty gas dynamics, and fluidized beds. To simulate such flows, volume averaging spatial operators are considered to incorporate pressure drag and skin friction experienced by a porous medium. In this work, a streamline-based Lagrangian methodology is extended for an efficient numerical approach to handle dispersion and diffusion of solvent saturation during a miscible flow. Overall pressure drag on the d…
