Mixed Convection

Nield, D. A.; Bejan, Adrian

doi:10.1007/978-1-4614-5541-7_8

Cited by 6 publications

(7 citation statements)

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“…In heterogeneous reservoirs it is difficult to define a suitable mean permeability, k, and we use the geometric mean for each cored well. Estimates of Ra for the NE segment are below 20 and therefore the same order of magnitude as Ra c in simple porous media (17). Given the additional perturbations provided by heterogeneity and complex geometry, buoyancy-driven convection is possible in the NE segment, but the expected convective flux is small for Ra ≈ Ra c .…”

Section: Discussionmentioning

confidence: 87%

“…Advective mass transport is possible, if the increase in brine density with aqueous CO 2 concentration destabilizes the diffusive boundary layer beneath the gas-water contact and induces convective overturn in the brine (10,13,15). It is therefore necessary to understand the occurrence and rate of convective overturn in the brine, which are determined by the balance of advective and diffusive mass transport, expressed by the Rayleigh number (16,17). Most work on convective CO 2 dissolution has focused on idealized homogeneous Significance Carbon capture and geological storage allow immediate and significant reductions in CO 2 emissions from fossil fuels.…”

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confidence: 99%

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Constraints on the Magnitude and Rate of CO2 Dissolution at Bravo Dome Natural Gas Field

Sathaye

Hesse

2014

Proceedings

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The injection of carbon dioxide (CO 2 ) captured at large point sources into deep saline aquifers can significantly reduce anthropogenic CO 2 emissions from fossil fuels. Dissolution of the injected CO 2 into the formation brine is a trapping mechanism that helps to ensure the long-term security of geological CO 2 storage. We use thermochronology to estimate the timing of CO 2 emplacement at Bravo Dome, a large natural CO 2 field at a depth of 700 m in New Mexico. Together with estimates of the total mass loss from the field we present, to our knowledge, the first constraints on the magnitude, mechanisms, and rates of CO 2 dissolution on millennial timescales. Apatite (U-Th)/He thermochronology records heating of the Bravo Dome reservoir due to the emplacement of hot volcanic gases 1.2-1.5 Ma. The CO 2 accumulation is therefore significantly older than previous estimates of 10 ka, which demonstrates that safe long-term geological CO 2 storage is possible. Integrating geophysical and geochemical data, we estimate that 1.3 Gt CO 2 are currently stored at Bravo Dome, but that only 22% of the emplaced CO 2 has dissolved into the brine over 1.2 My. Roughly 40% of the dissolution occurred during the emplacement. The CO 2 dissolved after emplacement exceeds the amount expected from diffusion and provides field evidence for convective dissolution with a rate of 0.1 g/(m 2 y). The similarity between Bravo Dome and major US saline aquifers suggests that significant amounts of CO 2 are likely to dissolve during injection at US storage sites, but that convective dissolution is unlikely to trap all injected CO 2 on the 10-ky timescale typically considered for storage projects.geological carbon storage | thermochronology | noble gases | porous media convection | carbon sequestration C arbon capture and storage has been identified as a potential technology for reductions in carbon dioxide (CO 2 ) emissions from coal-and natural gas-fired power plants. CO 2 that would otherwise be released into the atmosphere is captured at power plants and injected into porous geological formations for permanent storage. Carbon capture and storage has the potential for significant reductions of anthropogenic CO 2 emissions, because deep saline aquifers provide large storage volumes (1, 2) and existing operations have demonstrated that CO 2 injection and monitoring in saline aquifers are feasible (3).The leakage of CO 2 from the storage formation into potable aquifers or back into the atmosphere is an inherent risk of largescale geological CO 2 storage (4-6). Long-term storage security is therefore enhanced by physical and chemical processes that increasingly trap the injected CO 2 in the subsurface over time. Injected CO 2 can be trapped by capillary forces through the formation of disconnected ganglia or by precipitation as solid phases (7-9). Dissolution of CO 2 into the brine not only is a required first step for the subsequent permanent trapping in stable minerals, but also is considered a trapping mechanism itself. The density of the brin...

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Section: Discussionmentioning

confidence: 87%

mentioning

confidence: 99%

Constraints on the Magnitude and Rate of CO2 Dissolution at Bravo Dome Natural Gas Field

Sathaye

Hesse

2014

Proceedings

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“…For instance, hydrodynamic pressure can generate a convective flow across a porous sample (8), but the high pressure required to generate the flow can deform fragile samples such as soft tissues or polymeric materials (9). An electric field can drive electrophoresis of charged particles through a porous sample (10), but if the sample contains charged molecules, the electric field can also damage the sample.…”

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confidence: 99%

Stochastic electrotransport selectively enhances the transport of highly electromobile molecules

Kim

Cho

Murray

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

209

235

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Nondestructive chemical processing of porous samples such as fixed biological tissues typically relies on molecular diffusion. Diffusion into a porous structure is a slow process that significantly delays completion of chemical processing. Here, we present a novel electrokinetic method termed stochastic electrotransport for rapid nondestructive processing of porous samples. This method uses a rotational electric field to selectively disperse highly electromobile molecules throughout a porous sample without displacing the low-electromobility molecules that constitute the sample. Using computational models, we show that stochastic electrotransport can rapidly disperse electromobile molecules in a porous medium. We apply this method to completely clear mouse organs within 1-3 days and to stain them with nuclear dyes, proteins, and antibodies within 1 day. Our results demonstrate the potential of stochastic electrotransport to process large and dense tissue samples that were previously infeasible in time when relying on diffusion.stochastic electrotransport | molecular transport | tissue clearing | tissue labeling | CLARITY

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“…3 and 2 respectively. For problems involving heat transport, if the convective term dominates over the diffusive term, the solution of the energy transport equation typically contains interior and boundary layers and its solution by the Galerkin finite-element technique is usually globally unstable (Nield and Bejan, 2012). Numerical instabilities which take the form of spurious oscillations around sharp gradients and boundary layers and likely lead to nonconvergent solutions have been observed to occur independent of the level of mesh refinement (Diersch and Kolditz, 1998).…”

Section: Nonlinearities and Their Stabilizationmentioning

confidence: 99%

Flexible parallel implicit modelling of coupled thermal–hydraulic–mechanical processes in fractured rocks

Cacace

Jacquey

2017

Solid Earth

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Abstract. Theory and numerical implementation describing groundwater flow and the transport of heat and solute mass in fully saturated fractured rocks with elasto-plastic mechanical feedbacks are developed. In our formulation, fractures are considered as being of lower dimension than the hosting deformable porous rock and we consider their hydraulic and mechanical apertures as scaling parameters to ensure continuous exchange of fluid mass and energy within the fracturesolid matrix system. The coupled system of equations is implemented in a new simulator code that makes use of a Galerkin finite-element technique. The code builds on a flexible, object-oriented numerical framework (MOOSE, Multiphysics Object Oriented Simulation Environment) which provides an extensive scalable parallel and implicit coupling to solve for the multiphysics problem. The governing equations of groundwater flow, heat and mass transport, and rock deformation are solved in a weak sense (either by classical Newton-Raphson or by free Jacobian inexact NewtonKrylow schemes) on an underlying unstructured mesh. Nonlinear feedbacks among the active processes are enforced by considering evolving fluid and rock properties depending on the thermo-hydro-mechanical state of the system and the local structure, i.e. degree of connectivity, of the fracture system. A suite of applications is presented to illustrate the flexibility and capability of the new simulator to address problems of increasing complexity and occurring at different spatial (from centimetres to tens of kilometres) and temporal scales (from minutes to hundreds of years).

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Mixed Convection

Cited by 6 publications

References 366 publications

Constraints on the Magnitude and Rate of CO2 Dissolution at Bravo Dome Natural Gas Field

Constraints on the Magnitude and Rate of CO2 Dissolution at Bravo Dome Natural Gas Field

Stochastic electrotransport selectively enhances the transport of highly electromobile molecules

Flexible parallel implicit modelling of coupled thermal–hydraulic–mechanical processes in fractured rocks

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