Effects of the geothermal gradient on the convective dissolution in CO<sub>2</sub>sequestration

Hu, Cheng-Yu; Xu, Ke; Yang, Yantao

doi:10.1017/jfm.2023.349

Cited by 4 publications

(1 citation statement)

References 45 publications

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“…For instance, in case of iso-thermal brine transport, fluid volume changes may be neglected when Ra ρr /∆ρ ≫ 1, being ∆ρ the maximum density difference and ρr the reference fluid density. Interestingly, this condition is independent of ∆ρ and it is widely fulfilled for geothermal processes, when Ra ≈ 10 1 − 10 3 and ρ r /∆ρ ≈ 10 2 − 10 3 [147]. Numerical simulations of the fully compressible CO 2 sequestration process suggest that compressibility and non-Boussinesq effects do not significantly impact spreading and mixing [90].…”

Section: Additional Effects Influencing Mixingmentioning

confidence: 96%

Convective mixing in porous media: a review of Darcy, pore-scale and Hele-Shaw studies

De Paoli

2023

Eur. Phys. J. E

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Convection-driven porous media flows are common in industrial processes and in nature. The multiscale and multiphase character of these systems and the inherent nonlinear flow dynamics make convection in porous media a complex phenomenon. As a result, a combination of different complementary approaches, namely theory, simulations and experiments, have been deployed to elucidate the intricate physics of convection in porous media. In this work, we review recent findings on mixing in fluid-saturated porous media convection. We focus on the dissolution of a heavy fluid layer into a lighter one, and we consider different flow configurations. We present Darcy, pore-scale and Hele-Shaw investigations inspired by geophysical processes. While the results obtained for Darcy flows match the dissolution behaviour predicted theoretically, Hele-Shaw and pore-scale investigations reveal a different and tangled scenario in which finite-size effects play a key role. Finally, we present recent numerical and experimental developments and we highlight possible future research directions. The findings reviewed in this work will be crucial to make reliable predictions about the long-term behaviour of dissolution and mixing in engineering and natural processes, which are required to tackle societal challenges such as climate change mitigation and energy transition. Graphic abstract

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Section: Additional Effects Influencing Mixingmentioning

confidence: 96%

Convective mixing in porous media: a review of Darcy, pore-scale and Hele-Shaw studies

De Paoli

2023

Eur. Phys. J. E

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Pore-scale study of CO₂ desublimation and sublimation in a packed bed during cryogenic carbon capture

Lei,

Luo,

Hernández Pérez

et al. 2024

J. Fluid Mech.

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Cryogenic carbon capture (CCC) is an innovative technology to desublimate $\text {CO}_2$ out of industrial flue gases. A comprehensive understanding of $\text {CO}_2$ desublimation and sublimation is essential for widespread application of CCC, which is highly challenging due to the complex physics behind. In this work, a lattice Boltzmann (LB) model is proposed to study $\text {CO}_2$ desublimation and sublimation for different operating conditions, including the bed temperature (subcooling degree $\Delta T_s$ ), gas feed rate (Péclet number $Pe $ ) and bed porosity ( $\psi$ ). The $\text {CO}_2$ desublimation and sublimation properties are reproduced. Interactions between convective $\text {CO}_2$ supply and desublimation/sublimation intensity are analysed. In the single-grain case, $Pe $ is suggested to exceed a critical value $Pe _c$ at each $\Delta T_s$ to avoid the convection-limited regime. Beyond $Pe _c$ , the $\text {CO}_2$ capture rate ( $v_c$ ) grows monotonically with $\Delta T_s$ , indicating a desublimation-limited regime. In the packed bed case, multiple grains render the convective $\text {CO}_2$ supply insufficient and make CCC operate under the convection-limited mechanism. Besides, in small- $\Delta T_s$ and high- $Pe $ tests, $\text {CO}_2$ desublimation becomes insufficient compared with convective $\text {CO}_2$ supply, thus introducing the desublimation-limited regime with severe $\text {CO}_2$ capture capacity loss ( $\eta _d$ ). Moreover, large $\psi$ enhances gas mobility while decreasing cold grain volume. A moderate porosity $\psi _c$ is recommended for improving the $\text {CO}_2$ capture performance. By analysing $v_c$ and $\eta _d$ , regime diagrams are proposed in $\Delta T_s$ – $Pe $ space to show distributions of convection-limited and desublimation-limited regimes, thus suggesting optimal conditions for efficient $\text {CO}_2$ capture. This work develops a viable LB model to examine CCC under extensive operating conditions, contributing to facilitating its application.

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Double-diffusive convection with gravitationally unstable temperature and concentration gradients in homogeneous and heterogeneous porous media

Hu,

Yang

2024

J. Fluid Mech.

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Geothermal gradients and heterogeneous permeability are commonly observed in natural geological formations for underground CO $_2$ sequestration. In this study, we conduct three-dimensional direct numerical simulations on the double-diffusive convection with both unstable temperature and concentration gradients in homogeneous and heterogeneous porous media. For homogeneous porous media, the root-mean-squared velocity increases linearly with density ratio defined as the buoyancy ratio by temperature and concentration differences. The flow structures show no remarkable changes when temperature Rayleigh number ${Ra}_T$ is less than its critical value, but alter from sheet-like to cellular structures as ${Ra}_T$ surpasses this threshold. The concentration wavenumber scales approximately as $k_{rS}\sim {Ra}_e^{0.47}$ with a defined effective Rayleigh number ${Ra}_e$ . By using a scale analysis, the concentration flux exhibits a consistent linear relation with the total driving forces for all simulations. For heterogeneous porous media, where the Dykstra–Parsons coefficient $V_{DP}$ and correlation length $l_{r}$ determine the spatial distribution of the permeability field, the flow is strengthened in places with higher permeability. The velocity and concentration flux are less affected by $l_{r}$ than that by $V_{DP}$ . For small correlation length, the flow structures coarsen and their characteristic width generally increases with increasing heterogeneity. For large correlation length, small structures emerge in the regions with large permeability, which can be attributed to the intensified local Rayleigh number triggering more vigorous convection there. The variations of concentration flux with $l_{r}$ and $V_{DP}$ can be explained by the portion of area covered by high concentration with large vertical velocity near the boundaries.

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Effects of the geothermal gradient on the convective dissolution in CO₂sequestration

Cited by 4 publications

References 45 publications

Convective mixing in porous media: a review of Darcy, pore-scale and Hele-Shaw studies

Convective mixing in porous media: a review of Darcy, pore-scale and Hele-Shaw studies

Pore-scale study of CO₂ desublimation and sublimation in a packed bed during cryogenic carbon capture

Double-diffusive convection with gravitationally unstable temperature and concentration gradients in homogeneous and heterogeneous porous media

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Effects of the geothermal gradient on the convective dissolution in CO2sequestration

Cited by 4 publications

References 45 publications

Convective mixing in porous media: a review of Darcy, pore-scale and Hele-Shaw studies

Convective mixing in porous media: a review of Darcy, pore-scale and Hele-Shaw studies

Pore-scale study of CO2 desublimation and sublimation in a packed bed during cryogenic carbon capture

Double-diffusive convection with gravitationally unstable temperature and concentration gradients in homogeneous and heterogeneous porous media

Contact Info

Product

Resources

About

Effects of the geothermal gradient on the convective dissolution in CO₂sequestration

Pore-scale study of CO₂ desublimation and sublimation in a packed bed during cryogenic carbon capture