A new model for hydrodynamics and mass transfer of hydrated bubble rising in deep water

Sun, Xiaohui; Sun, Baojiang; Wang, Zhiyuan; Chen, Litao; Gao, Yonghai

doi:10.1016/j.ces.2017.07.040

Cited by 18 publications

(15 citation statements)

References 40 publications

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“…Experimental evidence of the existence of this hydrate shell is presented for static systems [25][26][27][28] , but has never been presented for non-static systems due to the lack of instrumentation capable of tracking one single particle along the flow during the time-scale a particle takes to initially form and grow. Recent studies in flowing systems put in question the stability of the formed shell, with probable splitting and rearrangement of the particles into a hydrate-water-oil network [29][30][31] , which in a macro-scale form a cream/gel-like non-Newtonian mixture 32,33 (see as well videos published by Chen et al 29 ). Shell formation is associated to heterogeneous kinetics (that is, the existence of a preferential growth direction) and is reasonable in the point-of-view that hydrates will mostly grow tangentially over the droplet, where contact between water and gas is facilitated.…”

Section: Introductionmentioning

confidence: 99%

A Multiscale Approach for Gas Hydrates Considering Structure, Agglomeration, and Transportability under Multiphase Flow Conditions: I. Phenomenological Model

Bassani

Melchuna

Cameirão

et al. 2019

Ind. Eng. Chem. Res.

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A new topological model on how gas hydrates form, grow, and agglomerate for oil and water continuous flow, with and without surfactant additives, is presented. A multiscale approach is used to explain how the porous structure of gas hydrates and the affinity between the phases affect the particle morphology and their agglomeration. We propose that gas consumption due to hydrate growth happens mostly in the water trapped inside the capillaries of the hydrate structure near the outer surface of the particles. This approach is herein referred to as the “sponge approach” and is treated as a surface problem, instead of the volume problem often treated in literature (the “shell approach”). Affinity between phases (which in a macro point of view is interpreted as a wetted angle that gives rise to capillarity forces and that can be changed by the use of surfactant additives) describes the preferential entrapment of oil or water inside the hydrate sponge structure. Yet by splitting agglomeration into smaller processes and depending on the morphology of the particles and on the evolution of the porous structure of the hydrates, (i) capillarity bridges may form, causing particles to be sticky, and (ii) water may be available at the outer surface of the particles and may promote consolidation of particle–particle (agglomeration) or particle-wall (deposition). The settling of slurries is treated as a separated solid–liquid flow instability problem once mixture deceleration (due to phase consumption during crystallization) and particle size (due to growth and agglomeration) are known. We also propose a new explanation on how surfactants act as anti-agglomerants in oil continuous flow, differently from the common DLVO theory used in literature, which can only explain anti-agglomeration of particles much smaller than the ones formed over droplets of a very fine dispersion flow.

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Section: Introductionmentioning

confidence: 99%

A Multiscale Approach for Gas Hydrates Considering Structure, Agglomeration, and Transportability under Multiphase Flow Conditions: I. Phenomenological Model

Bassani

Melchuna

Cameirão

et al. 2019

Ind. Eng. Chem. Res.

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“…The general expression for mass transfer models is as follows:

\frac{d δ}{d t} = K Δ C / δ

where t is the hydrate growth time, s; δ is the hydrate film thickness, m; K represents the mass transfer parameter; and Δ C represents the driving force. K is the coefficient of gas diffusion in hydrates for the gas diffusion models, while it is the geometric parameter of porous hydrates for water permeation models . Δ C is the difference in gas concentrations for the gas diffusion models, while it is the capillary force for water permeation models.…”

Section: Vertical Growth Of Hydrate Shellmentioning

confidence: 99%

Research on the heat and mass transfer mechanisms for growth of hydrate shell from gas bubbles

et al. 2019

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As a fundamental study for hydrate utilization technologies, hydrate growth is a complicated rate‐limiting process controlled by heat and mass transfer mechanisms. Generally, the experimental data of hydrate shell lateral growth in the literature are compiled based on the system subcooling, while those of hydrate shell vertical growth are compiled based on the molecular mobility of the hydrate formers and water. In this study, we quantitatively investigate the dominating factors for hydrate film growth considering the opposite mass or heat transfer limitations, which can explain the observed phenomena from the literature more comprehensively. Firstly, a model is derived to describe the lateral growth of hydrate shell considering the convective mass transfer and effective concentration driving force at the film front. It can demonstrate the important effects of subcooling and other system factors such as gas type, aqueous solution, and system pressure on hydrate shell lateral growth. Secondly, an improved self‐similar model is presented to simulate the process of hydrate shell thickening considering the heat transfer limitation. The simulation results indicate that the hydrate shell growth rate decreases with a decrease in the subcooling and an increase in the bubble radius.

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“…In literature, many studies addressed mass transfer phenomena in clathrate hydrate formation . In the most usual case, crystallization occurs at an interface between water and another liquid phase, acting as a reservoir of the guest species.…”

Section: Introductionmentioning

confidence: 99%

“…It is worth mentioning here the early experimental studies that addressed the crystal growth rates and mass transfer rates through the hydrate layer , , provide models , , , , , , , or perform molecular dynamics (MD) simulations , . The pioneering work of Mori and co‐workers , explored theoretically the evolution of a hydrate layer thickness at the interface between water and another non‐miscible phase of guest molecules.…”

Section: Introductionmentioning

confidence: 99%

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Crystallization Mechanisms and Rates of Cyclopentane Hydrates Formation in Brine

et al. 2019

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Clathrate hydrates most often grow at the interface between liquid water and another fluid phase (hydrocarbon) acting as a provider for the hydrate guest molecules, and some transfer through this shell is required for the hydrate growth to proceed, thus self-limiting the reaction rate. An optical microscope and a horizontal reaction cell are utilized to capture the shell growth phenomenology and to estimate the hydrate layer growth rates from sequential pictures. Cyclopentane (CP) is chosen as the hydrate-forming molecule to obtain hydrates at low pressure. Experimental hydrate layer growth rates are provided for the CP+brine system, using various combinations of salts and degrees of subcooling.

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A new model for hydrodynamics and mass transfer of hydrated bubble rising in deep water

Cited by 18 publications

References 40 publications

A Multiscale Approach for Gas Hydrates Considering Structure, Agglomeration, and Transportability under Multiphase Flow Conditions: I. Phenomenological Model

A Multiscale Approach for Gas Hydrates Considering Structure, Agglomeration, and Transportability under Multiphase Flow Conditions: I. Phenomenological Model

Research on the heat and mass transfer mechanisms for growth of hydrate shell from gas bubbles

Crystallization Mechanisms and Rates of Cyclopentane Hydrates Formation in Brine

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