Molecular Dynamics Characterization of Temperature and Pressure Effects on the Water-Methane Interface

Mirzaeifard, Sina; Servio, Phillip; Rey, Alejandro D.

doi:10.1016/j.colcom.2018.04.004

Cited by 27 publications

(22 citation statements)

References 39 publications

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“…Figure shows that the interfacial energy decreases as we increase the temperature of the system over a wide range of pressure (5–30 MPa). Such a trend for the interfacial energy is observed for the liquid water and methane gas mixtures. ,,,− In contrast to the interfacial energy, the τ contribution increases with the system temperature. The τ values are consistent with the reported results for other crystals and metals .…”

Section: Resultsmentioning

confidence: 62%

“…A favorable interaction between the hydrogen bonds and the molecules at the interfacial zone leads to the molecular adsorption. In the liquid water–methane gas mixture, a peak in the number of hydrogen bonds has been observed to explain adsorption onto the interface. ,,, Conversely, Figure shows a minimum in the hydrogen bond density profile near the interface of the liquid water–methane clathrate mixture at the different temperature and pressure regimes. Temperature increases trigger larger thermal fluctuations at the interface that diminish the stable hydrogen-bonding network and, consequently, its favorable interaction with the bulk water molecules, which leads to less molecular adsorption and higher tension.…”

Section: Resultsmentioning

confidence: 99%

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Multiscale Modeling and Simulation of Water and Methane Hydrate Crystal Interface

Mirzaeifard

Servio

Rey

2019

Crystal Growth & Design

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Water–methane hydrate interfaces are ubiquitous in oil and gas technologies and in Nature. The structure and properties of this liquid/crystal interface plays a significant role in transport phenomena between the bulk phases. In this paper, we use molecular dynamics techniques to characterize the liquid water–crystalline methane hydrate in the bulk and, particularly, the interface. We show that the interfacial mechanical approach based on the novel constant normal pressure-cross-sectional area (NPNAT) ensemble with a computational slab length equal to the lattice parameter of the methane clathrates can accurately predict the interfacial free energy of a curved interface. Notably, the computational platform for the interfacial tension characterization includes contributions from elastic strains. In the studied temperature and pressure ranges, we find that the interfacial tension slightly increases with temperature upturn or pressure drop due to less disordered orientation and dispersed distribution of the molecules at the interface. We generate a full molecular-level characterization by computing the excess enthalpy and stress, local density profile, radial distribution function, hydrogen bonding density, and charge distribution to confirm the observed interfacial tension trend, which significantly contributes to the evolving understanding of gas hydrate formation.

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Section: Resultsmentioning

confidence: 62%

Section: Resultsmentioning

confidence: 99%

Multiscale Modeling and Simulation of Water and Methane Hydrate Crystal Interface

Mirzaeifard

Servio

Rey

2019

Crystal Growth & Design

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“…[30] Contrary to standard DFT, MD simulations can occur at reasonable temperatures, instead of 0 K. There has been remarkable success in studying gas hydrates with MD in the past, with systems ranging in size from hundreds to millions of atoms. [28,52,[54][55][56][57][58][59] MD applies classical mechanics to atomic and molecular structures. The forces acting on all the atoms are calculated, and Newton's equations are solved to calculate how the molecules move.…”

Section: Molecular Dynamicsmentioning

confidence: 99%

Recent advances in density functional theory and molecular dynamics simulation of mechanical, interfacial, and thermal properties of natural gas hydrates in Canada

et al. 2022

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Gas hydrates are inclusion compounds of a water backbone that encloses gaseous molecules. Thanks to their applications in gas recovery, carbon capture and storage, gas storage, and flow assurance, generating high quality data and predictions of their properties is paramount. A review of novel techniques using first principles density functional theory and molecular dynamics simulations methods coupled to auxiliary simulations methods is presented herein.Structure I (sI), structure II (sII), and structure H (sH) hydrates have been studied extensively, with studies of their material strength showing that it is often misleading to use the properties of ice instead of the difficult-todetermine gas hydrate properties. Key differences between the three structures and their possible guests are presented. The interfacial properties of gas hydrates display key behaviours that control nucleation and growth, which are important phases in controlling and monitoring their formation. Gas hydrate thermal properties are also examined, with key differences existing between guests and some unusual alignment in the cages shown for carbon dioxide, ethane, and ethylene oxide sI hydrates. First principles infrared spectroscopy is also examined, with techniques showing that these signatures can be tied to and predict material properties to improve the speed of analysis. Therefore, by quantifying, modelling, predicting, and explaining their formation and dissociation, and linking these to their thermal, material, and interfacial properties, a database of reliable data for science and engineering methods and applications is formed to provide a basis for further work.

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“…Molecular dynamics (MD) has also been a promising tool to investigate gas hydrate phenomena. It has been used to explore gas hydrate interfacial thickness and tension with high agreement to experimental results [ 37 ]. Additionally, MD has been used to investigate methane hydrate growth with impingement, which led to the observation of some cages being occupied by two methane molecules at the same time [ 38 ].…”

Section: Introductionmentioning

confidence: 99%

All-Atom Molecular Dynamics of Pure Water–Methane Gas Hydrate Systems under Pre-Nucleation Conditions: A Direct Comparison between Experiments and Simulations of Transport Properties for the Tip4p/Ice Water Model

et al. 2022

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(1) Background: New technologies involving gas hydrates under pre-nucleation conditions such as gas separations and storage have become more prominent. This has necessitated the characterization and modeling of the transport properties of such systems. (2) Methodology: This work explored methane hydrate systems under pre-nucleation conditions. All-atom molecular dynamics simulations were used to quantify the performance of the TIP4P/2005 and TIP4P/Ice water models to predict the viscosity, diffusivity, and thermal conductivity using various formulations. (3) Results: Molecular simulation equilibrium was robustly demonstrated using various measures. The Green–Kubo estimation of viscosity outperformed other formulations when combined with TIP4P/Ice, and the same combination outperformed all TIP4P/2005 formulations. The Green–Kubo TIP4P/Ice estimation of viscosity overestimates (by 84% on average) the viscosity of methane hydrate systems under pre-nucleation conditions across all pressures considered (0–5 MPag). The presence of methane was found to increase the average number of hydrogen bonds over time (6.7–7.8%). TIP4P/Ice methane systems were also found to have 16–19% longer hydrogen bond lifetimes over pure water systems. (4) Conclusion: An inherent limitation in the current water force field for its application in the context of transport properties estimations for methane gas hydrate systems. A re-parametrization of the current force field is suggested as a starting point. Until then, this work may serve as a characterization of the deviance in viscosity prediction.

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Molecular Dynamics Characterization of Temperature and Pressure Effects on the Water-Methane Interface

Cited by 27 publications

References 39 publications

Multiscale Modeling and Simulation of Water and Methane Hydrate Crystal Interface

Multiscale Modeling and Simulation of Water and Methane Hydrate Crystal Interface

Recent advances in density functional theory and molecular dynamics simulation of mechanical, interfacial, and thermal properties of natural gas hydrates in Canada

All-Atom Molecular Dynamics of Pure Water–Methane Gas Hydrate Systems under Pre-Nucleation Conditions: A Direct Comparison between Experiments and Simulations of Transport Properties for the Tip4p/Ice Water Model

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