Elastic moduli calculation and instability in structureI methane clathrate hydrate

Shpakov, V. P.; Tse, John S.; Tulk, C. A.; Kvamme, B.; Belosludov, V. R.

doi:10.1016/s0009-2614(97)01241-4

Cited by 80 publications

(75 citation statements)

References 18 publications

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“…The sums in the denominator include all species present in the system. Note that, even if it has been shown that the size of the cages can be reduced by ∼10−15% at low temperatures (Shpakov et al 1998;Besludov et al 2002), we assume here that this size remains fixed. In the same way, we neglect possible cage distortion due to large guests.…”

Section: Clathrate Hydrates Compositionmentioning

confidence: 99%

Clathrate hydrates as a sink of noble gases in Titan's atmosphere

Thomas¹,

Mousis²,

Ballenegger³

et al. 2007

A&A

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We use a statistical thermodynamic approach to determine the composition of clathrate hydrates which may form from a multiple compound gas whose composition is similar to that of Titan's atmosphere. Assuming that noble gases are initially present in this gas phase, we calculate the ratios of xenon, krypton and argon to species trapped in clathrate hydrates. We find that these ratios calculated for xenon and krypton are several orders of magnitude higher than in the coexisting gas at temperature and pressure conditions close to those of Titan's present atmosphere at ground level. Furthermore we show that, by contrast, argon is poorly trapped in these ices. This trapping mechanism implies that the gas-phase is progressively depleted in xenon and krypton when the coexisting clathrate hydrates form whereas the initial abundance of argon remains almost constant. Our results are thus compatible with the deficiency of Titan's atmosphere in xenon and krypton measured by the Huygens probe during its descent on January 14, 2005. However, in order to interpret the subsolar abundance of primordial Ar also revealed by Huygens, other processes that occurred either during the formation of Titan or during its evolution must be also invoked.

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Section: Clathrate Hydrates Compositionmentioning

confidence: 99%

Clathrate hydrates as a sink of noble gases in Titan's atmosphere

Thomas¹,

Mousis²,

Ballenegger³

et al. 2007

A&A

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“…In this work, we, therefore, focus on hydrates of methane and carbon dioxide and their mixtures, known to form hydrates of structure I. 8,9 Hydrate formation from methane and water can follow a number of different pathways. The most commonly discussed route is hydrate formation on the interface between the hydrate-former phase and water.…”

Section: Introductionmentioning

confidence: 99%

Impact of water film thickness on kinetic rate of mixed hydrate formation during injection of CO₂ into CH₄ hydrate

2015

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In this work, nonequilibrium thermodynamics and phase field theory (PFT) has been applied to study the kinetics of phase transitions associated with CO 2 injection into systems containing CH 4 hydrate, free CH 4 gas, and varying amounts of liquid water. The CH 4 hydrate was converted into either pure CO 2 or mixed CO 2 ACH 4 hydrate to investigate the impact of two primary mechanisms governing the relevant phase transitions: solid-state mass transport through hydrate and heat transfer away from the newly formed CO 2 hydrate. Experimentally proven dependence of kinetic conversion rate on the amount of available free pore water was investigated and successfully reproduced in our model systems. It was found that rate of conversion was directly proportional to the amount of liquid water initially surrounding the hydrate. When all of the liquid has been converted into either CO 2 or mixed CO 2 ACH 4 hydrate, a much slower solid-state mass transport becomes the dominant mechanism. V C 2015 American Institute of Chemical Engineers AIChE J, 61: [3944][3945][3946][3947][3948][3949][3950][3951][3952][3953][3954][3955][3956][3957] 2015

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“…36) It was show in 23,24) for methane hydrate the coincidence of the calculated results and experimental data is sufficiently good at temperatures below 200 K. At higher temperatures than 195 K the methane hydrate exists as a metastable phase, and the calculated relative changes of the volume V/V (195 K) The calculated temperature dependence of pressure in hydrate at heating ice from T ¼ 195 K at pressure P ¼ 0:1 MPa are displayed in Fig. 9.…”

Section: Hydrate Phases Immersed In the Ice Phasementioning

confidence: 69%

“…The lattice dynamic (LD) calculations also give larger values of thermal expansion of gas hydrates than that of the ice. [22][23][24] For practical application of clathrate hydrates as storage materials, it is important to know the region of stability of these compounds (there are several type of gas hydrate structures with different cage shapes) at various pressure and temperatures. Currently, analytical theories of clathrate compounds, which allow one to construct the T-P diagram of gas hydrates, are still based on the pioneering work of van der Waals and Platteeuw.…”

Section: Introductionmentioning

confidence: 99%

Physical and Chemical Properties of Gas Hydrates: Theoretical Aspects of Energy Storage Application

et al. 2007

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A model has been developed permitting to accurately predict on molecular level phase diagram of the clathrate hydrates. This model allows to take into account the influence of guest molecules on the host lattice and to extend the interval of temperatures and pressures of computed thermodynamic potentials and significantly improves known van der Waals and Platteeu theory. The theoretical study of phase equilibrium in gas-gas hydrate-ice Ih system for methane and xenon hydrates has been performed. The obtained results are in a good agreement with experimental data. A new interpretation of so-called self-preservation effect has been proposed. The self-preservation of gas hydrates can be connected with differences in thermal expansions of ice Ih and gas hydrates. This is confirmed by calculations performed for methane and mixed methane-ethane hydrates.

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Elastic moduli calculation and instability in structureI methane clathrate hydrate

Cited by 80 publications

References 18 publications

Clathrate hydrates as a sink of noble gases in Titan's atmosphere

Clathrate hydrates as a sink of noble gases in Titan's atmosphere

Impact of water film thickness on kinetic rate of mixed hydrate formation during injection of CO₂ into CH₄ hydrate

Physical and Chemical Properties of Gas Hydrates: Theoretical Aspects of Energy Storage Application

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Elastic moduli calculation and instability in structureI methane clathrate hydrate

Cited by 80 publications

References 18 publications

Clathrate hydrates as a sink of noble gases in Titan's atmosphere

Clathrate hydrates as a sink of noble gases in Titan's atmosphere

Impact of water film thickness on kinetic rate of mixed hydrate formation during injection of CO2 into CH4 hydrate

Physical and Chemical Properties of Gas Hydrates: Theoretical Aspects of Energy Storage Application

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Impact of water film thickness on kinetic rate of mixed hydrate formation during injection of CO₂ into CH₄ hydrate