Insight into the thermo-physics of gas hydrates: Three phase equilibrium in presence of electrolyte

Dongre, Harshal J.; Jana, Amiya K.

doi:10.1016/j.jct.2020.106182

Cited by 9 publications

(15 citation statements)

References 63 publications

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“…The total sum of such contributions is approximated by using the pair potential function. These contributions are extensively used in the hydrate phase equilibrium studies and to estimate the Langmuir adsorption constant of the host cavity 8,14–17,23 . The summed interactions over the water molecules of the host cavity is,

W ((), r) goodbreak= 2 italicze ([], \frac{σ^{12}}{R_{cell}^{11} r} ((), δ^{10} goodbreak+ \frac{a}{R} δ^{11}) goodbreak- \frac{σ^{6}}{R_{cell}^{5} r} ((), δ^{4} goodbreak+ \frac{a}{R} δ^{5}))

where,

z

and

R_{cell}

are the coordination number and radius of the host cavity, respectively.…”

Section: Thermodynamic Modelingmentioning

confidence: 99%

“…However, the hydrate phase is assumed to be stabilized only by interactions with the host cavity. 3,8,[14][15][16][17]23 As identified through the NCI analysis, these guest-host interactions partake the overall lattice stability, and additional interactions need to be considered to inclusively describe the hydrate phase.…”

Section: Thermodynamic Modelingmentioning

confidence: 99%

“…The classical description of bulk phase 53 appropriately considers the influence of temperature, pressure, and composition on the bulk to hydrate transition. However, the hydrate phase is assumed to be stabilized only by interactions with the host cavity 3,8,14–17,23 . As identified through the NCI analysis, these guest–host interactions partake the overall lattice stability, and additional interactions need to be considered to inclusively describe the hydrate phase.…”

Section: Thermodynamic Modelingmentioning

confidence: 99%

“…The steric effects of the adsorbing cavity regulate its occupancy. Stress in the hydrate lattice arising due to adsorption and temperature fluctuations is relieved as deformation of the neighboring cells 8 . Steric effects are highly localized functions influenced by temperature, guest size, and fractional occupancy of the host cavity.…”

Section: Thermodynamic Modelingmentioning

confidence: 99%

“…To account for these alterations, the experimental HLV phase equilibrium data of methane, ethane, and their mixtures are simultaneously regressed to find the parameters of Kihara potential function 7 . This function typically estimates the interaction that an encaged guest exhibits with a water molecule of the host cavity 8 . The Langmuir adsorption constant is then approximated by summing up such interactions across all the water molecules constituting the host cavity 9 .…”

Section: Introductionmentioning

confidence: 99%

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Formulating noncovalent interactions to predict structural transition in mixed guest hydrates

Dongre

Jana

2022

AIChE Journal

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This work aims at formulating the noncovalent interactions of the mixed guest hydrate lattices of sI and sII structures. The reduced density plots obtained at the B3LYP level with 6‐31G(d) split valence set unveil the crucial contributions of hydrogen bonding, dispersion, van der Waals interaction, and steric effects toward lattice stability. These contributions are rather unreported in the hydrate phase equilibrium modeling. With this research gap, we attempt to formulate the natural regularity in the nonstoichiometric hydrates by the spherical harmonics shape descriptor. The van der Waals and hydrogen‐bond interactions are described with Kihara spherical cell potential and ab initio based calculations, respectively. Further, the ionization potential and polarizability of the guest molecule describe the dispersion interactions. Combining these contributions, we introduce a theoretical framework for the phase equilibrium modeling of mixed guest hydrates. This novel formulation offers various appealing advantages as: significantly reduced parametric structure, standardization of the parameter value for host–host pair, and generalized model framework. Despite of making the proposed theory so simple, it consistently outperforms the existing latest models, which employ various state equations, ab initio based calculations and CSMGem, for a wide variety of systems (total 26 systems tested) with reference to the experimental data.

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