Prediction of the phase equilibria of methane hydrates using the direct phase coexistence methodology

Vasileios K. Michalis, Joseph Costandy, Ioannis N. Tsimpanogiannis, Athanassios K. Stubos, Ioannis Economou

Research output: Contribution to journalArticle

54 Citations (Scopus)

Abstract

The direct phase coexistence method is used for the determination of the three-phase coexistence line of sI methane hydrates. Molecular dynamics (MD) simulations are carried out in the isothermal-isobaric ensemble in order to determine the coexistence temperature (T3) at four different pressures, namely, 40, 100, 400, and 600 bar. Methane bubble formation that results in supersaturation of water with methane is generally avoided. The observed stochasticity of the hydrate growth and dissociation processes, which can be misleading in the determination of T3, is treated with long simulations in the range of 1000-4000 ns and a relatively large number of independent runs. Statistical averaging of 25 runs per pressure results in T3 predictions that are found to deviate systematically by approximately 3.5 K from the experimental values. This is in good agreement with the deviation of 3.15 K between the prediction of TIP4P/Ice water force field used and the experimental melting temperature of ice Ih. The current results offer the most consistent and accurate predictions from MD simulation for the determination of T3 of methane hydrates. Methane solubility values are also calculated at the predicted equilibrium conditions and are found in good agreement with continuum-scale models.

Original languageEnglish
Article number044501
JournalJournal of Chemical Physics
Volume142
Issue number4
DOIs
Publication statusPublished - 28 Jan 2015

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Methane
Hydrates
Phase equilibria
hydrates
methane
methodology
predictions
Ice
Molecular dynamics
ice
molecular dynamics
Bubble formation
Water
simulation
Supersaturation
Computer simulation
scale models
supersaturation
water
field theory (physics)

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

Cite this

Prediction of the phase equilibria of methane hydrates using the direct phase coexistence methodology. / Michalis, Vasileios K.; Costandy, Joseph; Tsimpanogiannis, Ioannis N.; Stubos, Athanassios K.; Economou, Ioannis.

In: Journal of Chemical Physics, Vol. 142, No. 4, 044501, 28.01.2015.

Research output: Contribution to journalArticle

Michalis, Vasileios K. ; Costandy, Joseph ; Tsimpanogiannis, Ioannis N. ; Stubos, Athanassios K. ; Economou, Ioannis. / Prediction of the phase equilibria of methane hydrates using the direct phase coexistence methodology. In: Journal of Chemical Physics. 2015 ; Vol. 142, No. 4.
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