On the limitation of the van der Waals-Platteeuw-based thermodynamic models for hydrates with multiple occupancy of cavities

Abstract

Thermodynamic models based on the van der Waals–Platteeuw statistical theory (Adv. Chem. Phys. 2, 1 (1959)) can be very accurate in describing hydrate equilibrium conditions, even for some occasions when multiple cavity occupancy occurs. These are cases outside the range of assumptions used for the development of the original statistical theory. However, during multiple cavity occupancy such models can perform poorly when calculating the cavity occupancies. This paper reports novel Grand Canonical Monte Carlo molecular simulations for the case of pure structure II N₂ hydrate and compares the calculated cavity occupancies with experimental data and observe reasonable agreement. Also examined are the van der Waals–Platteeuw-based modifications that retained the single-occupancy assumption of the original theory and how they perform when predicting cavity occupancies and hydrate equilibrium pressures.

Keywords:

• hydrate equilibria
• van der Waals-Platteeuw theory
• Grand Canonical Monte Carlo
• cavity occupancy

Acknowledgements

Partial funding by the European Commission EC Grant PERL (contract REGPOT-2008-1-229773) is gratefully acknowledged by the authors. The authors would like to thank the reviewer for valuable suggestions regarding the use of Lorentz–Berthelot combining rules.

Notes

Visiting scientist

Additional information

Notes on contributors

Ioannis N. Tsimpanogiannis

Visiting scientist