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Updated: Aug 9, 2026
05:46
High-pressure Sapphire Cell for Phase Equilibria Measurements of CO2/Organic/Water Systems
Published on: January 24, 2014
Thermodynamic properties and phase transtions in the H2O/CO2/CH4 system
Atle Svandal1, Tatyana Kuznetsova, Bjørn Kvamme
1Department of Physics and Technology, University of Bergen, Allègaten 55, N-5007, Bergen, Norway. atle.svandal@ift.uib.no
Physical Chemistry Chemical Physics : PCCP
|April 25, 2006
Summary
This study develops a thermodynamic model for hydrate phase transitions, accurately predicting water-hydrate equilibrium. Molecular dynamics simulations provide crucial interface properties for phase field theory applications.
Area of Science:
- Thermodynamics
- Materials Science
- Chemical Engineering
Background:
- Developing a robust phase field theory for hydrate phase transitions requires accurate free energy densities.
- Existing theories need expansion to incorporate specific hydrate systems like carbon dioxide (CO2) and methane (CH4).
Purpose of the Study:
- To broaden the extended adsorption theory for CO2 and CH4 hydrate phase transitions.
- To develop a comprehensive thermodynamic model for predicting hydrate equilibrium properties.
- To utilize molecular dynamics simulations for estimating critical interface parameters.
Main Methods:
- Derived free energy density surfaces for CO2 and CH4 hydrates.
- Combined free energy surfaces for liquid phases using SRK equation of state and solubility data.
- Employed molecular dynamics simulations at 200 bar and various temperatures.
- Applied phase field analysis to estimate interface depth and concentration fields.
Main Results:
- The thermodynamic model accurately predicts water-hydrate equilibrium properties, aligning with experimental data.
- Estimated the 5-95 confidence interval for methane hydrate/liquid water interface thickness at 8.54 Å.
- Demonstrated the phase field theory's application to model hydrate phase transition kinetics.
- Identified mass transport as the rate-limiting step in hydrate growth from aqueous solutions.
- Interface depth from phase field analysis closely matched molecular simulation results.
Conclusions:
- The developed thermodynamic model, incorporating interface free energy, offers a parameter-free phase field theory for hydrate transitions.
- The study provides essential input parameters for practical applications of hydrate phase field theories.
- Understanding hydrate kinetics and interface properties is crucial for predicting phase transition behavior.
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