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### Interfacial tensions of systems comprising water, carbon dioxide and diluent gases at high pressures: experimental measurements and modelling with SAFT-VR Mie and square-gradient theory

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Accepted Manuscript.pdf | Accepted version | 1.91 MB | Adobe PDF | View/Open |

Title: | Interfacial tensions of systems comprising water, carbon dioxide and diluent gases at high pressures: experimental measurements and modelling with SAFT-VR Mie and square-gradient theory |

Authors: | Chow, YTF Eriksen, DK Galindo, A Haslam, AJ Jackson, G Maitland, GC Trusler, JPM |

Item Type: | Journal Article |

Abstract: | Experimental interfacial tensions of the systems (H<inf>2</inf>O+CO<inf>2</inf>), (H<inf>2</inf>O+N<inf>2</inf>), (H<inf>2</inf>O+Ar), (H<inf>2</inf>O+CO<inf>2</inf> +N<inf>2</inf>) and (H<inf>2</inf>O+CO<inf>2</inf> +Ar) are compared with calculations based on the statistical associating fluid theory for variable range potentials of the Mie form (SAFT-VR Mie) in combination with the square-gradient theory (SGT). Comparisons are made at temperatures from (298 to 473)K and at pressures up to 60MPa. Experimental data for the systems (H<inf>2</inf>O+CO<inf>2</inf>), (H<inf>2</inf>O+N<inf>2</inf>) and (H<inf>2</inf>O+CO<inf>2</inf> +N<inf>2</inf>) are taken from the literature. For the (H<inf>2</inf>O+Ar) and (H<inf>2</inf>O+CO<inf>2</inf> +Ar) systems, we report new experimental interfacial-tension data at temperatures of (298.15-473.15)K and pressures from (2 to 50)MPa, measured by the pendant-drop method. The expanded uncertainties at 95% confidence are 0.05K for temperature, 70kPa for pressure, 0.016× γ for interfacial tension in the binary (Ar+H<inf>2</inf>O) system and 0.018× γ for interfacial tension in the ternary (CO<inf>2</inf> +Ar+H<inf>2</inf>O) system. The parameters in the SAFT-VR Mie equation of state are estimated entirely from phase-equilibrium data for the pure components and binary mixtures. For pure water, the SGT influence parameter is determined from vapour-liquid surface-tension data, as is common practice. Since the other components are supercritical over most or the entire temperature range under consideration, their pure-component influence parameters are regressed by comparison with the binary interfacial-tension data. A geometric-mean combining rule is used for the unlike influence parameter in mixtures without incorporation of adjustable binary parameters. The SAFT-VR Mie+SGT approach is found to provide an excellent correlation of the surface tension of water and of the interfacial tensions of the binary systems comprising H<inf>2</inf>O with CO<inf>2</inf> or Ar or N<inf>2</inf>. When applied to predict the interfacial tensions of the two ternary systems, generally good results are found for (H<inf>2</inf>O+CO<inf>2</inf> +N<inf>2</inf>) while, for (H<inf>2</inf>O+CO<inf>2</inf> +Ar), the theory performs well at high temperatures but significant deviations are found at low temperatures. Overall, the SAFT-VR Mie+SGT approach can be recommended as a means of modelling the interfacial properties of systems comprising water, carbon dioxide and diluent gases. |

Issue Date: | 15-Jan-2016 |

Date of Acceptance: | 13-Jul-2015 |

URI: | http://hdl.handle.net/10044/1/26806 |

DOI: | 10.1016/j.fluid.2015.07.026 |

ISSN: | 0378-3812 |

Publisher: | Elsevier |

Start Page: | 159 |

End Page: | 176 |

Journal / Book Title: | Fluid Phase Equilibria |

Volume: | 407 |

Issue: | 1 |

Copyright Statement: | © 2015, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/ |

Sponsor/Funder: | Qatar Shell Research and Technology Center QSTP LLC Engineering & Physical Science Research Council (EPSRC) Engineering & Physical Science Research Council (EPSRC) |

Funder's Grant Number: | 490000724 EP/J014958/1 EP/E016340/1 |

Keywords: | Carbon dioxide Interfacial tension SAFT-VR Square-gradient theory Water Science & Technology Physical Sciences Technology Thermodynamics Chemistry, Physical Engineering, Chemical Chemistry Engineering Carbon dioxide Interfacial tension SAFT-VR Square-gradient theory Water EQUATION-OF-STATE DIRECTIONAL ATTRACTIVE FORCES ASSOCIATING FLUID THEORY NITROGEN PLUS WATER SURFACE-TENSION THERMODYNAMIC PROPERTIES PERTURBATION-THEORY PHASE-EQUILIBRIA NONPOLAR FLUIDS CHAIN MOLECULES Chemical Engineering 0203 Classical Physics 0306 Physical Chemistry (incl. Structural) 0904 Chemical Engineering |

Publication Status: | Published |

Open Access location: | http://www.sciencedirect.com/science/article/pii/S0378381215300418 |

Online Publication Date: | 2015-07-26 |

Appears in Collections: | Chemical Engineering Faculty of Engineering |