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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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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