Use of monomer fraction data in the parametrization of association theories

Kontogeorgis, Georgios M.; Tsivintzelis, Ioannis; Solms, Nicolas von; Grenner, Andreas; Bøgh, David; Frost, Michael Grynnerup; Knage-Rasmussen, Anders; Economou, Ioannis G.

doi:10.1016/j.fluid.2010.05.028

Cited by 58 publications

(52 citation statements)

References 52 publications

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“…fields and the predictions with our novel SAFT-VR Mie models are in remarkable agreement, and that the values from neither approach are consistent with those reported by Luck. The issue about possible inconsistencies in the values for the degree of association in water, methanol, and ethanol estimated by Luck from IR spectroscopic data has been raised before [186,189,191]. We reiterate that the neutron scattering data of Soper and Phillips [202], though only available for limited thermodynamic conditions, is consistent with the corresponding values predicted theoretically with the SAFT-VR Mie models of water and by simulation with the SPC/E and TIP4P/2005 models, but is not in line with the IR data of Luck.…”

Section: Tip4p/2005mentioning

confidence: 99%

The A in SAFT: developing the contribution of association to the Helmholtz free energy within a Wertheim TPT1 treatment of generic Mie fluids

et al. 2015

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(2015) The A in SAFT: developing the contribution of association to the Helmholtz free energy within a Wertheim TPT1 treatment of generic Mie fluids, Molecular Physics, 113:9-10, 948-984, DOI: 10.1080/00268976.2015 An accurate representation of molecular association is a vital ingredient of advanced equations of state (EOSs), providing a description of thermodynamic properties of complex fluids where hydrogen bonding plays an important role. The combination of the first-order thermodynamic perturbation theory (TPT1) of Wertheim for associating systems with an accurate description of the structural and thermodynamic properties of the monomer fluid forms the basis of the statistical associating fluid theory (SAFT) family of EOSs. The contribution of association to the free energy in SAFT and related EOSs is very sensitive to the nature of intermolecular potential used to describe the monomers and, crucially, to the accuracy of the representation of the thermodynamic and structural properties. Here we develop an accurate description of the association contribution for use within the recently developed SAFT-VR Mie framework for chain molecules formed from segments interacting through a Mie potential [T. Lafitte, A. Apostolakou, C. Avendaño, A, Galindo, C. S. Adjiman, E. A. Müller, and G. Jackson, J. Chem. Phys. 139, 154504 (2013)]. As the Mie interaction represents a soft-core potential model, a method similar to that adopted for the Lennard-Jones potential [E. A. Müller and K. E. Gubbins, Ind. Eng. Chem. Res. 34, 3662 (1995)] is employed to describe the association contribution to the Helmholtz free energy. The radial distribution function (RDF) of the Mie fluid (which is required for the evaluation of the integral at the heart of the association term) is determined for a broad range of thermodynamic conditions (temperatures and densities) using the reference hyper-netted chain (RHNC) integral-equation theory. The numerical data for the association kernel of Mie fluids with different association geometries are then correlated for a range of thermodynamic states to obtain a general expression for the association contribution which can be applied for varying values of the Mie repulsive exponent. The resulting SAFT-VR Mie EOS allows for a much improved description of the vapour-liquid equilibria and single-phase properties of associating fluids such as water, methanol, ammonia, hydrogen sulphide, and their mixtures. A comparison is also made between the theoretical predictions of the degree of association for water and the extent of hydrogen bonding obtained from molecular simulations of the SPC/E and TIP4P/2005 atomistic models.

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Section: Tip4p/2005mentioning

confidence: 99%

The A in SAFT: developing the contribution of association to the Helmholtz free energy within a Wertheim TPT1 treatment of generic Mie fluids

et al. 2015

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“…However, as it will also be shown next, all these sets do not describe with the same accuracy the phase behaviour of binary mixtures. This is a rather common difficulty in the parameter estimation of many equations of state models, such as the SAFT-type models, or the advanced lattice theories [141,142].…”

Section: Setmentioning

confidence: 99%

Equation of state modelling of systems with ionic liquids: Literature review and application with the Cubic Plus Association (CPA) model

Maia

Tsivintzelis

Rodrı́guez

et al. 2012

Fluid Phase Equilibria

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“…Several authors have proposed extended fitting procedures [56,[60][61][62], where for instance properties such as the heat of vapor-410 ization or the speed of sound has been used in the objective function.…”

Section: The Effect Of Adding Additional Output Propertiesmentioning

confidence: 99%

Uncertainty analysis of the CPA and a quadrupolar CPA equation of state – With emphasis on CO2

Bjørner

Sin

Kontogeorgis

2016

Fluid Phase Equilibria

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The parameters of thermodynamic models, such as the cubic plus association (CPA) equation of state, are subject to uncertainties due to measurement errors in the experimental data that the models are correlated to. More importantly as the number of adjustable parameters increase, the parameter estimation problem becomes more complicated due to parameter identifiability issues. In this work the uncertainties in the pure compound parameters of CO 2 are investigated using several different CPA approaches, including a new quadrupolar CPA. The uncertainties are estimated using both least squares estimation and the bootstrap method for parameter estimation. The uncertainties in the parameters estimated from the bootstrap method are propagated to physical property and vapor liquid equilibrium predictions using Monte Carlo simulations.The results indicate that both the pure compound parameter uncertainty and the propagated uncertainty is negligible for the modeling approaches which employ three adjustable parameters. For modeling approaches with more than three adjustable parameters, however, there may be significant uncertainties in the pure compound parameters, as well as a high degree of correlation between the adjustable parameters. This results in significant propagated errors * Corresponding author Email address: mgabj@kt.dtu.dk (Martin G. Bjørner)Preprint submitted to Fluid Phase Equilibria December 31, 2015for certain output properties. To reduce the uncertainty in the adjustable model parameters the heat of vaporization was included as additional correlation data.This resulted in parameter distributions which followed a normal distribution more closely, however, the correlation between the adjustable parameters remained high. Overall the results indicate, that it is important to report parameter uncertainties together with their correlation matrix when a model is developed, so that better informed decisions can be made, for instance about which model extension, or association scheme should be employed.

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Use of monomer fraction data in the parametrization of association theories

Cited by 58 publications

References 52 publications

The A in SAFT: developing the contribution of association to the Helmholtz free energy within a Wertheim TPT1 treatment of generic Mie fluids

The A in SAFT: developing the contribution of association to the Helmholtz free energy within a Wertheim TPT1 treatment of generic Mie fluids

Equation of state modelling of systems with ionic liquids: Literature review and application with the Cubic Plus Association (CPA) model

Uncertainty analysis of the CPA and a quadrupolar CPA equation of state – With emphasis on CO2

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