Coarse grained force field for the molecular simulation of natural gases and condensates

Herdes, Carmelo; Totton, Tim S.; Müller, Erich A.

doi:10.1016/j.fluid.2015.07.014

Cited by 92 publications

(115 citation statements)

References 79 publications

(70 reference statements)

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“…The model is obtained from a corresponding states parametrization of the SAFT equation of state [23], which provides force field parameters given the knowledge of the critical temperature, the acentric factor and a given liquid density. The parameters for this particular molecule have been described by Herdes et al [24] as λ = 18.41 ; ε/k B = 378.56 K and σ = 4.351 Å. In the case of the chain fluid, there is a restriction added by an angle bending potential between three consecutive beads, ψ = k(θ -θ 0 ) 2 where θ is the angle subtended by three consecutively bonded spheres.…”

Section: Pure Componentsmentioning

confidence: 99%

Prediction of the water/oil interfacial tension from molecular simulations using the coarse-grained SAFT-γ Mie force field

Herdes

Ervik

Mejı́a

et al. 2018

Fluid Phase Equilibria

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This work is framed within the Ninth Industrial Fluid Properties Simulation Challenge, with the aim of assessing the capability of molecular simulation methods and force fields to accurately predict the interfacial tension of oil + water mixtures at high temperatures and pressures. The challenge focused on predicting the liquid-liquid interfacial tension of binary mixtures of dodecane + water, toluene + water and a 50:50 (wt%) mixture of dodecane:toluene + water at 1.825 MPa (250 psig) and temperatures from 110 to 170 °C. In our entry for the challenge, we employed coarse-grained intermolecular models parametrized via a top-down technique in which an accurate equation of state is used to link experimentally observed macroscopic properties of fluids with the force-field parameters. The state-of-the-art version of the statistical associating fluid theory (SAFT) for potentials of variable range as reformulated in terms of the Mie potential is employed here. Interfacial tensions are calculated through a direct method, where an elongated simulation cell is sampled through molecular dynamics in the isobaric-isothermal constant area ensemble (NP zz AT). The coarse-grained nature of the force field allows for the accelerated calculation of relatively large systems. The binary interaction parameters that describe the crossinteractions have been obtained in previous works by fitting to interfacial tensions of the constituent binaries at lower pressures and temperatures; these are taken as constant for all conditions and mixtures studied. After disclosure of the challenge results, we observe that the interfacial properties of the mixtures are described with an error of less than 5 mN/m over the whole range of conditions, demonstrating the accuracy and transferability of the top-down SAFT-γ Mie force field approach.

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Section: Pure Componentsmentioning

confidence: 99%

Prediction of the water/oil interfacial tension from molecular simulations using the coarse-grained SAFT-γ Mie force field

Herdes

Ervik

Mejı́a

et al. 2018

Fluid Phase Equilibria

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“…However, possibly, the most interesting feature of these equations is the direct and quantitative link to the underlying potential, such that information gathered experiments can be incorporated into intermolecular potentials of interest here, is to garner experience from the molecular simulation of vapor-liquid interfaces to directly feed into this framework, in order to build a robust and transferable model capable of predicting the properties of an interfacial system from a minimal amount of commonly available experimental information, such as critical constants (see Refs. [65][66][67][81][82][83][84][85][86][87] for a complete discussion).…”

Section: -21mentioning

confidence: 99%

Interfacial tensions of industrial fluids from a molecular‐based square gradient theory

et al. 2016

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This work reports a procedure for predicting the interfacial tension of pure fluids. It is based on scaling arguments applied to the influence parameter of the van der Waals theory of inhomogeneous fluids. The molecular model stems from the application of the Square Gradient Theory to the SAFT-VR Mie equation of state. The theory is validated against computer simulation results for homonuclear pearl-necklace linear chains made up to six Mie (λ − 6) beads with repulsive exponents spanning from λ = 8 to 44 by combining the theory with a corresponding states correlation to determine the intermolecular potential parameters. We provide a predictive tool to determine interfacial tensions for a wide range of molecules including hydrocarbons, fluorocarbons, polar molecules, among others. The proposed methodology is tested against comparable existing correlations in the literature, proving to be vastly superior, exhibiting an average absolute deviation of 2.2 %.

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“…Finally, following the general methodology proposed by Segura et al, 43,44 the molecular parameters of pure fluids can be calculated by forcing the EoS to exactly reproduce the experimental vapor pressure, the local slope of the vapor pressure curve, and the density and compressibility of the liquid phase at one single reference temperature in terms of the theory of displacements. 45,46 In this work we modeled THF as a single-and double-segment pearl-necklace model, without any additional electrostatic interactions, estimated from the corresponding states principle (or critical data) proposed by Mejía et al 41 This methodology has shown great flexibility to characterize vapor-liquid interfacial properties of pure fluids 47 and complex mixtures of dilute surfactant solutions 48 and natural gases and condensates. 47,[49][50][51] Table I summarizes the SAFT parameters for THF as used in molecular simulations in this work.…”

Section: A Saft-coarse Grained Mie Force Fieldmentioning

confidence: 99%

“…45,46 In this work we modeled THF as a single-and double-segment pearl-necklace model, without any additional electrostatic interactions, estimated from the corresponding states principle (or critical data) proposed by Mejía et al 41 This methodology has shown great flexibility to characterize vapor-liquid interfacial properties of pure fluids 47 and complex mixtures of dilute surfactant solutions 48 and natural gases and condensates. 47,[49][50][51] Table I summarizes the SAFT parameters for THF as used in molecular simulations in this work. Nevertheless, the methodology proposed by Mejía et al 41 cannot be used directly in a rigid configuration, because energy contribution in Eq.…”

Section: A Saft-coarse Grained Mie Force Fieldmentioning

confidence: 99%

On interfacial properties of tetrahydrofuran: Atomistic and coarse-grained models from molecular dynamics simulation

Garrido

Algaba

Mı́guez

et al. 2016

The Journal of Chemical Physics

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We have determined the interfacial properties of tetrahydrofuran (THF) from direct simulation of the vapor-liquid interface. The molecules are modeled using six di↵erent molecular models, three of them based on the united-atom approach and the other three based on a coarse-grained (CG) approach. In the first case, THF is modeled using the transferable parameters potential functions approach proposed by Chandrasekhar and Jorgensen [J. Chem. Phys. 77, 5073 (1982) (2014)]. Simulations were performed in the molecular dynamics canonical ensemble and the vapor-liquid surface tension is evaluated from the normal and tangential components of the pressure tensor along the simulation box. In addition to the surface tension, we have also obtained density profiles, coexistence densities, critical temperature, density, and pressure, and interfacial thickness as functions of temperature, paying special attention to the comparison between the estimations obtained from di↵erent models and literature experimental data. The simulation results obtained from the three CG models as described by the SAFTMie approach are able to predict accurately the vapor-liquid phase envelope of THF, in excellent agreement with estimations obtained from TraPPE model and experimental data in the whole range of coexistence. However, Chandrasekhar and Jorgensen model presents significant deviations from experimental results. We also compare the predictions for surface tension as obtained from simulation results for all the models with experimental data. The three CG models predict reasonably well (but only qualitatively) the surface tension of THF, as a function of temperature, from the triple point to the critical temperature. On the other hand, only the TraPPE united-atoms models are able to predict accurately the experimental surface tension of the system in the whole temperature range. C 2016 AIP Publishing LLC. [http://dx

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Coarse grained force field for the molecular simulation of natural gases and condensates

Cited by 92 publications

References 79 publications

Prediction of the water/oil interfacial tension from molecular simulations using the coarse-grained SAFT-γ Mie force field

Prediction of the water/oil interfacial tension from molecular simulations using the coarse-grained SAFT-γ Mie force field

Interfacial tensions of industrial fluids from a molecular‐based square gradient theory

On interfacial properties of tetrahydrofuran: Atomistic and coarse-grained models from molecular dynamics simulation

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