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  • 1
    Electronic Resource
    Electronic Resource
    Heats of transport from diffusion thermoeffect measurements on binary liquid mixtures of carbon tetrachloride with benzene, toluene, 2-propanone, n-hexane, and n-octane (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 7208-7213 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Measurements of heats of transport are reported for binary liquid mixtures containing carbon tetrachloride and benzene, toluene, 2-propanone, n-hexane, or n-octane at 298 K and ambient pressure. Additionally, measurements were made at 308 K for carbon tetrachloride with benzene, toluene, and 2-propanone. The corresponding heat-mass Onsager coefficients are also reported, from which thermal diffusion ratios have been calculated based on Onsager reciprocity. These data will be used in a companion paper to report a modified Enskog method for correlation and prediction of heats of transport.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.453364
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  • 2
    Electronic Resource
    Electronic Resource
    On the use of a modified square-well model for prediction and correlation of thermal diffusion factors in binary liquid mixtures (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 7214-7220 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Recently reported thermal diffusion factors obtained from heats of transport have been used to test the ability of existing theories to predict thermal diffusivities using model parameters regressed from pure component transport data. None of the theories tested were able to provide even qualitative agreement with experiment. However, predictions using a square-well Enskog theory, modified here for consistency with normal experimental definitions, were found to be approximately correct using pure-component square-well parameters regressed from viscosity and thermal conductivity and an assumed mixing rule for cross terms. Predicted values are very sensitive to the energy mixing rule, and correlation of experimental data is possible for some systems using this theory with one adjustable parameter in the mixing rule.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.453365
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  • 3
    Electronic Resource
    Electronic Resource
    Heats of transport from the diffusion thermoeffect in binary liquid mixtures of toluene, chlorobenzene, and bromobenzene (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 85 (1986), S. 3550-3555 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Measurements of heats of transport in binary liquid mixtures of toluene, chlorobenzene, and bromobenzene utilizing the diffusion thermoeffect, or Dufour effect, are reported at 298 and 308 K. The corresponding heat-mass Onsager coefficients are also reported, from which thermal diffusion ratios have been calculated based on Onsager reciprocity. The resultant binary thermal diffusion ratios have been correlated as a function of composition in an attempt to study the relationship between values in binary and ternary mixtures. It was found that the single independent binary values can be used to estimate the two independent thermal diffusion ratios previously reported in toluene+chlorobenzene+bromobenzene ternary mixtures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.450927
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  • 4
    Electronic Resource
    Electronic Resource
    Molecular dynamics simulation of real-fluid mutual diffusion coefficients with the Lennard-Jones potential model (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 3670-3676 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Mutual diffusion coefficients for selected alkanes in carbon tetrachloride were calculated using molecular dynamics and Lennard-Jones (LJ) potentials. Use of effective spherical LJ parameters is desirable when possible for two reasons: (i) computer time is saved due to the simplicity of the model and (ii) the number of parameters in the model is kept to a minimum. Results of this study indicate that mutual diffusivity is particularly sensitive to the molecular size cross parameter, σ12, and that the commonly used Lorentz–Berthelot rules are inadequate for mixtures in which the component structures differ significantly. Good agreement between simulated and experimental mutual diffusivities is obtained with a combining rule for σ12 which better represents these asymmetric mixtures using pure component LJ parameters obtained from self-diffusion coefficient data. The effect of alkane chain length on the mutual diffusion coefficient is correctly predicted. While the effects of alkane branching upon the diffusion coefficient are comparable in size to the uncertainty of these calculations, the qualitative trend due to branching is also correctly predicted by the MD results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.456847
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  • 5
    Electronic Resource
    Electronic Resource
    Molecular-dynamics simulation of mutual diffusion in nonideal liquid mixtures (1991)
    Springer
    International journal of thermophysics 12 (1991), S. 501-513 
    Details
    ISSN: 1572-9567
    Keywords: liquid mixtures ; molecular dynamics ; mutual diffusion ; nonideal mixtures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The mutual-diffusion coefficients, D 12, of n-hexane, n-heptane, and n-octane in chloroform were modeled using equilibrium molecular-dynamics (MD) simulations of simple Lennard-Jones (LJ) fluids. Pure-component LJ parameters were obtained by comparison of simulations to experimental self-diffusion coefficients. While values of “effective” LJ parameters are not expected to simulate accurately diverse thermophysical properties over a wide range of conditions, it was recently shown that effective parameters obtained from pure self-diffusion coefficients can accurately model mutual diffusion in ideal, liquid mixtures. In this work, similar simulations are used to model diffusion in nonideal mixtures. The same combining rules used in the previous study for the cross-interaction parameters were found to be adequate to represent the composition dependence of D 12. The effect of alkane chain length on D 12 is also correctly predicted by the simulations. A commonly used assumption in empirical correlations of D 12, that its kinetic portion is a simple, compositional average of the intradiffusion coefficients, is inconsistent with the simulation results. In fact, the value of the kinetic portion of D 12 was often outside the range of values bracketed by the two intradiffusion coefficients for the nonideal system modeled here.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00502365
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  • 6
    Electronic Resource
    Electronic Resource
    The Effect of Model Internal Flexibility Upon NEMD Simulations of Viscosity (2000)
    Springer
    International journal of thermophysics 21 (2000), S. 45-55 
    Details
    ISSN: 1572-9567
    Keywords: viscosity ; NEMD simulation ; flexible models ; rigid bond lengths
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The influence of model flexibility upon simulated viscosity was investigated. Nonequilibrium molecular dynamics (NEMD) simulations of viscosity were performed on seven pure fluids using three models for each: one with rigid bonds and angles, one with flexible angles and rigid bonds, and one with flexible bonds and angles. Three nonpolar fluids (propane, n-butane, and isobutane), two moderately polar fluids (propyl chloride and acetone), and two strongly polar fluids (methanol and water) were studied. Internal flexibility had little effect upon the simulated viscosity of nonpolar fluids. While model flexibility did affect the simulated viscosity of the polar fluids, it did so principally by allowing a density-dependent change in the dipole moment of the fluid. By using a rigid model with the same geometry and dipole moment as the average flexible molecule at the same density, it was shown that the direct effect of flexibility is small even in polar fluids. It was concluded that internal model flexibility does not enhance the accuracy of viscosities obtained from NEMD simulations as long as the appropriate model geometry is used in the rigid model for the desired simulation density.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006600719847
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  • 7
    Electronic Resource
    Electronic Resource
    Application of an extended Lee-Kesler corresponding-states technique to prediction of vapor-liquid equilibria in multicomponent mixtures containing polar components (1989)
    Springer
    International journal of thermophysics 10 (1989), S. 479-492 
    Details
    ISSN: 1572-9567
    Keywords: corresponding states ; mixing rules ; multicomponent fluids ; polar fluids ; vapor-liquid equilibrium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Mixing rules for an extended Lee-Kesler (ELK) corresponding-states method for prediction of thermodynamic properties are presented. The mixing rules, which do not contain adjustable parameters, permit calculation of vapor-liquid equilibria in mixtures containing one or more polar components. While a single heat-of-mixing datum may be included for strongly associating components, generally only pure component properties are used in the calculations. A comparison of calculated bubble-point pressures and equilibrium vaporization ratios to experimental values is made for 26 ternary mixtures (791 points) and 5 quaternary mixtures (175 points). Bubble-point pressures are predicted quite well with ELK (9.1 % AAD for ternaries and 7.9% for quaternaries). Composition predictions are difficult to compare in multicomponent systems, but ELK predictions appear to be acceptable on both a system-by-system and an overall AAD basis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01133544
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  • 8
    Electronic Resource
    Electronic Resource
    A four-parameter corresponding-states method for prediction of Newtonian, pure-component viscosity (1991)
    Springer
    International journal of thermophysics 12 (1991), S. 119-136 
    Details
    ISSN: 1572-9567
    Keywords: corresponding states ; Lee-Kesler method ; polar fluids ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The extended Lee-Kesler (ELK) method, introduced for calculating thermodynamic properties of polar as well as nonpolar fluids and their mixtures, has been adapted to the calculation of Newtonian, pure-fluid viscosity. The method is a four-parameter, corresponding-states technique requiring as input the critical temperature, critical pressure, a size/shape parameter α, and a polar interaction parameter β. Because α and β have been previously tabulated for many fluids (for calculation of thermodynamic properties) and may also be obtained directly from the radius of gyration and a single liquid density, respectively, the method contains no adjustable parameters and is predictive in nature. ELK viscosity predictions were compared to experimental data for nonpolar and polar fluids. For 36 different nonpolar fluids and a total of 5748 different points, the comparison yielded an absolute average deviation (AAD) of 7.88% with a bias of −4.45%. Similarly, the AAD was 10.62% with a bias of −5.34% for a comparison of 15 different polar fluids involving 1500 different points. With this method, viscosities can be calculated within the range 0.55 ⩽T r⩽2.00 and 0〈P r⩽10.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00506126
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  • 9
    Electronic Resource
    Electronic Resource
    Nonequilibrium Molecular Dynamics Simulation of Shear Viscosity of Polar Liquids (1998)
    Springer
    International journal of thermophysics 19 (1998), S. 1039-1048 
    Details
    ISSN: 1572-9567
    Keywords: acetone ; dimethyl formamide ; Ewald sum ; formamide ; molecular simulations ; nonequilibrium molecular dynamics ; polar fluids ; propyl chloride ; shear viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Nonequilibrium molecular dynamics (NEMD) simulations were performed on model polar fluids representing acetone, propyl chloride, formamide, and dimethyl formamide. The purposes of the study were (1) to test further a recently developed method for applying the Ewald sum treatment of long-range forces to NEMD simulations with Lees–Edwards boundary conditions, (2) to study the effect of different constituent groups and their partial charges upon fluid viscosity, and (3) to examine the relative magnitudes of the van der Waals and coulombic contributions to fluid viscosity. The new Ewald sum method worked well, producing simulated viscosities for all four fluids that were in good agreement with correlated experimental data. Generally, viscosities predicted without the partial charges were significantly low and exhibited an incorrect density dependence. While methyl chloride's viscosity is due primarily to the dispersion interactions, coulombic interactions contribute substantially to the viscosity of the other three fluids, particularly at higher densities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022625306269
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  • 10
    Electronic Resource
    Electronic Resource
    Nonequilibrium Molecular Dynamics Simulations of Shear Viscosity: Isoamyl Alcohol, n-Butyl Acetate, and Their Mixtures (2000)
    Springer
    International journal of thermophysics 21 (2000), S. 703-717 
    Details
    ISSN: 1572-9567
    Keywords: binary mixtures ; isoamyl alcohol ; n-butyl acetate ; nonequilibrium molecular dynamics ; shear viscosity ; zero-shear viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Nonequilibrium, NVT, molecular dynamics (NEMD) simulations were used to obtain the shear viscosity, η, of isoamyl alcohol, n-butyl acetate, and their binary mixtures at 35°C and 0.1 MPa. The fluids were modeled using rigid bonds, rigid bond angles, appropriate torsional potentials, pairwise-additive Lennard–Jones dispersion interactions between united-atom sites, and partial point charges located at atomic centers. Simulations were performed at different shear rates, γ, and values obtained at γ=0 are compared to experimental values. Two methods are commonly used to extrapolate pure-fluid simulated data to zero shear, η(0). The applicability of these two methods to mixtures of polar fluids was examined in this study. It was found that linear extrapolation with respect to γ 1/2 can lead to ambiguous η(0) results for some mixtures because of a curvature in the data that shows no observably distinct change in rheology. On the other hand, a log–log plot of η(γ) versus γ is consistently very linear with a distinct change from shear-thinning to Newtonian rheology at lower shear rates. The latter method is recommended for consistency sake, even though agreement between experiment and η(0) values was better with the former method. This agreement was 12 and 21% for the two methods, respectively. A negative bias in the simulated values is attributable to the united-atom model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006693519615
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