Prediction of viscosity-density dependence of liquid methane+n-butane+n-pentane mixtures using the molecular dynamics method and empirical correlations

Abstract

We present a study of viscosities of n-pentane and binary and ternary methane–n-butane–n-pentane mixtures in liquid state at the temperature 360 K by the non-equilibrium molecular dynamics simulations with a modified fully flexible version of the all-atom TraPPE-EH force field. The Batchinski correlation η=C/(v−b) is used to describe the viscosities of pure n-pentane. The calculated viscosity-density dependence for liquid n-pentane is in agreement with the experimental data. We show that the viscosity-volume dependencies of liquid binary and ternary mixtures can be fitted by the Batchinski's equation as well, and the coefficients for the mixtures are obtained by linear mixing of the coefficients for pure components. The model can be used for the interpretation and interpolation of the experimental data on viscosities of hydrocarbon liquids. The Batchinski-like behavior of viscosity of liquid mixtures in some density range can be used as a test for more complex correlations, which we show by comparing the hard sphere correlation and the expanded fluid correlation for hydrocarbons.