Thermodynamic model of viscosity of hydrocarbons and their mixtures

Activation hypothesis suggested by Eyring for modeling viscosity of liquids is generalized for calculation coefficient of dynamic viscosity of pure hydrocarbons and their mixtures in wide region of temperature, pressure and concentrations. Energy of vacancy activation is modeled as difference between enthalpy of ideal gas and enthalpy of real substance. Enthalpy and other thermodynamic parameters for pure substances and mixtures are calculated on the base of well-known Lee–Kesler equation of state. Thermodynamics of mixture calculated in the frame of pseudofluid hypothesis with pseudocritical thermodynamic constants. Pseudocritical thermodynamic constants are estimated with the help of mixing rules offered also by Lee–Kesler. Two additional constants are including in the suggested model of viscosity. For normal paraffin these constant have universal value. For other substances, for example, oxygen containing hydrocarbons values of the constant are installed in accordance to the experimental data. The model with sufficiently accuracy reproduces viscosity experimental data as pure substances in vapor and liquid phases and also solutions in the wide regions of thermodynamical parameters and concentrations. Calculation results are compared with the literature experimental data.