A theory-based method for correlation and prediction of dense-fluid transport properties

Dense-fluid transport property data for a wide range of compounds have been successlully correlated on tile basis of tmiversal curves for tile reduced dillhsion coelt]cient. D*. tile reduced viscosity, q*. and tile reduced thermal conductivity, ),*, against tile reduced volttme I"1",,. where I" is tile molar volume, and I",, is a characteristic volume equal to the volume of close packing I\~r a system of hard spheres. The reduced transport properties. X*, are defined in terms of the low-density hard-sphere values by (AA,,)[ I I,.)-" ~. where X is q, 2, or the product of tile nunlber density and tile dilRision coell]cient. To provide a theoretical justification Ibr this approach, extensive computer simulation results liar these transport properties, given in the literature lbr u system of Lennard .Ioncs (12 6) nlolecules, have been considered. It is Ibund that the reduced transport properties Ibr different temperatures are superimposable upon tile results Ibr any reference isotherm when plotted versus log I: as Ibund previously for real fluids. However. to reproduce this density dependence at any given temperature on tile basis o[ the universal curves, tile characteristic volume for sell2dill"usion nlust be greater than that for viscosity or thermal conductivity.