MODELS FOR SELF-DIFFUSION COEFFICIENTS OF DENSE FLUIDS, INCLUDING HYDROGEN-BONDING SUBSTANCES

This work comprises two main and independent purposes: (1) A new four- parameter model is proposed for the description of self-diffusion coef ficients of polar, nonspherical and even hydrogen-bonding substances. It gives accurate results over wide ranges of temperature and pressure (AAD = 4.45%; 2471 data points). This equation is devised from an ext ension of a Lennard-Jones fluid model embodying the van der Waals mode l approach. (2) Generalized correlations are suggested for the estimat ion of the Lennard-Jones force constants (energy and diameter) of a tw o-parameter equation. From these it is possible to predict tracer diff usivities with satisfactory results, by means of simple combining rule s. (C) 1998 Elsevier Science Ltd. All rights reserved.