Entropy Scaling of Viscosity-II: Predictive Scheme for Normal Alkanes

In this work, a residual entropy value of 6/10 of the way between the critical point and a value of -2/3 of Boltzmann constant is shown to collapse the scaled viscosity for the family of normal alkanes. Based on this approach, a nearly universal correlation is proposed that can reproduce 95% of the experimental data for normal alkanes within +/- 18% (without removal of clearly erroneous data). This universal correlation has no new fluid-specific empirical parameters and is based on experimentally accessible values. This collapse is shown to be valid to a residual entropy half-way between the critical point and the triple point, beyond which the macroscopically scaled viscosity has a superexponential dependence on residual entropy, terminating at the triple point. A key outcome of this study is a better understanding of entropy scaling for fluids with intramolecular degrees of freedom. A study of the transport and thermodynamic properties at the triple point rounds out the analysis.