Free volume vacancy behaviour and dynamic viscosity of diesel fuels with additives at elevated temperature and pressure: thermo-occupancy function

Abstract

The reported pressure-volume-temperature (PVT) data of five different diesel fuels atT= 297.95-373.06 K andP= 0.1-457.2 MPa were described by the Simha-Somcynsky (SS) equation of state (eos). From the equilibrium condition imposed on the eos, the hole fraction,h=h(P,T), a form of free volume measure, was computed. Furthermore, our physically-based correlation implicating the thermo-occupancy function,Yh=Yh(h,T), in terms of a function ofh=h(P,T) andThas been extended in this study to estimate the dynamic viscosity,η, for the mixtures of commercially available fuels. The model bridges a direct relation from an equilibrium property,h, to the transport process,η, of the system and predicts the viscosity with the range from 0.15% to 0.31%. Newly designates \"viscoholibility\" function defined as the derivative of logarithm of viscosity with respect to hole fraction has been discussed. It has an exponential decaying behaviour with respect toh.