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 at T=297. 95−373.06 K and P=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 of h=h(P,T) and T has been extended in this study to estimate the dynamic viscosity, , for the mixtures of commercially available fuels. The model bridges a direct relation from an equilibrium property, h, to the transport process, , 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 to h.