A liquid phase viscosity-temperature model for long-chain n-alkanes up to C64H130 based on the Free Volume Theory

The viscosity, as a function of density and temperature, of long chain normal alkanes (n-alkanes) in the liquid phase, is modelled using the Free Volume model, as presented by Allal, Moha-Ouchane and Boned in 2001. Free Volume molecular characteristics as a function of molecular weight are calculated at discrete points, using a least-squares method to fit the model to measured data available from literature. The results are used as control points in developing polynomials to extrapolate the characteristic parameters to all n-alkanes up to C64H130. Results obtained with the Free Volume model for long-chain n-alkanes are compared to those obtained from other models and methods, such as the Hard Sphere model, the Lohrenz-Bray-Clark correlation, and Pedersen's corresponding states method. The Extended Free Volume model resulted in an average absolute deviation of 5.3% for n-alkanes with carbon numbers C6-C64, over pressure ranges up to 142 MPa (1400 bar) and temperatures up to 573.15 K (300 degrees C). (C) 2014 Elsevier Ltd. All rights reserved.