One-parameter friction theory viscosity model for the cubic-plus-chain equation of state

A general one-parameter friction theory model based on the recently developed cubic-plus-chain equation of state (Sisco and Abutaqiya et al., Industrial & Engineering Chemistry Research, 2019, 58, 7341) is proposed to describe the viscosity behavior of n-alkanes. The model is considered a one-parameter model because it only requires one characteristic critical viscosity per compound to predict viscosity. This general model showed accurate viscosity modeling results for 15 n-alkanes ranging from methane to n-octadecane over a wide range of temperatures and pressures up to 1000 bar (1.51% AAPD). By using simple mixing rules, the model is further applied to predict the viscosity of 13 binary to quaternary mixtures of n-alkanes with accuracies close to experimental uncertainty (3.77% AAPD), making it a promising viscosity prediction methodology for industrial applications. A quantitative and qualitative comparison of the different friction theory viscosity models is also included. Additionally, an empirical correlation for estimating the characteristic critical viscosity is provided to extend the model to n-alkanes whose characteristic critical viscosity is not reported. The proposed viscosity model strikes a reasonable balance between the accuracy of viscosity predictions, simplicity of use and faster computational times. (C) 2020 Elsevier B.V. All rights reserved.