Correlation of the viscosity of pure liquids at high pressures based on an equation of state

Abstract

A novel model has been presented for correlating the dynamic viscosity of Newtonian liquids at high pressures. The proposed model was started with the activation volume, which could simultaneously be influenced by temperature and pressure. The core of the model was based on Hu and Liu's work to calculate the compressibility factor. The final expression may contain two adjustable parameters, namely κ 1 and κ 2, which had been determined by fitting literature viscosity data. The results show that the agreement between experimental data of viscosity and the calculated ones with the proposed model was reasonably good for the selected systems. It was found that the logarithm of parameter κ 1 was a linear function of the reciprocal of the temperature, and κ 1 was approximately equal to viscosity of liquid at 0.1 MPa. Besides, for linear chain hydrocarbons, the logarithm of the parameter κ 1 was completely a linear function of the number of the carbon atoms under certain temperature. A comparison between model with two-parameter and one with one-parameter had been given to show their applicability. The results calculated by not only two-parameter but also one-parameter were superior to corresponding ones by previous pressure equation for estimating viscosity.