Simultaneous Measurement of Dynamic Viscosity and Density of n-Alkanes at High Pressures

New experimental data of the dynamic viscosity and density of pentane, octane, nonane, decane, and dodecane are reported. The experimental method was validated by determining and comparing the dynamic viscosity and the density of decane with the data previously published in the international literature, obtaining a maximum deviation of 12 μPa·s and 0.35 kg·m^-3 for dynamic viscosity and density, respectively. The measurements were performed simultaneously using a capillary tube viscometer and a vibrating tube densimeter at temperatures between 293 and 353 K and pressures up to 30 MPa. The estimated relative combined expanded uncertainties (k = 2), considering the impurities of the compounds (including content of water), are 0.9% for the dynamic viscosity and 0.13% for the density over the entire measurement range. The viscosity data were successfully correlated as a function of pressure and temperature with an empirical model proposed in this study. Also, the experimental density data were successfully modeled with an equation previously published in the international literature. Besides, the experimental density data were used to obtain the isothermal compressibilities and isobaric thermal expansivities.