Viscosity of Several Liquid Hydrocarbons as a Function of Temperature, Pressure, and Free Volume

Abstract

Viscosity measurements have been made on nine pure hydrocarbon liquids at six temperatures ranging from 15.56° to 135°C and at pressures as high as 4000 bars. The samples included rigid bicyclic compounds of relatively high symmetry and three n-alkanes, n-C12, n-C15, and n-C18. These data were analyzed using the Eyring significant-structure theory, the Cohen—Turnbull free-volume model, and the empirical Doolittle equations. All of these equations produced essentially identical fits to the data at atmospheric pressure. The hypothesis that the constants v0 and vs in these equations represent the specific volume of a ``solid'' or condensed phase was tested by comparing best-fit values of these constants with experimental values for the solid-phase specific volume. The Cohen—Turnbull and Doolittle equations were modified for use at elevated pressures with the result that the values of v0 necessary to satisfy the equations at high pressures were shown to be analogous to the specific volumes of a glassy state at high pressures. Further, the change in v0 as a function of pressure was compared with the change in the experimental values of the solid-phase volume at the melting point as a function of pressure and a definite correlation between the two was established.

The Viscosity and Density of n-Dodecane and n-Octadecane at Pressures up to 200�MPa and Temperatures up to 473 K

“…6 and 7. The density agrees reasonably well with values determined from sound-speed measurements by Dutour et al [26] although the deviations show a marked temperature dependence with errors ranging from around −0.15% at 323.15 K to around +0.15% at 383.15 K. In the case of viscosity, the results of Ducolombier et al [23] and Hogenboom et al [25] agree with this work at low pressures but show positive deviations of up to 6% at higher pressures. It is interesting to note that, for n-dodecane, the results of Ducolombier et al were in agreement with this work to ±3%.…”

Effect of an Improved Yasutomi Pressure-Viscosity Relationship on the Elastohydrodynamic Line Contact Problem

“…Figure 1 illustrates the comparison between the values predicted from the Yasutomi free-volume model and measured from viscometer showing a good agreement. Furthermore, a better agreement with the measured data of the Yasutomi results compared to the Roelands law is observed [4,24]. Since the Roelands model was not intended to be accurate at high pressures [10], comparisons at EHL pressures are not really sensible.…”

Viscous behavior of linear and three-branch alkanes: Linking the equilibrium and transport theories

“…[15][16][17] In particular, eight saturated hydrocarbons: three linear C n H 2nϩ2 (where n ϭ 12, 15, and 18) and four 3-branch ones CH(C na H 2naϪ1 ) 3 , are of interest. In the latter case, the branch length is: n a ϭ 6, 8, 10, and 12 (for the latter alkane one branch arm was C 13 H 27 ).…”