New equipment has been designed and constructed to simultaneously measure dynamic viscosity and density on the basis of capillary flow technique and vibrating tube method, respectively, up to 70 MPa and 423.15 K. This apparatus has been built taking into account a number of physical parameters such as volumetric flow, length, and inner radius of the capillary tube and border effects. On the basis of the results of this work, densities for liquids are measured with relative combined expanded uncertainties of 0.07 % for water and ethanol, 0.7 % for hexane, 0.2 % for heptane, and 0.17 % for 1-pentanol and 1-heptanol. For the dynamic viscosity, the corresponding relative combined expanded uncertainties are 0.7 % for water and ethanol, 4.0 % for hexane, and 1.1 % for heptane, 1-pentanol, and 1-heptanol. In the calculated uncertainty for density and dynamic viscosity was included the contribution of the sample impurity. Experimental determinations of both dynamic viscosities and densities are performed, for several pure liquids, at the same conditions of temperature, pressure, and volumetric flow and recorded by means of an electronic device. Data reliability has been verified comparing the measured values with the available literature data for carbon dioxide, water, heptane, and ethanol up to 353 K and 30 MPa. The maximum deviations of the measured data compared to the literature data are ± 3 μPa•s for dynamic viscosity and ± 0.25 kg•m −3 for density. Furthermore, new experimental data are reported for hexane, 1-pentanol, and 1-heptanol up to 353 K and 30 MPa with a combined expanded uncertainty mentioned before.

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.

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The formation of gas hydrates is considered as a potential for oil and natural gas pipelines blockage and operational problems. It is also argued that gas hydrates can be considered as an alternative method to separate gases and many positive applications. The presence of additives in an aqueous solution can play an important role in determining gas hydrate formation conditions. In this work, hydrate dissociation conditions for the N 2 + ethanol + water system, the N 2 + 1-propanol + water system, and the CO 2 + tetra-butyl-ammonium fluoride (TBAF) + water system have been measured and are reported. The mass fractions of alcohols were 0.05, 0.10, 0.20, and 0.30. The mass fractions of TBAF were 0.05 and 0.10. The experimental measurements were performed using an isochoric pressure search method (synthetic nonvisual method) in the 262.87−294.52 K temperature range and 0.79−33.06 MPa pressure range. The viability of the method used was verified by the experimental determination and comparison with previously published data in the literature of hydrate dissociation conditions for the N 2 + H 2 O system, the CO 2 + C 2 H 6 O + H 2 O system, and the CO 2 + N 2 + TBAB + H 2 O system. Finally, the thermodynamic inhibition and promotion effects of ethanol, 1-propanol, and TBAF in aqueous solutions are discussed in terms of hydrate dissociation pressures and temperatures