Viscosity Measurements on Methanol Vapor and Their Evaluation

Abstract

The viscosity coefficient of methanol vapor was measured at low densities by means of an all-quartz oscillating-disk viscometer of high precision. The relative measurements were performed along 10 isochores at densities from (0.004 to 0.050) mol·dm-3 in the temperature range between (298 and 603) K. The uncertainty is estimated to be ± 0.2 % at room temperature, increasing up to ± 0.3 % at higher temperatures. Isothermal values recalculated from the original experimental data were evaluated with a first-order expansion for the viscosity in terms of density. A reasonable agreement with experimental values from the literature was found for those of Golubev and Likhachev (up to 1 % higher) measured with a capillary viscometer in an extended temperature range up to high pressures. The new results, some older ones obtained in our laboratory, and those of Golubev and Likhachev are used to model the viscosity of methanol vapor at moderately low densities. Whereas an individual correlation according to the extended theorem of corresponding states was necessary to represent the zero-density viscosity coefficient within its uncertainty, the Rainwater−Friend theory proved to be suitable for the description of the second viscosity virial coefficient. In addition, viscosity values of the saturated vapor were determined at low temperatures (299 to 339 K). They are in reasonable good consistency with values of Golubev determined at higher temperatures (373 to 513 K).

A New Reference Correlation for the Viscosity of Methanol

“…Primary data used in the correlation are the results by Vogel et al 135 as well as Teske and Vogel. 122 The new correlation reproduces the data of Vogel and collaborators to within 0.6% at the 95% confidence level. Substantial data sets were contributed by Golubev and Petrov, 47 Golubev and Kovarskaya, 49 as well as Golubev and Likhachev.…”

“…Monchick and Mason 94 presented the values of the reduced orientation-averaged collision integral ⍀ SM ͑2,2͒* calculated from the Stockmayer ͑12-6-3͒ potential in the range of 0.1ഛ T * ഛ 100 and 0 ഛ ␦ ഛ 2.5. Figure 3 shows the collision integral ⍀ SM ͑2,2͒* as a function of the inverse reduced tempera- available for methanol gas at low densities, and two sets 122,135 provide viscosity data in the limit of zero density. Vogel et al 135 obtained viscosity data for methanol in the very low-density vapor phase and derived zero-density viscosities between 310 and 615 K. Teske and Vogel 122 remeasured the viscosity of methanol vapor in this all-quartz oscillating disk viscometer of high precision along ten isochores at densities from 0.004 to 0.049 mol L −1 over the temperature range 298-598 K, and they also derived the viscosity in the limit of zero density.…”

“…Vogel et al 135 obtained viscosity data for methanol in the very low-density vapor phase and derived zero-density viscosities between 310 and 615 K. Teske and Vogel 122 remeasured the viscosity of methanol vapor in this all-quartz oscillating disk viscometer of high precision along ten isochores at densities from 0.004 to 0.049 mol L −1 over the temperature range 298-598 K, and they also derived the viscosity in the limit of zero density. Teske and Vogel 122 also examined the results of Golubev and Likhachev 51 and derived zerodensity viscosities from the measurements of these authors. For primary data we selected the zero-density data of Vogel et al 135 and Teske and Vogel, 122 and fitted the zero-density viscosity using Eq.…”

“…Teske and Vogel 122 also examined the results of Golubev and Likhachev 51 and derived zerodensity viscosities from the measurements of these authors. For primary data we selected the zero-density data of Vogel et al 135 and Teske and Vogel, 122 and fitted the zero-density viscosity using Eq. ͑10͒ with 1.7 D for the gas phase dipole moment of methanol.…”

“…5. We then adapted the equation for methanol, fitting the vapor-phase viscosity data of Golubev and Petrov, 47 Vogel et al, 135 and Teske and Vogel 122 and obtained the coefficients in Table 3͑b͒. The equation was scaled so that one set of potential parameters 0 / k, 0 can be used in Eqs.…”