T. Makita

Viscosity of twelve hydrocarbon liquids in the temperature range 298–348 K at pressures up to 110 MPa

New experimental data on the viscosity of 12 organic liquids are presented at temperatures of 25, 30, 50, and 75°C and at pressures up to 110 MPa. The liquids measured are five n-alkanes (C6, C7, C8, C10, C12), cyclohexane, and six aromatic hydrocarbons (benzene, toluene, ethylbenzene, o-, m-, p-xylenes). The measurements were performed using a torsionally vibrating crystal method on a relative basis with an uncertainty less than 2%. A linear relationship between fluidity and molar volume, which is predicted from the hard-sphere theory, fails at pressures above 50 MPa. The rough hard-sphere model proposed by Chandler provides a reasonable representation of the data for aromatic hydrocarbons, while for n-alkanes the agreement is not satisfactory because of an aspherical shape of molecules. The viscosity data can be correlated well with the molar volume by a free-volume expression and also can be represented as a function of pressure by a similar expression to the Tait equation.

Volumetric behavior of pure alcohols and their water mixtures under high pressure

The specific volumes of C1-C4 alcohols and binary mixtures of water with methanol, ethanol, 1-propanol, 2-propanol, and 2-methyl-2-propanol are presented as functions of temperature, pressure, and composition. The measurements were carried out using a modified Adams piezometer and a high-pressure burette method in a temperature range from 283.15 to 348.15 K at pressures up to 350 MPa. The uncertainties in the specific volume obtained are estimated to be less than 0.09%. The specific volumes of the pure alcohols and their mixtures with water are found to decrease monotonously with increasing pressure. The numerical P-V relations at each temperature and composition are correlated satisfactorily as a function of pressure by the Tait equation. Definite inflections appear on the isobars of isothermal compressibility or partial molar volume versus composition of alcohol + water mixtures.

Thermal conductivity and density of toluene in the temperature range 273–373 K at pressures up to 250 MPa

New experimental data on the thermal conductivity and the density of liquid toluene are presented in the temperature range 0–100°C at pressures up to 250 MPa. The measurements of thermal conductivity were performed with a transient hot-wire apparatus on an absolute basis with an inaccuracy less than 1.0%. The density was measured with a high-pressure burette method with an uncertainty within 0.1%. The experimental results for both properties are represented satisfactorily by the Tait-type equations, as well as empirical polynomials, covering the entire ranges of temperature and pressure. Furthermore, it is found that simple relations exist between the temperature dependence of thermal conductivity and the thermal expansion coefficient, and also between the pressure dependence of thermal conductivity and the isothermal compressibility, as are suggested theoretically.

Viscosity and density of binary mixtures of cyclohexane with n-octane, n-dodecane, and n-hexadecane under high pressures

The viscosity and density of three binary mixtures of cyclohexane with n-octane, n-dodecane, and n-hexadecane have been measured at 298, 323, and 348 K at pressures up to 150 MPa or freezing pressures. The measurements of the viscosity were performed by a torsionally vibrating crystal viscometer on a relative basis using benzene and cyclohexane as reference materials. The density was measured using a high-pressure burette apparatus. The uncertainties of the measurements are estimated to be less than 2% for viscosity and 0.1% for density, respectively. The effects of temperature, pressure, density, and composition on the viscosity are discussed. Applicabilities of several empirical correlating equations to the viscosity data were examined.

Viscosity of (water + alcohol) mixtures under high pressure

New experimental viscosity data are presented for aqueous solutions of methanol, ethanol, 1-propanol, 2-propanol, and 2-methyl-2-propanol (t-butyl alcohol) in the temperature range from 283 to 348 K and pressures up to 120 MPa. The viscosity measurements were performed using a falling-cylinder viscometer on a relative basis with an uncertainty of less than 2%. The viscosity of pure alcohols and aqueous solutions is found to increase almost linearly with increasing pressure, whereas that of water decreases slightly with pressure at temperatures below 298 K. As for the composition dependence of the viscosity, a distinct maximum appears near 0.3–0.4 mole fraction of alcohol on all isobars at each temperature. The viscosity maximum shifts gradually to a higher alcohol concentration with increasing temperature and pressure. The isobars of aqueous 2-propanol and 2-methyl-2-propanol solutions have another shallow minimum near 0.9 mole fraction of alcohol below 323 K. The experimental results were analized empirically by a Tait-type equation and a free-volume theory. It was found that the isothermal viscosity data were satisfactorily correlated by these equations as functions of pressure and composition or of density and composition.

Vapor pressures of new fluorocarbons

The vapor pressures of four fluorocarbons have been measured at the following temperature ranges: R123 (2,2-dichloro-l,l,l-trifluoroethane), 273–457 K; R123a (1,2-dichloro-1,1,2-trifluoroethane), 303–458 K; R134a (1,1,1,2-tetrafluoroethane), 253–373 K; and R132b (l,2-dichloro-l,l-difluoroethane), 273–398 K. Determinations of the vapor pressure were carried out by a constant-volume apparatus with an uncertainty of less than 1.0%. The vapor pressures of R123 and R123a are very similar to those of R11 over the whole experimental temperature range, but the vapor pressures of R134a and R132b differ somewhat from those of R12 and R113, respectively, as the temperature increases. The numerical vapor pressure data can be fitted by an empirical equation using the Chebyshev polynomial with a mean deviation of less than 0.3 %.

Thermal conductivity of fourteen liquids in the temperature range 298–373 K

New experimental data on the thermal conductivity of 14 organic liquids at atmospheric pressure are presented in the temperature range from 25 to 100°C. The liquids measured are five n-alkanes (C6, C7, C8, C10, C12), cyclohexane, six aromatic hydrocarbons (benzene, ethylbenzene, o-, m-, p-xylenes, isopropylbenzene) and two phenyl halides (chloro-, bromobenzenes). The measurements were performed by a transient hot-wire method on a relative basis. The thermal conductivity of toluene, which was selected as a reference liquid, was determined on an absolute basis with another transient apparatus. The precision of the present experimental results is within ±1.2%. The uncertainty of the thermal conductivity values is estimated to be within ±2%; this includes the uncertainty of the values of toluene as the reference liquid. The experimental results for each liquid are represented satisfactorily by a linear equation in temperature. At a reduced temperature T/Tc=0.5, thermal conductivity has a simple relation with the molar density for each homologous series of liquids.

Volumetric properties of 1-alkanols at temperatures in the range 298–348 K and pressures up to 40 MPa

Molar volumes, thermal expansion coefficients, and isothermal compressibilities of six higher 1-alkanols (1-hexanol, 1-octanol, 1-decanol, 1-dodecanol, 1-tetradecanol, and 1-hexadecanol) have been determined at temperatures from 298 to 348 K and pressures up to 40 MPa. The density measurements were performed using a vibrating densitometer with an uncertainty of ±0.06%. The relationship between the properties and the structures of these alkanols is discussed in terms of the carbon-chain lengths.

Viscosities of six 1-alkanols at temperatures in the range 298-348 K and pressures up to 200 MPa

Viscosities of six higher 1-alkanols (1-hexanol, 1-octanol, 1-decanol, 1-dodecanol, 1-tetradecanol, and 1-hexadecanol) have been determined at temperatures from 298 to 348 K and pressures up to 200 MPa. The viscosity measurements were performed using a falling-body viscometer with an uncertainty of ±5%. Simple equations are presented to express the experimental viscosities as a function of temperature and pressure within the experimental uncertainty. The relationship between the viscosity and the density of these alkanols is discussed in terms of the significant structure theory extended to high pressures.

Thermal conductivity of gaseous HFC-134a, HFC-143a, HCFC-141b, and HCFC-142b

The thermal conductivity of new environmentally acceptable fluorocarbons HFC-134a (CH2FCF3), HFC-143a (CH3CF3), HCFC-141b (CH3CCl2F), and HCFC-142b (CH3CCl2F) in the gaseous phase has been measured in the temperature range 293–353 K at pressures up to 4 MPa. The thermal conductivity has been measured with a coaxial-cylinder cell on a relative basis. The apparatus was calibrated with He, Ne, Ar, Kr, N2, CH4, and SF6 as reference fluids. The uncertainty of the experimental data obtained is estimated to be within 2% except for the uncertainty associated with the reference thermal-conductivity values. The excess thermal conductivity has been correlated satisfactorily as a function of density.