Isobaric thermal expansivities of mixtures ofm-cresol and quinoline from 0.1 to 400 MPa at 303 to 503 K

Isobaric thermal expansivities, α _p (p, T), of five binary mixtures ofm-cresol with quinoline (0.1499, 0.2998, 0.5005, 0.6325, and 0.8501 mol fraction ofm-cresol) were measured in a pressure-controlled scanning calorimeter over the pressure range from just above the saturation vapor pressures to 400 MPa, and at 303.15, 353.15, 403.15, 453.15, and 503.15 K. Molecular association ofm-cresol with itself and ofm-cresol with quinoline exerts large effects on the pressure and temperature behavior of α _p isotherms. The extent of association changes significantly with conditions in all except the 2∶1 mixture as demonstrated by the crossing of isotherms at lower pressures as the temperature increases. In the 2∶1m-cresol quinoline mixture the extent of association is not perturbed significantly by temperature change and the mixture behaves like a simple liquid, exhibiting a unique crossing point of α _p isotherms.     

Density and Viscosity of Mixtures of n-Hexane and 1-Hexanol from 303 to 423 K up to 50 MPa

Experimental results for the density and viscosity of n-hexane+1-hexanol mixtures are reported at temperatures from 303 to 423 K and pressures up to 50 MPa. The binary mixture was studied at three compositions, and measurements on pure 1-hexanol are also reported. The two properties were measured simultaneously using a single vibrating-wire sensor. The present results for density have a precision of ±0.07% and an estimated uncertainty of ±0.3%. The viscosity measurements have a precision of ±1% and an estimated uncertainty of ±4%. Representations of the density and viscosity of the mixture as a function of temperature and pressure are proposed using correlation schemes.     

Measurements of the viscosity of n-heptane + n-undecane mixtures at pressures up to 75 MPa

New absolute measurements of the viscosity of binary mixtures of n-heptane and n-undecane are presented. The measurements, performed in a vibrating-wire instrument, cover the temperature range 295–335 K and pressures up to 75 MPa. The concentrations studied were 40 and 70%, by weight, of n-heptane. The overall uncertainty in the reported viscosity data is estimated to be ±0.5%. A recently extended semiempirical scheme for the prediction of the thermal conductivity of mixtures from the pure components is used to predict successfully both the thermal conductivity and the viscosity of these mixtures, as a function of composition, temperature, and pressure.     

Thermophysical properties ofm-cresol as a function of temperture (303 to 503 K) and pressure (0.1 to 400 MPa)

Measured and derived thermophysical properties ofm-cresol are reported for pressures up to 400 MPa at temperatures from 303 to 503 K. Isobaric thermal expansivities were measured by pressure-scanning calorimetry from 303 to 503 K and 0.1 to 400 MPa. The specific volume at 353 K was determined by pycnometry at atmospheric pressure and calculated from isothermal compressibilities measured as a funtion of pressure up to 400 MPa. Specific volumes at other temperatures and pressures are calculated from isothermal compressibilities measured as a function of pressure up to 400 MPa. Specific volumes, isothermal compressibilities, thermal coefficients of pressure, and isobaric and isochoric heat capacities at pressures up to 400 MPa are derived at several temperatures. The effects of pressure on the isobaric heat capacities ofm-cresol,n-hexane, and water are compared. The effects of self-association ofm-cresol are apparent in both the thermal expansivity and the heat capacity data.     

Thermal conductivity of methane-ethane mixtures at temperatures between 140 and 330 K and at pressures up to 70 MPa

The paper presents new measurements on the thermal conductivity of three methane-ethane mixtures with methane mole fractions of 0.69, 0.50, and 0.35. The thermal conductivity surface for each mixture is defined by up to 13 isotherms at temperatures between 140 and 330 K with pressures up to 70 MPa and densities up to 25 mol · L^–1. The measurements were made with a transient hot-wire apparatus. They cover a wide range of physical states including the dilute gas, the single-phase fluid at temperatures above the maxcondentherm, the compressed liquid states, and the vapor at temperatures below the maxcondentherm. The results show an enhancement in the thermal conductivity in the single-phase fluid down to the maxcondentherm temperature, as well as in the vapor and in the compressed liquid. A curve fit of the thermal conductivity surface is developed separately for each mixture.Paper presented at the Ninth Symposium on Thermophysical Properties, June 24–27, 1985, Boulder, Colorado, U.S.A.     

Thermal conductivity of water and 2-n-butoxyethanol and their mixtures in the temperature range 305–350 K at pressures up to 150 MPa

The thermal conductivity of binary liquid mixtures of water and 2-n-butoxyethanol has been measured within the temperature range 305–350 K at pressures up to 150 MPa. The measurements have been carried out with a transient hotwire instrument suitable for electrically conducting liquids and have an estimated accuracy of ±0.3%. The liquid mixture has a closed-loop solubility and reveals a lower critical solution temperature for a mole fraction of 2-n-butoxyethanol of 0.0478 at a temperature of 322.25 K. The results of the measurements reveal a small, but discernible, enhancement of the thermal conductivity of the solution at the critical composition.Paper presented at the Twelfth Symposium on Thermophysical Properties. June 19–24, 1994, Boulder, Colorado, U.S.A.     

The viscosity of five liquid hydrocarbons at pressures up to 250 MPa

This paper reports new measurements of the viscosity of toluene, n-pentane, n-hexane, n-octane, and n-decane at pressures up to 250 MPa in the temperature range 303 to 348 K. The measurements were performed with a vibrating-wire viscometer and with a relative method of evaluation. Calibration of the instrument was carried out with respect to reference values of the viscosity of the same liquids at their saturation vapour pressure. The viscosity measurements have a precision of ±0.1% but the accuracy is limited by that of the calibration data to be ±0.5%. The experimental data have been represented by polynomial functions of pressure for the purposes of interpolation. The data are also used as the most precise test yet applied to a representation of the viscosity of liquids based upon hard-sphere theory.     

Viscosity and thermal conductivity of binary n-heptane + n-alkane mixtures

New absolute measurements of the viscosity of binary mixtures of n-heptane with n-hexane and n-nonane are presented. The measurements, performed in a vibrating-wire instrument, cover a temperature range 290–335 K and pressures up to 75 MPa. The concentrations studied are 40 and 70% by weight of n-heptane. The accuracy of the reported viscosity data is estimated to be ±0.5%. The present measurements, together with other n-heptane + n-alkane viscosity and thermal-conductivity measurements, are used to develop a consistent semiempirical scheme for the correlation and prediction of these mixture properties from those of the pure components.     

Viscosity of binary mixtures. IV. Triethylamine with alkanes and monoalkylamines at 303.15 and 313.15 K

Viscosities and densities of seven binary mixtures of n-hexane, n-octane, isooctane, n-propylamine, n-butylamine, n-hexylamine, and n-octylamine with triethylamine have been measured at 303.15 and 313.15 K. Deviations of viscosities from a linear dependence on the mole fraction and values of excess Gibbs energy of activation G ^*E of viscous flow are attributable to the H-bonding and to the size of the alkylamine and alkane molecules.     

Thermal conductivity of liquid mixtures of benzene and 2,2,4-trimethylpentane at pressures up to 350 MPa

This paper contains the results of new measurements of the thermal conductivity of mixtures of benzene and 2,2,4-trimethylpentane in the liquid phase within the temperature range 313 to 344 K at pressures up to 350 MPa. The measurements were carried out with a transient hot-wire instrument and have an estimated accuracy of ±0.3%. The study is the first conducted at high pressures on mixtures of components of greatly differing volatilities and therefore provides a further test of methods of representing the thermal conductivity of liquid mixtures based upon the hard-sphere theory of transport in liquids. It is shown that the procedure is capable of representing all of the present experimental data within ±5%. A more detailed examination of the results reveals small, but systematic, deviations from universality of the behavior of the thermal conductivity as a function of density implied by the hard-sphere theory, which merit further investigation.     

n-hexane as a model for compressed simple liquids

Isobaric thermal expansivities, _p, ofn-hexane have been measured by pressure-controlled scanning calorimetry from just above the saturation vapor pressure to 40 MPa at temperatures from 303 to 453 K and to 300 MPa at 503 K. These new data are combined with literature data to obtain a correlation equation for _p valid from 240 to 503 K at pressures up to 700 MPa. Correlation equations are developed for the saturated vapor pressure, specific volume, and isobaric heat capacity of liquid n-hexane from 240 to 503 K. Calculated volumes, isobaric and isochoric specific heat capacities. isothermal compressibilities, and thermal coefficients of pressure are presented for the entire range of pressure and temperature. The pressure-temperature behavior of these quantities is discussed as a model behavior for simple liquids without strong intermolecular interactions.     

Thermal conductivity of n-tridecane at pressures up to 500 MPa in the temperature range 35–75°C

Thermal conductivity coefficients are reported for liquid n-tridecane along three isotherms, 35, 48, and 73°C, and for pressures from 20 to 500 MPa. The measurements have been made with a transient hot-wire instrument, and the results, when corrected for the effects of radiation absorption, have an estimated uncertainty of ±0.7%. The thermal conductivity as a function of density along isotherms can be represented by means of the same form of equation as that found suitable for other normal alkanes, and this is based upon a heuristic modification of the van der Waals theory of liquids.     

Measurements of the viscosity of n-heptane,n-nonane,and n-undecane at pressures up to 70 MPa

New absolute measurements of the viscosity of n-heptane, n-nonane, and n-undecane are presented. The measurements were performed with a vibrating-wire instrument at temperatures of 303.15 and 323.15 K and pressures up to 70 MPa. The overall uncertainty in the reported viscosity data is estimated to be ±0.5%. A recently developed semiempirical scheme for the correlation and prediction of the thermal conductivity, viscosity, and self-diffusion coefficients of n-alkanes is applied to the prediction of the viscosity of n-heptane, n-nonane, and n-undecane. The comparison of these predicted values with the present high-pressure measurements demonstrates the predictive power of this scheme.     

Volume ratios for n-pentane in the temperature range 278–338 K and at pressures up to 280 MPa

Volume ratios (V _P/V _0.1), and isothermal compressibilities calculated from them, are reported for n-pentane for seven temperatures in the range 278 to 338 K for pressures up to 280 MPa. The isobaric measurements were made with a bellows volumometer for which a novel technique had to be devised to enable measurements to be made above the normal boiling point (309.3 K). The accuracy of the volume ratios is estimated to be ±0.05 to 0.1% up to 303.15 K and ±0.1 to 0.2% from 313.15 to 338.15 K. The volume ratios are in good agreement with those calculated from recent literature data up to the maximum pressure of the latter, viz., 60 MPa.     

Volumetric measurements under pressure for 2,2,4-trimethylpentane at temperatures up to 353.15 K and for benzene and three of their mixtures at temperatures up to 348.15 K

(p, V, T) data have been obtained in the form of volume ratios relative to 0.1 MPa for benzene (298.15 to 348.15 K), 2,2,4-trimethylpentane (TMP) (313.15 to 353.15 K), and their mixtures near 0.25, 0.5, and 0.75 mole fraction of benzene (313.15 to 348.15 K) for pressures up to near the freezing pressures for benzene and the mixtures, and up to 400 MPa for TMP. Isothermal compressibilitiesκ _T, isobaric expansivitie α, changes in heat capacity at constant pressureΔC _p, and excess molar volumesV ^E have been determined from the data. Literature data at atmospheric pressure have been used to convert theΔC _p toC _p at several temperatures. The isobars for α over the temperature range 278.15 to 353.15 K for TMP intersect near 47 MPa and reverse their order in temperature when plotted against pressure; normalization of the α's by dividing the values at each temperature by the α at 0.1 MPa prevents both the intersection and the reversal of the order. TheV ^E are positive and have an unusual dependence on pressure: they increase with temperature and pressure so that the order of the curves for 0.1, 50, and 100 MPa changes in going from 313.15 to 348.15 K.     

PVT and derived thermodynamic properties for the glycine-water system at temperatures from 298 to 323 K and pressures up to 300 MPa

The specific volumes for the glycine-water system have been measured in the temperature range 298–323 K and at pressures up to 300 MPa, using a glass piezometer. The uncertainties in the specific volume are estimated to be less than 0.03%. The PVT relations are correlated by the Tait equation. Good agreement was found with correlations by the Tait equation using a simple extension similar to that proposed by Dymond and Malhotra. The isothermal compressibility and apparent molar volume of glycine are calculated by the Tait equation. The apparent molar volume of glycine increases with increasing pressure.Paper presented at the Tenth Symposium on Thermophysical Properties, June 20–23, 1988, Gaithersburg, Maryland, U.S.A.     

Composition dependence of binary diffusion coefficients in alkane mixtures

The binary diffusion coefficients of mixtures of n-heptane with n-hexane and 2,2,4-trimethylpentane with n-hexane have been measured at various compositions at 308.1, 312.2, and 316.5 K using the Taylor dispersion technique. The experimental results for the n-hexane/n-heptane system were in good agreement with the literature values (<1.5%). The observed binary diffusion coefficients for this system exhibit a linear dependence on composition. On the contrary, the results of the n-hexane/2,2,4-trimethylpentane system reveal an interesting behavior of the composition dependence of the binary diffusion coefficients, presenting a slight maximum, for composition at a molar fraction of n-hexane of 0.86. In order to explain this difference in behavior, the influence of branching of molecules on diffusion is discussed. It was found that although the Enskog hard-sphere model for binary diffusion can reproduce the experimental results for the n-hexane/n-heptane system within 3%, it failed to predict the composition dependence of the n-hexane/2,2,4-trimethylpentane system within the experimental accuracy. The results showed that there is significant effect of branching in alkane molecules on the diffusion coefficient. This effect has been quantified using the roughness parameter, which represents the magnitude of coupling between translational and rotational motions.     

p,V, T and derived thermodynamic data for bromobenzene at temperatures from 278 to 323 K and pressures up to 280 MPa

Experimentally determined p, V, T data are reported for bromobenzene at 278, 288, 298, 313, and 323 K, at pressures up to about 280 MPa or (at 278 and 288 K) a lower pressure slightly below the freezing pressure at the temperature of measurement. Values of the isobaric expansivity, isothermal compressibility, internal pressure, and equivalent hard-sphere diameter, derived from the p, V, T data, are presented.On leave from the Department of Chemistry, The University of Auckland, Auckland, New Zealand.     

Absolute measurement of the thermal conductivity of alcohol + n-hexane mixtures

New absolute measurements, by the transient hot-wire technique, of the thermal conductivity of binary mixtures of n-hexane with methanol, ethanol, and hexanol are presented. The temperature range examined was 295–345 K and the pressure atmospheric. The concentrations studied were 75% by weight of methanol and 25, 50, and 75% by weight of ethanol and hexanol. The overall uncertainty in the reported thermal conductivity data is estimated to be ±0.5%, an estimate confirmed by the measurement of the thermal conductivity of water. A recently extended semiempirical scheme for the prediction of the thermal conductivity of mixtures from the pure components is used to correlate and predict the thermal conductivity of these mixtures, as a function of both composition and temperature.     

Thermophysical properties of quinoline as a function of temperature (303–503 K) and pressure (0.1–400 MPa)

Measured and derived thermophysical properties of quinoline are reported for pressures up to 400 MPa at temperatures from 303 to 503 K. The specific volume at 353 K was determined from the specific volume at atmospheric pressure measured b) pycnometry and from isothermal compressibilities measured as a function of pressure up to 400 M Pa. Specific volumes, isothermal compressibilities, thermal coellicients of pressure, and isobaric and isochoric heat capacities at pressures up to 4011 MPa are derived at several temperatures. The effects of pressure on the isobaric heat capacity of quinoline, a weakly self-associated liquid. are discussed and compared with the pressure effects on heat capacities ofn-hexane andm-cresol.