Densities of liquid R 114 at temperatures from 310 to 400 K and pressures up to 10 MPa

Density measurements for liquid R 114 (dichlorotetrafluoroethane) have been obtained with a variable-volume method. The results cover the high-density region from 1007 to 1462 kg·m^–3 along ten isotherms between 310 and 400 K at 16 pressures from 0.5 to 10.0 MPa. The experimental uncertainty in the density measurements was estimated to be no greater than 0.2%. Based on the present results the derivatives with respect to temperature and pressure were calculated, and numerical values of the volume expansion coefficient and of the isothermal compressibility are tabulated as a function of temperature and pressure.     

Bubble pressures and saturated liquid densities of R 22 + R 114 mixtures in the range 310–400 K

The bubble pressures and saturated liquid densities of mixtures of R 22 and R 114 have been measured with a static and synthetic method with a variable-volume cell. The results for five different compositions (100, 75, 50, 25, and 0 mol% R 22) cover the temperature range from 310 to 400 K. The experimental data for both pure components are compared with literature data, showing the reliability of the present results. The system shows positive deviations from Raoult's law at temperatures below 340 K and the deviations increase with decreasing temperature. The 25 mol % R 22 mixture shows the maximum non-ideality.     

Temperature and Pressure Dependence of the Volumetric Properties of Binary Liquid Mixtures Containing Dihaloalkanes

Densities of ethyl acetate + dibromomethane, + bromochloromethane, + 1,2-dichloroethane, or + 1-bromo-2-chloroethane binary mixtures were measured at 288.15, 298.15, and 308.15 K over the entire composition range. Thermal expansion coefficients and excess molar volumes were calculated. Moreover, densities at 298.15 K at pressures up to 200 bar were determined for the same mixtures. Isothermal compressibilities of the pure liquids and their mixtures were obtained. The excess molar volumes are positive, and the excess isothermal compressibilities are negative for all the studied mixtures.     

Thermodynamic properties and excess volumes of 2,2,4-trimethylpentane + n-heptane mixtures from 298 to 338 K for pressures up to 400 MPa

(p, V, T) data for mixtures of 2,2,4-trimethylpentane (TMP) and heptane have been obtained in the form of volume ratios for four temperatures in the range 298.15 to 338.15 K for pressures up to 390 MPa. The data have been represented by the Tait equation of state for the purposes of interpolation and extrapolation. The atmospheric pressure densities of both pure components and their mixtures for three temperatures have been measured and used to determine the excess molar volumes. Isothermal compressibilities have been evaluated from the volumetric data.     

Thermodynamic properties of R32 + R134a and R125 + R32 mixtures in and beyond the critical region

A parametric crossover equation of state for pure fluids is adapted to binary mixtures. This equation incorporates scaling laws asymptotically close to the critical point and is transformed into a regular classical expansion far away from the critical point. An isomorphic generalization of the law of corresponding states is applied to the prediction of thermodynamic properties and the phase behavior of binary mixtures over a wide region around the locus of vapor-liquid critical points. A comparison is made with experimental data for pure R32, R 125 and R 134a, and for R32 + R 134a and R 125 + R32 binary mixtures. The equation of state yields a good representation of thermodynamic property data in the range of temperatures 0.8T_c(x) ≤ T ≤ 1.5T_c(x) and densities 0.35 ?_c(x) ≤ ? ≤ 1.65?_c(x).     

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.     

Thermodynamic Properties of 1-Alkenes in the Liquid State: 1-Tetradecene

Thermodynamic properties of liquid 1-tetradecene have been calculated using a grid algorithm based on sound-speed data, obtained in a previous study over a wide range of temperatures and pressures. Since additional information such as densities and isobaric heat capacities at atmospheric pressure are needed for these calculations, the most reliable literature data and those obtained on the basis of structure–property correlations in the homologous series of 1-alkenes were used. Detailed tables, containing values of sound speed, density, isobaric, and isochoric heat capacities, isobaric expansion coefficient, isothermal compressibility, enthalpy, and entropy in the range of temperatures from 303 to 433 K and at pressures from 0.1 to 100 MPa, are given.Paper presented at the Seventeenth European Conference on Thermophysical Properties, September 5–8, 2005, Bratislava, Slovak Republic.     

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.     

Thermodynamic and transport properties of fluids and fluid mixtures in the extended critical region

A practical representation of the thermodynamic properties and the transport coefficients related to diffusion, heat conduction, and their cross-processes in pure fluids and binary mixtures near the liquid-vapor critical line is developed. Crossover equations for the critical enhancement of those coefficients incorporate the scaling laws near the critical point and are transformed to the regular background far away from the critical point. The crossover behavior of the thermal conductivity and the thermal diffusion ratio in binary mixtures is also discussed. A comparison is made with thermal-conductivity data for pure carbon dioxide, pure ethane, and carbon dioxide add ethane mixtures.     

Virial coefficients of methane-ethane mixtures in the temperature range from 0 to 60°C determined with an automated expansion apparatus

An automated expansion apparatus has been set up which can be used for PVT measurements on gases from Il to 60 C at pressures from 2 to 7 NIPa. It consists of two chambers connected by an expansion valve. The ratio of the two volumes is 1:54. The measurements along one isotherm. which take 20 h, can be per formed routinely and without operator attendance. The uncertainty of the com pressibility factor is estimated to be 10^–3. The compressibility factors of binary mixtures of the main components of most natural gases, methane and ethane, were determined on high-grade gas, the mole fractions of ethane being 0.05, 0.15. and 0.25. Seven isotherms were measured of each of the mixtures. Data from the literature for the virial coefficients of the pure substances were used to establish a virial equation of state which approximates the measured com pressibility factors with a standard deviation of 0.4 x 10 '. This is substantially smaller than the uncertainty. The interaction virial coefficients were calculated from this equation of state. The results obtained are in good agreement with other available data.Paper presented al the Twelfth Symposium on Thermophysical Properties. June 19–24, 1994, Boulder, Colorado. U.S.A.     

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.     

Critical evaluation of the thermodynamic properties of cobalt

The thermodynamic properties and the pressure-temperature phase diagram of Co have been evaluated from experimental information using thermodynamic models for the Gibbs energy of the various phases. For hcp and fcc Co the model describes the magnetic contribution to the molar volume, expansivity, and compressibility and the efect of pressure upon the Curie temperature. Experimental data of many different types are satisfactorily described by the evaluated model parameters.This work was supported by the Swedish Board for Technical Development, and by Sandvik Hard Materials, Stockholm, Sweden.     

Thermodynamic Properties of Heavy n-Alkanes in the Liquid State: n-Dodecane

A grid algorithm based on sound speed data, was used to calculate the thermodynamic properties of liquid n-dodecane. The density, isobaric expansion coefficient, isothermal compressibility, isobaric and isochoric heat capacities, enthalpy, and entropy of liquid n-dodecane were calculated in the range of temperatures from 293 to 433 K and pressures from 0.1 to 140 MPa. Coefficients of the Tait equation were determined in the above-identified range of parameters. A table of the thermodynamic properties of n-dodecane is presented.     

Transport properties of fluid mixtures in the critical region

Transport properties of fluid mixtures exhibit anomalous behavior near the vapor-liquid critical line. These anomalies are a result of long-range fluctuations in the system in the vicinity of a critical point. We use mode-coupling theory to describe the critical enhancements of the thermal conductivity, the viscosity, the mutual diffusivity, and the thermal-diffusion coefficients of binary mixtures. The resulting expressions not only are valid in the asymptotic critical region but also describe the crossover to regular behavior far away from a critical point. The crossover functions depend on the thermodynamic properties of the mixtures, background values of all transport coefficients, and two concentration-dependent cutoff wave numbers. We compare the proposed crossover model with experimental thermal-conductivity data for mixtures of carbon dioxide and ethane in the critical region and find good agreement between theory and experiment.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A.     

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.     

An automated volumometer: Thermodynamic properties of 1,1-dichloro-2,2,2-trifluoroethane (R123) for temperatures of 278.15 to 338.15 K and pressures of 0.1 to 380 MPa

An automated bellows volumometer is described which is capable of obtaining p-V-T data in the form of volume ratios for pressures up to 380 MPa. Volume ratios for 1,1-dichloro-2,2,2-trifluoroethane (R123) have been measured for six temperatures in the range of 278.15 to 338.15 K in the liquid phase. The accuracy of the volume ratios is estimated to be ±0.05 to 0.1% for the experimental temperatures up to 298.15 K and better than ±0.15% for temperatures above the normal boiling point of R123 (300.15 K). They agree with the literature data (which do not extend beyond 4 MPa) within the experimental uncertainty of those results. Isothermal compressibilities, isobaric expansivities, internal pressures, and isobaric molar heat capacities have been evaluated from the volumetric data. The pressure dependence of isobaric molar heat capacities obtained from the data generally agree with the pressure dependence of experimentally measured literature values within the latter's accuracy of ±0.4%.     

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.     

Reference Correlation for the Viscosity of Liquid Cyclopentane from 220 to 310 K at Pressures to 25 MPa

A correlation in terms of temperature and molar volume is recommended for the viscosity of liquid cyclopentane as a reference for low-temperature, high-pressure viscosity measurements. The temperature range covered is from 220 to 310 K and the pressure range from atmospheric up to 25 MPa. The standard deviation of the proposed correlation, within a 95% confidence limit, is 1%.     

A new equation of state for chlorodifluoromethane (R22) covering the entire fluid region from 116 K to 550 K at pressures up to 200 MPa

A new equation of state in the form of a fundamental equation explicit in the dimensionless Helmholtz free energy has been developed for chlorodifluoromethane (R 22). This equation, which contains 22 fitted coefficients, covers the entire fluid region from 116 K (triple point temperature) to 550 K at pressures up to 200 MPa. The mathematical form of the equation was determined with the help of a new method to optimize its structure. New pressure-density-temperature data in the liquid region and especially new vapour pressures and saturated liquid densities, as well as speed of sound data have been incorporated to extend the range of validity and to improve the accuracy of properties calculated with this equation beyond that of previous formulations. Independent equations are also included for the vapour pressure as well as for the saturated liquid and vapour densities. The uncertainty of the new wide-range equation of state can roughly be given as follows: ± 0.1% in density (with the exception of the critical region), ± 1% in heat capacity, ± 0.5% in speed of sound in the liquid and 0.1% in speed of sound in the gas phase. The new equation of state corresponds to the International Temperature Scale of 1990 (ITS-90).