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  • 1
    ISSN: 1572-9567
    Keywords: cyclohexane ; dielectric constant ; re-entrant radio-frequency resonator ; relative permittivity ; static dielectric constant ; water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The complex dielectric constant (relative electric permittivity) $$\varepsilon _{\text{r}} = \varepsilon ' - i\varepsilon ''$$ of liquid water was redetermined in the temperature range 0°C〈;t〈145°C at pressures less than 440 kPa. In this work, εr was deduced from measurements of the resonant frequencies f α of a novel, re-entrant, two-mode, radio-frequency resonator. The frequencies ranged from 23 to 84 MHz and were well within the low-frequency limit for ε′ because (2πf ατmax)2〈5×10−5 where τmax=1.8×10−11 s is the maximum relaxation time of water under the conditions studied. The data for ε′ for two water samples differing in conductivity by a factor of 3.6 and for the two resonant modes differing in frequency by a factor of 2.6 were simultaneously fit by the polynomial function ε′(t)=87.9144−0.404399t+9.58726×10−4 t 2−1.32802×10−6 t 3 with a remarkably small residual standard deviation of 0.0055. The present data are consistent with previously published data; however, they are more precise and internally consistent. The present apparatus was also tested with cyclohexane and yielded the values ε′(t)=2.0551−0.00156t for 20°C〈t〈30°C, in excellent agreement with previously published values.
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  • 2
    ISSN: 1572-9567
    Keywords: density ; 1,1-difluoroethane ; p-ρ-T data ; R143a ; R152a ; saturated liquid ; 1,1,1-trifluoroethane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The p-ρ-T relationships have been measured for 1,1-difluoroethane (R152a) and 1,1,1-trifluoroethane (R143a) by an isochoric method with gravimetric determinations of the amount of substance. Temperatures ranged from 158 to 400 K for R152a and from 166 to 400 K for R143a, while pressures were up to 35 MPa. Measurements were conducted on compressed liquid samples. Determinations of saturated liquid densities were made by extrapolating each isochore to the vapor pressure, and determining the temperature and density at the intersection. Published p-ρ-T data are in good agreement with this study. For the p-ρ-T apparatus, the uncertainty of the temperature is ±0.03 K, and for pressure it is ±0.01% at p〉3 MPa and ±0.05% at p<3 MPa. The principal source of uncertainty is the cell volume (∼28.5 cm3), which has a standard uncertainty of ±0.003 cm3. When all components of experimental uncertainty are considered, the expanded relative uncertainty (with a coverage factor k=2 and thus a two-standard deviation estimate) of the density measurements is estimated to be ±0.05%.
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  • 3
    ISSN: 1572-9567
    Keywords: argon ; experimental method ; helium ; low density ; propane ; thermal conductivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The paper reports further developments of the transient hot-wire technique. The particular development of interest is the extension of the technique to study polar, or electrically-conducting gases with a relatively low thermal conductivity but a high thermal diffusivity, circumstances which occur at low density and therefore low pressure, for gases of high molecular weight. The theory of the transient hot-wire instrument is examined again in order to guide a revised design of the thermal conductivity cell with this particular application in mind. Test measurements have then been conducted on helium, argon, and propane at low and moderate pressures to confirm that the instrument operates in accordance with the theory of it. The satisfactory completion of these tests demonstrates that the new equipment overcomes many of the defects observed in earlier variants of the instrument for application to the study of refrigerant gases.
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  • 4
    ISSN: 1572-9567
    Keywords: corresponding states ; petroleum fractions ; propane ; viscosity, thermal conductivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A corresponding-states model for the transport properties of petroleum fractions is presented. The model requires only the API specific gravity and the mean average boiling point as input parameters. The extended correspanding-states model uses propane as a reference fluid, and new generalized shape factor expressions that are functions of the acentric factor and the reduced temperature are presented. Also presented are new correlating functions for the viscosity and thermal conductivity of the reference fluid that can be extrapolated well below the freezing point of propane. The performance of the model is demonstrated by comparing with experimental data for viscosity and thermal conductivity of petroleum fractions.
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  • 5
    ISSN: 1572-9567
    Keywords: CINDAS ; data analysis ; data synthesis ; history of thermophysical properties ; statistical data
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A brief presentation is given on the establishment and history of the Center for Information and Numerical Data Analysis and Synthesis (CINDAS), along with the scope of its activities and accomplishments. In line with the Center's prime involvement, special emphasis is given to the existence of discord in numerical data in the literature, and the role of critical data analysis and synthesis is provided through illustrations. Statistical data are presented showing the growth of the literature on thermophysical properties between 1780 and 1980.
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  • 6
    ISSN: 1572-9567
    Keywords: viscosity ; benzene ; n-alkanes ; cyclohexane ; Grunberg and Nissan equation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Viscosity coefficient measurements at saturation pressure are reported for benzene + n-hexane, benzene + n-octane, benzene + n-decane, benzene + n-dodecane, benzene + n-hexadecane, and benzene + cyclohexane at temperatures from 283 to 393 K. The characteristic parameter G in the Grunberg and Nissan equation $$\ell n\eta = x_1 \ell n\eta _1 + x_2 \ell n\eta _2 + x_1 x_2 G$$ is found to be both composition and temperature dependent for benzene + n-alkane mixtures, but it is independent of composition for the system benzene + cyclohexane.
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  • 7
    ISSN: 1572-9567
    Keywords: transverse thermal conductivity ; unidirectional composites ; fiber shape
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The model for the traverse thermal conductivity of unidirectional composite materials published by Springer and Tsai, which yields good results when compared to experimental results, is generalized to include fibers having elliptical cross sections. It is shown that the thermal conductivity of the unidirectional composite normal to the filaments depends strongly on fiber shape.
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  • 8
    ISSN: 1572-9567
    Keywords: high pressure ; KCl ; solutions ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In this paper, new precise viscosity data are presented for aqueous solutions of KCl; these data cover the temperature range 25–200°C, the pressure range 0.1–30 MPa, and the concentration range 0–4.6 mol KCl/kg H2O. An empirical correlation which reproduces the data within the experimental precision of ±0.5% is given. The accuracy of the data is estimated to range from ±0.5 to ±1.5%.
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  • 9
    ISSN: 1572-9567
    Keywords: Kihara energy function ; radial distribution function ; water ; supercritical fluid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A theoretical and analytic expression for the first shell, and an analytic empirical expression for the whole radial distribution function (RDF) of water are introduced. All the asymptotic limits and functionalities of the RDF with temperature and density are incorporated in these expressions. An effective Kihara pair potential function is presented for water intermolecular interactions which incorporates the hydrogen bonding by using the chain association theory. The intermolecular pair potential parameters are adjusted to the experimental x-ray diffraction data of water RDF at various temperatures. The predicted first-shell results for water near critical and in supercritical conditions compare satisfactorily with the available neutron diffraction RDF data, with the simulation RDF results, and with the empirical RDF curves. The empirical expression initially proposed for the RDF of the Lennard–Jones fluid is extended to predict the RDF and the isothermal compressibility of water to conditions where experimental or simulated data are not available. Comparison with the Lennard–Jones fluid shows that the height of the first peak of water RDF changes much less at subcritical and supercritical conditions compared to that of the Lennard–Jones fluid which decreases appreciably going from subcritical to supercritical conditions.
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  • 10
    ISSN: 1572-9567
    Keywords: conformal solution theory ; local mole fraction ; nonequilibrium molecular dynamics ; radial distribution functions ; soft spheres ; Van der Waals one fluid theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A binary 50% mixture of soft spheres is studied via nonequilibrium molecular dynamics, and the equilibrium and nonequilibrium radial distribution functions for a nonconformal mixture with a mass ratio of 10 and a size ratio of about 2 are examined. This model system is related to the real methane/decane mixture, and it is shown that apparently anomalous properties of this mixture, especially the viscosity, could perhaps be understood in terms of the local or ambient mole fraction. In addition, the postulates of the Van der Waals one fluid conformal solution theory are discussed, and a mixing rule for the mass is derived.
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