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  • Articles  (43)
  • thermal conductivity  (43)
  • Springer  (43)
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  • Springer  (43)
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  • Physics  (43)
  • 1
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    International journal of thermophysics 4 (1983), S. 11-33 
    ISSN: 1572-9567
    Keywords: butane ; corresponding states ; critical region ; thermal conductivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The thermal conductivity of n-butane has been measured by a coaxial-cylinder method over a pressure range from 0.1 MPa up to 70 MPa and a temperature range from room temperature to 600 K, covering all fluid states. The estimated accuracy of the method is about 2%. Special emphasis has been given to the behavior of the thermal conductivity near the critical point, and the critical enhancement has been studied for 3.6 K〈δT〈176 K. The effect of inelastic collisions upon transport properties of the dilute gas has been discussed. The results obtained for the reduced critical enhancement as a function of the reduced critical temperature confirm the universality of the critical exponent, for the n-alkanes, whereas the reduced excess thermal conductivity outside the critical region is a function of the reduced density and of the n-alkane.
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  • 2
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    International journal of thermophysics 4 (1983), S. 115-125 
    ISSN: 1572-9567
    Keywords: heat capacity ; selenium ; sulfur ; thermal conductivity ; thermal diffusivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The thermal properties (thermal activity, heat capacity, thermal conductivity, and thermal diffusivity) of liquid sulfur and selenium were measured in the temperature range 160–400°C. These measurements were performed using an experimental apparatus, based on the ac heated-wire (strip) technique. Liquid sulfur shows a second order phase transition at 225°C. The present study has considered four different mechanisms of heat transfer: conduction, electrons, internal electromagnetic radiation, and convection. The results showed that heat transfer is mainly due to conduction, whereas that due to electrons and electromagnetic radiation is very small indeed. Suppression of convection by the cell configuration was studied, as well as the effect of locating the strip or the wire in horizontal form, which permits heat flow in one direction. Moreover, stability of the third harmonic shows that there is no hydrodynamic flow inside the liquid, which means that the convection is taken in consideration within the time of measurements.
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  • 3
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    International journal of thermophysics 5 (1984), S. 209-218 
    ISSN: 1572-9567
    Keywords: fluorocarbons ; liquid ; modified Li-Poole equations ; thermal conductivity ; toluene ; transient hot wire method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The thermal conductivity of ten liquid fluorocarbons, R 11, R 12, R 13, R 13B1, R 22, R 113, R 114, R 115, R 114B2, and R 124, was measured in the temperature range from 204–450 K by using the transient hot wire method. Prior to the measurement of the fluorocarbons, the thermal conductivity of toluene as the reference material was measured. The results for toluene agree with the recommended values by Nagasaka and Nagashima within ±1%. The accuracy of the present results for fluorocarbons is estimated to be better than ±1.5%. The results are compared with the equation by Li and Poole. The equation proves to be unsuitable for some fluorocarbons, and modified Li-Poole equations including the number of fluorine atoms are proposed for the three groups of fluorocarbons based on the smoothed values of this work and are compared with the experimental data.
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  • 4
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    International journal of thermophysics 5 (1984), S. 229-238 
    ISSN: 1572-9567
    Keywords: aluminosilicate fibrous insulator ; ceramic fiber ; hot wire method ; thermal conductivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The temperature and bulk density dependence of the thermal conductivity of commercial aluminosilicate fibrous insulators were studied by using the transient hot wire method. The thermal conductivity of ceramic fibrous insulators in both air and helium gas atmosphere increased with increasing bulk density. At high temperatures, however, the insulators with lower bulk density showed a higher thermal conductivity because of heat radiation. The following experimental relation between thermal conductivity λ and temperature θ was obtained for aluminosilicate fibruous insulators: λ=a exp(bθ). Relationships are given between the constants a and b and the bulk density. From the relation, the optimum bulk density of ceramic fibrous insulators can be calculated for each working temperature.
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  • 5
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    International journal of thermophysics 5 (1984), S. 265-279 
    ISSN: 1572-9567
    Keywords: methane ; thermal conductivity ; transport properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract This paper reports thermal conductivity data for methane measured in the temperature range 120–400 K and pressure range 25–700 bar with a maximum uncertainty of ± 1%. A simple correlation of these data accurate to within about 3% is obtained and used to prepare a table of recommended values.
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  • 6
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    International journal of thermophysics 5 (1984), S. 367-385 
    ISSN: 1572-9567
    Keywords: ethane ; thermal conductivity ; transport properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The paper presents thermal conductivity measurements of ethane over the temperature range of 290–600 K at pressures to 700 bar including the critical region with maximum uncertainty of 0.7 to 3% obtained with a transient line source instrument. A correlation of the data is presented and used to prepare tables of recommended values that are accurate to within 2.5% in the experimental range except near saturation, and in the critical region, where the anomalous thermal conductivity values are predicted to within 5%.
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  • 7
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    International journal of thermophysics 5 (1984), S. 41-52 
    ISSN: 1572-9567
    Keywords: heat capacity ; laser-flash method ; thermal diffusivity ; thermal conductivity ; vanadium-oxygen alloy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Several recent advances made in the author's laboratory in the experimental apparatus and measuring procedures for precise measurements of thermophysical properties by the laser-flash method are reviewed. Heat-capacity measurement has been done on metals and ceramics within an accuracy of ±0.5% in the range from 80 to 800 K, and within ±2% from 800 to 1100 K. Thermal diffusivity has been also measured from 80 to 1300 K with reasonable corrections for heat leak and finite pulse width. As an example of the experimental results by the method, the data of heat capacity, thermal diffusivity, and thermal conductivity of vanadium-oxygen alloys containing 1.07 and 3.46 at.% of oxygen from 80 to 800 K are presented and compared with those of pure vanadium metal.
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  • 8
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    International journal of thermophysics 5 (1984), S. 13-21 
    ISSN: 1572-9567
    Keywords: solids ; thermal conductivity ; thermal diffusivity ; thermophysical properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The research activities on thermophysical properties in many engineering fields in Japan have been promoted for the past 10 years. In this paper, the outlook is reviewed on recent research work on thermophysical properties, mainly on thermal conductivity and thermal diffusivity of solids, in Japan. The research activities are described in such areas as measuring methods, metals, nuclear fuels and ceramics, building materials and insulators, soils and rocks, energy storage materials and compound materials, and dispersed materials.
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  • 9
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    International journal of thermophysics 5 (1984), S. 301-313 
    ISSN: 1572-9567
    Keywords: electrical resistivity ; steels (Cr-Mo) ; thermal conductivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The electrical and thermal conductivities and Seebeck coefficients of three 9 Cr-1 Mo samples were measured over the temperature range 360–1000 K. All of the samples were in the normalized and tempered condition and two of the samples were from different heats of a new, modified alloy. The thermal conductivity of the third sample, which was from a commercial heat, was found to agree well with the ASME code values for this steel. The two heats of modified 9 Cr-1 Mo were found to have significantly higher thermal conductivities and this difference appears to be due to the lower Si content of the modified alloy. The results were compared with the predictions of standard transport theory and data on bcc Fe. These comparisons show that phonon energy transport is important and quite dependent upon the Si content.
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  • 10
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    International journal of thermophysics 4 (1983), S. 311-327 
    ISSN: 1572-9567
    Keywords: high pressure ; thermal conductivity ; toluene ; radiation contribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract New, absolute measurements of the thermal conductivity of liquid toluene are reported. The measurements extend over the temperature range 35–90°C and the pressure range 0.8–600 MPa. A new analytic evaluation of the contribution of radiation in an absorbing emitting fluid to the measurement process is presented. This analysis indicates that the thermal conductivity determined in a transient hot-wire instrument is the radiation-free value. As a consequence it is possible to assert that the overall uncertainty in the experimental data is one of ± 0.3%. A comparison of the data with the results of independent measurements by the same technique shows that the various sets of data are consistent within their mutual uncertainty.
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  • 11
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    International journal of thermophysics 1 (1980), S. 141-146 
    ISSN: 1572-9567
    Keywords: fluids ; hot-wire method ; specific heat ; thermal conductivity ; thermal diffusivity ; toluene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A method and an instrument for the measurement of a number of the thermophysical properties (thermal conductivity, thermal activity, volumetric specific heat, thermal diffusivity) are described. The results obtained for thermal conductivity and specific heat of toluene, over a temperature range 30–350°C and pressures of up to 30 MPa, are presented.
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  • 12
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    International journal of thermophysics 1 (1980), S. 159-175 
    ISSN: 1572-9567
    Keywords: liquids ; thermal conductivity ; transport properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Eighteen correlations appearing in the literature for the prediction of thermal conductivity, λ, of liquids are critically analyzed, and their reliability is checked using coherent input data and selected experimental λ values. The best results are obtained using the Reid, Sherwood, and Prausnitz correlation with a mean deviation of about 8% between predicted and experimental values. An improved correlation is proposed starting from the Viswanath equation, chosen because of its simplicity and convenience. The values of thermal conductivity obtained by this new correlation agree with the experimental values within 1%.
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  • 13
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    International journal of thermophysics 1 (1980), S. 375-381 
    ISSN: 1572-9567
    Keywords: thermal conductivity ; high pressure ; nitrogen ; computer simulation ; modified Enskog theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The results of the measurements of the thermal conductivity coefficients of nitrogen at 298.15 K from atmospheric pressure up to 1 GPa are reported. The experimental values are used to test the Modified Enskog Theory and the corresponding state principle. The experimental values are also compared with the results of computer simulation of the thermal conductivity of a Lennard Jones fluid.
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  • 14
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    International journal of thermophysics 3 (1982), S. 101-116 
    ISSN: 1572-9567
    Keywords: aromatic hydrocarbons ; cyclohexane ; n-alkanes ; phenyl halides ; thermal conductivity ; toluene ; transient hot-wire method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract 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/T c=0.5, thermal conductivity has a simple relation with the molar density for each homologous series of liquids.
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  • 15
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    International journal of thermophysics 5 (1984), S. 323-350 
    ISSN: 1572-9567
    Keywords: hot wire ; hydrogen ; normal hydrogen ; ortho hydrogen ; parahydrogen ; thermal conductivity ; transient ; measurements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The paper presents new experimental measurements of the thermal conductivity of hydrogen. The ortho-para compositions covered are normal, near normal, para, and para-rich. The measurements were made with a transient hot wire apparatus. The temperatures covered the range from 78 to 310 K with pressures to 70 MPa and densities from 0 to a maximum of 40 mol · L−1. For compositions normal and near normal, the isotherms cover the entire range of pressure, and the temperatures are 78, 100, 125, 150, 175, 200, 225, 250, 275, 294, 300, and 310K. The para measurements include eight isotherms at temperatures from 100 to 275 K with intervals of 25 K, pressures to 12 MPa, and densities from 0 to 12 mol · L−1. Three additional isotherms at 150, 250, and 275 K cover para-rich compositions with para percentages varying from 85 to 72%. For these three isotherms the pressures reach 70 MPa and the density a maximum of 30 mol · L−1. The data for all compositions are represented by a single thermal conductivity surface. The data are compared with the experimental measurements of others through the new correlation. The precision (2σ) of the hydrogen measurements is between 0.5 and 0.8% for wire temperature transients of 4 to 5 K, while the accuracy is estimated to be 1.5%.
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  • 16
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    International journal of thermophysics 2 (1981), S. 21-38 
    ISSN: 1572-9567
    Keywords: liquids ; property correlations ; thermal conductivity ; ransport properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A general correlation for organic liquid thermal conductivity, λ, estimation is proposed of the following type: $$\lambda = A \cdot \frac{{(1 - T_r )}}{{T_r^{{1 \mathord{\left/ {\vphantom {1 6}} \right. \kern-\nulldelimiterspace} 6}} }}^{0.38}$$ where T r is the reduced temperature and the factor A is practically temperature independent and characteristic of the particular compound investigated. The values of the factor A for 144 organic liquids are calculated (through selected experimental λ data) and are listed. The proposed correlation is tested, and the mean general deviation between calculated and selected experimental λ values is found to be smaller than 2% over wide temperature ranges (generally from T r = 0.3 to T r =0.8); the maximum deviations are normally smaller than 6%. Successively, the compounds are investigated as members of the respective families in order to provide an expression for A by means of the best available physical properties of the liquids. Correlations are proposed (for alcohols, aromatics, esters, refrigerant fluids, paraffins, cycloparaffins, ketones, organic acids, ethers, and olefins) that contain the same reduced temperature dependence evidenced in the above equation and that differ in the expression suggested for the factor A. In this way, the thermal conductivity of the organic liquids can be evaluated, with a mean deviation generally less than 5%, in absence of experimental λ data.
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  • 17
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    International journal of thermophysics 2 (1981), S. 55-62 
    ISSN: 1572-9567
    Keywords: anharmonic interactions ; grain boundaries ; lattice waves ; phonons ; point defects ; thermal conductivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The lattice thermal conductivity arises from contributions by phonons of all frequencies. The mean free path l(ω) is limited mainly by three-phonon interactions, and l i(ω)∝ω−2 T −1 where ω is the phonon frequency, and T is the absolute temperature. Since the spectral specific heat varies as ω 2, the spectral thermal conductivity is independent of frequency, and low frequencies play a larger role than they do in the heat content. The effect of additional scattering processes due to defects must be compared to intrinsic scattering, not just at the highest frequency, but over the full spectral range. This enhances the resistance due to grain boundaries and large obstacles, and reduces the effect of point defects. Some typical examples are discussed. The role of low-frequency phonons may be even further enhanced if longitudinal low-frequency phonons have their interaction with other phonons reduced by wave vector conservation. Such modes would then contribute substantially to the overall thermal conductivity, and this contribution would be sensitive to grain size and to large-scale defects. However, the mean free path must be consistent with ultrasonic attenuation data. This enhanced sensitivity may be observable.
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  • 18
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    International journal of thermophysics 2 (1981), S. 103-114 
    ISSN: 1572-9567
    Keywords: Air ; hot-wire technique ; thermal conductivity ; transient technique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have used the transient hot-wire technique to make absolute measurements of the thermal conductivity of dry, CO2-free air in the temperature range from 312 to 373 K and at pressures of up to 24 MPa. The precision of the data is typically ±0.1%, and the overall absolute uncertainty is thought to be less than 0.5%. The data may be expressed, within their uncertainty, by polynomials of second degree in the density. The values at zero-density agree with other reported data to within their combined uncertainties. The excess thermal conductivity as a function of density is found to be independent of the temperature in the experimental range. The excess values at the higher densities are lower than those reported in earlier work.
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  • 19
    ISSN: 1572-9567
    Keywords: Alcohol ; hydrogen bonding ; thermal conductivity ; thermodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Thermal conductivity measurements on the vapors of methanol, ethanol, isopropanol, and t-butanol are reported as a function of temperature (330–420 K) and pressure (11–240 kPa). The thermal conductivity versus pressure isotherms for all four alcohols exhibit upward curvatures at the lower temperatures and nearly linear increases at higher temperatures. This behavior is indicative of a dimeric species and one or more polymeric clusters in the vapor in addition to the monomer. Quantum mechanical calculations have indicated that tetramers are the most likely polymeric species. Detailed analyses of the data provide thermodynamic data (ΔH,ΔS) for the dimerization and tetramerization reactions and show interesting correlations with the size of the monomer unit.
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  • 20
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    International journal of thermophysics 2 (1981), S. 155-162 
    ISSN: 1572-9567
    Keywords: AC heated-wire technique ; heat capacity ; liquids ; thermal conductivity ; thermal diffusivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract An apparatus for the simultaneous absolute measurement of the thermal activity, thermal diffusivity, thermal conductivity, and heat capacity of nonconducting liquids with the AC heated-wire (strip) technique is described. The main advantage of this technique is that the temperature oscillations field can be confined around the sensor in a liquid layer thin enough to suppress the hydrodynamic currents. This leads to the elimination of the convective heat transport. Carrying measurements at different frequencies, the inertia of the sensor can be considered, and the radiative heat transport can be estimated for liquids with known optical properties. The apparatus was constructed and tested using six different liquids in a limited temperature range. The thermal properties of these liquids at 20°C are reported. The thermal conductivity data of toluene and n-heptane (recommended as proposed thermal conductivity standards) are given in the temperature range 10–40°C. Good agreement was found with data reported by other investigators at 20°C, but there is still a considerable discrepancy in the temperature coefficient of thermal conductivity.
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  • 21
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    International journal of thermophysics 2 (1981), S. 249-268 
    ISSN: 1572-9567
    Keywords: chorotrifluoromethane (R 13) ; chlorodifluoromethane (R 22) ; dichlorodifluoromethane (R 12) ; fluorocarbon ; pressure effect on thermal conductivity ; thermal conductivity ; trifluoromethane (R 23)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The thermal conductivity of four gaseous fluorocarbon refrigerants has been measured by a vertical coaxial cylinder apparatus on a relative basis. The fluorocarbon refrigerants used and the ranges of temperature and pressure covered are as follows: R 12 (Dichlorodifluoromethane CCl2F2): 298.15–393.15 K, 0.1–4.28 MPa R 13 (Chlorotrifluoromethane CClF3): 283.15–373.15 K, 0.1–6.96 MPa R 22 (Chlorodifluoromethane CHClF2): 298.15–393.15 K, 0.1–5.76 MPa R 23 (Trifluoromethane CHF3): 283.15–373.15 K, 0.1–6.96 MPa The apparatus was calibrated using Ar, N2, and CO2 as the standard gases. The uncertainty of the experimental data is estimated to be within 2%, except in the critical region. The behavior of the thermal conductivity for these fluorocarbons is quite similar; thermal conductivity increases with increasing pressure. The temperature coefficient of thermal conductivity at constant pressure, (∂λ/∂T) p , is positive at low pressures and becomes negative at high pressures. Therefore, the thermal conductivity isotherms of each refrigerant intersect each other in a specific range of pressure. A steep enhancement of thermal conductivity is observed near the critical point. The experimental results are statistically analyzed and the thermal conductivities are expressed as functions of temperature and pressure and of temperature and density.
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  • 22
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    International journal of thermophysics 2 (1981), S. 323-330 
    ISSN: 1572-9567
    Keywords: heat transfer ; isotopes ; lasers ; lattice waves ; phonons ; point defects ; silicon ; thermal conductivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The thermal conductivity of pure monoisotopic silicon is estimated by two methods, which give similar results. One estimate, based on the observed thermal conductivity of monoisotopic germanium, yields a maximum of 66 W · cm−1 · K−1 at 22 K. The other estimate, based on measurements of natural silicon and on the theoretical isotope scattering rate, yields 75 W · cm−1 · K−1 at 22 K, an increase of only 45% over the natural crystal. These values are for crystals of approximately 0.5 cm diameter; smaller crystals yield lower values of the maximum conductivity and smaller isotope effects. Silicon cooled to liquid hydrogen temperature seems promising for high-irradiance laser mirrors. The small gain obtained by using monoisotopic silicon would be substantially greater in cases when the generated phonon distribution is athermal and weighted to higher frequencies. The effective heat transport could then be increased by as much as a factor 60 through the use of monoisotopic silicon.
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  • 23
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    International journal of thermophysics 2 (1981), S. 341-353 
    ISSN: 1572-9567
    Keywords: aluminum ; low temperature ; neutron irradiation ; thermal conductivity
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    Topics: Physics
    Notes: Abstract Measurements of thermal conductivity of 6N to 3N pure aluminum in the temperature range 5–50 K subjected to fast neutron irradiation, with exposures of 1013 and 1016 n · cm−2, are reported. The thermal conductivity maximum was found to shift towards higher temperatures with an increase in the fast neutron irradiation exposure. At high temperatures, a departure from Wilson's theory was observed, which may be attributed to the existence of additional electron scattering mechanisms. An increase in both ideal and residual thermal resistivity components with an increase in the radiation exposure was noted.
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  • 24
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    International journal of thermophysics 2 (1981), S. 331-340 
    ISSN: 1572-9567
    Keywords: heat capacity ; high pressure ; silver bromide (AgBr) ; silver chloride (AgCl) ; thermal conductivity
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    Topics: Physics
    Notes: Abstract The thermal conductivity, λ, and the heat capacity per unit volume, ρc p , have been measured for solid silver bromide (AgBr) using the transient hot-wire method. Measurements were made at temperatures in the range 100–400 K and at pressures up to 2 GPa. ρc p was found to be independent of temperature and pressure over these ranges. λ of AgBr was found to be similar to that of AgCl, which was measured previously. For AgBr, only acoustic phonons needed to be taken into account up to 340 K, but optic phonons probably carried some heat at higher temperatures. The Leibfried-Schlömann (LS) formula could describe the ratio λ(AgCl)/λ(AgBr), but not the ratio λ(1 GPa)/λ(0) for either substance. An empirical modification of the LS formula could describe the latter ratios but not the former. Further theoretical developments are required for understanding of λ(P) for even such relatively simple substances as AgCl and AgBr.
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  • 25
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    International journal of thermophysics 1 (1980), S. 7-32 
    ISSN: 1572-9567
    Keywords: gas mixtures ; kinetic theory ; thermal conductivity ; transport theory
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    Topics: Physics
    Notes: Abstract This paper presents expressions for the evaluation of the second-and third-order Chapman-Cowling approximation to the thermal conductivity of a multicomponent monatomic gas mixture in the limit of zero density. Calculation of these higher-order corrections have been carried out for some monatomic gas mixtures. The higher-order corrections contribute as much as 3% to the thermal conductivity of binary mixtures of gases with a large mass ratio. It is found that the higher-order kinetic theory formulae provide an adequate description of recent thermal conductivity data that have an associated uncertainty of ±0.2%. The results of this analysis are employed to demonstrate that these thermal conductivity data are entirely consistent with earlier viscosity data on the same systems.
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  • 26
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    International journal of thermophysics 3 (1982), S. 201-215 
    ISSN: 1572-9567
    Keywords: density ; isothermal compressibility ; Tait equation ; thermal conductivity ; thermal expansion coefficient ; toluene ; transient hot-wire method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract 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.
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  • 27
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    International journal of thermophysics 4 (1983), S. 193-208 
    ISSN: 1572-9567
    Keywords: alkanes ; hydrocarbons ; liquids ; thermal conductivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The paper presents the results of new, absolute measurements of the thermal conductivity of five alkanes as a function of temperature at their saturation vapor pressure. The alkanes studied include the four normal alkanes n-octane, n-nonane, n-undecane, and n-tetradecane as well as the branched alkane, iso-octane. The results, which extend over the temperature range 282–373 K, have an estimated uncertainty limit of 1.5% deriving mainly from a correction for the effects of radiation absorption in the measurement process. The results are employed to generate effective core volumes for the fluids studied which may be employed to predict the density dependence of the thermal conductivity by means of an existing correlation.
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  • 28
    ISSN: 1572-9567
    Keywords: electrical conductivity ; heat capacity ; lead chalcogenides ; thermal conductivity ; thermal diffusivity
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    Topics: Physics
    Notes: Abstract Thermal properties (thermal conductivity λ, thermal diffusivity a, and specific heat capacity c p of polycrystalline PbS, PbSe, and PbTe were measured in the temperature range 300–700 K. The electrical conductivity was also measured for the three substances. Lattice, electronic and bipolar components of thermal conductivity are much larger than the electronic part. The specific heat capacity is observed to increase slightly with temperature.
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  • 29
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    International journal of thermophysics 5 (1984), S. 23-40 
    ISSN: 1572-9567
    Keywords: density ; liquid ; pressure ; Tait-type equation ; thermal conductivity ; viscosity
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    Topics: Physics
    Notes: Abstract Most of the thermophysical properties of fluids are greatly altered at high pressures, and the studies of these changes are of much scientific and technological importance. In this paper, the effects of temperature and pressure on the density, viscosity, and thermal conductivity of various liquids are described briefly, based on recent experimental results from the author's laboratory. The objectives of this investigation, methods of measurements, and some of the experimental results are reviewed, as well as the present aspects in this field. Several important problems to be interpreted are also pointed out from the present measurements.
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  • 30
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    International journal of thermophysics 5 (1984), S. 351-365 
    ISSN: 1572-9567
    Keywords: benzene ; cyclic hydrocarbons ; cyclohexane ; high pressure ; liquids ; thermal conductivity
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    Topics: Physics
    Notes: Abstract The paper describes new, accurate measurements of the thermal conductivity of benzene and cyclohexane in the temperature range 36–88°C and at pressures up to 0.33 GPa. The experimental data have an estimated accuracy of ±0.3%. The density dependence of the thermal conductivity for both liquids is well represented by a simple power law relationship which is almost independent of temperature. The connection of this correlation to one previously established for normal alkanes is examined.
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  • 31
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    International journal of thermophysics 1 (1980), S. 51-59 
    ISSN: 1572-9567
    Keywords: thermal conductivity ; transport properties ; Freon-152a and Freon-142b ; Prandtl and Schmidt numbers ; kinetic theory
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    Topics: Physics
    Notes: Abstract The thermal conductivity of 1,1 difluoroethane (Freon-152a) and 1 chloro-1 difluoroethane (Freon-142b) are measured at several pressures in the range 29.7–75.8 kPa and as a function of temperature in the range 280–510 K. The thermal conductivity column instrument is employed, and the experimental values are estimated to be accurate within a maximum uncertainty of ±5.6% at the lowest temperature, which reduces to ±2.4% at the highest temperature. These conductivity values are compared with the predictions of Chapman-Enskog kinetic theory, with the correction factor for the internal energy transport estimated from Hirschfelder's theory, and the Lennard-Jones (12-6) potential. The experimental conductivity data are also utilized to generate the values for the two other transport properties in conjunction with the interrelations obtained between different properties on the basis of kinetic theory. The data on transport properties are employed to give the best possible estimates of Prandtl and Schmidt numbers as a function of temperature.
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  • 32
    ISSN: 1572-9567
    Keywords: viscosity ; thermal conductivity ; Enskog theory ; diffusion coefficient ; Eucken relation
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    Topics: Physics
    Notes: Abstract A generalized correlation is developed for the viscosity and thermal conductivity of isotropic fluids under high pressures (up to 200 MPa) and low temperatures (down to 85 K). Two known observations have been taken into consideration in the development of the correlation. First, the Alder correction factors for the Enskog theory values of transport coefficients obtained from molecular dynamics simulations for hard sphere fluids are incorporated. The inclusion of these corrections in the theory makes it possible to describe correctly the density dependence of the hard sphere viscosity and thermal conductivity at high pressures. The hydrodynamic “cage” effect, which is manifested in the molecular motions of dense fluid systems, is thus correctly accounted for. Second, the generalized Eucken relation, which relates the thermal conductivity to the viscosity, is incorporated. As a consequence, an internally consistent correlation is obtained, which can adequately predict the behavior of the thermal conductivity from given values of viscosity. Tests on simple fluids, such as argon, krypton, etc., show that the correlation is valid within a few percent for the entire fluid range where experimental data are available for comparison, and also along the vapor-liquid saturation line, with the exclusion of the critical region. Furthermore, since the variables appearing in the theory are in reduced form, a corresponding states correlation is established for isotropic fluids.
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  • 33
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    International journal of thermophysics 3 (1982), S. 27-34 
    ISSN: 1572-9567
    Keywords: CFCl3-N2 mixtures ; CF2Cl2-N2 mixtures ; Freon ; thermal conductivity
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    Topics: Physics
    Notes: Abstract Thermal conductivity of the gases CFCl3 (Freon 11), CF2Cl2 (Freon 12), and their binary mixtures with nitrogen have been measured at 292 K. The results for the mixtures are compared with various theoretical models, which give the thermal conductivity as a function of concentration using properties of the pure components. From the experimental results, the mutual diffusion coefficients for the two systems are calculated.
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  • 34
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    International journal of thermophysics 3 (1982), S. 117-135 
    ISSN: 1572-9567
    Keywords: coexistence curve ; critical point ; oxygen ; Rayleigh scattering ; thermal conductivity ; thermal diffusivity
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    Topics: Physics
    Notes: Abstract The thermal conductivity of oxygen has been measured in a broad region around the critical point by means of Rayleigh light scattering. Measurements were made on two isochores and on the saturation boundary. The results are compared with current methods of predicting the anomalous thermal conductivity in the critical region.
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  • 35
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    International journal of thermophysics 3 (1982), S. 217-224 
    ISSN: 1572-9567
    Keywords: high pressure ; n-alkanes ; n-tridecane ; thermal conductivity
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    Topics: Physics
    Notes: Abstract 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.
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  • 36
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    International journal of thermophysics 4 (1983), S. 283-294 
    ISSN: 1572-9567
    Keywords: compressibility factor ; database system: density ; dielectric constant ; refractive index ; retrieval program ; specific enthalpy ; specific entropy ; specific heat capacity ; specific volume ; surface tension ; thermal conductivity ; vapor pressure ; viscosity
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    Topics: Physics
    Notes: Abstract A new database system was designed and constructed in order to provide the newest and most reliable numerical data on thermophysical properties of fluids to the scientific and technical community as quickly as possible. The database is concerned with 12 kinds of property data: density, specific volume, compressibility factor, vapor pressure, specific heat, specific enthalpy, specific entropy, viscosity, thermal conductivity, surface tension, refractive index, and dielectric constant of 340 pure fluids under all conditions of seven convenient physical states. Only the most probable data, which were critically evaluated in advance, are compiled as functions of temperature and pressure in the form of either numerical data tables or correlation formulas. Property values at desired grid points of temperature and pressure can be obtained in SI units directly or by interpolations with some supplementary information, such as the grade of reliability, source bibliography, and fundamental physical constants of the fluid. The database is usable as conversational processing by TSS, the tabulation of property data in a batch processing, and one of the subroutine libraries in the computation of a user's program. Ten kinds of application programs are prepared for multipurpose retrievals so that anyone can use the database without any special knowledge of the structure or machine languages of this system.
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  • 37
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    International journal of thermophysics 4 (1983), S. 1-10 
    ISSN: 1572-9567
    Keywords: carbon disulphide ; high pressure ; thermal conductivity ; transport properties
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    Topics: Physics
    Notes: Abstract The paper presents new, absolute measurements of the thermal conductivity of carbon disulphide in the temperature range 36–74
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  • 38
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    International journal of thermophysics 4 (1983), S. 183-188 
    ISSN: 1572-9567
    Keywords: LaCoO3 ; thermal conductivity
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    Topics: Physics
    Notes: Abstract The thermal conductivity of LaCoO3 was measured in air between 300 and 900 K. The conductivity increased sharply from 3.2 to 17.0 W · m−1 · K−1 in this temperature range and showed good agreement with previously published data. An excitonic mode of conduction due to the interaction of the high-low spin states of cobalt is found to be the main contribution to the measured thermal conductivity. Contributions of the other modes of conduction and the excitonic mean free path have been calculated.
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  • 39
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    International journal of thermophysics 4 (1983), S. 295-309 
    ISSN: 1572-9567
    Keywords: gas mixtures ; polyatomic gases ; thermal conductivity
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    Topics: Physics
    Notes: Abstract The paper discusses the prediction of the thermal conductivity of gas mixtures containing polyatomic components at low and moderate density. The prediction scheme adopted is based upon the rigorous kinetic theory of gases and makes use of other thermophysical properties of the pure gases and binary mixtures in the evaluation of the thermal conductivity. Comparisons with accurate experimental data indicate that only for systems in which the mass ratio of the species is near unity and for which inelastic collisions are rare, is a reliable prediction of the mixture thermal conductivity at low density possible. On the other hand, the density dependence of the thermal conductivity is quite accurately represented for most systems.
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  • 40
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    International journal of thermophysics 5 (1984), S. 219-228 
    ISSN: 1572-9567
    Keywords: iron oxide pellet ; reduction rate ; specific heat ; thermal conductivity ; thermal diffusivity
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    Topics: Physics
    Notes: Abstract The thermal properties of iron oxide pellets of different porosity and prepared by reduction at different rates were investigated in the range of room temperature to about 800°C. The thermal diffusivity a was measured by a laser flash method and the specific heat C p was measured by adiabatic scanning calorimetry. The thermal conductivity was calculated from the relation λ=aC ρ p, where ρ is the density of the specimen. For nonreduced iron oxide pellets, the thermal diffusivity and thermal conductivity decreased with increase in temperature and porosity. The specific heat increased with increasing temperature and there was a transformation point at which the specific heat reached a maximum. In prereduced iron oxide pellets, the thermal diffusivity and thermal conductivity were very small compared with the nonreduced pellets and they gradually increased with increasing temperature. The specific heat had a minimum and a maximum at about 300 and 600°C, respectively, and the scale of these features became smaller with increase in the reduction rate.
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  • 41
    ISSN: 1572-9567
    Keywords: Mixtures ; molten salts ; potassium nitrate ; sodium nitrate ; thermal conductivity ; transient method
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    Topics: Physics
    Notes: Abstract The thermal conductivity of KNO3-NaNO3 mixtures was measured by a modified transient hot-wire method using liquid metal in a capillary as a heat source. The method was developed for measurements on electrically conducting liquids at high temperatures. Measurements were performed on pure NaNO3 and its three mixtures with KNO3 in the temperature range from 498 to 593 K.
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  • 42
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    International journal of thermophysics 3 (1982), S. 67-77 
    ISSN: 1572-9567
    Keywords: Thermal conductance ; thermal conductivity ; thermal conductivity integral
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    Topics: Physics
    Notes: Abstract A discussion is presented regarding the significance of the spatial temperature gradient approximation normally used in thermal conductivity measurement. Examples are presented illustrating the magnitude of temperature differences allowed for conductivity integral (TCI) method of analysis is presented as an alternative method which totally eliminates the need to impose temperature difference restrictions on the measurement process, so long as other errors, such as radiative heat losses, do not become excessive.
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    International journal of thermophysics 3 (1982), S. 225-235 
    ISSN: 1572-9567
    Keywords: hot-wire method ; lithium bromide solution ; thermal conductivity
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    Topics: Physics
    Notes: Abstract This paper describes a novel type of transient hot-wire cell for thermal conductivity measurements on electrically conducting liquids. A tantalum wire of 25 μm. diameter is used as the sensing element in the cell, and it is insulated from the conducting liquids by an anodic film of tantalum pentoxide, 70 nm thick. The cell is suitable for measurements on conducting liquids at elevated temperatures. The results of test measurements on liquid water at its saturation vapor pressure are reported in order to confirm the correct operation of the thermal conductivity cell. The data, which have an estimated accuracy of ±3%, depart by less than ±1.8% from the correlation proposed by the International Association for the Properties of Steam. Results are also presented for concentrated aqueous solutions of lithium bromide, which are frequently used in absorption refrigerator cycles.
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