Thermal conductivity of Freon-218

The thermal conductivity of Freon-218 is investigated experimentally in a wide region of the parameters. Reference tables of thermal conductivity are compiled.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 38, No. 2, pp. 244–248, February, 1980.     

Thermal conductivity of composites

A general expression for the effective thermal conductivity of inhomogeneous media in terms of the Fourier components of the spatial variation of the conductivity is applied to composites consisting of inclusions in a continuous matrix. It is reformulated in terms of the mean square fluctuations of the conductivity. Specific cases treated are spherical inclusions and long cylinders, both random and with preferred directions. The results hold provided the difference in thermal conductivities is small or provided the concentration of inclusions is not too large. The theory fails if the thermal conductivity of the matrix is much smaller than that of the inclusions. The same considerations also apply to electrical conductivity.     

Thermal conductivity of methane

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.Nomenclature a _k ,b _ij ,b _k Parameters of the regression model, k= 0 to n; i =0 to m; j =0 to n - P Pressure (MPa or bar) - Q _kl Heat flux per unit length (mW · m^–1) - t time (s) - T Temperature (K) - T _cr Critical temperature (K) - T _r reduced temperature (= T/T _cr) - T _w Temperature rise of wire between times t ₁ and t ₂ (deg K) - T ^* Reduced temperature difference (TT _cr)/T _cr - Thermal conductivity (mW · m^–1 · K^–1) - ₁ Thermal conductivity at 1 bar (mW · m^–1 · K^–1) - _bg Background thermal conductivity (mW · m^–1 · K^–1) - _cr Anomalous thermal conductivity (mW · m^–1 · K^–1) - _e Excess thermal conductivity (mW · m^–1 · K^–1) - Density (g · cm^–3) - _cr Critical density (g · cm^–3) - _r Reduced density (= / _cr) - ^* Reduced density difference (– _cr )/ _cr      

Thermal conductivity of solutions

The results of an experimental and theoretical study of the thermal conductivity of binary, ternary, and multicomponent solutions are presented. A probable mechanism of heat conduction in solutions is proposed and calculation formulas are obtained.     

Thermal conductivity of consolidated systems

A structural model and method for calculating the effective thermal conductivity of consolidated granular materials are proposed.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 27, No. 1, pp. 55–62, July, 1974.     

Thermal conductivity of organic liquids

A new instrument and technique for determining the thermal conductivity of liquids by the coaxial cylinder method are described. Experimental values of the thermal conductivity, obtained over a broad temperature interval, are compared with the results of other investigators.     

Thermal conductivity of multicomponent mixtures

The authors propose a method of calculating the effective thermal conductivity of multicomponent mixtures as a function of their structure, the thermal conductivities of the components, their concentrations, and other parameters.     

Thermal conductivity of glass-fiber systems

Heat transfer in glass-fiber materials is considered. The effect of scattering on heat transfer is investigated, and the results of calculations are compared with published data.Inzhenerno-Fizicheskii Zhurnal, Vol. 21, No.5, pp. 797–803, November, 1971.     

Thermal conductivity of sulfur hexafluoride

This paper reports new measurements of the thermal conductivity of sulfur hexafluoride at the nominal temperature of 27.5°C as a function of density in the range up to 200 kg · m^–3. The measurements were performed in a transient, hot-wire instrument. When combined with earlier measurements of the viscosity of the gas, they allow us to calculate the rather large contribution stemming from the internal degrees of freedom. The present measurements compare well with those in the literature. All of them suggest that the excess thermal conductivity is a unique function of density in the present range of states. An empirical correlation of our measurements can serve users in the ranges 0 < t< 100°C and 0 < < 200 kg · m^–3.     

Thermal conductivity of coated microspheres

This paper includes the results of measurements of thermal conductivity k(T) of silver metallized microspheres at temperatures between 77 and 300 K. The k(T) measurements have been performed in a calorimeter for three samples of different metallized concentration of microspheres ie 0, 7 and 32%. The combined results prove the assumed diminishing of the radiation component of heat transport k_r caused by metallization. The growth of the conduction component k_c caused by metal at the sphere contact is observed simultaneously. The graphical dependence of the two components k_c and k_r on temperature is also presented.     

Thermal conductivity of epoxy resin-aluminium

Journal of Materials Science -     

Thermal conductivity of liquid tetrachlorides

The thermal conductivity of liquid carbon, silicon, titanium, germanium, and tin tetrachlorides overthe-20 to +60°C temperature range was measured by the transient relative null method with a hot wire.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 23, No. 5, pp. 835–841, November, 1972.     

Thermal conductivity of fibrous systems

The process of heat transfer in fibrous materials with a random structure is examined and a method is proposed for calculating the effective thermal conductivity as a function of the characteristic parameters of the system (thermal conductivities of the components, their volume concentration, temperature, pressure of the interstitial gas, etc.).     

Thermal conductivity of inhomogeneous materials

The effective thermal conductivity is calculated from the rate of entropy production per unit volume. Thermal conductivity and the temperature field are expressed in terms of Fourier components and these are related. The rate of entropy production is then obtained in terms of the volume-averaged thermal conductivity and the Fourier components of thermal conductivity. A simple expression for the effective thermal conductivity is found. In the case of striations it leads to well-known results. The formalism is applied to solids with inhomogeneously distributed solutes. It is shown that the thermal conductivity is less than the volume-averaged thermal conductivity and that homogenization by diffusion increases the thermal conductivity. Similar results would apply to the electrical conductivity of inhomogeneous alloys.     

Thermal conductivity of liquid n-alkanes

The thermal conductivity of liquids has been shown in the past to be difficult to predict with a reasonable accuracy, due to the lack of accurate experimental data and reliable prediction schemes. However, data of a high accuracy, and covering wide density ranges, obtained recently in laboratories in Boulder, Lisbon, and London with the transient hot-wire technique, can be used to revise an existing correlation scheme and to develop a new universal predictive technique for the thermal conductivity of liquid normal alkanes. The proposed correlation scheme is constructed on a theoretically based treatment of the van der Waals model of a liquid, which permits the prediction of the density dependence and the thermal conductivity of liquid n-alkanes, methane to tridecane, for temperatures between 110 and 370 K and pressures up to 0.6 MPa, i.e., for 0.3T/T _c0.7 and 2.4P/P _c3.7, with an accuracy of ±1%, given a known value of the thermal conductivity of the fluid at the desired temperature. A generalization of the hard-core volumes obtained, as a function of the number of carbon atoms, showed that it was possible to predict the thermal conductivity of pentane to tetradecane±2%, without the necessity of available experimental measurements.     

Thermal conductivity of carbon black

Experimental data are presented on the effective thermal conductivity of carbon black in particle sizes from 0.1 to 0.5 mm in an air medium over the temperature range 350–475°K under pressures of 0.04 to 0.42 MPa.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 37, No. 3, pp. 475–478, September, 1979.     

Thermal conductivity of mercury vapor

Tables of the thermal conductivity of mercury vapor for temperatures from 500 to 1200°K and pressures from 0 to 20 MPa are calculated from experimental data.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 41, No. 2, pp. 265–268, August, 1981.     

Thermal conductivity of liquid mixtures

This paper adopts a phenomenological approach and presents a new model of a mixture of nonreacting liquids as a mixture of two interpenetrating continuous media. An analytical relationship for calculating the effective thermal conductivity of a mixture of liquids is given and the results are compared with experimental data.