Determination of Thermal Conductivity

Heat conduction occurs when a temperature gradient exists in matter. Heat conduction is an energy transport process. For steady-state conditions of unidirectional heat flow in an isotropic matter, the Fourier-Biot equation holds  

Non-steady-state methods can be used to measure thermal conductivity according to 

The thermal conductivities of various materials differ widely, as shown below (see Ref. 7 and 

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The experimental methods used for the determination of thermal conductivity are described by Tsederberg (1965), who also lists values for many substances. The four-volume handbook by Yaws (1995-1999) is a useful source of thermal conductivity data for hydrocarbons and inorganic compounds. 

In order to understand and correlate the heat transfer data, the relevant physical properties of the suspensions must be carefully evaluated. The experimental determination of heat capacity and density pose no particular problem. In many instances it is possible to estimate these values accurately by assuming them to be weight averages of those of the two components. In contrast, great difficulty is associated with the accurate determination of thermal conductivity and viscosity, largely owing to the fact that the solids tend to settle readily in any device where convection currents are eliminated, as they must be for these... 

T. Log, Transient Hot-Strip Method for Simultaneous Determination of Thermal Conductivity and Thermal Diffusivity of Refractory Materials , Journal of the American Ceramic Society, 74 (3) 650-653 (1991). 

High pressure grown single crystals of GaN [15] were used in the determination of thermal conductivity. The measurement was made using the laser-flash method. The result of these measurements was k = 1.7 W/(cm K), which is in agreement with the theoretical estimate of Slack [12]. 

Chantrenne, P. and J.-L. Barrat, Finite Size Effects in Determination of Thermal Conductivities Comparing Molecular Dynamics Results with Simple Models. Journal of Heat Transfer, 2004. 126 p. 577-585. 

Figure 9 Determination of thermal conductivity. ANACON thermal conductivity analyrzer.

W. D. Coles, Experimental Determination of Thermal Conductivity of Low Density Ice, NACA TN3143 (1954). 

Hopper, F.C. and Lepper, F.R., Transient heat flow apparatus for the determination of thermal conductivities, ASHVE Trans., 56 309-324 (1950). 

DETERMINATION OF THERMAL-CONDUCTIVITY VALUES OF PLASTICS. //ENGLISH TRANSLATION OF KUNSTSTOFFE-PLASTICS 4 /3/ 265-8,1957.//... 

DIRECT DETERMINATION OF THERMAL CONDUCTIVITY OF EXPANDED PLASTICS. 

APPLICATION OF PROBE METHOD TO DETERMINATION OF THERMAL CONDUCTIVITY OF CHEMICALLY ACTIVE MEDIA IN THE TEMPERATURE RANGE OF -196 TO +20 C. FROM PROCEEDINGS OF THE NINTH CONFERENCE ON THERMAL CONDUCTIVITY. IOWA STATE UNIVERSITY, AMES, IOWA. 

Various other methods have been described for the determination of thermal conductivity. Capillarity has been used to measure the thermal conductivity of LDPE, HOPE and PP at various temperatures and pressures [30]. A transient plane source technique has been applied in a study of the dependence of the effective thermal conductivity and thermal diffusivity of polymer composites [31]. 

DIN 52612-2, Testing of Thermal Insulating Materials Determination of Thermal Conductivity by Means of the Guarded Hot Plate Apparatus, Conversion of the Measured Values for Building Applications, 1984. 

Determination of Thermal Conductivity. In determining the thermal conduc-... 

ISO 8894-1 1987 Refractory materials - determination of thermal conductivity. Part 1 Hot-wire method... 

Determination of thermal conductivity of composite wall apparatus... 

DIN 52612, Testing of thermal insulating materials. Determination of thermal conductivity by means of the guarded hotplate apparatus, 1984. 

Schematic representation of the main techniques used in the determination of thermal conductivity and diffusivity of reinforced...

A detailed experimental procedure for measuring thermal conductivity is given in the ASTM standard E1952 using MTDSC. Essentially, for determination of thermal conductivity, heat capacity measurements are made under two... 

ISO 22007-2 2015. Plastics — Determination of thermal conductivity and thermal diffu-sivity — Part 2 Transient plane heat source (hot disc) method. 

V. Z. Geller and V. G. Peredri [2.5] used a modified version of the stationary heated-filament method. A thin-wall platinum capillary was adopted as an external resistance thermometer this allowed an increase in the accuracy of determination of thermal conductivity. The absence of convection was ensured by measurements at two to four different temperature gradients in the layer (Rayleigh number did not exceed 1500). When computing, corrections were introduced to compensate for the eccentricity of the filament, heat outflow from the ends, and the change in geometric sizes of the measuring cell. In all, the corrections did not exceed 0.3-0.5%. Correction for radiative heat losses were not introduced due to the absence of infrared absorption in the spectrum of liquid Freon-21. This, however, as shown by the calculations did not noticeably distort the results of the measurements. The tests were carried out at a gap of 0.5 mm. 

Dynamic methods for the determination of thermal conductivity of porous catalyst pellets normally consist of experiments in which a spherically or cylindri-... 

The above equations indicate that values of and Ky are within approximately 5% of the bulk thermal conductivity if T/A fp > 7 (for Ky) and Lj> 4.5 (for K. Therefore, the above relations can be used for determination of thermal conductivity when A fp general guidelines exist for thermal conductivity calculation when < 1. 

T. Tsukada, H. Fukuyama, and H. Kobatake, 2007, Determination of thermal conductivity and emissivity of electromagnetically levitated high-temperature droplet based on the periodic laser-heating method Theory , Int. J. Heat Mass Trans. 50, 3054-3061. 

Guarded Heat-flow-meter Method. The previous two methods are absolute determinations of thermal conductivity, that is, all the quantities required for the application of equation 9 are measured directly. A widely used comparative method is illustrated schematically in Figure 6. This design is the basis of an ASTM procedure (22) it is characterized by a heat-flux transducer, a sensitive device that produces an electrical output proportional to heat flux. A number of configurations are available, each having certain advantages. 

FIGURE 9.1 Principle of divided bar (left) and needle probe (right) technique for determination of thermal conductivity. 

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