Anisotropic solids, heat conduction

In this part we study the stationer heat conduction in anisotropic solid, e.g. in triclinic crystal. We suppose certain energy deposit cr in all the volume elements of the system, and let the heat conduction tensor be temperature dependent. The stationer balance equation is... 

For anisotropic solids the heat conductivity k is a tensor of the second rank. The empirical Fourier law of heat conduction is then written as... 

Fi re 16.3 The method of Curie and Voigt to verify the reciprocal relations for anisotropic heat conduction. An anisotropic solid whose crystal symmetry implies Ki2 — — 21 is placed in contact with two heat reservoirs of temperature T and Tc. If the reciprocal relations are valid then K12 = K2i = 0. If this is true, the isotherms should be perpendicular to the direction xi, i.e. 0 should be 90°... 

M.p. 296 C. Accepts an electron from suitable donors forming a radical anion. Used for colorimetric determination of free radical precursors, replacement of Mn02 in aluminium solid electrolytic capacitors, construction of heat-sensitive resistors and ion-specific electrodes and for inducing radical polymerizations. The charge transfer complexes it forms with certain donors behave electrically like metals with anisotropic conductivity. Like tetracyanoethylene it belongs to a class of compounds called rr-acids. tetracyclines An important group of antibiotics isolated from Streptomyces spp., having structures based on a naphthacene skeleton. Tetracycline, the parent compound, has the structure ... 

Heat transfer inside the wood solid depend on its thermal conductivity. This property is anisotropic and increases with the density, the moisture content and the temperature [10-13], The thermal conductivity is higher in the longitudinal direction than in the radial and tangential directions from 1.8 [12] to 2.5 [14, 15]. 

Quasi-continuum models Of these, the quasi-continuum model is the most common. Here, the solid-fluid system is considered as a single pseudo-homogeneous phase with properties of its own. These properties, for example, diffusivity, thermal conductivity, and heat transfer coefficient, are not true thermodynamic properties but are termed as effective properties that depend on the properties of the gas and solid components of the pseudo-phase. Unlike in simple homogeneous systems, these properties are anisotropic, that is, they have different values in the radial and axial directions. KuUcami and Doraiswamy (1980) have compiled all the equations for predicting these effective properties. Both radial and axial gradients can be accounted for in this model, as well as the fact that the system is really heterogeneous and hence involves transport effects both within the particles and between the particles and the flowing fluid. 

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