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International Heat Transfer Conference 10

ISSN: 2377-424X (online)
ISSN: 2377-4371 (flashdrive)

CALCULATIONS OF SPECTRAL RADIATIVE PROPERTIES OF QUARTZ FIBROUS INSULATION IN THE INFRARED

Leonid A. Dombrovsky
Joint Institute for High Temperatures, 17A Krasnokazarmennaya Str., Moscow, 111116, Russia; Tyumen State University, 6 Volodarsky Str., Tyumen, 625003, Russia

DOI: 10.1615/IHTC10.4900
pages 25-30

Abstract

Calculations of absorption, transport scattering and radiation diffusion coefficients for a high-porous material of quartz fibers are performed by use of rigorous scattering theory for arbitrarily oriented cylinders. Known spectral dependences of quartz optical constants in the infrared are taken into account. New results concerning resonance absorption in the semitransparcnt region and intensive “scattering by absorption” at refractive index n ≈ 1 in the opaque region are obtained.
A comparison of calculations with experimental data in the semitransparent region confirms applicability of the theoretical model without collective effects at the material density up to 144 kg/m3.
The computational investigation allows to give some practical proposals to simplify the calculations: properties of a polydisperse material with randomly oriented fibers may be obtained on the base of properties of fibers of certain average radius at normal incidence.
Examples of radiative-conductive heat transfer calculations in the material considered are presented. The radiation transfer is described by use of diffusion approximation. The transient equation of energy is solved by the decomposition method.. Appropriate simplifications of the computational procedure and the spectral model used in determination of heat-shielding properties of fibrous materials are discussed.

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