Evaluation of Heat Transfer in a Flexible Fibrous Heat-Insulating Composition

A model of the structure of a flexible heat-insulating composition is proposed, which is a highly porous fibrous material, felt, covered on all sides with a cloth. The entire composition is stitched-out with thread. The felt, cloth, and sewing thread are made of silicon oxide fibers of various diameters. An algorithm is proposed for calculating the effective thermal conductivity of its components: radiative and conductive in the solid phase and molecular through the gas in pores. To estimate the radiative component of thermal conductivity in the fibrous core, the Mie theory and the approximation of an optically dense medium were used. The calculation results agree with the experimental data obtained by the stationary method on flat samples in the temperature range from 20 to 800oC in vacuum and in an inert gas medium.