Model of the Structure of Fibrous Heat-Insulating Materials for Analyzing Combined Heat Transfer Processes

Abstract

A model of the structure of a highly porous fibrous material is suggested within the framework of which deformation of a setting semifinished item is considered. An algorithm is suggested for calculating the effective thermal conductivity and its components. It accounts for heat transfer through a solid phase and a gas, as well as by radiation. The Mie theory is used to estimate the radiative heat transfer, which led to a somewhat underestimated result in determining the effective thermal conductivity. To refine the contribution of radiative heat transfer, it is suggested to determine the optical properties of materials by solving the inverse problem of radiation transfer, the initial data for which are furnished by experimentally measured values of the coefficients of radiation transmission through a set of samples of different thickness. As a result, the radiation absorption and diffusion coefficients of a fibrous heat-insulating material have been determined. The dependence of the effective thermal conductivity of a material on temperature has been obtained, which actually coincides with the results of experimental investigations.