A radiation heat transfer model based on the morphology and composition of fibrous insulation using isotropic scaling method

Abstract

This paper studies the radiation heat transfer model for high-porosity fibrous insulation under high-temperature conditions. Compared with heat convection and heat conduction, thermal radiation becomes more significant with temperature increasing. In addition to semi-empirical methods, i.e., inverse methods, predictive models based on the morphological properties have been proposed. The Lee model considered the distribution of fiber diameter, orientation in space and distribution characteristic of the radiation scattered by fibers. Nevertheless, the modification process for anisotropic media in the Lee Model is computationally challenging due to the singularity in the integral of the phase function. To tackle this issue, this study presents a similar modification method combining the Lee model and the isotropic scaling model to predict the thermal radiation in fibrous insulation based on diffusion approximation. It features a simplified integration process, leading to a decline in computational cost. The validation of the new prediction method against experimental measurements for carbon, alumina-based and silicon fibers reveals a remarkable agreement in effective thermal conductivity. This study provides significant perspectives regarding the precise prediction of thermal radiation within fibrous insulation materials. These insights have the potential to aid in the design and refinement of high-temperature insulation applications.