Poster: Design of Highly Reflective Fibrous Insulation at Extreme Temperatures

The high melting temperatures, large optical bandgaps, and large refractive indices of oxides favor their use as fibrous insulation at extreme temperatures where radiative heat transfer is significant. Radiation through oxide fibers can be modelled using the Monte Carlo method, incorporating fiber optical properties such as scattering efficiency and coefficient (from Mie theory), fiber radius, refractive index, volume fraction, and insulation thickness. Two key metrics are identified for designing highly reflective fibrous insulation. A novel metric, the Kuhn scattering length, is developed based on an analogy between the random walks in Monte Carlo calculations and polymer physics. The Kuhn scattering length can be used to approximate the necessary effective thickness of insulation. The second is a size metric, showing that fiber mats are most reflective when the fiber radius satisfies 2πr/λ≈0.5−1.2. The model is validated with experimental measurements on commercially available insulation consisting of fibers with 3–5 μm radii.