Thermal Conductivity of Xonotlite Insulation Material

A surface-contact hollow cubic model is developed for coupled heat transfer of gas and solid in xonotlite-type calcium silicate insulation material based on its microstructure features. Through one-dimensional heat conduction analysis in the unit cell structure, a conductive thermal conductivity expression is obtained. A transient hot strip method is used to measure the thermal conductivity of xonotlite from 300 to 970K and from 0.045Pa to atmospheric pressure. The spectral specific extinction coefficients are derived from transmission measurements on a thin xonotlite sample performed with a Fourier transform infrared (FTIR) spectrometer. The results show that the specific spectral extinction coefficients are larger than 7m2 · kg−1 over the whole measured spectra, and the diffusion approximation equation is a reasonable description of radiative heat transfer in xonotlite insulationmaterial. The effective thermal conductivity model matches extremely well with the experimental data, which is important for the thermal design and thermal analysis of xonotlite insulation material.