Experimental investigations on temperature-dependent effective thermal conductivity of nanoporous silica aerogel composite

This paper presents an inverse method for retrieving temperature-dependent effective thermal conductivity of nanoporous silica aerogel composite at temperature ranging from 280 K to 1080 K and gas pressure between 0.01 Pa and 100 kPa from experimentally measured transient temperature data. This was achieved by combining a forward method solving combined conductive and radiative heat transfer accounting for temperature-dependent thermal conductivity, and an inverse method based on a real-valued genetic algorithm (GA) optimization. First, the sensitivity coefficients for the transient temperature profiles with respect to the variation of effective thermal conductivity were investigated. Then, several numerical experiments, in which the “experimental data” was numerically generated, were performed to illustrate the robustness and accuracy of the inverse method for retrieving the temperature-dependent effective thermal conductivity from transient temperature history. The experimental data were used to retrieve the effective thermal conductivities of silica aerogel composite, the results fell within 0.014-0.044 W·m−1·K−1 for the temperature between 280 and 1080 K and gas pressure from 0.01 Pa to 100 kPa, and showed nonlinear increasing trend with increasing temperature, and with increasing gas pressure.