LAUSR

Abstract Drawn on the experience of the heat-flow-meter method, an experimental system is designed, established and validated to investigate the thermal insulation performance of SiC opacifier doped silica aerogel at large temperature difference. The test section of the experimental system is a symmetrical sandwich-structure, while the temperature of the cold surface keeps constant by circulating the water from the thermostat, NESLAB ThermoFlex2500, and the hot surface is electrically heated. Compared with the traditional method of the back-surface temperature response, the cold surface temperature is quantitatively controllable. Based on the present experimental system and method, the thermal insulation performance of insulator can be qualitatively and quantitatively evaluated by analyzing the temperature responses of the hot surface through the whole heat transfer process including the initial steady-state, the unsteady-state, and the final new steady-state. Qualitatively, the higher the temperature of the hot surface is and the faster the temperature rise of the hot surface is, the better the thermal insulation performance of the material has; quantitatively, the effective thermal conductivity of the materials is obtained based on the semi-infinite medium model and Fourier's Law. The present results show that the effective thermal conductivities of silica aerogel doped by 3.5 μm SiC opacifier with different volume fraction of 0%, 1%, and 5.84% are about 0.02559 W m−1 K−1, 0.02844 W m−1 K−1, and 0.03305 W m−1 K−1, respectively, at small temperature difference ( 400 K), the thermal insulation performance of silica aerogel doped by 3.5 μm SiC particle with a volume fraction of 1% is good enough, though 3.5 μm SiC particle with a volume fraction of 5.84% has a marginal improvement in blocking the thermal radiation within silica aerogel.