The thermal conductivity measurement for aerogel composite insulation materials by the step-wise transient method in temperature range from 25 to 1200˚C
An experimental system for the thermal conductivity and diffusivity measurement by the step-wise transient method in high temperatures is established, the effective measurement range of thermal conductivity is from 0 to 2.5 W/(m.K), and the highest working temperature is 1250ºC. Verification of apparatus was achieved by undertaking measurements on standard reference materials, the relative deviations for the thermal conductivity are within 5% at room temperature compared with the recommended values. The thermal conductivities and diffusivities for silica aerogel composite insulation material in temperature range 25–800ºC, and for alumina aerogel composite material in temperature range 25–1200ºC are measured in the pressure range 10–101300 Pa. The preliminary uncertainty analyses are performed for alumina aerogel composite material, the values of the overall uncertainties estimated are 3.57% for the thermal conductivity and 6.43% for thermal diffusivity at 25ºC, and 5.15% for the thermal conductivity and 8.56% for thermal diffusivity at 1200ºC, respectively.
Keywords: Thermal conductivity, thermal diffusivity, step-wise transient method, aerogel, insulation material, high temperature.