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单片的低密度 SiO_2气凝胶瓦(厚度为9mm,密度 p=80kg/m~3)的热损失已经在我们的抽真空带防护的热平板系统 LOLAⅡ中测定出来。该测量是对几种气体在各种不同温度和不同气压下的边界发射率上下限值(∈≈0.05和0.9)进行的。从测量结果可以得出这样的结论,即低密度的 SiO_2气凝胶瓦(约10mm厚),具有优异的隔热性能,当其在环境温度为10℃或238K,气压(?)10毫巴时,总热损系数K(?)0.7W/(m~2·k)。因此将他们应用在太阳能被动式利用系统中的窗户或盖板方面是极有希望的。根据随气压变化的热损的大小即可推导出约120nm 的抽真空构架内的平均自由程。
The heat loss of a monolithic low density SiO 2 airgel tile (thickness 9 mm, density p = 80 kg / m 3) has been determined in our vacuum protected LALA II hot plate system. The measurement is based on the boundary emissivity upper and lower limits (∈ ≈ 0.05 and 0.9) for several gases at various temperatures and pressures. From the measurement results, it can be concluded that the low-density SiO 2 airgel tile (about 10 mm in thickness) has excellent heat insulation performance when it is heated at an ambient temperature of 10 ° C. or 238 K and a pressure of 10 mbar , The total heat loss coefficient K (?) 0.7W / (m ~ 2 · k). It is therefore highly promising to apply them to windows or covers in solar passive utilization systems. The mean free path in the evacuated frame of about 120 nm can be deduced from the magnitude of heat loss as a function of barometric pressure.