纳米复合隔热材料辐射与导热耦合传热

Combined Radiation and Conduction Heat Transfer in Nanocomposite Insulation Materials

气凝胶是一种纳米多孔隔热材料,但力学强度差,通常添加纤维来提高材料的力学性能。建立基于光学厚的导热与辐射耦合传热模型,揭示纤维种类对气凝胶纤维复合材料的隔热影响机制。结果表明,高温下石英纤维b的消光系数最大,抑制辐射能力最强,钠钙玻璃纤维抑制辐射能力最差。纤维的选择对提高材料的隔热性能有显著的影响。纤维复折射系数平均值越大,同时围绕平均值向下波动越小,其消光系数越大。本文研究的4种复合材料,加入石英纤维b的复合材料的高温整体热导率最低。

The silica aerogel is a nanoporous super thermal insulation material with weak me- chanical strength. The fibers are usually filled into the aerogel to strengthen the material. A combined conduction and radiation heat transfer model based on the optically thick assumption was developed to investigate the effects of the fiber species effects on the heat transfer through the fiber-loaded aerogel composite. The results show that the silicon glass-b has the largest ex- tinction coefficient for best suppressing the radiation at higher temperatures while the soda lime silica fiber has the smallest extinction coefficient. The selection of proper fiber is important for improving the thermal insulation. The fiber, which has the largest complex refractive index with smallest fluctuations, has the largest extinction coefficient. For the 4 species of fibers in this study, the silicon glass-b is optimum for best reducing the total thermal conductivity for higher temperatures.