Geometric optimization of aerogel composites for high temperature thermal insulation applications

Silica aerogel has attracted great interest in thermal insulation applications due to its ultralow thermal conductivity. However, silica aerogel is transparent to the infrared radiation in the range of 3-8 mu m, making them be not suitable for high temperature thermal insulation applications. Here, we developed an optimization method considering both thermal radiation and heat conduction to design the geometric structures of aerogel composites with minimized thermal conductivity. The results show that when the ambient temperature is lower than similar to 600 K, the additives with low thermal conductivity are preferred. When the ambient temperature is higher than similar to 600 K, the additives with high extinction coefficients are needed. The additives with a broad size distribution could enable the aerogel composites to have an optimal thermal insulation performance in the environment with a changing temperature. The work provides a guideline for the geometric design of aerogel composites for high temperature thermal insulation applications.