Heat conduction mechanism in silica aerogel skeleton

Abstract

Abstract In order to study the specific heat conduction process of silica aerogels, a three-dimensional random fractal skeleton model of aerogels was generated by using the diffusion-limited cluster aggregation (DLCA) method to simulate the gel process. Based on the idea of finite volume method, a numerical model of heat conduction in porous framework was established and verified. The three-dimensional temperature field and apparent thermal conductivity of the skeleton were calculated. The results show that when the initial particle concentration is 0.0764 ~ 0.191, the fractal dimension range of the skeleton model is 2.0 ~ 2.45, which is consistent with the measured value. However, in the plane perpendicular to the heat flow direction, the particle temperature is not exactly the same, which can be approximately described by normal distribution. The apparent thermal conductivity of the skeleton is three orders of magnitude lower than that of the bulk material, which can be attributed to its open form network structure.