Numerical simulation of thermal transfer in polyimide nanofiber aerogels by 3D dual diameter Voronoi models

The investigation of heat transfer in nanofiber aerogels (NFAs) is crucial for predicting and designing aerogels that achieve desirable thermal performances for various industrial applications. However, limited research has been conducted on numerical modeling of NFAs due to the challenges associated with reconstructing their structure. In this work, we present a 3D dual diameter Voronoi model to evaluate the thermal conductivity of NFAs. As an example, polyimide NFAs are considered. The predicted thermal conductivity values show good agreement with various experimental data with all relative errors being less than 5%. Furthermore, several influential parametric factors including the nanofiber diameter, the ratio between different diameters nanofibers and the structure of nanofibers are investigated. The results indicated that the thermal conductivity of NFAs increase with both the nanofiber diameter and the ratio of coarse nanofibers. Additionally, the intersection between coarse and fine nanofibers which along with the heat transfer direction and the location will influences the thermal conductivity of NFAs. This certainly demonstrates the potential of the dual diameter Voronoi model for use in the predicting and designing of the NFAs in the various fields such as thermal insulation or the energy management.