Network decomposition model to describe the solid and gaseous thermal conductivity in open-porous (nano)materials

Understanding the interplay between the heat transport through the solid phase and the porous one may play a vital role in the inverse design of open-porous (nano)materials for thermal superinsulation applications. In this paper, we propose a mechanistic model using the finite element framework to independently describe the thermal transport through the solid phase and the porous one. The proposed model considers heat conduction through the solid and gaseous phases and does not account for convective and radiative effects. To this end, a network decomposition model is proposed wherein the open-porous material is decomposed into a solid network model (SNM) and a pore network model (PNM). An excluded volume concept is further introduced within the PNM, and is driven by the Knudsen diffusion for modelling in the case of nanoporous materials. The model predictions are validated with experimental data and the model is shown to accurately estimate the total thermal conductivity for nanoporous materials where convection and, at room temperature, radiation do not play any significant role.