Advances of thermal conductivity models of nanoscale silica aerogel insulation material

This paper summarized the development of the effective thermal conductivity models for the nanoporous silica aerogel insulation material. Firstly, the nanoscale heat transfer characteristics inside aerogel material was introduced. Secondly, the existing models and methods to calculate the thermal conductivity of each heat transfer mode at the nanoscale were reviewed. Next, the advances and developments of the effective thermal conductivity models for the nanoporous silica aerogel materials as well as its composite insulation material were also discussed. Then the procedure of establishing the effective thermal conductivity model of the aerogel insulation material from nanoscale to macroscale was introduced by taking our previous work as an illustration. Finally, it should be noted that for the nanoporous silica aerogel insulation material, there are still some key issues that need to be investigated to get deep understanding of the mechanism of nanoscale heat transfer inside the material, such as the coupled heat transfer behavior at the gas–solid contact interface, the influence of scale effect/interfacial effect on the thermal conductivity of nanoscale solid particles, etc. Thus it is necessary to keep on investigating these questions thoroughly to provide help for establishing more accurate heat transfer model as well as optimizing the insulation performance of the material.