Radiative properties of silica nanoporous matrices

Sylvain Lallich (1) , Franck Enguehard (1) , Dominique Baillis (2)

1 CEA Le Ripault - CEA Le Ripault
2 CETHIL - Centre de Thermique de Lyon

Nanoporous superinsulating materials are currently the subject of much attention because of their awesome thermal insulation properties: up to five times better than air, generally regarded as an excellent thermal insulator, when they are placed under primary vacuum. These materials are made of nanoporous matrices of amorphous silica nanoparticles, fibres to provide mechanical reinforcement and micrometric particles to improve opaqueness in the infrared wavelength region. Our aim is to determine experimentally and to model the radiative properties of such nanoporous materials, which are semi-transparent media in the considered wavelength range. In the simplified approach presented here, we consider the nanoporous matrix alone. We first present the characteristics of the samples and the way we used to get their optical properties. Then after a brief review of the radiative transfer equation (RTE) and of the parameter identification technique used, we discuss the radiative properties spectra obtained. Lastly, the radiative properties computed using two different theoretical methods are compared to the experimentally determined spectra.

Domaines: Thermique [physics.class-ph]

Sylvain Lallich, Franck Enguehard, Dominique Baillis. Radiative properties of silica nanoporous matrices. 8th International Vacuum Insulation Symposium, Sep 2007, Würzburg, Germany. ⟨hal-01290207⟩