Effective Thermal conductivity of divided silica xerogel beds

Antoine Bisson (1) , Arnaud Rigacci (1) , Didier Lecomte (2) , Patrick Achard (1)

1 CEP/Sophia
2 RAPSODEE - Centre de recherche d'Albi en génie des procédés des solides divisés, de l'énergie et de l'environnement

Apparent thermal conductivity (λ) measurements were made on monolithic silica aerogels and divided low-density xerogels. The objective of the tests on monoliths was to determine the variation of λ with the solid content. Additional compressive tests were also made to follow the evolution of bulk modulus with apparent density, in order to further optimize the solid content of xerogel particles. Divided xerogels were characterized under the following conditions: at ambient conditions (T, P, and relative humidity of water vapor in air), under partial vacuum (from atmospheric pressure to 4 × 10−7 bar) and under different relative humidities. The effect of the divided xerogel granularity on λ has been studied by using different size range and distributions. The results of our studies indicate an optimum particle density at 0.15 g cm−3, and a decrease in λ for samples containing fine particles.

Mots clés: Gas; Aerogels

Domaines: Physique [physics]; Matière Condensée [cond-mat]; Science des matériaux [cond-mat.mtrl-sci]

Antoine Bisson, Arnaud Rigacci, Didier Lecomte, Patrick Achard. Effective Thermal conductivity of divided silica xerogel beds. Journal of Non-Crystalline Solids, 2004, Aerogels 7. Proceedings of the 7th International Symposium on Aerogels, 350, pp.379-384. ⟨10.1016/j.jnoncrysol.2004.08.238⟩. ⟨hal-00528565⟩