Determination of the effective thermal conductivity of particulate composites based on VO2 and SiO2

Santiago Alvarez-Guerrero , Jose Ordonez-Miranda (1, 2) , Romeo de Coss , Juan Jose Alvarado-Gil

1 LIMMS-IIS/CNRS, Tokyo, JAPAN
2 PPrime [Poitiers] - Institut Pprime [UPR 3346]

The effective thermal conductivity of composites made up of VO2 (SiO2) spherical particles randomly distributed and embedded in a SiO2 (VO2) matrix are numerically studied in a range of temperatures around the metal-insulator transition of VO2. This is done by means of three-dimensional finite element simulations for different concentrations and sizes of the particles as well as various interface thermal resistances. Our results were validated against the Mori-Tanaka analytic model. In addition, we developed a numerical method to calculate the heat storage capacity for composites with VO2 particles dispersed into SiO2 matrix. It is shown that: i) The effective thermal conductivity of VO2/SiO2 composites increases with the VO2 particles' size, while the one of SiO2/VO2 composites is pretty much independent of the SiO2 particles' radius. ii) At the VO2 transition temperature (342.5 K), the effective thermal conductivity of VO2/SiO2 composites increases significantly at a rate of 2.7 x 10-3 Wm-1 K-2 , such that its value doubles up the SiO2 matrix thermal conductivity at the particle concentration of 40.2%. By contrast, the effective thermal conductivity of SiO2/VO2 composites decreases at a rate of 8.6 x 10-3 Wm-1 K-2. iii) The effective thermal conductivity is strongly affected by the thermal resistance in VO2/SiO2 composites, by contrast the resistance effect does not play an important role for particle volume fractions of SiO2 up to 34.1% in SiO2/VO2 composites. The Mori-Tanaka model and our simulations predict the same trend of the effective thermal conductivity values of VO2/SiO2 composites. However, the analytic model fails when the matrix is made up VO2 and the volumetric fraction exceeds 34.1% of SiO2. The latent heat storage capacity of VO2/SiO2 composites increases with the VO2 particles' concentration, such that at 40.2%, it takes the value of 24553 J kg-1 (486.7 cal mol-1), which is about half that of the pure VO2.

Mots clés: particulate composites; effective thermal conductivity; interfacial resistance; vanadium dioxide

Domaines: Matériaux

Santiago Alvarez-Guerrero, Jose Ordonez-Miranda, Romeo de Coss, Juan Jose Alvarado-Gil. Determination of the effective thermal conductivity of particulate composites based on VO2 and SiO2. International Journal of Thermal Sciences, 2022, 172, pp.107278. ⟨10.1016/j.ijthermalsci.2021.107278⟩. ⟨hal-03381559⟩