Modeling and measurement of effective thermal conductivity of core-shell-structured SiO2 MHSPs-silica aerogel composite

Abstract

To explore and optimize silica aerogel's thermal insulation performance, we model and test the effective thermal conductivity (λ) of SiO2 micro hollow sphere particle (MHSP)-silica aerogel. The models are for the infrared radiative λ of SiO2 MHSP-silica aerogel, with different core/shell ratios (ld), and the hot surface's temperature response is measured by the steady-state method. The results show that the radiative λ of aerogel doping SiO2 MHSP with ld=0.75 is equivalent to that of doping with solid spheres, whose weight is reduced by 42.19%, and the solid λ is reduced by 88.24%. Furthermore, the λ of aerogel with 60 μm SiO2 MHSPs of 0, 6.89, and 16.28 vol% is 0.02504∼0.02613, 0.02847∼0.03100, and 0.03635∼0.03955 W·m–1·K–1, respectively, at small temperature difference (ΔT <20 K). As ΔT increases (> 550 K), the ‘λ’ of aerogel with 16.28% SiO2 MHSP becomes smaller than aerogel with 6.89% SiO2 MHSP, indicating the optimal insulation performance.