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

To explore and optimize silica aerogel`s thermal insulation performance, we model and test the effective thermal conductivity ( λ) of SiO <sub>2</sub> micro hollow sphere particle (MHSP)-silica aerogel. The models are for the infrared radiative λ of SiO <sub>2</sub> MHSP-silica aerogel, with different core/shell ratios ( l <sub>d</sub>), and the hot surface`s temperature response is measured by the steady-state method. The results show that the radiative λ of aerogel doping SiO ₂ MHSP with l _d=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 SiO ₂ 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 (Δ T <20 K). As Δ T increases (> 550 K), the ‘ λ’ of aerogel with 16.28% SiO ₂ MHSP becomes smaller than aerogel with 6.89% SiO ₂ MHSP, indicating the optimal insulation performance.