Coupling model for heat transfer between solid and gas phases in aerogel and experimental investigation

The coupling heat conduction between the aerogel solid and gas phases is of important contribution to the total effective thermal conductivity of aerogel. Based on the assumption of spherical particles in the aerogel backbone, a theoretical model is proposed to calculate the coupling thermal conductivity in aerogel which relates aerogel mean pore size, mean particle size, gaseous thermal conductivity and solid particle thermal conductivity. An experimental study on the thermal conductivity of silica aerogel is carried out to validate the coupling model, and good agreement between the measured data and the coupling model is found. The present coupling model is also verified by available data including experimental results, numerical results and theoretical predictions in the literature. The comparison among the coupling models shows that the present model is of high accuracy without complex and difficult calculations.