Thermal conductivity of powder silica hollow spheres

The thermophysical property of hollow silica spheres was studied by the experimental test 3ω method, theoretical calculation and finite element simulation. The experimental values of the thermal conductivity, less than 0.02 W m−1 K−1, indicated that the powder silica hollow spheres are indeed the high efficient heat-insulating materials. The influences of the particle size and packing density on the thermal conductivity were observed. Then the formula interpreting aerogels were used to calculate the thermal conductivity of hollow silica spheres. The calculated values were larger than the experimental ones. Moreover, ANSYS software was applied to develop a heat conduction model for this type materials based on their hollow structure features. The geometry of the materials was discrete and finite element analysis was performed. The simulated values were close to that of air and a little higher than the experimental and calculated ones. And the possible reasons causing such differences were proposed.