Abstract
Thermal conductivity of powder materials under vacuum depends on several parameters such as particle size, temperature, porosity, etc. However, there appears to be no model that quantitatively expresses these dependencies. In this study, we investigated particle size and temperature dependencies by way of thermal conductivity measurements under vacuum environment using glass beads. As a result, it was found that the conductive and radiative contributions on the effective thermal conductivity increased with increasing the particle size, which might be explained by combination of both number of contact points per unit volume and thermal resistance at interpaticle contacts and pore size between particles, respectively.
