Pressure Effect on Thermal Diffusion in Aluminum Powders Composed of Nanometer- and Micrometer-Sized Particles

摘要

Nanoparticles show a variety of size-dependent properties due to the dramatic changes in the ratio of surface area to volume. The characteristics of nanoparticles different fromthe bulk material make the properties of the powders composed of these nanoparticles attract more attention. The thermal diffusion in the powder composed of nanoparticles is experimentally investigated in this paper. The powder is wrapped up in the slendertube made of insulating material. One end of the slender tube filled with powder is maintained at low temperature and the other end is kept at room temperature. The temperature histories at two different locations in the slender tube are recorded using thermalcouples. The results show that the heat transfer depends on the bed porosity and the thermal conductivities of the solid and the gas. The pressure on the Al powders enhances the rate of heat transport due to the decrease of the bed porosity and a small fraction of gas.