Enhancement of the effective thermal conductivity in packed beds by direct synthesis of carbon nanotubes

Abstract

The low heat conductivity of the packed bed is a key issue in thermal engineering fields. It is also one of the dominant factors behind realizing a fuel cell vehicle society because it prevents quick recharging of hydrogen due to its exothermic reaction. In this study, we examined the enhancement in the effective thermal conductivity of the packed bed with the use of single-walled carbon nanotubes, which were directly synthesized on the particles of the packed bed. We employed two kinds of particles for the packed bed; one was alumina of 10 µm in diameter, which is comparable to usually used in actual system and the other was zeolite, which was used for synthesizing high quality carbon nanotube. Consequently, 10 vol. % of carbon nanotube enhanced three times of effective thermal conductivity.