Drastic enhancement of effective thermal conductivity of a metal hydride packed bed by direct synthesis of single-walled carbon nanotubes

Abstract

Low heat conductivity restricts the rate of hydrogen absorption into a metal hydride, and this leads to a mismatch of the required absorption rate. The use of fin systems is standard in such cases, and the use of several different materials has been attempted. This includes high thermal conductivity carbon brushes and carbon nanotube. Unfortunately, such efforts have not been effective because the boundary thermal resistance has not been addressed. In this study, we focused on the direct synthesis of a single-walled carbon nanotube (SWCNT), which has high thermal conductivity, on particles in a packed bed, for reducing boundary thermal resistance and estimated effective thermal conductivity. Referring to Raman spectra, we succeeded in growing SWCNT on a metal hydride and effective thermal conductivity was estimated as a function of the filling ratios of the metal hydride and the SWCNT. Consequently, the effective thermal conductivity can satisfy the required value.