Effects of graphite content and compaction pressure on hydrogen desorption properties of Mg(NH2)2–2LiH based tank

Abstract

Cylindrical lab-scale tank based on compacts of Mg(NH2)2–2LiH–0.07KOH mixed with expanded natural graphite (ENG) was designed. And the influences of ENG content and compaction pressure on the hydrogen desorption properties of the tank, including bed temperature, hydrogen flow rate and desorption capacity were investigated under the constant flow rate mode. As the ENG content increases, the heat transfer property of the hydride bed improves significantly, which results in the rise of the central temperature of the hydride bed and the increase of the hydrogen desorption time at the constant flow rate. As the compaction pressure increases, the hydrogen permeability of the hydride bed decreases obviously, but the entire desorption process changes a little. The results indicate that the heat transfer behavior of the hydride bed dominates the hydrogen desorption process of the tank.