Heat and mass transfer characteristics of charging in a metal hydride-phase change material reactor with nano oxide additives: The large scale-approach

Integrating metal hydride (MH) for hydrogen storage with phase change materials (PCMs) received increasing attention today to ensure effective thermal management in MH-storage reactors and reduce the operating cost of the process. This study revealed the first coupling approach (at large scale) of hydrogen storage in LaNi5 alloys with heat recovery by using a PCM loaded with nanoparticles (i.e. the MH-nano-PCM system) in a cylindrical MH-tank reactor (diameter: 1 m) equipped with four tubes of nano-PCM. Mass and heat transfer phenomena were computationally analyzed in the diverse regions of the reactor. The temporal temperature profiles (average and contours), the MH-hydrogenation efficiency, the velocity contours and PCM-liquid fraction were established in the presence (at 5% v/v) and absence of four types of nano-oxides (Al2O3, MgO, SnO2 and SiO2). Significant results were obtained. The nano-PCM system efficiently recuperates the heat lost from the exothermal absorption reaction; however, a slight reduction in the latent energy storage unit's performance is obtained compared to pure paraffin, probably due to the thermo-transfer resistant created by the nano-particles agglomeration during the melting cycle. The PCM-tube position plays a crucial role in the PCM melting rate, where the tube located above the H2-charging pipe melts more quickly than the other tubes.

Automated summary

This study investigated the coupling of MH with PCM to ensure effective thermal management and reduce operating costs. The nano-PCM system efficiently recovers heat lost from exothermal reactions, but shows slightly reduced performance compared to pure paraffin. The position of PCM tubes plays a crucial role in melting rates.