Industrial-scale for hydrogen charging in activated carbon (AX-21)-phase change material-nano-oxides systems

Abstract

As a plausible solution for the issue of heat management during hydrogen adsorption on the activated carbon bed, in the present paper, the effects of different metal oxides nanoparticles (MgO, TiO2, CuO, or ZnO), scattered into a phase change material (PCM), have been investigated over the adsorption and dormancy phases in a large-scale bottle. This study has been conducted using Fluent software, in which a computational fluid dynamics (CFD) model (based on finite volume simulations) was implemented. This model has been validated via the experimental and theoretical results available in literature. Throughout the duration of the charging process, it has been found that the presence of nanoparticles in PCM body does not affect the thermal performance of the solid bed of activated carbon,. However, the melt fraction of PCM is steeply increased to 20 % in the range ~ 0–1300 s, whereas over 1300 s, the melting process of paraffin is amortized until the end of the dormancy phase (attaining ~ 30–35 % of liquid PCM). This trend is observed either in the presence or in the absence of metal oxides, where 16 % of enhancement in the liquid fraction of PCM is retrieved in the presence of nanoparticles (5 %) at the end of the dormancy phase (10,000 s). As a result, The nano-PCM system could be a proposed pathway for recovering the heat generated from the H2 adsorption and then replacing the fluid cooling system (cost). However, it was recommended that future research works should be focused on the improvement of the solid bed thermal conductivity in addition to the enhancement of the reactor geometry via new innovative solution pathways.