Numerical Modeling of Metal Hydride-Phase Change Material Hydrogen Storage Systems with Increased Heat Exchange surface area

Coupling Metal Hydrides (MH) with Phase Change Materials (PCM) provides a promising way of storing hydrogen without using any active systems to control the MH temperature during cycling. In this study, we perform numerical assessments on the performance of cylindrical MH-PCM storage systems with varying geometrical configurations. We investigate the ab/desorption kinetics in a straight cylindrical geometry (case A), where the PCM surrounds the MH. Its cycle time and gravimetric density for the absorption of 1.04kWh are 2,200 s and 0.30%. We then investigate two improved configurations, namely the addition of fins to the external surface of the MH and within the PCM domain (case B), and the containment of the MH powder into a helix-shaped tube immersed in the PCM (case C). Number and thickness of fins are also varied to assess their impact. Compared to case A, the helix-shaped design is 49% and 40% faster in absorption and desorption, respectively, whereas the finned geometry is 28.9% and 30% faster. The gravimetric density is 0.27% and 0.62% in case B and C, respectively.