Impact of fins and cooling fluid on the hydrogenation process in a LaNi5-Based metal hydride reactor for hydrogen storage

Abstract

This study investigates the influence of different reactors incorporating copper circular fins within the hydride, along with variations in the reactor coolant—specifically water, oil, and nitrogen. Employing user-defined functions in the commercial software Ansys Fluent 15, a 2D numerical model was developed to assess thermal characteristics (temperature, heat flux, etc.) and kinetics of MH-hydrogenation, with a focus on the cooling fluid type. The reactor experiences diverse pressures (5–15 bar), an initial temperature of 298 K, and a coolant speed of 1 m/s. Validation of numerical results was performed against experimental data. The study delves into absorption properties of the storage reactor, examining crucial parameters such as hydrogen concentration, heat transfer coefficient of forced convection, and average temperature within the reactor. The findings reveal that coupling internal fins with water or oil as a coolant yields optimal performance, especially on an industrial scale. Nitrogen, on the other hand, exhibited the least favorable thermal performance, while the addition of fins significantly improved the cooling performance of the storage unit. Results were quantitatively analyzed across various scenarios to enhance understanding of the synergistic role of fins and cooling fluids in the storage performance of H2 within LaNi5 alloy.