Multi-physical thermofluidynamic simulations of hydrogen absorption performance in double-layered cylindrical ZrCo-based hydride beds

Abstract

This work established a two-dimensional mathematical model to evaluate the thermofluidynamic behavior of a newly developed double-layered cylindrical ZrCo-based hydride bed during the hydrogenation reaction process. Numerical simulations by using COMSOL Multiphysics were conducted to solve the governing partial differential equations associated with chemical reaction and thermal transfer. Importantly, the local thermal nonequilibrium theory was applied to analyze the heat transfer between the ZrCo particle and hydrogen. Detailed analysis revealed the effects of operating conditions, material thermophysical properties, and the bed configuration, in addition to the ZrCo hydride particle sizes on hydrogen recovery characteristics. The simulation results indicated that increasing the heat transfer coefficient, reducing the coolant temperature, improving the thermal conductivity of the metal hydride, using the thinner hydride layer, and being equipped with copper fins were more beneficial to accelerate the heat transfer rate and the hydrogen charging rate of the metal hydride bed (MHB). Furthermore, along the radial direction, tremendous temperature gradient and distribution of absorbed hydrogen were found in the hydrogenated zones. The present model can effectively characterize the reaction kinetic mechanisms of ZrCo hydriding process as to further promote the practical application of the proposed MHB designs.