CFD-DEM Modeling of Cryogenic Hydrogen Flow and Heat Transfer in Packed Bed

Hydrogen is an important component of renewable energy and is essential for sustainable development. The cryogenic energy storage system can solve the problem of hydrogen storage. A packed bed can be applied in a cryogenic energy storage system. It is crucial to understand the cryogenic energy discharging in a packed bed. In the present work, the CFD-DEM coupling method is used to investigate the pore-scale flow and heat transfer characteristics of cryogenic hydrogen flowing through the packed bed. To demonstrate the characteristics of the pore-scale heat transfer of the hydrogen flow in a packed bed, the local radial-averaged and axial-averaged temperatures and velocities are analyzed in detail, depending on the local porosity distribution. The pore-scale radial-averaged velocity distribution is proportional to the local radial porosity distribution, whereas the pore-scale radial-averaged temperature characteristics are inverse. Moreover, for the heat exchange of the cryogenic hydrogen flow in a packed bed, it can be found that the cryogenic hydrogen flow is fully heated at an axial distance of approximately 7 dp. Finally, considering that the thermo-physical properties of cryogenic hydrogen are sensitive to the temperature in a packed bed, the friction factor and Nusselt number in the packed bed are also analyzed under various operating parameters, which are in good agreement with certain classic empirical correlations.