Thermal management and desorption modeling of a cryo-adsorbent hydrogen storage system

Adsorbent based hydrogen storage systems using activated carbon or metal organic framework (MOF) materials are among the most promising material based hydrogen storage systems. In this effort, a complete 3-D discharge model to simulate extraction of hydrogen from the storage bed for fuel cell operation is developed. The desorption process is endothermic and the heating requirement is met by a heating element which includes a helical coil and a central longitudinal rod placed inside the bed. Since thermal conductivity of adsorbent bed plays a crucial role in determining the temperature distribution, simulations were performed to find an optimum conductivity range that can facilitate maximum extraction of hydrogen from the bed along with a fairly uniform bed temperature distribution. Finally, storage system designs including the adsorbent bed and heating system for two adsorbents – an activated carbon (AX-21) and a MOF material (MOF-5) – are presented.