A critical analysis of transport models for refueling of MOF-5 based hydrogen adsorption system

This work presents a critical analysis of 2D model of refueling a hydrogen storage tank containing MOF-5 adsorbent under cryogenic and room temperature conditions. Three isotherm models, viz. Unilan, modified Dubinin–Astakhov DA and Tóth, were fitted with experimental data of hydrogen adsorption from the literature, and their effect on refueling of adsorbent bed is analyzed. The choice of isotherm has the greatest impact on predicting refueling behavior, for both flow-through and end-flow (i.e., batch) systems. A comparison between the ideal gas assumption and virial equation of state indicates that the former reasonably captures the overall behavior at lower computational cost. Analysis of the role of momentum balance, solved as full Navier–Stokes model and with Darcy's approximation, indicates same hydrogen uptake in the adsorbent bed and only a minor difference in the predicted velocity profiles. Finally, effect of temperature-dependent physical properties of gas, adsorbent and walls is analyzed.