Simulation of hydrogen adsorption systems adopting the flow through cooling concept

• Hydrogen adsorbent tank detailed model set up.
• Modeling carried out for flow through cooling adsorption concept.
• Performance of carbon based material evaluated with experimental data comparison.
• Comparison between carbon based material and MOF material carried out.

Hydrogen storage systems based on adsorbent materials have the potential of achieving the U.S. Department of Energy (DOE) targets, especially in terms of gravimetric capacity (the 2017 DOE target for the system weight capacity is 5.5%). This paper deals with analysis of adsorption storage systems adopting the flow through cooling concept. By this approach the feeding hydrogen provides the needed cold to maintain the tank at low temperatures. Two adsorption systems have been examined and modeled adopting the Dubinin–Astakhov model, to see their performance under selected operating conditions. A first case has been analyzed, modeling a storage tank filled with carbon based material (namely MaxSorb®) and comparing the numerical outcomes with the available experimental results for a 2.5 L tank. Under selected operating conditions (minimum inlet hydrogen temperature of approximately 100 K and maximum pressure on the order of 8.5 MPa) and adopting the flow through cooling concept the material shows a gravimetric capacity of about 5.7%. A second case has been modeled, examining the same tank filled with metal organic framework material (MOF5®) under approximately the same conditions. The model shows that the latter material can achieve a (material) gravimetric capacity on the order of 11%, making the system potentially able to achieve the DOE 2017 target.