Optimization of Adsorbent Tanks for Hydrogen Storage for Automotive Applications

A key technical hurdle to an energy economy focused on clean-burning hydrogen over non-renewable petroleum is on-board storage of hydrogen for automotive vehicular applications. Adsorbents provide one possible solution to the need for improved gravimetric and volumetric capacities. However, while the heat of adsorption released upon sorption of hydrogen is relatively low, so it the thermal conductivity. The subsequent rise in storage temperature results in decreases in maximum hydrogen storage capacity and loading rate at the short fill times mandated by the Department of Energy (DOE) targets. Novel designs for integrated heat exchangers are needed to maximize the heat transfer out of system to maximize storage rate and capacity.

While many literature studies focus on maximum capacity assuming an (impossible) infinite fill time, full, detailed modeling of the coupled heat and mass transfer is needed. The focus of this presentation will be our work developing detailed numerical models that couple heat and mass transfer via the general purpose finite element solver COMSOL Multiphysics^® for various adsorbent media and bed designs and the automatic optimization of the designs by linking the COMSOL models with routines in MATLAB^®.