Suitability analysis of lumped-capacitance formulations for adsorbed gas storage

Mathematical modeling and numerical solutions can be of great assistance for simulating heat transfer in adsorbed gas (AG) storage operations, leading to better thermal designs of AG reservoirs. Nevertheless, the complexities associated with modeling heat and mass transfer that occur within adsorbed gas processes can lead to formulations that require a great computational effort. In this paper, a complex multidimensional formulation is shown to be reducible to a simple lumped-capacitance model via an averaging procedure. Naturally, this simpler formulation cannot represent accurately a significant number of cases. Hence, a comparison between the simpler lumped formulation with one that considers spatial dependence is provided for estimating ranges of applicability for the simpler form. The results indicate that the Biot number alone cannot be used as a criteria for determining whether a lumped-capacitance model can be accurately employed.