Low-cost lumped parameter modelling of hydrogen storage in solid-state materials

A low-cost lumped parameter model (LPM) is developed to simulate hydrogen storage in solid-state materials. The proposed LPM is a zero-dimensional model based on an analogous transient thermal resistance network that considers the whole storage system as a resistor–capacitor (RC) circuit with a current source. Combined with the mass conservation, sorption kinetics, and equation of state, the LPM is capable of predicting key thermofluidic quantities of the storage system, such as the storage bed temperature and pressure, hydrogen fraction and flowrate, and storage tank temperature. To test the applicability of the LPM, chemisorptive (Mg and LaNi5) and physisorptive (activated carbon) solid-state materials are simulated for adsorption and desorption processes. For both material types, LPM achieves predictive accuracies comparable to three-dimensional computational fluid dynamics (CFD) simulations, especially for hydrogen fraction and storage times (with maximum errors less than 9.6%), for a fraction of the computational cost (23,734 times lower memory requirement and 126 times faster calculation time). In addition, several formulations of the bed thermal resistance are proposed and discussed in terms of their impact on the accuracy of the LPM predictions. For slender cylindrical tanks, an equivalent annulus formula achieves the best balance of simplicity and accuracy.