Effect of precooling the in-charged on the performance of hydrogen storage systems packed with typical kinds of adsorbents

Selecting suitable adsorbents and managing the thermal effect are two important aspects on the practical application of the hydrogen storage system by adsorption. In this research, three kinds of promising adsorbents, which include MOF-5, MIL-101(Cr) and activated carbon AX-21, were selected for evaluating the effect of pre-cooling of hydrogen in-charged into a 0.5 L cylindrical vessel experimentally and numerically as per the temperature fluctuation, heat generated, accumulated amount of the charge under the flow rate of hydrogen required by an on board 5 kW PEMFC power unit. The validation of the prediction accuracy of the model was performed by the experiments conducted respectively at 77.15 K and 298.15 K where the vessel was packed with MIL-101(Cr). Simulations were further performed to evaluate the performance of the vessel respectively packed with three kinds of adsorbents within the flow rate range 15–40 L min⁻¹ and temperature range 77.15–298.15 K. Results show that precooling the hydrogen in-charged is conducive to weakening the temperature fluctuation of the storage system, and heat from adsorption is the main factor affecting the accumulated amount of charge and the temperature fluctuation within the hydrogen storage system. It suggests that MOF-5 is a more suitable hydrogen storage medium than MIL-101(Cr) and AX-21, and charging the system with hydrogen precooled at 77.15 K under a smaller flow rate is beneficial to improving the performance of the storage system.