Performance Assessment of AB5 Hydride-Based Hydrogen Storage Reactors Configured with The Identical Heat Exchange Volume of Straight Embedded and Helically Coiled Cooling Tubes

Abstract

The performance of metal hydride-based hydrogen storage systems requires understanding the efficient design of heat exchanger bed configurations. The present research examines the absorption time of embedded straight tubes and helically configured layouts while maintaining identical weight ratios, heat exchange volumes, reaction dimensions, and operating conditions. Embedded cooling tubes (ECT) are the widely configured bed assembly employed in hydride reactors. In contrast, helically coiled tubes (HCT) have gained attention in the recent past for their ease of fabrication, and HCT inheritably fits the length and width of the reactor. The developed 3-D thermal model examines the absorption time by keeping the weight ratio constant for the reactor layouts for identical volumes of ECT and HCT-based reactor geometry to determine the bettered bed configuration based on hydrogen saturation time using COMSOL Multiphysics® 5.6. The ECT reactor comprises 60 straight tubes, whereas the HCT reactor comprises three helical tubes of the same diameter and heat exchange volume with the metal hydride. The metal hydride alloy used inside the reactor is LaNi5 for both designs. Moreover, a sensitivity analysis is conducted for both designs to assess the effects of supply pressure and inlet ethylene glycol-water temperatures on absorption and to emphasize the most suitable configuration under various operating conditions. The unified comparison under the basis of identical weight ratio, heat exchange, and reactor dimensions reveals that the helically configured three spiral tube design layout emerged as the performance-effective configuration at higher supply pressure for hydride-based hydrogen storage systems.