Investigation of coupled AB5 type high-power metal hydride reactors

The objective of this study is to investigate the coupled AB5 type high-power metal hydride reactors in thermal energy applications. A system to test the reactors was set up coupling two reactors containing either LaNixAl5−x or CayMm1−yNi5 alloys, used as low and high pressure metal hydrides, respectively. In order to develop the high-power reactor, the metal hydrides were thinly coated (about 1–2 μm thickness) with copper and compressed to form the Porous Metal Hydrides (PMH) compacts. During the experiments, the dynamic behaviors of the reactive kinetics of the system were monitored. Among the tested systems, the coupling of Ca0.6Mm0.4Ni5 and LaNi4.75Al0.25 was the most effective for thermal energy applications. It took the least time to reach the equilibrium state in both hydriding and dehydriding processes (approximately 250 s) and had the highest amount of heat generation/absorption. The smaller the value of y in Ca1−yMmyNi5 alloys, causing the alloy to contain more calcium, the faster the reaction kinetics. In the case of the LaNixAl5−x reactor, the addition of aluminum enhanced the reaction kinetics. Moreover, the reactor with the low pressure metal hydride, LaNixAl5−x, took a longer period of time to reach the equilibrium state than when the high pressure metal hydride, Ca1−yMmyNi5, was employed.