Comparison, advancement, and performance evaluation of heat exchanger assembly in solid-state hydrogen storage device

Despite myriads of mathematical and experimental studies using various heat exchanger-metal hydride assemblies, an adept comparison of reactors on standard performance defining parameters, i.e., reactor weight, external energy utilization, and alloy material, are not studied or reported for industrial storage containers and onboard applications. This lacuna is a critical barrier in developing efficacious hydrogen storage reactors for various applications. This article chronicles the 3-D design and optimization of three basic heat exchanger setups of solid-state hydrogen storage systems (shell and tube, spiral tube, and tubular) on critical parameters. For 5 kg LaNi5, a tubular design with small tube diameters has resulted in a shorter reaction time (120 s) for 90% saturation at 303 K and 15 bar inlet conditions; however, the reactor's gravimetric density was exceptionally high. In contrast, the reactor with three spiral tubes accomplished an exemplary reaction rate at a reasonable gravimetric density. This spiral arrangement became the base for developing a novel reactor that integrated heat pipes to reduce the sorption time. The proposed design achieved a specific output energy rate of 527 W/kg for 90% saturation in 366 s at a supply pressure of 15 bar, which is 23.7% higher than the reactor without heat pipes.