Performance of a solid state hydrogen storage device with finned tube heat exchanger

In the present study, a cylindrical solid state hydrogen storage device embedded with finned heat exchanger is numerically investigated. The finned heat exchanger consists of two 'U' shaped tube and circular fins brazed on the periphery of the tubes. 1 kg of LaNi5 alloy is filled inside the device and 80 g of copper flakes is evenly distributed in between the fins to increase the overall thermal conductivity of the metal hydride. Water is used as heat transfer fluid. Absorption performance of the storage device is investigated at constant hydrogen supply pressure of 15 bar and cooling fluid temperature and velocity of 298 K and 1 m/s respectively. At these operating conditions, the required charging time is found to be around 610 s for a storage capacity of 12 g (1.2 wt%). The study is extended to examine the influence of different heat exchanger configurations based on number of fins, thickness of the fins, diameter of tubes, holes in fins, amount of copper flakes etc. An analysis for the same weight of the heat exchanger assembly has also been carried out by changing the number of fins at different thickness and pitch.