Numerical Simulation on Heating Effects during Hydrogen Absorption in Metal Hydride Systems for Hydrogen Storage

A 2-D numerical simulation model was established based on a small-sized metal hydride storage tank, and the model was validated by the existing experiments. An external cooling bath was equipped to simulate the heating effects of hydrogen absorption reactions. Furthermore, both the type and the flow rate of the cooling fluids in the cooling bath were altered, so that changes in temperature and hydrogen storage capacity in the hydrogen storage model could be analyzed. It is demonstrated that the reaction rate in the center of the hydrogen storage tank gradually becomes lower than that at the wall surface. When the flow rate of the fluid is small, significant differences can be found in the cooling liquid temperature at the inlet and the outlet cooling bath. In areas adjacent to its inlet, the reaction rate is higher than that at the outlet, and a better cooling effect is produced by water. As the flow rate increases, the total time consumed by hydrogen adsorption reaction is gradually reduced to a constant value. At the same flow rate, the wall surface of the tank shows a reaction rate insignificantly different from that in its center, provided that cooling water or oil coolant is replaced with air.