Dynamic reaction characteristics of the tubular hydride bed with large mass

In order to investigate the dynamic reaction properties of hydride in the hydride beds with large mass, the dynamic P-C-T curve of MmNi(4.6)Al(0.2)Fe(0.2)V(0.03) has been obtained experimentally, using tubular reactors simulating a module of a full-size multitube heat exchanger of a metal hydride heat pump. The dynamic P-C-T curves were obtained for the reactors with the aluminum plates inserted at different intervals. It was found that the hysteresis of the dynamic P-C-T curve increased as the number of the aluminum plates decreased. The dynamic behavior of the reactor, in which the aluminum plates were installed, was investigated at different hydrogen flow rates. The dynamic P-C-T curves were compared with the measured distributions of temperature and pressure. With increasing hydrogen flow rate, the hysteresis increased; the measured gradient of temperature and pressure increased too. It was concluded that the dynamic behavior of the hydride bed could be predicted by means of the effective temperature calculated from the measured inner pressure by using static van't Hoff plot when no pressure gradient exists. In this work, no pressure gradient was found when the flow rate was relatively low and it is suggested that the hydride beds are in thermal equilibrium under this reaction condition.