Abstract
In this work, the cold start behavior of a thermally coupled metal-hydride hydrogen storage system for automotive application was experimentally investigated. The experiments per-formed consisted of the study of steady-state load points and WLTP for cold start and In-operando reloading, the reloading of the starter tanks during operation. The parameters varied for investigation were the scaling of the hydrogen flow, the scaling of the supplied heat amount, the starting load and the starting temperature. The downscaling of the mass flow rate required by the fuel cell resulted in a reduction of the desorption time and the desorbed hydrogen quantity to the parameters required by the fuel cell. Furthermore, this caused a slower increase in temperature due to the endothermic reaction. By reducing the amount of heat supplied and lowering the starting charge, the desorption time and the amount of hydrogen desorbed to the parameters required by the fuel cell were also short-ened. Slower heating of the tank results in a longer pressure rise and lower maximum pres-sures. The slower pressure rise caused the cold start phase to take longer and the time to reach maximum pressure to increase. The time between these two points, which represent the switchover points for in-operando reloading, also increased. Lower starting loads lead to an increase in the proportion of desorbed hydrogen compared to that previously ab-sorbed. The time to the first pressure rise is prolonged by lower starting loadings, but there-after the pressure rises faster due to the larger slope of the temperature. Reaching the two switchover points takes longer. A higher starting temperature leads to earlier reaching of the desired pressure or temperature. As a result, higher maximum pressures are also achieved.
