Optimization of cold startup strategy with quasi 2-D model of metal hydride hydrogen storage with fuel cell

Abstract

In this work, a novel cold startup strategy is presented for a large-scale metal hydride–fuel cell system. Due to the thermal requirement of the system, when the initial temperature of metal hydride and ambient air is low, the system cannot be started because the hydrogen pressure in the metal hydrides storage system is lower than the minimal pressure required by the fuel cell. The cold startup is achieved by maintaining a part of metal hydride storage at a target temperature and using coolant control to transfer heat to the remaining cold metal hydride storage upon operation of the fuel cells. The strategy is studied numerically and a novel Quasi-2-Dimensional approach is developed to describe heat transfer within metal hydrides and validated. By the proper selection of the value of the control variable, both fast startup and immediate uninterrupted fuel cell power supply are achieved. The effect of initial conditions on the startup process is studied and the strategy consumed 30 % less energy than the alternative without control. The proposed strategy is suitable and efficient for the cold startup of large-scale metal hydride-fuel cell systems.