Dehydrogenation of Metal Hydride Reactor-Phase Change Materials Coupled with Light-Duty Fuel Cell Vehicles

Abstract

The popularity of using phase change materials (PCMs) for heat storage and recovery of metal hydrides’ reaction has grown tremendously. However, a fundamental study of the coupling of such a system with a low-temperature PEM (polymer electrolyte membrane) fuel cell is still lacking. This work presents a numerical investigation of the dehydrogenation performance of a metal hydride reactor (MHR)-PCM system coupled with a fuel cell. It is shown that to supply the fuel cell with a constant H2 flow rate, the PCM properties need to be in an optimized range. The effects of some design parameters (PCM freezing point, the initial desorption temperature, the nature and the size of the PCM) on the dehydrogenation performance of MHR-PCM system are discussed in detail. The results showed that the MHR-PCM could supply hydrogen at 12 NL/min only for 20 min maximum due to the significant endothermic effect occurring in the MHR. However, reducing the requested H2 flowrate to 5.5 NL/min, the hydrogen desorption to a fuel cell is prolonged to 79 min. Moreover, this system can accommodate different PCMs such as paraffin and salt hydrates for comparable performance. This study demonstrates the ability of MHR-PCM systems to be used as range extenders in light-duty fuel cell vehicles.