Design of Ammonia Oxidation Reactor for Portable Fuel Cell Applications

In this paper a packed bed reactor is designed and analyzed, in which ammonia is oxidized to produce sufficient hydrogen for generating 100 W of power. Mass and energy balance equations are developed for each species in the reactor. The pressure drop is modeled via the Ergun equation. Simulations are conducted in MATLAB to determine the effect of process parameters (e.g. ammonia flow rate, pressure, temperature at the reactor inlet) on the production of hydrogen. For a range of catalyst particle sizes considered, it is shown that the pressure drop is negligible. Energy is provided for the endothermic reaction via electrical heating. Energy balance calculations are conducted to estimate the excess power required for heating the reactor. An appropriate PEM fuel cell stack is designed that generates 100 W of usable power plus the necessary power to electrically heat the reactor jacket. Finally, a simple economic model is developed to estimate the cost of fabricating and operating this system.