Hydrogen production from burning and reforming of ammonia in a microreforming system

Hydrogen (H2) is produced by burning and reforming ammonia (NH3) in a microreforming system. A micro-combustor that burns H2-added NH3–air mixtures as a heat source is a cylinder with an expanded exhaust outlet that facilitates ignition and an annular-type shield that adopts a heat-recirculation concept. A micro-reformer that converts NH3 to H2 using ruthenium as a catalyst surrounds the micro-combustor, which facilitates heat transfer between the micro-combustor and micro-reformer. Performance of the microreforming system is affected by the fuel-equivalence ratio and micro-combustor inlet velocity of NH3–H2–air mixtures and the concentration of the substituted H2 in the fuel gas. The production rate of H2, the conversion rate of NH3, the overall efficiency of the microreforming system and the NOx concentration in the exhaust gas from the micro-combustor for optimized operating conditions are 5.4 W (based on lower heating value), 97.0%, 10.4% and 158 ppm, respectively. This supports the potential of using NH3 as a clean, carbon-free fuel for both burning and reforming in microreforming systems.