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

Abstract

Hydrogen (H 2) is produced by burning and reforming ammonia (NH 3) in a microreforming system. A micro-combustor that burns H 2-added NH 3–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 NH 3 to H 2 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 NH 3–H 2–air mixtures and the concentration of the substituted H 2 in the fuel gas. The production rate of H 2, the conversion rate of NH 3, the overall efficiency of the microreforming system and the NO x 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 NH 3 as a clean, carbon-free fuel for both burning and reforming in microreforming systems.