Wednesday, November 10, 2010: 10:35 AM
Alta Room (Marriott Downtown)
In order to evaluate the potential of reforming ammonia as a carbon-free fuel in production of hydrogen, an annulus-type micro reforming system integrated with a micro-combustor is studied experimentally. The micro-combustor is a simple cylinder with an annular-type shield to apply for a heat-recirculation concept and an expanded exhaust outlet to control ignition, satisfying the primary requirements for designing a micro-combustor as a heat source, i.e., stable burning in a small confinement and uniform distribution of temperature along a wall. The micro-combustor is surrounded with a micro-reformer for converting ammonia gas to hydrogen. The annulus-type micro reforming system is designed to produce 1-10 W (based on lower heating value, LHV) of hydrogen using various catalysts (Ru, Ni/SiO2/Al2O3 or Ir), which satisfies the primary requirements for designing an effective micro reforming system, i.e., maximum heat transfer through the micro-combustor wall and enhanced hydrogen production. The feed rate of ammonia, the micro-combustor inlet velocity of fuel-air mixtures and the catalyst materials substantially affect the performance of the designed micro reforming system. Under optimized design and operating conditions, the micro reforming system using Ru produces 5.4 W (based on LHV) of hydrogen with a conversion rate of 98% and an overall system efficiency of 13.7%. Thus, the present configuration can be applied to practical micro reforming systems, supporting the potential of using ammonia as a clean fuel.