Numerical Study of Nox Formation Mechanisms of Opposed-Jet Ch4/H2/Co and Ch4/H2/Nh3 Diffusion Flames

Due to the shortage of hydrocarbon fuels and the increasing concerns of greenhouse gas emissions, this research project is aimed at the combustion and NOx formation mechanisms of CH4/H2/CO and CH4/H2/NH3 blended fuels. The numerical model which composed of the conservation equations of mass, momentum, species, and energy with narrowband radiation calculation and detailed chemistry is to resolve the laminar diffusion flames stabilized near the stagnation point region between two opposing jet flows. To reduce the CO2 emission, hydrogen with the advantages of high combustion efficiency and no carbon is considered as the future energy carrier, but the cost and the wide flammable range is the primary concern in the storage and utilization. Syngas, obtained from coal, biomass, and refinery residual through gasification processes, is mainly composed of H2 and CO and is then emerged as the bridge toward hydrogen economic. There is considerable variation of H2/CO ratio with the rest being primarily CH4 and diluents such as CO2, H2O and N2. On the other hand, hydrogen can be delivered and stored with the addition of CH4 or NH3 since NH3 is more stable and no carbon emission after combustion. Therefore, the blended fuels of CH4/H2/NH3 make it attractive as a potential alternative fuel. However, the wide variations of compositions in these blended fuels have a direct impact on the combustion and NOx emission characteristics, which will be a key in the combustion applications. Therefore, this research project is to investigate the combustion and NOx formation mechanisms of opposed-jet CH4/H2/CO and CH4/H2/NH3 diffusion flames. The effects of fuel compositions, strain rates and diluents on the NOx formation behaviors and reaction pathways are analyzed and compared.

Project ID:PB10607-1398
External Project ID:MOST106-2221-E182-036