Numerical study on the effects of adding NH3 into syngas/NH3 mixtures on combustion characteristics and NOx emissions in diluted hot co-flows.

NH 3 is a carbon-free fuel with good storage and transport characteristics. Applying Moderate or Intense Low-oxygen Dilution (MILD) combustion to NH 3 /syngas blended fuel is expected to achieve clean and low-carbon combustion. This work explores the impacts of changing the NH 3 /syngas ratio and O 2 content in co-flow on the combustion characteristics and the NO x formation and transformation mechanisms. As the proportion of NH 3 increases, the flame is gradually lifted, while the rise of H 2 in syngas reduces the lifted height. As the O 2 proportion is increased to 15%, almost the entire computational domain is transformed from MILD to high-temperature combustion when the ratio of NH 3 to syngas is 3:7. NH that is derived from the decomposition of NH 3 participates more actively in the consumption process of NO and N 2 O. N radicals are more likely to generate N 2 when O 2 content in hot co-flow increases. [Display omitted] • Higher NH 3 ratio results in a shorter flame length and higher flame lifted-height. • The MILD combustion boundary of NH 3 /syngas mixed fuel is depicted. • The increase in syngas promotes the consumption of NH 3. • Detailed NH 3 conversion routes of NH 3 /syngas in JHC burner are explored. • Patterns of NO formation routes with the rise of NH 3 and O 2 ratio are revealed. [ABSTRACT FROM AUTHOR]