Oxy‐ and air‐ammonia premixed combustion in a two‐inlet cyclone combustor

Summary Many scientists have received significant attention since ammonia comprises a carbon‐free chemical and could be derived from renewable hydrogen and air‐separated nitrogen. Most of them think it could be an alternative fuel rather than methane in a cyclonic burner. The main goal of this study is to investigate the possible ways of using ammonia as a clean and sustainable fuel. For this purpose, we first investigated the premixed oxy‐ammonia combustion behaviour using a two‐inlet cyclone combustor. Then, the findings values are compared with the combustion performance of air‐ammonia and air‐methane combustion. Cyclone combustors provide improved mixing quality and longer combustion residence time. The computational fluid dynamics (CFD) simulation was used in this study to estimate the temperature and emissions levels. The findings demonstrate that the highest predicted temperature values of oxy‐ammonia combustion (1828 K) are higher than air‐methane (1538 K) and air‐ammonia combustion (994 K). In addition, NOx emissions have been predicted by post‐processing the CFD code used in this study. According to predicted NOx levels, oxygen usage as an oxidizer rather than air significantly influences NOx emission levels due to thermal and fuel NOx mechanisms. The NOx levels of stoichiometric combustion are higher than the fuel‐rich combustion in all cases. Besides, the lowest NO emission levels are predicted under fuel‐rich conditions of ammonia at the combustor outlet. It is also determined that while the highest axial velocity values occur in the flame regions, ammonia's highest laminar burning velocity is achieved under the fuel‐rich states with Ø = 1.1 for oxy‐ammonia. Therefore, it is concluded that oxy‐ammonia combustion has a more significant combustion performance than air‐methane combustion with the robust whirling flow, sound mixing, and combustion structure.