Numerical investigation on the combustion characteristics of premixed NH3-air flames using gliding arc plasma

In this study, a numerical model is developed to predict the combustion characteristics of gliding arc plasma (GAP) assisted ammonia (NH 3 )-air mixture, integrating ZDPlasKin and Chemkin. To the best of the authors' knowledge, this is the first validated model capable of accurately predicting NO emissions from GAP-assisted NH 3 -air combustion. Initially, three well-known plasma mechanisms are evaluated against non-reacting GAP experiments to assess their effectiveness in modelling NH 3 -air plasma chemistry. The most accurate mechanism is then coupled with an optimized combustion mechanism to improve NO prediction accuracy. The results indicate that NH 2 radical formation is enhanced by approximately 7% at a reduced electric field of 30 Td, playing a crucial role in NO reduction. Additionally, NH 2 is primarily generated through two key reactions: O( 1 D) + NH 3 → OH + NH 2 and N 2 (A) + NH 3 → NH 2 + N 2 + H, occurring before combustion. Furthermore, increasing plasma power significantly accelerates NO consumption by promoting the formation of excited NH 3 states (NH 3 (e 1 ), NH 3 (e 2 )), which enhance NH 2 and NH radical production. Sensitivity analysis reveals that NH 2 exhibits a 52.1% sensitivity to the reaction N( 2 D) + NH 3 → NH 2 + H + N 2 at 90 Td, highlighting its dominant role in NO reduction. • Model supports low-NOx design of plasma-assisted NH 3 combustion systems • First validated model predicting NO from GAP-assisted NH 3 -air combustion • Mechanism of NO formation in GAP-assisted NH 3 -air combustion is investigated