Simulation Study on NH3 Combustion and NOx Emissions Under Gas Turbine-Relevant Conditions

Ammonia (NH3) is a zero-carbon fuel and an attractive hydrogen (H2) carrier for gas turbine power generation due to its high energy density, ease of storage, and transportation. This study numerically investigates NH3/air combustion using a hybrid Well-Stirred Reactor (WSR) and Plug Flow Reactor (PFR) model in Cantera at pressures of 1–20 atm, temperatures of 1850–2150 K, and equivalence ratios (ϕ) of 0.7–1.2. The effects of pressure, equivalence ratio, and temperature on NH3 conversion and NO formation are examined. Results show that NH3 exhibits a non-monotonic conversion curve with pressure after the WSR, reaching a minimum near 5 atm, whereas NO formation decreases monotonically from 1 to 20 atm. Equivalence ratio sweeps show that NO decreases steeply as ϕ increases from 0.7 to ~1.1 as nitrogen is redirected toward N2 and oxidizer availability declines; residual NH3 increases rapidly for ϕ > 1.0, especially at high pressure. Increasing temperature accelerates NH3 oxidation and raises NO formation, most strongly at low pressure where thermal and NH/OH pathways are least inhibited. These results indicate that co-tuning pressure and equivalence ratio near rich operation enables low-NOx ammonia combustion suitable for advanced gas turbine applications.