Numerical simulation study on hydrogen ammonia mixed combustion in a swirl combustion chamber

Abstract The NO x emissions and combustion performance of pure ammonia and hydrogen-doped combustion (90% NH 3 volume fraction and 10% H 2 volume fraction) in the cyclone combustion chamber were comprehensively analyzed through numerical simulations under varying thermal operating conditions. The findings reveal that the flame characteristic length in hydrogen-doped combustion surpasses that in pure ammonia combustion, indicating an extended migration of the high-temperature zone after hydrogen doping. Furthermore, the addition of hydrogen results in an elevated exhaust temperature within the combustion chamber, while the Outlet Temperature Distribution Function (OTDF) decreases, signifies an enhancement in the uniformity of temperature distribution at the outlet. Moreover, the reflux zone experiences less impact, and the mixed gas velocity increases following hydrogen doping. Notably, NO x emissions demonstrate a significant decrease after the addition of hydrogen. The average NO emission concentration in pure ammonia combustion, under various operating conditions, is measured at 212.47 mg/m 3 , representing a 3.51-fold increase compared to hydrogen-doped combustion.