Effect of Intermediate Radicals on NOx and De‐NOx Characteristics of NH3/H2/Air Flames at High Pressure

Abstract

AbstractThe effect of NH, NH2, and HNO on NOx and De‐NOx chemistry of a NH3/H2/air mixture at a pressure of 20 bar is investigated. Results suggest that the increase in pressure reduces NOx emissions and increases HO2 radical production through the reaction H + O2(+M) → HO2(+M). In contrast with OH and O radicals, the HO2 radical is less reactive, which prevents NO formation. The fuel‐bound NOx emissions mainly depend on the reactions NH + OH → NO + H, HNO(+M) → NO + H(+M), HNO + OH → NO + H2O, and HNO + O2 → NO + HO2, and thermal NOx depends on the reactions N + O2 → NO + N and N + OH → NO + H. At a pressure of 20 bar, the N2O is further converted to NO2 and N2 through the reaction N2O + NO → NO2 + N2. The abundance of HO2 radicals at high pressure also initiates the conversion of NO to NO2 via the reaction NO + HO2 → NO2 + H.