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

The effect of NH, NH2, and HNO on NOx and De-NOx chemistry of a NH3/H-2/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 + O-2(+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 + O-2 -> NO + HO2, and thermal NOx depends on the reactions N + O-2 -> NO + N and N + OH -> NO + H. At a pressure of 20 bar, the N2O is further converted to NO2 and N-2 through the reaction N2O + NO -> NO2 + N-2. The abundance of HO2 radicals at high pressure also initiates the conversion of NO to NO2 via the reaction NO + HO2 -> NO2 + H.

Automated summary

The effect of NH, NH2, and HNO on NOx and De-NOx chemistry of a NH3/H-2/air mixture at 20 bar pressure was investigated. It was found that increasing pressure reduces NOx emissions and increases HO2 radical production. The fuel-bound NOx emissions are mainly influenced by reactions involving NH, OH, HNO, and O2, while thermal NOx is determined by reactions involving N and OH. At 20 bar pressure, N2O is further converted to NO2 and N-2, and the abundance of HO2 radicals initiates the conversion of NO to NO2.