Experimental and kinetic modeling study on propane enhancing the laminar flame speeds of ammonia

Abstract

The laminar flame speeds of ammonia/propane in air were investigated in a constant volume combustion bomb at 1–5 atm, over 298–453 K, at the equivalence ratios of 0.7–1.6, with the propane in fuel varying from 0 to 90 vol%. The measured data were provided for the validity of the proposed M-NUIG model. The comparison showed that M-NUIG model could successfully predict the measured data of propane, ammonia and mixtures under wide conditions. The results showed that the addition of 20% propane can enhance the LBV of ammonia by a factor of 3 at 1 atm, 298 K. Based on kinetic analysis, NH2 is mainly consumed by the oxidation of N-contained species in NH3/air flame, and it is completely consumed through reacting with O, OH, H and HO2 in NH3/C3H8/air flame. As for the NH3/C3H8 interactions, NH can react with CH3, forming CH2NH which completely converts to HCN. HNO also reacts with CH3 to generate NO. Thus, the CN interactions are crucial to the formation of harmful emissions. Moreover, with 50% propane addition, the peak concentrations of OH and H radicals are much higher than in NH3/air flame which is the main reason for the higher LBV.