Laminar Burning Velocities of Ammonia/<i>n</i>-Heptane/Air Mixtures at Pressures up to 1.0 MPa

Abstract

The present study expanded the available database of laminar burning velocities (LBVs) of ammonia/n-heptane/air premixed flames (blending ratios of n-C7H16 up to 100%) to 1.0 MPa using a high-pressure, constant-volume combustion vessel with a pressure release tank. A relatively small-scale NH3/n-C7H16 mechanism (named WUT-NH3/n-C7H16) was developed via a modular and hierarchical approach. The developed mechanism was validated by the laminar burning velocities of pure NH3 and n-C7H16, NH3/H2, NH3/H2/CO, NH3/CH4, NH3/C2H6, NH3/C3H8, and NH3/n-C7H16. In addition, the mutual interactions between ammonia and n-heptane in premixed flames were examined. Kinetic analysis shows that n-C7H16 enhances NH3 consumption by providing the radicals (Ḣ, ȮH, Ö, etc.). Compared to the cases for the mixture ratios of n-C7H16 of 5 and 20%, it is found that reaction pathways of NH3 consumption: NH3 → ṄH2 → HNO → NO are strengthened with the increase of n-heptane addition. Overall, the effects of n-C7H16 on NH3 in LBV at an elevated pressure and the interaction processes were identified.