An experimental study on H₂/NH₃/CH₄-air laminar propagating spherical flames at elevated pressure and oxygen enrichment

This study measures the accurate Laminar Burning Velocities (LBVs) of (H₂/NH₃/CH₄) ternary fuels-air flames under elevated pressure and oxygen enrichment using a constant volume chamber, providing reliable experimental data to verify the detailed chemical kinetic mechanism. Results show that the LBV values for blending ratios of H₂/NH₃ of 10%–50% demonstrate a suitable alternative energy-generated fuel for conventional fuels in industrial applications, and the maximum value of LBV is achieved at an equivalence ratio close to 1.05. Increasing H₂ blends will increase LBV non-linearly under any conditions and decrease with an increase in ammonia blends. Increasing the initial pressure decreases LBV; at 10% H₂, LBV decreases by 33% at 0.3 MPa and 45% at 0.5 MPa compared to atmospheric pressure. Furthermore, increasing oxygen content improves the reactivity of the mixture and accelerates LBV due to increasing the OH, NH₂, and CH₃ radicals. Maintaining a constant value of LBV requires controlling the blending ratio of the ternary fuels, where increasing LBV values shift the blending of the mixture towards higher hydrogen and methane concentrations and fewer ammonia concentrations. Finally, the effect of maintaining a constant value of adiabatic flame temperature and density ratio on flame characteristics is explained, making the selection of an alternative ternary blending fuel more precise.