Numerical investigation on the effect of hydrogen share in NH3/H2 blends in a turbulent lean-premixed swirl burner

Abstract

Climate change and the energy crisis urge the transition from fossil to renewable fuels. Ammonia and hydrogen are the most versatile carbon-free chemical energy carriers. Hydrogen-diluted ammonia combustion can drastically lower the emission of nitrogen oxides. The present paper focuses on the numerical analysis of ammonia/hydrogen combustion in a lean-premixed swirl burner, highlighting the effect of hydrogen share and equivalence ratio. The hydrogen share notably influences the axial position of the heat release maximum due to the higher reactivity, while it marginally influences the global velocity field. Unburned ammonia was observed at lean condition and low hydrogen concentration. At ultra-lean conditions, nitrogen oxide emission increases with hydrogen content, while a maximum can be reached by increasing the equivalence ratio. The values are compared to experimental data from the literature. Dinitrogen oxide emission decreases with both hydrogen concentration and equivalence ratio. Non-reacting flow field was validated by Particle Image Velocimetry measurements.