Study of ozone-enhanced combustion in H2/CO/N2/air premixed flames by laminar burning velocity measurements and kinetic modeling

The enhancement effect of ozone addition for H2/CO/N2/Air premixed flames at ambient condition is investigated both experimentally and computationally. Adiabatic laminar velocities under different amount of O3 addition were directly measured using the Heat Flux Method. The ozone concentration in the oxidizer is monitored online to ensure the precise control and stability of ozone injection. Experimental data shows significant enhancement of the burning velocities due to O3 addition. With 8500 ppm ozone seeded, maximum 18.74% of burning velocity enhancement is observed at equivalence ratio Φ = 0.7. Kinetic modeling works were conducted by integrating ozone sub-mechanism with three kinetic mechanisms: GRI-Mech 3.0, Davis mechanism and USC Mech II. The modeling results were compared with experimental data. GRI-Mech 3.0 + Ozone mechanism demonstrated the ability to reproduce the experimental data. Extra OH radicals promoted by ozone was found in the pre-heat regime which initiates the chain-branching reaction and results in the combustion enhancement.

► The first investigation of the ozone enhancement on syngas/air premixed flame. ► The evaluated average uncertainty of the experiment is 0.946 cm/s ► 18.74% enhancement is observed with 8500 ppm O3 added when Φ = 0.7. ► Higher enhancement at both rich and lean sides, lower near stoichiometric ratio. ► The extra OH generated by O3 is the initiator the chain-branching reactions.