Premixed ammonia-methane-air combustion

To better understand the combustion characteristics of ammonia as a potential fuel additive, the adiabatic burning velocities were determined for premixed methane-air and ammonia-methane-air flat flames. A 30 mm diameter flat flame burner was built on the basis of the design of the perforated plate burner of van Maaren et al [1], This burner facilitated the direct measurement of the adiabatic burning velocity based on the measurement of the unburned gas velocity. In addition, the flame was simulated as a one-dimensional, freely propagating flame using CHEMKIN. The measured burning velocity data for methane-air mixtures was found to be in good agreement with the literature and simulations. Additions of 1% to 4% ammonia in the fuel yielded lower burning velocities than pure methane-air flames. The burning velocity decreased from 32 to 26 cm/s under stoichiometric conditions, from 17 to 14 cm/s at an equivalence ratio of 0.7, and from 21 to 15 cm/s at an equivalence ratio of 1.4, when 4% of the fuel was ammonia in a mixture of ammonia-methane-air. This general trend was also found in the simulations