Experimental and kinetic study on the laminar burning velocities of NH3 mixing with CH3OH and C2H5OH in premixed flames

Abstract

Ammonia (NH3) is a promising carbon-free alternative fuel, and blending NH3 with other more active fuels can enhance the low burning rate of pure NH3 flames, which makes it more compatible with existing combustors. There are laminar burning velocity data of NH3+H2, NH3+CO/syngas, and NH3+CH4 flames in literature, however, blending NH3 with the oxygenated alternative fuel alcohols have not yet been checked. In the present work, the laminar burning velocities of NH3+CH3OH/air and NH3+C2H5OH/air flames were measured using the heat flux method at 1 atm with varied equivalence ratios and mixing ratios. Measurements were carried out at 298 K and elevated temperatures until 448 K unburnt temperatures, in order to check the data consistency via the temperature coefficient α in SLSL0=(TuTu0)α. A new updated kinetic mechanism, based on our previous mechanism named CEU-NH3, was proposed and validated based on the present and published experimental data for laminar burning velocity, ignition delay times and species profiles. This mechanism contains 91 species and 444 reactions, which is small in size and thus advantageous to be used in the modeling of complex combustion fields. By numerical analyses using the CEU-NH3 and the detailed Konnov mechanisms, the interactions between C- and N- containing species are found to be insignificant for the laminar burning velocities of the various NH3 blending mixtures.