Effects of nitromethane addition on the laminar burning velocity and ignition delay of syngas/air flames

Nitromethane can be blended with syngas to improve the volumetric energy content of the fuel. The effects of blending nitromethane in different proportions to syngas on the laminar burning velocity and ignition delay time of the fuel/air mixture have been studied. The syngas is assumed to be an equimolecular mixture of H2 and CO. A novel reaction mechanism containing 167 species and 1220 reactions has been developed and validated against the state-of-the-art experimental data in order to simulate the syngas/nitromethane/air flame. It has been found that the blending of nitromethane with syngas fuel reduces the laminar burning velocity due to the reductions in thermal diffusivity of the reactant mixture and the concentrations of the active radicals, such as H and OH, in the flame zone. The effect of nitromethane addition in the fuel on the formation and emission of NO has also been analyzed. The ignition delay of the fuel/air mixture also reduces when nitromethane is blended with syngas. Some key reaction steps for the combustion of the syngas/nitromethane/air mixture have been identified through sensitivity analysis.