Intensification of syngas ignition through the excitation of CO molecule vibrations: a numerical study

A comparative analysis of the kinetic mechanisms that proceed in CO–O2 and syngas–air mixtures when CO molecule vibrations are excited by laser radiation with a wavelength of 4.7 µm and when the laser radiation energy supplied to the gas is spent on heating the mixture is conducted. The efficiencies of both methods of combustion initiation are compared. The simulation shows that the excitation of CO molecule vibrations by laser photons allows significant intensification of the chain processes both in CO–O2(air) and in syngas–air mixtures. This method is much more effective in shortening the induction time and in decreasing the ignition temperature than the method of laser-induced thermal ignition. It was found that in order to ensure the identical delay time it is necessary to add a noticeably higher energy in the case of heating the gas by laser radiation than when exciting the CO molecule vibrations. In addition, a low temperature ignition of the mixture with laser-excited CO molecules makes it possible to raise the efficiency of conversion of the reactant chemical energy to the thermal energy released during combustion compared with the method of heating the mixture by laser radiation.