Prediction of species concentration and temperature profile in methanol oxygen and argon flame

Abstract

A chemical kinetic model is developed to predict the adiabatic flame temperature and the species concentration profiles for the methanol/oxygen/argon flames. The Modelling is carried out for atmospheric pressure and sub-atmospheric pressure (0.167 atmosphere) and for the equivalence ratio ranging from 0.6 to 1.5. The reaction mechanism for the modelling is used as given by Thomas and Dryer in 1989. It contains 84 elementary reactions and 25 stable and unstable species. The concentration profiles of the stable and unstable species are computed as a function of distance over the burner and a comparison is made between the calculated and the experimental concentration profiles. As the reaction zone is very narrow in the case of atmospheric pressure flame, the comparison is made in the post flame zone only for the species CO₂, CO, H₂ and H₂O. For low pressure flames, the comparisons are made for every point and a good quantitative and qualitative agreement is observed between the computed and the experimental concentration profiles in reaction zone. The study shows a difference between the computed and the experimental concentrations for the post flame zone at low pressure and it may occur due to the diffusion effect which is neglected in this modelling work. A sharp concentration gradient for CO after the peak value at equivalence ratio 1.0 also suggests that the molecular diffusion may effect the profile. This modelling work is useful to analyze the methanol as an alternate fuel and provides an understanding of the combustion phenomena and exhaust emission of methanol.