Modeling Study of the Effect of Hydrogen Addition on n-Propanol Combustion in Premixed Flames

Abstract

Based on models resulting from the merging of validated kinetic schemes, a reaction mechanism is developed and especially tailored to describe combustion of n-propanol/hydrogen blends in high temperature regimes. The proposed model, featuring 287 species and 2761 reactions, has been validated using stoichiometric, low-pressure, premixed n-propanol/oxygen/argon flames available in the literature. Reasonably good agreement between calculated and measured data is observed for the reactants and some intermediates. However, computed maxima for some intermediates hydrocarbons and oxygenated products were higher than experimental ones. The proposed kinetic scheme, in conjunction with a modified one-dimensional model (Premix) and Chemkin II package, was used to investigate the kinetic effects of hydrogen addition on the flame structure and pollutant emissions from low-pressure (3333 Pa), stoichiometric n-propanol/hydrogen mixtures. The blended fuels were formed by incrementally adding 10% of hydrogen to the neat n-propanol flame, while keeping the mole fraction of the inert gas (argon) and the equivalence ratio constants. The modeling results showed that adiabatic flame temperature in the H₂-doped fuels is lower than that in the flame without hydrogen. The higher the hydrogen level the lower is the adiabatic temperature. Whatever the hydrogen proportion in the fuel mixture, n-propanol is mainly consumed via metathesis reactions with OH and H radicals. Besides, CH₄, C₂H₂, CH₂O, CH₃CHO, and CO₂ mole fractions decreased upon raising the hydrogen amount in the fuel mixture.