Kinetic modeling study of hydrogen addition to premixed dimethyl ether-oxygen-argon flames

The chemical composition of flames was examined systematically for a series of laminar, premixed low-pressure Dimethyl ether (DME)-oxygen-argon flames blended with hydrogen. The effects of hydrogen addition to the DME base flame were seen to result in interesting differences. The flame is analyzed with a comprehensive kinetic model that combines the chemistries of hydrogen and DME combustion. The results indicated that the reduction of CH3OCH3 mole fraction in the blend is the dominant factor for the reduction of CH3OCH3 and CO mole fractions in the flame. The rate of the primary reactions related to CH3OCH3 and CO increases obviously with the addition of hydrogen. When the volume fractions of H2 to the total of DME and H2 exceeds 40%, H2 will change from an intermediate species to a reactant, which means the effect of H2 on the premixed combustion will be more significant. The free radicals in the radical pool, such as H, O and OH radicals, increase as hydrogen is added, which promote the combustion process. The mole fraction of CH2O is decreased as hydrogen is added. Less soot precursors (acetylene (C2H2)) were produced with the addition of H2.

► We model the DME-hydrogen-O2 freely propagated laminar premixed flames.
► H2 will change to a reactant when the volume fraction exceeds 40%.
► The H, O and OH mole fractions increase as hydrogen is added.
► The mole fraction of CH2O is decreased as hydrogen is added.
► Less soot precursors were produced with the addition of H2.