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

摘要

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 CH_3OCH_3 mole fraction in the blend is the dominant factor for the reduction of CH_3OCH_3 and CO mole fractions in the flame. The rate of the primary reactions related to CH_3OCH_3 and CO increases obviously with the addition of hydrogen. When the volume fractions of H_2 to the total of DME and H_2 exceeds 40%, H_2 will change from an intermediate species to a reactant, which means the effect of H_2 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 CH_2O is decreased as hydrogen is added. Less soot precursors (acetylene (C_2H_2)) were produced with the addition of H_2.