Ignition and Extinction of Hydrogen and Gasoline Blended Methanol Flames

Chemical kinetics effects on fundamental laminar combustion processes were investigated for 20% methanol-blended gasoline and 20% hydrogen-blended methanol for a range of equivalence ratios, 0.5 < ϕ< 2 using a detailed reaction mechanism comprising of 2027 species and 8619 reactions. Fundamental laminar combustion properties—flame speed, flame thickness, minimum ignition energy, ignition, and extinction strain rates of the two fuel blends were compared with base fuels, methanol, gasoline, and hydrogen. Mean extinction strain rates were nearly twice the ignition strain rates which indicated a hysteresis behaviour of laminar flames. An in-depth analysis of the thermal and chemical flame structure of lean fuel blends was conducted to explore the significance of intermediate products and radical species on flame behaviour. Chemical kinetics caused a greater impact on the ignition process compared to extinction. A sensitivity analysis of ignition and extinction strain rates showed the importance of key reactions and their role in the improvement of laminar flame characteristics of fuel blends. The sensitivity coefficients for ignition were greater compared to extinction signifying a stronger influence of chemical kinetics on the ignition process compared to extinction. The knowledge obtained from this study can be leveraged in creating tailored fuel blends with superior laminar combustion competencies enabling higher efficiency and lesser pollutant emission for automotive applications.