Modeling the Auto-Ignition of Oxygenated Fuels using a Multistep Model

The research presented here describes the application of a multistep (8-step) autoignition model to oxygenated fuels such as alcohols and esters in a rapid compression machine. This modeling concept is aimed at capturing the ignition behavior of new oxygenated fuel blends, where detailed or reduced chemical kinetics data are not available. The predicted ignition delays from the multistep autoignition model using the biodiesel surrogate fuel methyl butanoate are validated against results attained using a detailed chemical kinetic mechanism (Dooley, S.; Curran, H.J.; Simmie, J.M. Combust. Flame 2008, 153 (1-2), 2-32.) in conjunction with CHEMKIN. Once the multistep model constants were calibrated for methyl butanoate, the model showed good agreement with the detailed mechanism ignition delays, but with significantly reduced computational time. The multistep model was tested over a compressed temperature range of 750-925 K, compressed pressures from 10 to 46 atm and equivalence ratios from 0.5 to stoichiometric, with the percent relative error in the ignition delay between the multistep and CHEMKIN modeling found to be less than 15%.