Autoignition of Methyl Decanoate, a Biodiesel Surrogate, under High-Pressure Exhaust Gas Recirculation Conditions

摘要

The autoignition of methyl decanoate, a standalone biodiesel surrogate or surrogate component, is studied under high-pressure exhaust gas recirculation (EGR) conditions relevant to internal combustion engines. Ignition delay times were determined in reflected-shock experiments using measured pressure and electronically excited OH chemiluminescence for stoichiometric methyl decanoate/air/EGR mixtures containing 0-60% EGR at 900-1300 K and 20 and SO atm. Ignition delay time dependence upon pressure and EGR fraction was found to obey τ ∝ P~(-0.8) and ta(l- EGR %/100)~(-1) for the conditions studied. Experimental results are compared to three comprehensive kinetic models for methyl decanoate oxidation from the recent literature: Herbinet et al. (Herbinet, O.; Pitz, W. J.; Westbrook, C. K. Combust Flame 2008, J54, S07-S28 and Herbinet, O.; Pitz, W. J.; Westbrook, C. K. Combust. Flame 2010,1S7, 893-908), Glaude et al. (Glaude, P. A.; Herbinet, O.; Bax, S.; Biet, J.; Warth, V.; Battin-Lederc, F. Combust. Flame 2010, 157, 203S-20S0), and Dievart et al. (Dievart, P.; Won, S. H.; Dooley, S.; Dryer, F. L; Ju, Y. Combust. Flame 2012, J59, 1793-180S). Model-experiment comparisons are generally favorable, with some differences in model performance because of variations in C_0C_2 chemistry, of predominate sensitivity at the conditions studied, and methyl decanoate hydrogen-atom abstraction rates. Ignition delay times for stoichiometric mixtures containing EGR, defined as the complete products of combustion, and synthetic EGR, defined here as pure N_υ are indiscernible, indicating that the primary influence of EGR is to simply displace fuel and O_2, thereby decreasing radical branching, a conclusion that is supported by the kinetic models.