Construction of Skeletal Oxidation Mechanisms for the Saturated Fatty Acid Methyl Esters from Methyl Butanoate to Methyl Palmitate

A series
of skeletal oxidation mechanisms for the saturated fatty acid methyl
esters (FAMEs) from methyl butanoate to methyl palmitate were developed
on the basis of a decoupling methodology with special emphasis on
engine-relevant conditions from low to high temperatures at high pressures.
When detailed H2/CO/C1, reduced C2–C3, and skeletal C4–Cn submechanisms are introduced, the final mechanism
consists of 42 species and around 135 reactions for each methyl ester.
Both the high-temperature reactions of the methyl ester moiety and
the low-temperature reactions of the aliphatic chain of the ester
are included in the mechanism. The skeletal mechanisms were verified
against experimental data in shock tubes, jet-stirred reactors, flow
reactors, and premixed and opposite flames over the temperatures from
500 to 1700 K at pressures of 1–50 atm from fuel-lean to fuel-rich
mixtures. An overall satisfactory agreement between the measurements
and computational results was achieved for all of the saturated methyl
esters, especially for the large saturated methyl esters with a long
aliphatic main chain. The results also indicate that the ignition
delay time and the consumption of reactants could be reproduced by
employing a skeletal C4–Cn submechanism reasonably well. In addition, the evolution of
major products and flame propagation and extinction characteristics
were satisfactorily reproduced because the detailed H2/CO/C1 mechanism was used. The compact size makes it easy to integrate
the mechanism into multi-dimensional computational fluid dynamics
(CFD) simulation.