Numerical Study on Combustion Characteristics of Biodiesel Using a New Reduced Mechanism for Methyl Decanoate as Surrogate

A skeletal mechanism with 118 species and 837 reactions was developed from a detailed LLNL mechanism for a biodiesel surrogate mixture with equal mole fraction of methyl decanoate, methy-9-decenoate and n-heptane, through subsequent applications of a revised method for directed relation graph (DRG), isomer lumping, and DRG-aided sensitivity analysis (DRGASA). The reduction was performed within a parameter range of pressure from 1 to 100atm, equivalence ratio from 0.5 to 2, and temperature above 1000K for both auto-ignition and perfect stirred reactors. The detailed mechanism consists of 3329 species and 10806 reactions. With the reduction in mechanism size by almost a factor of 30, the skeletal mechanism was shown to still feature a good accuracy for temperature higher than 1000K, both in predicting the system parameters, such as ignition delay and extinction time, and detailed species profiles, compared with the detailed mechanism. Numerical simulations in jet stirred reactors were also performed and compared with experimental measurements for rapeseed oil methyl ester. This skeletal mechanism can be used to model methyl esters from different feedstocks since it is a tri-component mixture.