Development of a skeletal mechanism for biodiesel blend surrogates with varying fatty acid methyl esters proportion

A skeletal four-component biodiesel combustion mechanism comprising methyl decenoate, methyl-5-decenoate, n-decane and methyl linoleate is proposed in the present study. The motivation of this work is to develop a mechanism for accurate modeling on the effect of varying fatty acid methyl ester proportion on biodiesel ignition and combustion. The skeletal mechanism was generated by coupling an existed methyl decenoate, methyl-5-decenoate, n-decane skeletal mechanism with a new developed skeletal methyl linoleate mechanism, which was reduced from a penta-component detailed mechanism consisting of 5025 species and 20,163 reactions. The employed reduction strategies are directed relation graph error propagation and sensitivity analysis (DRGEPSA), isomer lumping, computational singular perturbation and reaction rate adjustment. The skeletal methyl linoleate mechanism consists of 92 species and 249 reactions, and the coupled biodiesel blend surrogates mechanism consists of 106 species and 263 reactions. In order to validate the feasibility of the new developed skeletal mechanism, zero-dimension ignition delay testing, reflected shock tube experiment validation and 3-dimensional engine testing about cylinder pressures, heat release rates and NOx emission trends were conducted at different conditions. And the new developed skeletal mechanism was compared with a biodiesel surrogates skeletal mechanism without double-bond species in the 3-dimensional engine testing. The results indicate that the new developed skeletal mechanism is suitable to predict ignition behavior, combustion characteristics, NOx emission trends of biodiesel with varying fatty acid methyl ester, and it is more accurate than a biodiesel surrogates skeletal mechanism without double-bond species in the 3-dimensional engine testing.