A skeletal mechanism for biodiesel-dimethyl ether combustion in engines

•A skeletal mechanism for the oxidation of biodiesel-dimethyl ether was developed.•The mechanism including 255 species and 1253 reactions was widely validated.•Combustion characteristics of biodiesel-dimethyl ether were well predicted by the mechanism. The blending of biodiesel and dimethyl ether (DME) can compensate for the shortcomings of the physicochemical properties of each other, which can be used as an alternative fuel in internal combustion engines. A skeletal mechanism including 255 species and 1253 reactions has been developed herein for further in-depth research on the biodiesel-DME blends combustion in an engine. The mechanism consists of four sub-mechanisms associated with fuels, ester groups, small molecules and emissions. During the hierarchical construction of the mechanism, the methyl esters with long carbon chain and high polyunsaturated degree, including methyl-palmitate, methyl-stearate, methyl-linoleate, methyl-5-decenoate and n-decane were used to represent the biodiesel to accurately reflect the combustion behavior of different types of biodiesel fuels. The mechanism has been widely validated against zero-dimensional ignition delay, one-dimensional laminar flame speed, premixed flame species concentration, three-dimensional in-cylinder pressure, heat release rate and soot emissions. The findings reveal that the combustion and emissions characteristics of biodiesel-DME blends can be accurately reproduced by the mechanism. It has been observed that the increasing DME proportion resulted in the extended ignition delay, increasing in-cylinder pressure peak, NOx emissions, and decreasing soot emissions.