A comprehensive experimental and kinetic modeling study of dimethoxymethane combustion

摘要

Dimethoxymethane (DMM, CH_3OCH_2OCH_3 ), the simplest member in the class of polyoxymethylenedimethyl ethers (PODE), is regarded as a promising fuel substitute for compression ignition engines.To better understand its combustion characteristics, a comprehensive experimental and kinetic modelingstudy on the combustion of DMM was conducted. Ignition delay times (IDTs) of DMM/O_2 /Ar mixtureswere measured in a shock tube at pressures from 1.0 to 10 atm, for temperatures from 1050 to1450 K, and equivalence ratios of 0.5, 1.0 and 2.0. A predominantly ab initio derived detailed kineticmodel of DMM with 121 species and 646 reactions was developed based on AramcoMech2.0 with anupdated sub-mechanism of methyl formate (MF, CH 3 OCHO). C –O bond fissions occurred in CH_2 –O andCH_3 –O moieties were demonstrated to be the dominating reaction pathways in DMM high temperaturechemistry rather than the competing non-radical decomposition channels. Flux and sensitivity analysesindicated that the two C –O bond fissions have a comparatively promoting effect on reactivity, while theDMM = CH_3OCH_2O + CH_3 reaction was the dominating channel at high temperatures. The proposedmodel was also validated against literature experimental data, including ignition delay times, jet stirredreactor species concentrations, laminar pre-mixed flame speciation, laminar burning velocities and plugflowreactor speciation. The good performance of the proposed model for reproducing these data revealedits ability to predict DMM combustion over a wide range of conditions. Major reaction pathways of DMMcould also apply to larger PODE compounds.