Experimental and modeling study of the pyrolysis and combustion of dimethoxymethane

The pyrolysis and low- to intermediate temperature oxidation chemistry of dimethoxymethane (DMM), the simplest oxymethylene ether, is studied theoretically and experimentally in a JSR setup. The potential energy surfaces for peroxy species relevant during the low-temperature oxidation of dimethoxymethane are studied at the CBS-QB3 level of theory and the results are used to calculate thermodynamic properties of the main species as well as rate expressions for important reactions. An elementary step model for DMM pyrolysis and oxidation is built with the automatic kinetic model generation software Genesys. To describe the chemistry of small species not directly related to DMM, the AramcoMech 1.3 mechanism developed by Metcalfe et al. is used. If the more recently extended version of this mechanism, i.e. the propene oxidation mechanism published by Burke et al., was used as alternative base mechanism, large discrepancies for the mole fractions of CO2, methyl formate and methanol during the pyrolysis of DMM were observed. The validation of the new DMM model is carried out with new experimental data that is acquired in an isothermal quartz jet-stirred reactor at low and intermediate temperatures. Different equivalence ratios, ϕ= 0.25, ϕ= 1.0, ϕ= 2.0 and ϕ= ∞, are studied in a temperature range from 500 K to 1100 K, at a pressure of 1.07 bar and with an inlet DMM mole fraction of 0.01. The experimental trends are well predicted by the model without any tuning of the model parameters although some improvements are possible to increase quantitative agreement. The largest discrepancies are observed at fuel lean conditions for the hydrocarbon mole fractions, and at low-temperatures as can be noticed by the over prediction of formaldehyde and methyl formate. The kinetic model is also validated against plug flow reactor, jet-stirred reactor and lean and rich premixed flames data from the literature. Rate of production analyses are performed to identify important pathways for low- and intermediate-temperature oxidation and pyrolysis.