Chemical\nKinetics Investigations of Dibutyl Ether\nIsomers Oxidation in a Laminar Flow Reactor

The combustion kinetics of three symmetric diesel-boiling-range\nether isomers were investigated experimentally using a plug flow reactor.\nThe isomers were di-<i>n</i>-butyl ether (DNBE), diisobutyl\nether (DIBE), and di-<i>sec</i>-butyl ether (DSBE). The\nflow reactor experiments employed oxygen as the oxidizer and helium\nas the diluent, with oxidation carried out at atmospheric and elevated\npressure conditions and temperatures from 400 to 1000 at 20 K intervals.\nThe fuel, oxidizer, and diluent flow rates were varied at different\ntemperatures to maintain a constant initial fuel mole fraction of\n1000 ppm under stoichiometric conditions and a residence time of 2\ns. Reaction products were analyzed by gas chromatography (GC). Depending\non the structure, ethers showed different degrees of negative temperature\ncoefficient (NTC) behavior. Speciation results from the GC analysis\nwere then compared to simulations using existing and newly developed\nchemical kinetic models. Most of the simulated product concentrations\nshowed reasonable agreement with the experimental data. The chemical\nkinetic models were utilized to elucidate key features of the reactivity\nand NTC behavior of the different isomers. The chemical kinetic analysis\nindicates that the combustion behaviors of the three isomers are influenced\nby the key species formed at the low-temperature reaction regime.\nThe key species identified for DNBE, DIBE, and DSBE at atmospheric\npressure are <i>n</i>-butanal, isobutanal, and <i>sec</i>-butanol, respectively.