The combustion kinetics of three symmetric diesel boiling range ether isomers were investigated using a plug flow reactor. The flow reactor experiments employed oxygen as the oxidizer and helium as the diluent with oxidation carried out at atmospheric conditions at temperatures from 420 – 1000 K at 20 K intervals. The fuel, oxidizer, and diluent flow rates were varied at different temperatures to maintain a constant initial fuel mole fraction of 1000 ppm, stoichiometric condition, and a residence time of 2.0 s. The reacted gas was fed to two separate GC systems that could detect qualitatively and quantitatively the product species. The first GC system, GC1, contains a flame ionization detector (FID) equipped with a methanizer for quantitation and a mass spectrometer (MS) for identification and was used to detect higher carbon number compounds (&gt; C5). The second GC system, GC2, utilizes three detectors and is set to detect lighter compounds (C1 – C5). GC2 contains an FID for quantitation of hydrocarbon species and two thermal conductivity detectors (TCDs) to quantitate carbon monoxide and carbon dioxide. Depending on structure, ethers showed different degrees of negative temperature coefficient (NTC) behavior. The product distribution from the plug flow reactor was then compared to the 0-D simulation with existing and under development chemical kinetic models using the Reaction Mechanism Generator (RMG). Most of the product concentrations showed quantitative agreement with experimental data, but few species were not reproduced from the simulation, as several reaction pathways were missing in the developed models. Including these pathways and updating the kinetic models with recently calculated rate constants resulted in a better agreement with our flow reactor experiments. The developed chemical kinetic models were then utilized to elucidate the reactivity and NTC behavior of different isomers.

Understanding the effects of structural isomers on the combustion characteristics of diesel boiling range ethers

ACS Spring 2022

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