Coupling experimental and modeling approaches for understanding diethoxymethane low-temperature oxidation at high pressure

Abstract

Diethoxymethane (DEM) has attracted significant attention as a potential renewable alternative fuel. The lack of detailed product species distributions for DEM oxdation led to insufficient exploration of its low-temperature oxidation chemistry. In this study, the low-temperature oxidation reactions of DEM were conducted using a jet-stirred reactor (JSR) coupled with synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS) under conditions of 10 atm, an equivalence ratio of 0.5, and temperatures ranging from 470 to 850 K. Identification and quantification of various oxygenated species were performed. Additionally, complementing our previous kinetic theoretical studies for low-temperature oxidation of DEM radicals, previously calculated rate constants were incorporated into an earlier DEM combustion model, accompanied by additional adjustments to the rate constants of hydrogen abstraction reactions by C˙2H3 radicals. The modified model exhibits good agreement between the predicted and experimentally obtained product mole fraction distributions. Remarkably, a relatively weak negative temperature coefficient (NTC) was observed under the studied conditions, highlighting differences in the self-ignition behavior of DEM compared to other highly reactive fuels. Analyzing the rates of production (ROP) in the modified model indicates that the use of oxygenated fuels might elevate the production of small-molecule oxygenated pollutants while reducing the formation of carbon soot precursors and consequently curbing soot generation. Moreover, keto-hydroperoxides (KHPs) were detected during the experimental process. This study lays a foundation for further detailed exploration of the DEM oxidation mechanism, aiding in untangling its intricate reaction processes.