Temperature dependence of chemical effects of ethanol and dimethyl ether mixing on benzene and PAHs formation in ethylene counter-flow diffusion flames

Abstract

The present work investigates the chemical, thermal, and dilution effects of ethanol and dimethyl ether mixing (10%/20%) on aromatics formation in ethylene counter-flow diffusion flames (CDFs) under different thermal conditions (Tmax≈1729/2000/2063 K). The fuel mixing effects were studied experimentally by gas chromatography measurements and computationally using two detailed chemical reaction mechanisms. The effects of ethanol and DME mixing on benzene and PAHs formation was found to be temperature-dependent in ethylene CDFs. Ethanol and dimethyl ether blending promoted benzene formation in high-temperature flames (2000 K and 2063 K) in comparison to low-temperature flames (1729 K). A slight reduction of benzene concentration was found after dimethyl ether addition under low-temperature conditions. The total effects of ethanol and dimethyl ether mixing on typical PAHs (C10H8, C14H10, C16H10) in low-temperature ethylene flames were also weaker than those in high-temperature flames. The temperature dependence of the total fuel mixing effects was dominated by chemical effects, while dilution and thermal effects were not significantly affected by the temperature. Pathway analysis showed that the temperature dependence of chemical mixing effects on benzene and PAHs formation originated from the C4+C2→C6→PAHs and C3+C3→C6→PAHs pathways.