Special features of soot formation in a standard premixed ethylene/air flame diluted with DME

This paper presents the experimental and calculated results of the investigation of soot formation in a standard premixed ethylene/air flame with the addition of 15-100% dimethyl ether. The soot volume fraction was measured using the laser light extinction method at a wavelength of 520 nm. The flame temperature versus height above the burner was measured using standard Pt-Rh thermocouples. It was experimentally shown that the addition of 15% dimethyl ether to ethylene/air flame resulted in a 20% increase of soot volume fraction. The further replacement of ethylene by 60% dimethyl ether decreased the soot volume fraction at 5 fold relatively to a pure ethylene/air flame. Kinetic modeling of soot vol-ume fraction growth with height above the burner was carried out based on the kinetic mechanisms developed by CRECK group ( http://creckmodeling.chem.polimi.it/ ). The calculations were carried out us-ing open software package OpenSMOKE ++ , which includes the modeling of gas-dynamic processes in the premixed laminar flame reactor. Good agreement between the experimental and calculated data was obtained. The analysis of kinetic mechanism used in this study allowed determining the peculiarity of kinetic pathways of benzene formation, which is proposed as an initial substance for soot precursor. It was found, that increase of soot concentration at 15% dimethyl ether addition to the ethylene/air flame is caused by intensification of channel of benzene formation via C3H3 recombination, which additionally produced from C3H4-p (propyne). In turn, the increase of C3H4-p concentration occurred due to reactions of acetylene with CH3 radical formed during DME decomposition. These results obtained in a standard ethylene/air flame could be used for development and validation of various kinetic mechanisms of soot formation.(c) 2022 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

Automated summary

This paper presents the experimental and calculated results of investigating the soot formation in a premixed ethylene/air flame with the addition of dimethyl ether. The experimental results show that the addition of dimethyl ether affects the soot volume fraction. The kinetic modeling and analysis reveal the importance of benzene formation as a precursor to soot.