Chemical and Sooting Structures of Counterflow Diffusion Flames of Butanol Isomers: An Experimental and Modeling Study

ABSTRACT

This work reports an experimental and numerical analysis on the sooting characteristics of butanol isomers. Light extinction and gas chromatography were used to measure soot and gas-phase species, respectively. Kinetic analysis of the tested flames was performed with detailed gas-phase mechanism and a sectional soot model. The present work aims to provide an understanding on the effects of butanol isomeric structures on sooting tendencies. For a comprehensive analysis, flames of both neat butanol fuels and butanol/hydrocarbon mixtures were studied. The results showed that the relative ranking of sooting tendencies among the butanol isomers were similar in neat butanol flames and in butanol-doped ethylene flames. In addition, we show that a small amount of butanol addition in ethylene flame enhanced soot formation. It was found that different isomeric structures mainly affected the formation of C₃H₃, which led to the different concentrations of important aromatic soot precursors. In the butanol-doped ethylene flames, the blending of the four butanol isomers increased the number of C₃H₃ formation pathways, which in turn significantly increased the production of benzene. Structural effects explaining for the differences in the sooting tendencies of the four butanol isomers in neat butanol flames and ethylene/butanol flames were found to be the same.

KEYWORDS:

• Butanol isomers
• synergistic effects
• structural effects
• soot formation
• counterflow diffusion flame

Acknowledgments

This work was supported by the National Natural Science Foundation of China (51976142) and the National Engineering Laboratory for Mobile Source Emission Control Technology (NELMS2018A11). Y.W. acknowledges informative and insightful discussions with Dr. S. Mani Sarathy, Dr. Can Shao from KAUST and Dr. Sungwoo Park from Korea Aerospace University regarding butanol chemistries.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

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Additional information

Funding

This work was supported by the National Natural Science Foundation of China [51976142] and National Engineering Laboratory for Mobile Source Control Technology [NELMS2018A11].