Experimental and kinetic modeling study of n-propanol and i-propanol combustion: Flow reactor pyrolysis and laminar flame propagation

Wei Li, Yan Zhang, Bowen Mei, Yuyang Li*, Chuangchuang Cao, Jiabiao Zou, Jiuzhong Yang, Zhanjun Cheng

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

47 Scopus citations

Abstract

Flow reactor pyrolysis and laminar flame propagation are investigated for n-propanol and i-propanol, which are the smallest alcohol fuels with isomeric structures. Pyrolysis products of propanol isomers at 0.04–1 atm are detected using the synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). Experimental observations demonstrate ethylene and propene are respective dominant hydrocarbon products in the n-propanol and i-propanol pyrolysis, while the most abundant oxygenated products are formaldehyde, acetaldehyde and ethenol in the n-propanol pyrolysis and acetone and acetaldehyde in the i-propanol pyrolysis. Higher concentrations of aromatic and oxygenated pollutants are observed in the i-propanol pyrolysis. The laminar burning velocities of propanol isomers are measured in a high-pressure constant-volume cylindrical combustion vessel at the initial temperature of 423 K, pressures of 1–10 atm and equivalence ratios of 0.6–1.5. A general trend that n-propanol has much faster LBVs than i-propanol is noticed under all investigated conditions. A kinetic model of propanol isomers is developed and validated against the present experimental data, as well as other experimental data in literature covering wide ranges of temperatures, pressures and equivalence ratios. Rate of production analysis and sensitivity analysis are performed together to provide insight into the fuel isomeric effects on key reaction pathways and fuel reactivities. In the flow reactor pyrolysis, different dominant primary decomposition pathways of n-propanol and i-propanol lead to the differences in both molecular structures and concentration levels of pyrolysis products. In laminar flame propagation, different radical pool distributions of propanol isomers are illustrated and found to be largely influenced by fuel isomeric structures. The linear structure of n-propanol promotes the formation of more active radicals like formyl, vinyl and ethyl, while the branched structure of i-propanol facilitates the production of more stable radicals including methyl and allyl. Thus, the promoted chain-branching in n-propanol flames and enhanced chain-termination in i-propanol flames can explain the higher laminar burning velocities and reactivities of n-propanol than that of i-propanol.

Original languageEnglish (US)
Pages (from-to)171-185
Number of pages15
JournalCombustion and Flame
Volume207
DOIs
StatePublished - Sep 2019

Bibliographical note

Funding Information:
The research was supported by the National Key R&D Program of China (2017YFE0123100) and National Natural Science Foundation of China (51622605, U1832171). The authors appreciate the technical assistance from Dr. Wenhao Yuan and Ms. Xiaoyuan Zhang.

Funding Information:
The research was supported by the National Key R&D Program of China ( 2017YFE0123100 ) and National Natural Science Foundation of China ( 51622605 , U1832171 ). The authors appreciate the technical assistance from Dr. Wenhao Yuan and Ms. Xiaoyuan Zhang.

Publisher Copyright:
© 2019 The Combustion Institute

Keywords

  • Flow reactor pyrolysis
  • Kinetic model
  • Laminar burning velocity
  • n-propanol and i-propanol
  • SVUV-PIMS

ASJC Scopus subject areas

  • General Chemistry
  • General Chemical Engineering
  • Fuel Technology
  • Energy Engineering and Power Technology
  • General Physics and Astronomy

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