Experimental and kinetic investigation on the effects of hydrogen additive on laminar premixed methanol–air flames

Peng Xiao, Han Wu, Ziyu Wang, Saifei Zhang, Chia fon Lee, Z. Wang, Fushui Liu

Research output: Contribution to journalArticlepeer-review

Abstract

The effects of hydrogen addition on laminar premixed methanol–air flames were studied both experimentally and numerically. To achieve this, a constant volume chamber (CVC) and the premix code in CHEMKIN were used. During the experiments, the equivalence ratios (ϕ) and hydrogen mole fractions (Xh) were set to 0.6 to 1.8 and 0%–100%, respectively. In addition, initial environmental conditions were set to 375 K and 1 atm. The results indicate that the laminar flame speed (LFS) and burning velocity (LBV) both increase when more hydrogen is added into the methanol–air mixtures. For premixed methanol–air flames, the Markstein length (Lb) decreases monotonically with an increase in the equivalence ratio; however, when the hydrogen fraction is greater than 40%, an increasing trend in the Markstein length is presented as the mixtures move toward the fuel-rich side. The variation in Markstein length is non-monotonic with the hydrogen fraction. A kinetics analysis indicates that methanol is mainly consumed by the dehydrogenation reaction caused from the impact of the active free radicals (OH and H). Reactions involving active free radicals and light intermediate species have the highest sensitivity and contribute the most to the propagation of a laminar flame. Therefore, the promotion effect of hydrogen additive is due to an enhancement in the radical pooling of H, OH, and O. The chain branching reaction R5 (O2 + H = O + OH) is essential for the geometric growth of free radicals. In addition, the amount of formaldehyde decreases owing to the hydrogen blending.

Original languageEnglish (US)
Pages (from-to)22263-22281
Number of pages19
JournalInternational Journal of Hydrogen Energy
Volume44
Issue number39
DOIs
StatePublished - Aug 13 2019

Keywords

  • Burning velocity
  • Hydrogen enrichment
  • Kinetics analysis
  • Laminar flame
  • Methanol

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Fuel Technology
  • Condensed Matter Physics
  • Energy Engineering and Power Technology

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