Characterization of biogas-hydrogen premixed flames using Bunsen burner

H. S. Zhen, Chun Wah Leung, Chun Shun Cheung, Z. H. Huang

Research output: Journal article publicationJournal articleAcademic researchpeer-review

48 Citations (Scopus)

Abstract

Experimental study is conducted to clarify the effects of hydrogen addition to biogas and hydrogen fraction in the biogas-H2mixture on the stability, thermal and emission characteristics of biogas-H2-air premixed flames using a 9 mm-ID-tube Bunsen burner. Variation in biogas composition is allowed to range from BG60(60%CH4- 40%CO2), down to BG50(50%CH4-50%CO2) and to BG40(40%CH4-60%CO2). For each biogas, the fraction of hydrogen in the biogas-H2mixture is varied from 10% to 50%. The results show that upon hydrogen addition and increasing hydrogen fraction in the fuel mixture, there are corresponding changes in flame stability, laminar burning velocity, flame tip temperature and CO pollutant emission. Under the tested conditions of 400 ≤ Re ≤ 800 and 0.8 ≤ φ ≤ 1.2, the otherwise incombustible biogas-air mixture becomes flammable upon hydrogen addition and the threshold value of hydrogen fraction for occurrence of stable flames increases with the increase in the CO concentration of biogas. Overall, the flame stability is best at rich equivalence ratio of φ = 1.2. The laminar burning velocity of the biogas-H2-air mixture is found to be higher than pure biogas due to addition of hydrogen, and it monotonically increases at higher hydrogen fraction. Further, a shift in equivalence ratio for peak laminar burning velocity from stoichiometric ≤ = 1.0 to φ = 1.2 is observed. The results also show a monotonic increase in flame temperature and a monotonic decrease in CO emission at higher hydrogen fraction. The more efficient oxidation of CO into CO2reveals that more complete combustion is induced by hydrogen addition.
Original languageEnglish
Pages (from-to)13292-13299
Number of pages8
JournalInternational Journal of Hydrogen Energy
Volume39
Issue number25
DOIs
Publication statusPublished - 22 Aug 2014

Keywords

  • CO emission
  • Flame stabiltiy
  • Laminar burnig velocity

ASJC Scopus subject areas

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

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