Effects of radiative emission and absorption on the propagation and extinction of premixed gas flames

Yiguang Ju, Goro Masuya, Paul D. Ronney

研究成果: Conference article査読

117 被引用数 (Scopus)

抄録

Premixed gas flames in mixtures of CH4, O2, N 2 , and CO2 were studied numerically using detailed chemical and radiative emission-absorption models to establish the conditions for which radiatively induced extinction limits may exist independent of the system dimensions. It was found that reabsorption of emitted radiation led to substantially higher burning velocities and wider extinction limits than calculations using optically thin radiation models, particularly when CO 2, a strong absorber, is present in the unburned gas. Two heat loss mechanisms that lead to flammability limits even with reabsorption were identified. One is that for dry hydrocarbon-air mixtures, because of the differences in the absorption spectra of H2O and CO2, most of the radiation from product H2O that is emitted in the upstream direction cannot be absorbed by the reactants. The second is that the emission spectrum of CO2 is broader at flame temperatures than ambient temperature; thus, some radiation emitted near the flame front cannot be absorbed by the reactants even when they are seeded with CO2. Via both mechanisms, some net upstream heat loss due to radiation will always occur, leading to extinction of sufficiently weak mixtures. Downstream loss has practically no influence. Comparison with experiment demonstrates the importance of reabsorption in CO2-diluted mixtures. It is concluded that fundamental flammability limits can exist due to radiative heat loss, but these limits are strongly dependent on the emission-absorption spectra of the reactant and product gases and their temperature dependence and cannot be predicted using gray-gas or optically thin model parameters. Applications to practical flames at high pressure, in large combustion chambers, and with exhaust-gas or flue-gas recirculation are discussed.

本文言語English
ページ(範囲)2619-2626
ページ数8
ジャーナルSymposium (International) on Combustion
27
2
DOI
出版ステータスPublished - 1998
外部発表はい
イベント27th International Symposium on Combustion - Boulder, CO, United States
継続期間: 1998 8月 21998 8月 7

ASJC Scopus subject areas

  • 化学工学(全般)
  • 燃料技術
  • エネルギー工学および電力技術
  • 機械工学
  • 物理化学および理論化学
  • 流体および伝熱

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