Inhibition of Nonpremixed Hydrogen Flames by CF3Br

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This article discusses the inhibition of non-premixed hydrogen flames by CF3Br.

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24 p.

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Truett, Leonard August 1998.

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This article is part of the collection entitled: UNT Scholarly Works and was provided by UNT College of Arts and Sciences to Digital Library, a digital repository hosted by the UNT Libraries. It has been viewed 22 times . More information about this article can be viewed below.

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This article discusses the inhibition of non-premixed hydrogen flames by CF3Br.

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24 p.

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This is the accepted manuscript version of the article. Reprinted with permission from Elsevier Science Ltd., all rights reserved. The final definitive version is available here: http://www.sciencedirect.com/science/article/pii/S0082078498801306

Abstract: Experimental and numerical studies are performed to elucidate the fundamental chemical mechanisms by which CF3Br inhibits non-premixed hydrogen flames. These studies are motivated by previous work, which shows that CF3Br and its decomposition products inhibit hydrocarbon flames primarily by reacting directly with the radicals and by depleting radicals in the region where hydrogen and carbon monoxide are oxidized to form water and carbon dioxide. The elementary reaction CF3Br+H=CF3+HBr plays a prominent role in flame inhibition, but there are considerable uncertainties in the value of the rate parameters for this reaction. In view of these uncertainties, the rate of this reaction is measured directly by employing the flash-photolysis resonance fluorescence (PF-RF) technique and is compared with that predicted using transition state theory based on ab initio calculations. Predicted and measured rate parameters agree well but differ significantly from those used in previous studies. The improved rate parameters are tested by conducting numerical computations and experiments on flames stabilized between two counterflowing streams. The fuel stream is a mixture of hydrogen and nitrogen and the oxidizing stream consists of air and CF3Br. The strain rate at extinction is measured and given as a function of the concentration of CF3Br in the oxidizing stream. Numerical calculations are performed at conditions identical to those used in the experiments using detailed chemistry. Two different chemical kinetic mechanisms are used. The chemical kinetic mechanism describing the oxidation of the fuel is the same in both mechanisms, but the inhibition chemistries are different. One of the mechanisms has not been tested before on non-premixed flames. One mechanism is found to generally overpredict and the other to underpredict the inhibiting effect of CF3Br. The degree of overprediction and underprediction is evaluated using asymptotic theory. The differences between the mechanisms are discussed.

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  • Proceedings of the International Symposium on Combustion, 1998, Boulder, Colorado, United States

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  • Publication Title: Proceedings of the International Symposium on Combustion
  • Volume: 27
  • Issue: 2
  • Page Start: 2741
  • Page End: 2748
  • Peer Reviewed: Yes

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  • August 1998

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  • Oct. 2, 2015, 9:40 a.m.

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Truett, Leonard. Inhibition of Nonpremixed Hydrogen Flames by CF3Br, article, August 1998; [Amsterdam, Netherlands]. (digital.library.unt.edu/ark:/67531/metadc725845/: accessed April 26, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT College of Arts and Sciences.