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Ionic Mechanisms of Soot Nucleation in Premixed Flames

  • D. B. Olson
  • H. F. Calcote

Abstract

Although numerous chemical mechanisms have been postulated for the formation of soot in hydrocarbon combustion, none have received quantitative support. Understanding of this process is complicated by the large number of species involved and by the phase change associated with nucleation.

An experimental program is underway at AeroChem to determine the role of ionic processes in soot formation in premixed hydrocarbon flames. The hypothesis being tested is that ions produced via chemi-ionization serve as nuclei for initial formation of soot particles. Rapid ion-molecular kinetics, rapid structural rearrangements, and thermochemistry favorable toward growth to larger species are characteristics of the ion chemistry, in agreement with observations about the soot formation process.

Mass spectrometric measurements of flame ion concentration profiles have been made in low pressure rich and sooting acetylene/oxygen and benzene/oxygen flames. As both flames are made increasingly fuel rich and approach sooting the predominant ion C3H3 + is replaced by large positive aromatic ions with mass greater than 300. It is argued that these ions are the soot precursors.

Similarities and differences betweeen the ion spectra of rich and sooting acetylene and benzene flames are discussed along with possible reasons for dual maxima in ion concentration profiles observed in sooting flames. A detailed chemical mechanism considering both neutral and ionic flame chemistry is being developed for which it is necessary to estimate the thermochemical parameters for large ionic species. Preliminary results of computer simulations of the chemical kinetics using this scheme are presented. The results are consistent with an ionic mechanism of soot formation.

Keywords

Equivalence Ratio Flame Front Soot Particle Premix Flame Soot Formation 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. 1.
    H. B. Palmer and C. F. Cullis, in “Chemistry and Physics of Carbon,” P. L. Walker, Ed., Marcel Dekker, New York, Vol. 1(1965), p. 265.Google Scholar
  2. 2.
    H. F. Calcote, March, 1980; Accepted for publication in Combust. and Flame.Google Scholar
  3. 3.
    D. B. Olson and H. F. Calcote, “Eighteenth Symposium (International) on Combustion,” The Combustion Institute, Pittsburgh, (in press).Google Scholar
  4. 4.
    H. F. Calcote, “Eighth Symposium ( International) on Combustion,” Williams and Wilkins Co., Baltimore, (1962), p. 184.Google Scholar
  5. 5.
    J. Peeters and C. Vinckier, “Fifteenth Symposium ( International) on Combustion,” The Combusition Institute, Pittsburgh, (1975), p. 969.Google Scholar
  6. 6.
    J. W. McGowan, P. M. Mul, V. S. D’Angelo, J. B. A. Mitchell, P. Defiance and H. R. Froelich, Phys. Rev. Lett., Vol. 42 (1979), p. 373.CrossRefGoogle Scholar
  7. 7.
    H. F. Calcote and W. J. Miller, in “Reactions Under Plasma Conditions,” M. Venugopalan, Ed., John Wiley & Sons, New York, Vol. 2 (1971), p. 327.Google Scholar
  8. 8.
    J. M. Goodings, D. K. Bohme and T. M. Sugden, “Sixteenth Symposium ( International) on Combustion,” The Combustion Institute, Pittsburgh, (1977), p. 891.Google Scholar
  9. 9.
    H. F. Calcote, in “Ion-Molecule Reactions,” J. L. Franklin, Ed., Plenum Press, New York, Vol. 2 (1972), p. 673.Google Scholar
  10. 10.
    W. J. Miller, “Eleventh Symposium ( International) on Combustion,” The Combustion Institute, Pittsburgh, (1967), p. 311.Google Scholar
  11. 11.
    H. F. Calcote, S. C. Kurzius and W. J. Miller, “Tenth Symposium ( International) on Combustion,” The Combustion Institute, Pittsburgh, (1965), p. 605.Google Scholar
  12. 12.
    G. P. Glass, G. B. Kistiakowsky, J. V. Michael and H. Niki, J. Chem. Phys., Vol. 42 (196.5)p. 608.Google Scholar
  13. 13.
    P. F. Knewstubb and T.M., Sugden, “Seventh Symposium ( International) on Combustion,” Butterworths, London, (1959), p. 247.Google Scholar
  14. 14.
    W. J. Miller, Oxid. Combust. Rev., Vol. 3 (1968), p. 97.Google Scholar
  15. 15.
    R. J. Bowser, and F. J. Weinberg, Combust. Flame, Vol. 27 (1976), p. 21.CrossRefGoogle Scholar
  16. 16.
    G. Prado and J. B. Howard, in “Evaporation-Combustion of Fuels,” J. T. Zung, Ed., American Chemical Society, Washington, DC, (1978) p. 153.CrossRefGoogle Scholar
  17. 17.
    B. L. Wersborg, A. C. Yeung and J. B. Howard, “Fifteenth Symposium ( International) on Combustion,” The Combustion Institute, Pittsburgh, (1975), p. 1439.Google Scholar
  18. 18.
    J. L. Delfau, P. Michaud and A. Barassin, Combust. Sci. Technol., Vol. 20 (1979), p. 165.CrossRefGoogle Scholar
  19. 19.
    K. H. Homann, Ber. Bunsenges. Phys. Chem., Vol. 83 (1979), p. 738.CrossRefGoogle Scholar
  20. 20.
    D. E. Jensen and W. J. Miller, J. Chem. Phys., Vol. 53 (1970), p. 3287.CrossRefGoogle Scholar
  21. 21.
    J. D. Bittner, and J. B. Howard, “Eighteenth Symposium (International) on Combustion,” The Combustion Institute, Pittsburgh, (in press).Google Scholar
  22. 22.
    P. Michaud, personal communication, (1980).Google Scholar
  23. 23.
    S. G. Lias and P. Ausloos, “Ion-Molecule Reactions. Their Role in Radiation Chemistry,” The American Chemical Society, Washington, DC, (1975), p. 94.Google Scholar
  24. 24.
    T. Tanzawa and W. C. Gardiner, Jr., “Seventeenth Symposium ( International) on Combustion,” The Combustion Institute, Pittsburgh, (1979), p. 563.Google Scholar
  25. 25.
    T. Tanzawa and W. C. Gardiner, Jr., J. Phys. Chem., Vol. 84 (1980), p. 236.CrossRefGoogle Scholar
  26. 26.
    S. E. Stein, J. Phys. Chem., Vol. 82 (1978), p. 566.CrossRefGoogle Scholar
  27. 27.
    S. E. Stein, D. M. Golden and S. W. Benson, J. Phys. Chem., Vol. 81 (1977), p. 314.CrossRefGoogle Scholar
  28. 28.
    H. M. Rosenstock, K. Draxl, B. W. Steimer and J. T. Herron, J. Phys. Chem. Ref. Data, Vol. 6 (1977), Suppl. No. 1.Google Scholar
  29. 29.
    R. G. McLoughlin, J. D. Morrison and J. C. Troeger, Organic Mass Spectr. Vol. 14 (1979), p. 104.CrossRefGoogle Scholar
  30. 30.
    R. D. Bowen and D. H. Williams, J. Amer. Chem. Soc., Vol. 100 (1978), p. 7454.CrossRefGoogle Scholar
  31. 31.
    D. R. Stull and H. Prophet, “JANAFThermochemical Tables,” Second Ed., NSRDSNBS-37, National Bureau of Standards, Washington, DC, (1971).Google Scholar
  32. 32.
    R. S. Duff and S. H. Bauer, J. Chem. Phys., 36 (1962), p. 1754.CrossRefGoogle Scholar
  33. 33.
    C. J. Jachimowski, Combust. Flame, Vol. 29 (1977), p. 55.CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 1981

Authors and Affiliations

  • D. B. Olson
    • 1
  • H. F. Calcote
    • 1
  1. 1.AeroChem Research Laboratories, Inc.PrincetonUSA

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