Soot formation and inert addition in diffusion flames

R. L. Axelbaum, Chung King Law

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An experimental study has been conducted in coflow diffusion flames in order to identify the relative importance of fuel concentration dilution and flame temperature reduction on soot formation when inert is added to fuel. Two different methodologies were used to isolate dilution and temperature effects, both involving substitution of inerts with different specific heats. To quantify the extent of soot reduction, laser-light extinction as well as smoke point measurements were made. The results are in agreement with previous studies in counterflow flames and show that soot formation rates in the coflow flame behave nearly linearly with fuel concentration. Furthermore, white temperature exerts a strong influence on soot formation, dilution can also affect formation rates and smoke points when inerts are added to fuels. It is found that the relative importance of dilution and temperature depends on the extent of addition. When moderate amounts of inert are added, the temperature reduction is typically very small so that the effect of dilution can be considerably greater than that of temperature. When large amounts of inert are added, temperature effects may dominate those of dilution although, in an absolute sense, dilution effects could still be important because fuel concentrations are low.

Original languageEnglish (US)
Pages (from-to)1517-1523
Number of pages7
JournalSymposium (International) on Combustion
Issue number1
StatePublished - 1991

All Science Journal Classification (ASJC) codes

  • General Chemical Engineering
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Mechanical Engineering
  • Physical and Theoretical Chemistry
  • Fluid Flow and Transfer Processes


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