Soot formation in strained diffusion flames with gaseous additives
- Zhejiang Univ., Hangzhou (China). Dept. of Energy Engineering
- Washington Univ., St Louis, MO (United States). Dept. of Mechanical Engineering
- Princeton Univ., NJ (United States). Dept. of Mechanical and Aerospace Engineering
The effects of various gaseous additives on soot formation in strained diffusion flames are reported. The additives N{sub 2}, Ar, He, H{sub 2}, and CO were introduced with fuels C{sub 2}H{sub 4}, C{sub 3}H{sub 8}, and C{sub 4}H{sub 10}, and were selected to isolate the effects of dilution, temperature, preferential diffusion, and active chemical participation resulting from the additive. Special emphasis was placed on understanding the mechanisms by which CO and H{sub 2} addition influence soot inception. Measurements were made of the limiting strain rate for complete suppression of soot, i.e., the soot-particle inception limit, K{sub P}, in the counterflow diffusion flame. Some laser-extinction measurements of soot volume fraction were also made in the coflow flame to determine the applicability of the results to this geometry. The addition of inerts to the fuel decreases the sooting limit due to the reduction in fuel concentration and temperature. Concentration modification due to preferential diffusion enhances the suppressive effect of He, causing it to be the most effective additive considered. The addition of H{sub 2} increases flame temperature but decreases K{sub P} for the fuels considered. The chemical role of H{sub 2} is discussed in the context of Frenklach`s H abstraction/C{sub 2}H{sub 2} addition model for PAH formation. Carbon monoxide addition to C{sub 2}H{sub 4} results in a monotonic decrease in K{sub P} that is primarily a consequence of dilution. For C{sub 2}H{sub 4} the results are consistent with dilution while for C{sub 3}H{sub 8} a small chemical enhancement combined with suppression due to dilution nets a weak suppression of soot formation.
- OSTI ID:
- 89624
- Journal Information:
- Combustion and Flame, Vol. 102, Issue 1-2; Other Information: PBD: Jul 1995
- Country of Publication:
- United States
- Language:
- English
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