Measurements of the growth and coagulation of soot particles in a high-pressure shock tube
The advantage of well-defined experimental conditions in shock tubes has been used to investigate the growth and coagulation of soot particles at high pressures. The measurements have been made for fuel-rich oxidation and pyrolysis of different hydrocarbons behind the reflected shock at pressures between 10 and 60 bar and temperatures between 1,500 and 2,300 K. In addition to soot volume fraction, time-resolved scattering measurements yielded particle diameters and number densities; all these give insight into both surface growth and coagulation at enhanced pressures. The temperature behind the reflected shock was monitored by two-color pyrometry. Soot growth was characterized by induction periods and soot growth rates. At low final soot yields, the growth rate of soot depends on the square of the carbon concentration. At high soot yields, reduced growth rates of soot volume fraction were observed and can be attributed to a lack of growth species. At constant carbon concentration no pressure dependence of soot volume fraction could be found. Particle diameters between 15 and 40 nm were measured. The number density of particles was found to increase strongly with soot volume fraction. Calculated and measured particle number densities agree well during early soot growth. However, at longer times the experiments reveal coagulation rates which are significantly smaller than predicted. This behavior indicates that collisions of deactivated soot particles are characterized by sticking probabilities lower than unity. A correlation for the sticking probability has been established to match both the experimental results and calculations.
- Research Organization:
- Univ. Karlsruhe (DE)
- OSTI ID:
- 20006284
- Journal Information:
- Combustion and Flame, Journal Name: Combustion and Flame Journal Issue: 1-2 Vol. 120; ISSN CBFMAO; ISSN 0010-2180
- Country of Publication:
- United States
- Language:
- English
Similar Records
Soot mass growth and coagulation of soot particles in C{sub 2}H{sub 4}/air-flames at 15 bar
Study of soot formation in premixed propane/oxygen flames by in-situ optical techniques and sampling probes