Grantee Research Project Results
2001 Progress Report: Soot, Precursor Particle and Higher Hydrocarbon Production in Flames
EPA Grant Number: R828167Title: Soot, Precursor Particle and Higher Hydrocarbon Production in Flames
Investigators: Pfefferle, Lisa , McEnally, Charles
Institution: Yale University
EPA Project Officer: Hahn, Intaek
Project Period: August 1, 2000 through July 31, 2002 (Extended to July 31, 2003)
Project Period Covered by this Report: August 1, 2000 through July 31, 2001
Project Amount: $224,170
RFA: Exploratory Research - Engineering, Chemistry, and Physics) (1999) RFA Text | Recipients Lists
Research Category: Water , Air , Safer Chemicals , Land and Waste Management
Objective:
The overall objective of this research project is to understand the initial growth processes for soot in flames. The specific objectives are to: (1) compare species and particulate loadings to follow carbon flows in the flame as a function of flame condition and fuel (with and without dopants); (2) identify the flame location/gaseous environment where precursor particles are born; (3) use dopant studies to probe different mechanisms for soot nucleation and the relative importance of surface growth; and (4) develop methodologies for characterization of precursor and mature soot.
Progress Summary:
Our focus throughout this research project is concentrated on the initial steps of soot production. We directly analyze the relative importance of mass growth of mature soot from conversion of the precursor particles and from surface growth under a wide range of conditions. We have addressed these problems by developing methodologies for primary particle size measurement of both mature and precursor soot particles and by using our doped flame methodologies to decouple soot nucleation and growth processes from the other complex mechanisms occurring in the flames. This is accomplished using a doping strategy with large hydrocarbons that do not perturb the acetylene concentration profiles in the studied flame. Work on objectives 1 and 3 are proceeding: this is a cumulative comparison and initial studies were reported at the U.S. Section Combustion Institute Meeting in March 2001. Objective 2 has nearly been completed. In our lightly sooting coflow flames, precursor particles are born at the region where the naphthalene concentration as measured by mass spectrometry reaches its maximum on the centerline of the flame. Gas phase naphthalene concentrations are coincident with broadband laser-induced fluorescence, a likely marker for precursor particles in the flame. Objective 4 has been completed. The analysis of time-resolved LII data was conducted and compared to time-domain electromagnetic (TEM) data. This complemented Professor Long's group using the analysis to compare the time-resolved laser-induced incandescence (LII) with TEM data in their ethylene jet flame.
Future Activities:
The next experiments will involve varying the concentrations of aromatic dopants to assess the contribution of acetylene surface growth to the incremental soot observed. Because the aromatics used do not perturb the acetylene concentration by more than several percent, assessment of different soot mass growth mechanisms will be possible. In our lightly sooting flames, soot concentrations peak on the centerline. This makes the doping strategy particularly useful because centerline concentrations of key growth intermediates can be varied over orders of magnitude from the undoped base flame.
Journal Articles:
No journal articles submitted with this report: View all 8 publications for this projectSupplemental Keywords:
soot, precursor particle, hydrocarbon protection, polycyclic aromatic hydrocarbon, PAH, laser-induced incandescence, LII., RFA, Air, Scientific Discipline, Waste, Toxics, Engineering, particulate matter, HAPS, Environmental Chemistry, Engineering, Chemistry, & Physics, Incineration/Combustion, hydrocarbon, particle size, thermophoretic sampled particle diagnostic, combustion, gas flow rates, laser induced incandescense, combustion products, particle surface interactions, particulates, doped flame method, surface growth, particles, particle size measurement, PAH, particle precursorProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.