Modeling Study to Evaluate the Ionic Mechanism of Soot Formation.
Abstract
Development of a thermochemical data base containing seventy cations of possible importance in soot formation was completed. The results were generalized for the estimation of the Gibbs energies of cations not included in the data base. The chemical kinetic model was expanded to include the chemiionization step by adding concentration profiles of O atoms and electronically excite CH as inputs to the program. The computer code was modified to include the chemiionization step, electron attachment and cation-anion recombination. Under some conditions the computer model and experiment were in excellent agreement, but questions remained. Analysis performed in this project indicated that gas sample cooling by the mass spectrometer sampling cone could have, for some cations, caused reactions to occur so that the mass analysis indicated a different ion from that in the flame. Calculations showed that energy liberated in rapid ion-molecule reactions accumulates in the product cation complicating the reaction kinetics. A survey of published flame measurements found that only ions dramatically change at soot threshold, but no explanation for this change was identified. The possible importance of choosing a neutral or ionic mechanism on the results of modeling soot formation in turbulent flow was considered.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 14, 1998
- Accession Number
- ADA349991
Entities
People
- D. G. Keil
- H. F. Calcote