Ionic Mechanisms of Carbon Formation in Flames.
Abstract
Premixed laboratory test flames of a number of hydrocarbons have been examined to determine the effects of pressure and fuel structure on the critical fuel are mixture ratio for soot onset. The tendency for flames to soot increases, in general, with the aromaticity and molecular weight of the fuel; pressure has little effect. Mass spectrometric probing of nearly sooting acetylene/air and benzene/air flames reveals a wide variety of naturally occurring high molecular weight hydrocarbon ions. As the equivalence ratio at which soot appears is approached, the average molecular weight of these flame ions increases. Both fuels give rise to very similar ionic species in the mass range above about 150 amu. These ions are separated by 12 0r 13 amu and correlate with the molecular weights of stable polycyclic aromatic species or free radicals. Distinct differences appear in the charged species distributions of benzene and acetylene flames in the mass range below about 150 amu, i.e., in the nucleation and early polymerization processes. The reactions subsequent to this early reaction mechanism apparently lead to aromatic species which are essentially independent of the identity of the fuel and which can grow rapidly to a complex array of polycyclic aromatics and soot.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1978
- Accession Number
- ADA056023
Entities
People
- Hartwell F. Calcote
- William J. Miller