Off-campus UMass Amherst users: To download dissertations, please use the following link to log into our proxy server with your UMass Amherst user name and password.
Non-UMass Amherst users, please click the view more button below to purchase a copy of this dissertation from Proquest.
(Some titles may also be available free of charge in our Open Access Dissertation Collection, so please check there first.)
Molecular beam mass spectrometry and mechanistic modeling of lean and rich propene flames
Abstract
Flat flames of propene and oxygen at fuel-lean and fuel-rich, low-pressure conditions have been characterized by measuring profiles of area expansion, temperature, and mole fraction. Temperature profiles were measured by ceramically coated thermocouples, and mole fraction profiles were measured using molecular-beam mass spectrometry. The fuel-lean flame had an unburned gas composition of 4.7 mol% $\rm C\sb3H\sb6,$ 92.7 mol% O$\sb2,$ 2.6 mol% Ar $(\phi=0.299).$ It was operated at 3.999 kPa (30.00 Torr) with burner velocity of 57.5 cm/s (300 K), and mole fraction profiles for 14 stable and 7 free radical species were measured. The fuel-rich flame had an unburned gas composition of 24.9 mol% $\rm C\sb3H\sb6,$ 68.4 mol% O$\sb2,$ 6.7 mol% Ar $(\phi=1.64).$ This flame was operated at 4.667 kPa (35.00 Torr) with burner velocity of 27.4 cm/s (300 K); mole fraction profiles were measured for 22 stable species and 11 free radicals. These data were compared to a reaction mechanism having 323 reversible reactions and 57 species. This reaction mechanism was composed from existing reaction mechanisms for hydrocarbon flames and propene combustion. Although the mechanism predicted the proper functional form of most mole fraction profiles, it poorly predicted the position of these profiles and substantially overpredicted the magnitude of allyl mole fraction. Reaction path analysis revealed that reactions of H-atom with propene and reactions of all C$\sb3$ species with O-atom and O$\sb2$ require further consideration. A chemically activated reaction pathway for the formation of benzene from propargyl combination has been proposed. Rate constants for the formation of five $\rm C\sb6H\sb6$ isomers and phenyl from propargyl combination were calculated by Bimolecular Quantum-RRK. Benzene was not predicted to be the dominant $\rm C\sb6H\sb6$ isomer formed from propargyl combination. Using predicted rate constants and data from the fuel-rich propene flame, the total rate of propargyl combination was found to be too slow to account for the observed formation rate of mass 78 in the fuel-rich propene flames.
Subject Area
Chemical engineering
Recommended Citation
Thomas, Scott Daniel, "Molecular beam mass spectrometry and mechanistic modeling of lean and rich propene flames" (1992). Doctoral Dissertations Available from Proquest. AAI9305908.
https://scholarworks.umass.edu/dissertations/AAI9305908