Detailed chemical kinetics studies of an NH3/N2O/Ar flame by laser-induced fluorescence, mass spectrometry, and modeling

✍ Scribed by D.T. Venizelos; R.C. Sausa

• Book ID: 104270778
• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 209 KB
• Volume: 28
• Category: Article
• ISSN: 1540-7489
• DOI: 10.1016/s0082-0784(00)80654-2

✦ Synopsis

Experimental and chemical modeling studies of a 60 torr NH 3 /N 2 O/Ar flame were performed to provide further testing and refinements of a detailed chemical mechanism developed previously in our laboratory. This mechanism, which is denoted as VS, consists of 87 reactions and 20 species. Flame temperatures were measured with a coated, thin-wire thermocouple and by rotational analyses of OH and NH laserinduced fluorescence (LIF) spectra. Species concentration profiles of NH 3 , N 2 O, N 2 , H 2 O, NO, O 2 , NH, O, and OH were recorded using molecular beam mass spectrometry (MB/MS), LIF, or both. The experimental species concentrations were compared with those obtained with both equilibrium and PREMIX flame code calculations. The NH 3 /N 2 O mixture equilibrium calculations agree very well with both the PREMIX and measured postflame N 2 and H 2 O concentrations but underpredict the postflame NO concentration and overpredict the O 2 concentration. The PREMIX calculations predict very well the shapes of the experimental NH 3 , N 2 O, N 2 , H 2 O, NO, OH, and NH profiles throughout the flame but do not adequately predict the shape of the O-atom profile and overpredict the O 2 concentration by ϳ60% at 16.25 mm, suggesting that the VS mechanism requires some refinement. A modified mechanism, VSmodified, which provides better agreement with the experimental results, is proposed. In this mechanism the rate constants of the following reactions are altered to the limit of their experimental or calculated uncertainties: ( ) N 2 O ‫ם‬ H ‫ס‬ OH ‫ם‬ N 2 , (2) NH 2 ‫ם‬ O ‫ס‬ HNO ‫ם‬ H, (3) NH 2 ‫ם‬ OH ‫ס‬ NH ‫ם‬ H 2 O, (4) NH 2 ‫ם‬ H ‫ס‬ H 2 ‫ם‬ NH, (5) NH 3 ‫ם‬ OH ‫ס‬ NH 2 ‫ם‬ H 2 O, and (6) NO ‫ם‬ H ‫ם‬ M ‫ס‬ HNO ‫ם‬ M.