Methanol-air Flames Research Articles

ChemInform Abstract: ELECTRON PARAMAGNETIC RESONANCE STUDIES ON LABILE INTERMEDIATES IN A FREE‐BURNING METHANOL‐AIR FLAME. EFFECTS OF WATER AND HYDROGEN BROMIDE ADDITIONS

Chemischer InformationsdienstVolume 15, Issue 39 Other Subjects ChemInform Abstract: ELECTRON PARAMAGNETIC RESONANCE STUDIES ON LABILE INTERMEDIATES IN A FREE-BURNING METHANOL-AIR FLAME. EFFECTS OF WATER AND HYDROGEN BROMIDE ADDITIONS S. NODA, S. NODASearch for more papers by this authorH. DEMISE, H. DEMISESearch for more papers by this authorO. CLAESSON, O. CLAESSONSearch for more papers by this authorH. YOSHIDA, H. YOSHIDASearch for more papers by this author S. NODA, S. NODASearch for more papers by this authorH. DEMISE, H. DEMISESearch for more papers by this authorO. CLAESSON, O. CLAESSONSearch for more papers by this authorH. YOSHIDA, H. YOSHIDASearch for more papers by this author First published: September 25, 1984 https://doi.org/10.1002/chin.198439331AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume15, Issue39September 25, 1984 RelatedInformation

Electron paramagnetic resonance studies on labile intermediates in a free-burning methanol-air flame. Effects of water and hydrogen bromide additions

Labile intermediates in a premixed methanol-air flame burning freely at atmospheric pressure have been studied by probe sampling and EPR detection. H, O, and OH have been detected at a pressure of 0.45 torr in the EPR cavity. It was found that H and O atoms have their maximum concentrations in the inner flame region within 1 mm from the burner mouth, while the OH concentration slowly increases in the outer flame region to reach a maximum at about 8 mm from the burner mouth. The slow increase in OH concentration is attributed to the reaction H + O/sub 2/ ..-->.. OH + O effectuated by diffusion of O/sub 2/ from the surrounding air into the flame. Addition of H/sub 2/O reduced the O atom concentration and increased the OH radical concentration in the inner flame region. The reaction O + H/sub 2/O ..-->.. 2OH is suggested as an explanation. Addition of HBr gave additional signals from Br and was found to reduce the H, O, and OH concentrations in the flame. It also caused the flame to shrink probably as a result of H atom deficiency in the inner flame region leading to insufficient generation of O and OHmore » in the outer flame region. About 70% of the bromine was found to exist in the atomic form.« less

High sensitivity quadrupole mass spectrometer system for flame studies

A new quadrupole mass spectrometer system for flame studies is described. The three-stage differential pumping system accepts working pressures up to 1 bar. Use of the modulated molecular beam technique allows the detection of highly reactive particles like atoms, radicals or condensable species. The profiles of reactants and final products from a methanol-air flame show the outstanding performance of the instrument.

Analysis by gas-phase electron spin resonance of hydrogen, oxygen, hydroxyl, and halogen atoms in flames

A new development of Westenberg and Fristrom's method is proposed to detect, by ESR, labile species in flames. The species extracted by a sampling probe are detected at low pressure (p = 4 x 10/sup -2/ torr) after a time of residence in the probe close to 8 ms. H, O, OH, as well as halogen atoms in inhibited flames have been detected with a good signal-to-noise ration. To account for species destruction in the probe, especially on the NaOH/HNO/sub 3/-treated surface of the probe (epsilon + 10/sup -3/-10/sup -4/), an extrapolation method to p = 0 is proposed. Mole fraction profiles of H, O, and OH in methanol-air flames stabilized at 80 torr in a flat flame burner were obtained. The results are in relatively good agreement with those calculated by Westbrook and Dryer for methanol flames. In the burned gases, the mole fractions of the species are consistent with the partial equilibrium hypothesis.

Inhibition of Laminar Methane-Air and Methanol-Air Flames by Hydrogen Bromide

Abstract The general problem of chemical kinetic flame inhibition is examined by means of a theoretical model. This model combines fluid mechanics, energy transport, and detailed chemical kinetics for the oxidation of methane and methanol, coupled with the elementary reactions of the inhibitor, hydrogen bromide. The effects of the inhibitor on laminar flame structure and flame speed are examined over wide ranges of pressure and equivalence ratio. Computed results are found to agree well with available experimental data. It is found that for the same amount of added inhibitor, lean flames are inhibited more rapidly than stoichiometric and rich flames. The efficiency of inhibition is also found to increase with increasing pressure. These trends apply to both methane-air and methanol-air flames. The kinetic mechanisms affecting the inhibition process have been identified and are found to depend strongly on hydrogen atom balance in the flame and pre-flame regions. At higher pressures recombination reactions i...

Prediction of laminar flame properties of methanol-air mixtures

A numerical model has been used to study the propagation of laminar methanol-air flames. The model consists of a one-dimensional time-dependent treatment of the conservation equations together with a detailed chemical kinetic oxidation mechanism having 84 elementary chemical reactions involving 26 chemical species. Solutions are used to study the dependence of laminar flame speed and flame structure on pressure, equivalence ratio, and unburned-gas temperature, and computed flame properties are compared with available experimental data. At low pressures, flame properties vary only slightly with changes in pressure, but at high pressures, this variation is considerably larger. This change in behavior from low to high pressures is a result of the increasing importance of radical recombination reactions. Most of this pressure-dependent inhibition is caused by the competition of a single reaction H + O 2 + M = HO 2 + M, with the key chain branching reaction H + O 2 = O + OH.

Flame profiles and combustion mechanisms of methanol-air flames under reduced pressure

If methanol is to be used as a fuel or as an additive to hydrocarbons, more information is required on its combustion kinetics. Three methanol-air flames (9.3%, 12.6%, and 16.9% by volume) have been stabilized on a flat-flame burner and their concentration, and temperature profiles have been measured. Over all rates for stable species have been deduced from mass and species conservation equations. Despite different experimental conditions (atmospheric pressure versus shock tube conditions) results are in agreement with those published by Bowman [8].