Slow combustion and cool-flame behavior of iso-octane

1973 ◽  
Vol 21 (3) ◽  
pp. 345-355 ◽  
Author(s):  
J.A. Barnard ◽  
B.A. Harwood
Keyword(s):  
Cool Flame ◽  
Slow Combustion ◽  
Flame Behavior

The cool-flame oxidation of 3-methylpentane

1972 ◽  
Vol 329 (1579) ◽  
pp. 433-452 ◽  
Keyword(s):  
Hydrogen Transfer ◽  
Detailed Comparison ◽  
Combustion Products ◽  
Experimental Conditions ◽  
Cool Flame ◽  
Slow Combustion ◽  
Flame Region ◽  
The Difference ◽  
Increasing Temperature ◽  
Flame Oxidation

Kinetic and analytical studies of the gaseous oxidation of 3-methylpentane have been carried out both under slow combustion conditions and more especially in the cool-flame region. Analysis of the complex mixtures of in termediate products provides strong evidence for the occurrence of 3-methylpentylperoxy radical isomerization, which leads initially to the formation mainly of the corresponding β- and γ-hydroperoxyalkyl radicals. Detailed comparison of the yields of partial combustion products with those obtained from 3-ethylpentane under similar experimental conditions shows that formation of γ-hydro-peroxyalkyl radicals takes place less readily during the oxidation of 3-methylpentane due to the restricted number of modes of 1:6 hydrogen transfer. In consequence, this branched C 6 alkane gives smaller yields of the corresponding O -heterocycles but larger amounts of β-scission products. During the isomerization of 3-methylpentylperoxy radicals there is evidence for the occurrence of some alkyl group shifts. The results show that there is a somewhat greater tendency for m ethyl groups to migrate than there is for ethyl groups, the difference becoming more marked with increasing temperature.

Numerical analysis of the cool flame behavior of igniting n-Heptane droplets

2005 ◽  
Vol 17 (3) ◽  
pp. 5-9 ◽  
Author(s):  
Stefan Schnaubelt ◽  
C. Eigenbrod ◽  
H. J. Rath
Keyword(s):  
Numerical Analysis ◽  
Cool Flame ◽  
Flame Behavior

scholarly journals The combustion of aromatic and alicyclic hydrocarbons. III. Ignition and cool-flame characteristics

1940 ◽  
Vol 174 (958) ◽  
pp. 379-393 ◽  
Keyword(s):  
Temperature Coefficient ◽  
Experimental Technique ◽  
Aromatic Hydrocarbons ◽  
High Pressures ◽  
The Other ◽  
General Survey ◽  
Cool Flame ◽  
Slow Combustion ◽  
Ignition Characteristics ◽  
Butyl Benzene

In a previous communication (Burgoyne 1937), attention was drawn to certain apparently anomalous features of the slow combustion of n -butyl benzene, and it was shown, inter alia , that the observed irregularities in the temperature coefficient of the reaction could be accounted for by the occurrence of cool-flame ignitions of the same type as those exhibited by the higher aliphatic hydrocarbons (Townend and Chamberlain 1936). These circumstances suggested that a general survey of the ignition characteristics of the aromatic hydrocarbons would be desirable as an aid to elucidating the mechanism of their combustion; and the present paper embodies the results for the series previously studied, together with two members of the alicyclic series which have been included to serve as a connecting link with the paraffins and olefines. Owing to the wide variations in reactivity towards oxygen of the compounds in question, it was found impracticable to employ the same experimental technique throughout the series; for whilst the ignitions of the more reactive members could safely be studied in silica and glass vessels, the remainder involved high pressures and required the use of steel apparatus. Comparative experiments, however, showed that no essential alteration in the ignition characteristics resulted from the substitution of one material for the other.

Alkylperoxy radical rearrangements during the gaseous oxidation of isobutene

1963 ◽  
Vol 273 (1354) ◽  
pp. 427-434 ◽  
Keyword(s):  
Methyl Ethyl Ketone ◽  
Peroxy Radical ◽  
Methyl Ethyl ◽  
Isotopic Tracer ◽  
Cool Flame ◽  
Cool Flames ◽  
Tracer Techniques ◽  
Slow Combustion ◽  
Flame Region ◽  
Subsequent Decomposition

Isotopic tracer techniques have been used to elucidate the mechanism of production of ketones in the gaseous oxidation of isobutane. Both acetone and methyl ethyl ketone are formed from this hydrocarbon, the former predominating in the products of slow combustion and the latter in the products of cool flames. Addition of [1,3- 14 C] acetone to reacting isobutane + oxygen mixtures has established that none of the methyl ethyl ketone formed in the cool-flame region and only 25% of that formed during slow combustion arises from further reactions of acetone. The formation of methyl ethyl ketone probably involves predominantly rearrangement and subsequent decomposition of the tert .-butyl peroxy radical and this indeed appears to be the almost exclusive fate of this radical under cool-flame conditions.

The non-isothermal oxidation of 2-methylpentane. II. The chemistry of cool flames

1967 ◽  
Vol 298 (1453) ◽  
pp. 204-237 ◽  
Keyword(s):  
Flame Temperature ◽  
Complex Mixture ◽  
Isothermal Oxidation ◽  
Qualitative Description ◽  
Cool Flame ◽  
Slow Combustion ◽  
Aldehydes And Ketones ◽  
Flame Region ◽  
Alkylperoxy Radicals ◽  
Liquid Chromatographic

The products of all the modes of non-isothermal oxidation of 2-methylpentane by molecu­lar oxygen and of the attendant slow combustion reactions have been analysed by gas-liquid chromatographic and chemical methods. Oxidation in the cool-flame temperature range produces more than forty molecular species, including O -heterocycles, peroxides, alkenes and saturated and unsaturated aldehydes and ketones. A good qualitative description of the mode of formation of this complex mixture and of its variation with temperature is afforded by the alkylperoxy radical isomerization theory. This theory is developed semi-quantitatively and is in reasonable agreement with the quantitative experimental results. It is concluded that chain propagation in the cool-flame region occurs predominantly by attack on the fuel by hydroxyl radicals; the resulting oxidation is rapid and unselective. In contrast, at temperatures too low for cool-flame formation alkylperoxy radicals are the likely chain-propagating species, whereas at temperatures above the upper cool-flame limit hydroperoxy radicals probably propagate the chain. The mechanism of chain branch­ing is not clear but it is established that, in the cool-flame region, peroxidic compounds are involved.

The cool-flame combustion of decane

1982 ◽  
Vol 382 (1783) ◽  
pp. 429-440 ◽  
Keyword(s):  
Carbonyl Compounds ◽  
Hydrogen Bromide ◽  
Combustion Products ◽  
Cool Flame ◽  
Flame Combustion ◽  
Hydroperoxide Formation ◽  
Slow Combustion ◽  
Flame Region ◽  
Increasing Temperature ◽  
Oxidative Attack

Three approaches have been used to elucidate the mechanism of combustion of decane in the cool-flame region. First, measurements have been made of cool-flame and ignition parameters. These show a well defined change in activation energy at about 530 K. Second, analytical studies have been made of the effect of increasing temperature on the combustion products. These indicate that hydroperoxide formation ceases and that C 10 O-heterocycles become the predominant products at 500-530 K; the relative amounts of decanal and decanone do not however change. Finally, small amounts of hydrogen bromide have been added. These cause the complete conversion of hydroperoxides into decanones even at low temperatures; no lower carbonyl compounds are formed above 500 K. This work has led to two principal conclusions. One, which is shown by all three methods of study, is that the cool-flame combustion of decane involves two distinct mechanisms with a transition at 500-530 K. The other is that the selectivity of initial oxidative attack on decane remains low over the whole of the slow combustion and cool-flame regions between 440 and 680 K, suggesting that hydroxyl radicals are the main attacking species throughout.

The non-isothermal oxidation of 2-methylpentane I. The properties of cool flames

1966 ◽  
Vol 293 (1434) ◽  
pp. 378-394 ◽  
Keyword(s):  
High Pressure ◽  
Pressure Rise ◽  
Isothermal Oxidation ◽  
Temperature Sensitive ◽  
Gaseous Mixtures ◽  
Cool Flame ◽  
Cool Flames ◽  
Slow Combustion ◽  
Subsequent Passage ◽  
Limiting Pressure

The conditions of pressure and temperature under which gaseous mixtures of 2-methylpentane with oxygen react non-iso thermally have been established. At temperatures greater than 307 °C, 1:2 fuel-oxygen mixtures of sufficiently high pressure ignite by a one-stage mechanism. At lower temperatures, the limiting pressure for ignition decreases and the resulting ignition is a two stage phenomenon, the passage of a cool flame preceding that of the hot flame. At similar temperatures but lower pressures, multiple and single cool flames propagate but do not lead to ignition. Correlation of the intensities of and rates of pressure rise due to cool flames with the limiting conditions for low temperature ignition has shown that cool flames affect profoundly the subsequent passage of a hot flame and that this effect is not purely thermal. The complexity of the limiting pressure/temperature relationship for cool flame propagation shows that the transition from slow combustion to cool flame is dependent upon several temperature-sensitive branching reactions. Moreover, the formation of periodic cool flames would appear to necessitate the participation, even under given conditions of pressure and temperature, of more than one branching agent.

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