The attachment of the flame sheet to the carbon surface in a carbon combustion model: On the combustion rate

Journal Article · Wed Sep 01 04:00:00 EDT 1999 · Combustion and Flame

DOI:https://doi.org/10.1016/S0010-2180(99)00024-3· OSTI ID:20000567

Matsui, Kiyoshi

The behavior of the combustion rate of carbon, when the flame sheet attaches to or collapses at the carbon surface, is studied in a model in which the heterogeneous reactions 2C{sub (s)} + O{sub 2} {r{underscore}arrow} 2CO[reaction (I)] and C{sub (s)} + CO{sub 2} {r{underscore}arrow} 2CO[(IV)] and the homogeneous reaction 2CO + O{sub 2} {r{underscore}arrow} 2CO{sub 2}[(III)] occur in a stagnation flow of air. In this model the surface mass fraction of CO{sub 2} increases with an increase in the combustion rate. In a restricted case in which the heterogeneous reaction is solely (IV), CO{sub 2} is on the one hand the product of an overall surface reaction [reaction (III) plus (IV)] but on the other hand the reactant of reaction (IV) which determines the rate of this overall reaction. This causes peculiar variations of the combustion rate: (1) the combustion rate vanishes at a nonvanishing D{sub s(IV)}(D{sub 2(n)} is the surface Damkoehler number of the nth reaction); (2) the combustion rate varies dramatically with D{sub s(IV)} in the D{sub s(IV)} range in which the combustion rate is nonvanishing. When reaction (I) occurs at all, CO{sub 2} is made from CO by reaction (III); therefore, reaction (IV) occurs even in the D{sub s(IV)} range in which this reaction never occurs by itself. When D{sub s(IV)} is kept constant and D{sub s(I)} is increased, the combustion rate and the contribution of the gasification of carbon by reaction (I) naturally increase, but, because of an increase in the surface mass fraction of CO{sub 2} with increasing combustion rate, the contribution by reaction (IV) also increases.

• Research Organization: Daicel Chemical Industries, Ltd., Hyogo (JP)
• OSTI ID: 20000567
• Journal Information: Combustion and Flame, Journal Name: Combustion and Flame Journal Issue: 4 Vol. 118; ISSN CBFMAO; ISSN 0010-2180
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
CARBON
CARBON DIOXIDE
CARBON MONOXIDE
CARBONACEOUS MATERIALS
COMBUSTION KINETICS
MATHEMATICAL MODELS