Disappearance of criticality for small activation energy with arbitrary Biot number

Journal Article · Mon Mar 01 04:00:00 EST 1982 · Combust. Flame; (United States)

DOI:https://doi.org/10.1016/0010-2180(82)90053-0· OSTI ID:6202991

Fenaughty, K F; Lacey, A A; Wake, G C

For exothermic reactions obeying the Arrhenius equation the critical conditions for thermal ignition are known to exist for activation energy E large enough satisfying epsilon is identical to RT/sub a//E < epsilon/sub tr/. This transition value epsilon/sub tr/ has values less than 0.25 in all geometries, (Boddington et al.) and exactly 0.25 for the uniform temperature reactor (the Semenov case). The precise values of ..cap alpha../sub tr/ and the corresponding values of the maximum dimensionless temperature theta and the Frank-Kamenetskii parameter delta (the transition values) were calculated for a slab by Boddington et al. and Kordylewski for infinite Biot number (Frank-Kamenetskii conditions). Kordylewski gave a precise criterion for the appearance of these transition conditions and calculated the transition values for the other class A geometries of an infinite circular cylinder and a sphere, also for infinite Biot number. This criterion is modified here to the case of finite Biot number to obtain the transition values for a range of Biot numbers. The transition values are shown to match on to the values of the Semenov case for small values of the Biot number ..cap alpha...

• Research Organization: Victoria Univ., Wellington, New Zealand
• OSTI ID: 6202991
• Journal Information: Combust. Flame; (United States), Journal Name: Combust. Flame; (United States) Vol. 45:3; ISSN CBFMA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400800* -- Combustion
Pyrolysis
&amp; High-Temperature Chemistry
ACTIVATION ENERGY
ARRHENIUS EQUATION
CALCULATION METHODS
CHEMICAL REACTION KINETICS
COMPARATIVE EVALUATIONS
DATA
ENERGY
EQUATIONS
IGNITION
INFORMATION
KINETICS
NUMERICAL DATA
REACTION KINETICS
TEMPERATURE EFFECTS
THEORETICAL DATA