Two-Stage Self-Ignition

The combustion of hydrocarbons and of certain other compounds (alcohols, aldehydes, etc.) often involves two stages that of cool flame and that of hot flame. Accordingly, self-ignition of such mixtures is also of a two-stage nature in a time Ti after the admission of the mixture into the heated reactor there appears a cool 

The idea that a cool flame prepares the mixture for hot ignition underlies the theory of the two-stage ignition first proposed by Neiman and widely used since (see e.g. [437]). 

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Fig. 3. Self-ignition of polypropylene (PP) in oxygen 1) slow oxidation, 2) cold flame, 3) multiplet secondary cold flames, 4) two-stage self-ignition. The single-stage self-ignition is not shown (After Ref. 29), with permission)...

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