Evaluation of Hydroperoxide Concentrations During the Delay of Autoignition in an Experimental Four Stroke Engine: Comparison with Cool Flame Studies in a Flow System

Organic peroxides were extracted in a flow system, from the combustion chamber of a motored C.F.R. engine operated as a compressor and running on n-heptane. The concentration of the only organic peroxide found before self ignition was estimated to be 6 x 10 15 molecules cm −3 . The decomposition rate was equal to 10 18 molecules cm −3 S −1 . This value is the same as the rate of decomposition of organic peroxides found in the region before a stabilized cool flame of n-heptane in a flow reactor: these results illustrate the importance of low temperature oxidation during the delay of autoignition in spark ignition engines.