Critical Energy Characteristics of Ignition Source

Not every source of heat is capable of igniting a combustible mixture. A motionless mixture and the mixture moving at a high velocity differ widely in ignition conditions. 

Experimental data for the minimum combustion energy of H2 + air mixtures are given in [21]. These data were determined for motionless mixtures ignited with a spark at normal temperature and pressure conditions. Other measurements of the minimum ignition energy have been performed using laser radiation focusing [27]. 

In hydrogenous diluted mixtures, in particular, in (H2 + CO2) mixtures, the laser ignition energy measured data also correspond to a U-shaped relation. It follows from Fig. 4.19 that the minimum ignition energy increases and the area of the measured data narrows when the mixture is diluted by CO2. 

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