Methane ignition energy

Relationship between minimum ignition energy and equivalence ratio for hydrogen-air and methane-air mixtures. 

Yuasa, T., Kadota, S., Tsue, M., Kono, M., Nomuta, H., and Ujiie, Y, Effects of energy deposition schedule on minimum ignition energy in spark ignition of methane-air mixtures, Proc. Combust. Inst., 29, 743, 2002. 

The explosion of an unconfined hydrogen gas doud in the presence of a weak ignition source was never observed to have turned into a detonation [45]. The ignition energy required for a direct detonation can only be provided by either an intensive turbulent hot gas jet or by an explosive. For a stoichiometric mixture, the minimum energy was experimentally determined to be 4.7 kJ ( 1 g TNT). A methane-air mixture even requires... 

Hydrogen is also one of the easiest explosives to ignite when suitably mixed with air or oxygen. For example, the ignition energy of hydrogen (H2), methane (CH4), and propane (CsHg) are 0.02,... 

Figure 7-46 illustrates a typical relationship of limits of flammability and ignitibility for a methane air mixture. Note that energy required to ignite a flammable mixture (within its LET and UEL) varies with the composition, and that a 0.2 millijoule (mj) spark is inadequate to ignite even a stoichiometric mixture at atmospheric pressure at 26°C, while 1-mj spark can ignite any... 

When you ignite methane in a Bunsen burner, the amount of heat evolved is very close to 885 kj/mol. There is a small work effect, due to the decrease in volume that occurs when the reaction takes place (Fig. 8.11, p. 216), but this amounts to less than 1% of the energy change. 

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