Recent numerical calculations have predicted minimum ignition energies for stoichiometric methane-air mixtures which are a factor of 70 lower than experimental values. We show that most of this discrepancy is due to the use of a one-step kinetic model whose numerical values were chosen to reproduce burning velocities and heat-release profiles of steady one-dimensional flames. When a detailed chemical mechanism is employed, the predicted minimum ignition energies are close to the experimental values,especially when losses present in the experiments are considered. The reasons why these one-step models do not provide good quantitative predictions of ignition phenomena are discussed and the implications for the modelling of transient name phenomena with simplified chemical models are given.
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