Autoignition in methanehydrogen mixtures

Abstract

Induction time and strong ignition limit associated with autoignition are determined experimentally for 11 mixtures of methanehydrogenoxygen using the reflected shock technique. The experimental conditions cover temperatures from 800 to 2400K and pressures from 1 to 3 atm. The induction time data, τ, obtained for the methaneoxygen and the hydrogenoxygen mixtures are correlated with conventional Arrhenius-type correlation formulas. The results compare well with those reported in the literature. For the methanehydrogenoxygen mixtures, a heuristic formula based on the correlations for methaneoxygen and hydrogenoxygen is proposed. This formula incorporates a parameter expressing the ratio of methanehydrogen concentrations and is found to be quite satisfactory. The strong ignition limits for the 11 mixtures are expressed by a specific value of κ = ( δτ δT ) P , which is deduced for each mixture from the induction time correlation. The results show that κ is not highly sensitive to mixture compositions. This leads to the conclusion that the dominating factor in establishing strong ignition is the sensitivity of the induction time to the rate of change in temperature.