ИСТИНА

The possibility of using hydrogen and its mixtures as a motor fuel aimed at improving the economic and environmental characteristics of internal combustion engines (ICE) is a subject of intense discussion. Accordingly, it becomes necessary to study the detonation characteristics of methane-hydrogen mixtures in conditions that correspond to the possibility of self-ignition in the ICE cylinder to analyze the effectiveness and safety of their use. Here we present the results of studying impact of hydrogen concentration on the delay of self-ignition τ for stoichiometric methane-hydrogen-air mixtures. Both experimental studies and kinetic modeling of self-ignition of such mixtures were carried out in the initial temperature range T0 = 700–1000 K and initial pressure P0 = 1–15 atm. The self-ignition delay was experimentally determined in a closed volume of static installation (high-pressure bomb method), which allowed covering the specified range. It has been established that the addition of less than 50% hydrogen to methane has a weak effect on the burning rate and flame propagation limits, which raises the issue of feasibility of using mixed methane-hydrogen fuels. A significant difference in the temperature dependence of the delay of self-ignition of methane and hydrogen is shown, which is probably associated with fundamental differences in the mechanism of their oxidation, as well as the nature of changes in the mechanisms of oxidation of methane and hydrogen occurring near the temperature of 900 K, which has a significant impact on the processes of their self-ignition. The possibility of both promotion and inhibition of self-ignition of methane by hydrogen additives has been shown. An interpretation of these phenomena is proposed.