Limiting Conditions of Flame Propagation in Gas Mixtures at Reduced Pressures

In this paper, we experimentally studied the limiting conditions for the combustion of hydrogen, methane, and propane in mixtures with air or oxygen at pressures below atmospheric. A significant effect is shown for the size of the reaction vessel and the ignition energy on both the minimal pressure value and the change in the concentration range of flame propagation. The dimensions of the reaction vessel and the magnitude of the ignition energy, the increase of which does not lead to a change in the minimal pressure and concentration region of flame propagation, are established. The minimal pressures P min of gas mixtures, below which flame propagation is impossible, were determined. A qualitative interpretation of the data is presented.