Investigation of concentration limits of flame propagation in ammonia-based gas mixtures

The concentration limits of flame propagation in NH$_3$–O$_2$, NH$_3$–H$_2$–O$_2$, NH$_3$–O$_2$–N$_2$, and NH$_3$–H$_2$–O$_2$–N$_2$ mixtures at temperatures of up to 70$^\circ$C and pressures of up to1.0 MPa were studied experimentally. The lower concentration limit of propagation of ammonia flame in oxygen decreases significantly at elevated temperature and pressure, the effect of temperature being stronger than for organic combustible substances. It is shown that the Le Chatelier rule for the limits of N$_2$–NH$_3$–O$_2$ mixtures is satisfied with sufficient accuracy.