Experimental study on the equivalence ratio effects in ammonia-hydrogen-air premixed gas duct-vented explosions

To explore the combustion characteristics of ammonia-hydrogen-air flame, explosion venting experiments of ammonia-hydrogen-air mixtures with different equivalence ratios (Phi), in the range of 0.6-1.7, are carried out in a 2 m long duct. The results show that the pressure-time histories inside the duct have a three-peak structure (P-b, P-out, and P-ext), which is caused by the burst of the vent cover, venting of burned mixtures, and counterflow flame generated by the external explosion, respectively. P-out evolves into three pressure peak types with increasing Phi. The pressure peak value P-e is generated at the pressure measuring point outside the duct because of the external explosion. The change in P-e with Phi is consistent with P-out and P-ext, all of which increase first and then decrease with increasing Phi and reach a maximum value at Phi = 1.3. This study provides basic theoretical support for the promotion and application of ammonia mixed fuel.