Study on the explosion characteristics of hydrogen/ammonia and the influence of key factor in a confined vessel

Abstract

This experiment researched on the explosion characteristics of ammonia and hydrogen mixed gases and the effects of the equivalence ratio, the hydrogen doping ratio, the ignition energy, and the initial pressure on explosion characteristic parameters based on a self-developed visualization experimental apparatus. The results show that the flame underwent a transient development process from the “spherical” to “ellipsoidal”, “finger” and “tulip” structures in sequence. Meanwhile, the impact of equivalence ratio on explosion parameters emerged a trend of increasing first and then decreasing, and the explosion reaction was the most intense at an equivalence ratio of 1.0. The hydrogen doping ratio exhibited an evident promoting effect on the explosion, further increasing the reaction activity and evidently enhancing the corresponding explosion parameter. When the hydrogen doping ratio was raised from 25% to 75%, the peak values of explosion parameters were all greatly increased. The ignition energy mainly accelerated the reaction rates of ammonia and hydrogen explosions by improving the activation energy and ignition area during the ignition stage. Noteworthily, the velocity history of flame propagation showed a change of increasing first and then decreasing during the transition from negative pressure to positive pressure. Nevertheless, the pressure and its rise rate presented an increasing trend of change. The corresponding temperature peak value also appeared the same pattern.