AN EXPERIMENTAL STUDY OF AMMONIA COMBUSTION INTENSIFICATION IN A BIDIRECTIONAL SWIRLING FLOW

The paper presents new experimental findings on ammonia–air combustion in bidirectional swirling flows. Recent results indicate that pure ammonia combustion is characterized by a narrow low emission range and a narrow range of ignition limits, making combustion intensification an important issue for environmentally friendly ammonia combustion. This study considers initial air heating, the use of an afterburning chamber, and oxygen enrichment as methods to increase combustion efficiency. It then analyzes their effects on the stable range of combustion conditions. Experiments have shown that preheating the airflow up to 510 K can decrease the equivalence ratio corresponding to lean blow-off by 20% for Reynolds numbers (Re) below 4000 and by 8% for Re > 5500. The use of an afterburning chamber also enhances combustion intensification, even at lower temperatures of preheating 40 to 60 K. The maximum combustion intensity is observed under conditions of oxygen enrichment of the air, when a twofold reduction in the lean blow-off value is achieved as the oxygen concentration increases from 23% to 42%. However, all factors show positive results in terms of enhancing the combustion of pure ammonia in a bidirectional airflow and can be applied in various industrial settings.