Experimental study on gasoline-ammonia combustion characteristics with pre-chamber jet ignition

Abstract

In terms of the characteristics of slow combustion rate and high ignition energy of ammonia, an experimental study of gasoline-ammonia combustion characteristics was conducted and the difference in the combustion process between active and passive pre-chambers was revealed, utilizing gasoline as the ignition fuel in conjunction with jet ignition technology. The results show that employing active pre-chamber jet ignition can achieve a maximum ammonia ratio of 85 %. When the ammonia ratio is lower than 70 %, the coefficient of variation can be controlled with 1.5 %. There exists a sensitive zone around 50 % ammonia ratio, where combustion characteristics display heightened sensitivity to changes in ammonia ratio. As the ammonia ratio increases, the combustion process transitions from gasoline-dominated to ammonia-dominated. Consequently, when the ammonia ratio increases from 43 % to 50 %, the combustion duration increases by 62.8 % and the peak of heat release rate decreases by 43.8 %. With the increase of ammonia ratio, CO2 emissions decrease significantly, and the lowest is within 80 g/kW∙h. NOx emissions increase significantly with ammonia ratio increasing, but the rate of increase slows down when ammonia ratio beyond 50 %, which is attributed to the reduction in combustion temperature. Compared with the passive pre-chamber, the active pre-chamber is less influenced by the proportion of ammonia within main chamber, exhibiting a faster combustion rate, especially for conditions with ammonia ratio exceeding 40 %. At lower ammonia proportions, the combustion process exhibited similarities between active and passive pre-chambers. Furthermore, active pre-chambers exhibit a superior capacity to achieve higher ammonia ratios, underscoring their advantages in enhancing both combustion rate and ammonia concentration.