Visualization investigation of jet ignition ammonia-methanol by an ignition chamber fueled H2

Abstract

Ammonia is an ideal carbon-free fuel if the burning velocity problem can be successfully addressed. Blending ammonia with high-activity fuels and utilizing high-energy ignition are both suitable solutions for accelerating ammonia combustion. In this study, jet-controlled compound ignition (JCCI) by an ignition chamber fueled H2 was proposed to accelerate the premixed ammonia /methanol combustion. Visualization experiments were applied to evaluate the combustion performance. The effects of hydrogen energy substitution ratios (Ri) in the ignition chamber, methanol blend (Rm) in the main chamber, and orifice diameters (d) between the ignition chamber and main chamber on the combustion were investigated. By utilizing JCCI, it achieved a combustion duration of 85 ms, which is 47.7% shorter than spark ignition (SI) under an equivalent ratio of 1.0. Furthermore, JCCI produced excellent lean burn performance. At the equivalent ratio of 0.8 and 1.0 in the main chamber, JCCI model shortened the combustion duration by 20.9% and 52.2% respectively, compared with SI ignition. Additionally, it is necessary to adapt the appropriate hydrogen energy substitution ratio for different equivalent ratios of ammonia blends. For the equivalent ratio of 1.0 and 0.8 in the main chamber, the Ri = 1% and Ri = 2% achieved shorter jet delay and combustion duration, respectively. In addition, when the equivalent ratio was 1.0 and the methanol blend ratio Rm = 10%, Rm = 30% and Rm = 50%, the combustion duration reduced by 11.9%, 28.0%, and 42.1%, respectively, compared to Rm = 0%. This reduction resulted mainly from changes in the jet flow and flame structures due to the various hydrogen energy substitution ratios and methanol blend ratios. Furthermore, using a 3 mm orifice diameter, compared to a 6 mm orifice diameter, caused the combustion duration to decline by 63.4% and 54.3% for equivalent ratios of 1.0 and 0.8, respectively.