Optical investigation of ammonia rich combustion based on methanol jet ignition by means of an ignition chamber

• Published in: Fuel (Guildford) 2023-08, Vol.345, p.128202, Article 128202
• Main Authors: Dong, Dongsheng, Wei, Fuxing, Long, Wuqiang, Dong, Pengbo, Tian, Hua, Tian, Jiangping, Wang, Peng, Lu, Mingfei, Meng, Xiangyu
• Format: Article
• Language: English
• Subjects: Ammonia rich combustion; Ignition chamber; Methanol jet ignition ammonia; Visualization experiment
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2023.128202

•Ammonia rich combustion induced to low NOx emissions.•The ignition chamber fueled with methanol increased the jet ignition ammonia performance.•The rich equivalent ratios of ammonia led to a slow combustion speed of premixed ammonia.•The channel diameter of 3 mm with the equivalent ratio of 1.1 achieved a low NOx emissions and high combustion speed of ammonia. Ammonia, as a carbon-free alternative fuel, has attracted a lot of attention. However, ammonia has slow laminar burning velocity and high ignition energy and NOx emissions. The ignition chamber has been proven to greatly enhance ignition energy. Methanol, as a low-carbon liquid fuel with a low evaporation temperature (64.5 °C), is easy to store and transport and has the potential to become a good jet ignition fuel in the ignition chamber (pre-chamber). In addition, chemical reaction kinetics analysis of ammonia demonstrated that there are few NOx emissions when the equivalent ratio is higher than 1.2. In this study, the ignition chamber fueled with methanol was used to investigate the jet flow, jet ignition, and combustion process of rich ammonia using visualization experiments and instantaneous pressure measurement. The research results showed that the ignition chamber fueled with methanol improved the jet ignition and combustion of ammonia compared to the ignition chamber fueled with ammonia. Experimental studies of energy substitution ratios of methanol from 1% to 4% showed that a 2% energy substitution ratio achieved better jet ignition performance. Comparing with the stoichiometric combustion of ammonia, the combustion performance deteriorated with the increase of ammonia rich equivalent ratio. A slightly richer equivalent ratio of 1.1 tended to be a good choice for jet ignition of ammonia. The difference in channel diameter between the ignition chamber and the main chamber had large effects on the performance of jet ignition ammonia. The 3 mm channel diameter achieved the highest ammonia-rich combustion speed under the rich equivalent ratios of 1.1 and 1.2 in the main chamber, compared to the diameters of 4.5 mm and 6 mm.