{"title":"Effect of ammonia reforming on combustion and emission characteristics of a 4-valve engine with an active pre-chamber","authors":"","doi":"10.1016/j.joei.2024.101861","DOIUrl":null,"url":null,"abstract":"<div><div>Ammonia (NH<sub>3</sub>), as a hydrogen carrier and carbon-free fuel, offers an attractive opportunity for engines to achieve carbon neutrality. Turbulent jet ignition (TJI) combined with ammonia reforming shows the great capacity in ammonia-fueled engines. In this study, the effects of reforming strategy in an ammonia-fueled TJI are numerically studied, addressing the reforming ratio and reforming region. The results show that when only using reformate in the pre-chamber, the promoting effect of jet flame is more effective on the initial combustion phase. There are still very high NH<sub>3</sub> emissions due to the low reactivity in the main chamber. Further using reformate both in the pre-chamber and the main chamber, all the combustion stages (ST-CA10, CA10-50, CA50-90) can be shortened almost linearly with the increase of reforming ratio. Besides, the unburned NH<sub>3</sub> can be reduced to an acceptable level when the reforming ratio reaches 200 ‰ (hydrogen energy ratio of 18.50 %). The main reason is that the jet-induced strong flow field is coincident with the whole combustion stage. Further increasing the reforming ratio (pure hydrogen) in the pre-chamber, a high combustion efficiency and acceptable NH<sub>3</sub> emission can be achieved at a low hydrogen energy ratio (7.08 %). However, knocking combustion will happen at high reforming ratio with a low knock intensity. The results can provide some guidance for making the best-promoting benefit of the limited hydrogen in ammonia TJI engines with different reforming strategies.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":null,"pages":null},"PeriodicalIF":5.6000,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of The Energy Institute","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1743967124003398","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENERGY & FUELS","Score":null,"Total":0}
引用次数: 0
Abstract
Ammonia (NH3), as a hydrogen carrier and carbon-free fuel, offers an attractive opportunity for engines to achieve carbon neutrality. Turbulent jet ignition (TJI) combined with ammonia reforming shows the great capacity in ammonia-fueled engines. In this study, the effects of reforming strategy in an ammonia-fueled TJI are numerically studied, addressing the reforming ratio and reforming region. The results show that when only using reformate in the pre-chamber, the promoting effect of jet flame is more effective on the initial combustion phase. There are still very high NH3 emissions due to the low reactivity in the main chamber. Further using reformate both in the pre-chamber and the main chamber, all the combustion stages (ST-CA10, CA10-50, CA50-90) can be shortened almost linearly with the increase of reforming ratio. Besides, the unburned NH3 can be reduced to an acceptable level when the reforming ratio reaches 200 ‰ (hydrogen energy ratio of 18.50 %). The main reason is that the jet-induced strong flow field is coincident with the whole combustion stage. Further increasing the reforming ratio (pure hydrogen) in the pre-chamber, a high combustion efficiency and acceptable NH3 emission can be achieved at a low hydrogen energy ratio (7.08 %). However, knocking combustion will happen at high reforming ratio with a low knock intensity. The results can provide some guidance for making the best-promoting benefit of the limited hydrogen in ammonia TJI engines with different reforming strategies.
期刊介绍:
The Journal of the Energy Institute provides peer reviewed coverage of original high quality research on energy, engineering and technology.The coverage is broad and the main areas of interest include:
Combustion engineering and associated technologies; process heating; power generation; engines and propulsion; emissions and environmental pollution control; clean coal technologies; carbon abatement technologies
Emissions and environmental pollution control; safety and hazards;
Clean coal technologies; carbon abatement technologies, including carbon capture and storage, CCS;
Petroleum engineering and fuel quality, including storage and transport
Alternative energy sources; biomass utilisation and biomass conversion technologies; energy from waste, incineration and recycling
Energy conversion, energy recovery and energy efficiency; space heating, fuel cells, heat pumps and cooling systems
Energy storage
The journal''s coverage reflects changes in energy technology that result from the transition to more efficient energy production and end use together with reduced carbon emission.