Combustion and emission characteristics of diesel/n-butanol blends with split-injection and exhaust gas recirculation stratification  

分段喷射耦合EGR分层的柴油/正丁醇混合物燃烧和排放特性研究

作　　者：SUN Yi SUN Wan-chen GUO Liang YAN Yu-ying ZHANG Hao LI Xiu-ling 孙毅;孙万臣;郭亮;闫玉英;张浩;李秀岭(State Key Laboratory of Automotive Simulation and Control,Jilin University,Changchun 130025,China;Faculty of Engineering,the University of Nottingham,Nottingham NG72RD,United Kingdom)

机构地区：[1]State Key Laboratory of Automotive Simulation and Control,Jilin University,Changchun 130025,China [2]Faculty of Engineering,the University of Nottingham,Nottingham NG72RD,United Kingdom

出　　处：《Journal of Central South University》2022年第7期2189-2200,共12页中南大学学报（英文版）

基　　金：Projects(51476069,51676084)supported by the National Natural Science Foundation of China;Project(2019C058-3)supported by the Jilin Provincial Industrial Innovation Special Guidance Fund Project,China;Project(20180101059JC)supported by the Jilin Provincial Science and Technology Development Plan Project,China;Project(2020C025-2)supported by the Jilin Provincial Specific Project of Industrial Technology Research&Development,China。

摘　　要：Oxygen fuels have broad application prospects and great potential for realizing efficient and clean combustion,and hence this study applies diesel/n-butanol blends to explore the influence of split-injection strategy on combustion and emission characteristics.Simultaneously,changing the way of exhaust gas recirculation(EGR)gas introduction forms uneven in-cylinder components distribution,and utilizing EGR stratification optimizes the combustion process and allows better emission results.The results show that the split-injection strategy can reduce the NO_(x)emissions and keep smoke opacity low compared with the single injection,but the rise in accumulation mode particles is noticeable.NO_(x)emissions show an upward trend as the injection interval expands,while soot emissions are significantly reduced.The increase in pre-injection proportion causes the apparent low-temperature heat release,and the two-stage heat release can be observed during the process of main combustion heat release.More pre-injection mass makes NO_(x)gradually increase,but smoke opacity reaches the lowest point at 15%pre-injection proportion.EGR stratification can optimize the emission results under the split injection strategy,especially the considerable suppression of accumulation mode particulate emissions.Above all,fuel stratification coupled with EGR stratification is beneficial for further realizing the in-cylinder purification of pollutants.含氧燃料具有广阔的应用前景和实现高效清洁燃烧的巨大潜力,因此本研究探索了分段喷射策略对燃用柴油/正丁醇混合物的燃烧和排放特性的影响。同时通过改变EGR气体引入方式以在缸内形成组分不均匀分布,利用EGR分层优化燃烧过程并获得了更好的排放结果。结果表明,与单次喷射相比,分段喷射策略可以有效减少NO_(x)的排放并保持较低烟度,但积聚态微粒颗粒的数量明显增加。NO_(x)的排放量随着喷射间隔的扩大而呈现上升趋势,而碳烟排放量则随之显著减少。预喷比例的增加引起了明显的低温放热,并可以观察到在主放热过程中出现了两级放热。更多的预喷质量使NO_(x)逐渐增加,但在15%的预喷比例时获得了最小的不透光烟度值。EGR分层可以优化分段喷射策略下燃料燃烧的排放结果,不仅可以进一步降低NO_(x)排放而且对积聚态微粒排放也有着出色的抑制能力。总之,燃油分层结合EGR分层有利于实现污染物的缸内净化。

关 键 词：oxygen fuel split-injection exhaust gas recirculation(EGR)stratification pollutant emissions particle size distribution 

分 类 号：TE626[石油与天然气工程—油气加工工程]