预喷耦合EGR对重型柴油机燃烧和排放的影响  

Effect of Pilot-Injection Coupled EGR on Combustion and Emissions of a Heavy-Duty Diesel Engine

作　　者：陈雨凤 鹿盈盈[1] 张道陈 裴毅强[2] Chen Yufeng;Lu Yingying;Zhang Daochen;Pei Yiqiang(School of Mechanical and Power Engineering,Nanjing Tech University,Nanjing 211816,China;State Key Laboratory of Engines,Tianjin University,Tianjin 300350,China)

机构地区：[1]南京工业大学机械与动力工程学院,江苏南京211816 [2]天津大学先进内燃动力全国重点实验室,天津300350

出　　处：《内燃机学报》2024年第5期394-402,共9页Transactions of CSICE

基　　金：先进内燃动力全国重点实验室开放研究资助项目(K2023-01).

摘　　要：数值研究了预喷和预喷耦合废气再循环(EGR)对重型柴油机大负荷工况下燃烧和排放的影响.通过优化预喷参数和耦合的EGR率,提高了指示热效率,并降低了NO_(x)排放.结果表明:在柴油机大负荷工况下,与单次喷射相比,仅使用预喷方案可使指示热效率提升,碳烟排放下降,但会导致NO_(x)排放恶化.将预喷方案和EGR策略耦合,采用预喷比例为20%配合EGR率为10%~20%,可以保证良好的燃烧相位,在提高指示热效率的同时,降低缸内局部高温和NO_(x)排放.最终选取预喷(预喷比例为20%+预-主喷间隔为8°CA)并耦合EGR策略(EGR率为20%)作为最优方案.该方案使NO_(x)排放较原机下降57.4%,指示热效率提高2.28%.A numerical study was conducted to investigate the impact of pilot-injection and pilot-injection coupled exhaust gas recirculation(EGR)on combustion and emissions of a heavy-duty diesel engine under high load conditions.The pilot-injection parameters and the coupled EGR rate were optimized to improve the indicated thermal efficiency and reduce the NO_(x) emissions.The results indicate that,under high load conditions,the pilot-injection and pilot-injection coupled EGR have an impact on combustion and emissions for the heavy-duty diesel engine.The optimization of pilot-injection parameters and the coupled EGR rate improves the indicated thermal efficiency and reduces the NO_(x) emissions.Comparing with single injection,using only the pilot-injection scheme increases the indicated thermal efficiency and reduces the soot emission,but worsens the NO_(x) emissions.Coupling the pilotinjection scheme with an EGR strategy,with a pilot-injection ratio of 20%and an EGR rate ranging from 10%to 20%,ensures a favorable combustion phase,which improves the indicated thermal efficiency and reduces local high temperatures and NO_(x) emissions in the combustion chamber.The optimal solution finally chosen is a pilotinjection scheme(with a pilot-injection ratio of 20%and a pilot-main injection interval of 8°CA)coupled with an EGR strategy(with an EGR rate of 20%).This solution results in a 57.4%reduction in NO_(x) emissions and a 2.28%increase in indicated thermal efficiency,compared with the original engine.

关 键 词：重型柴油机 预喷方案 废气再循环 指示热效率 

分 类 号：TK422[动力工程及工程热物理—动力机械及工程]