基于喷射策略的氨柴双燃料发动机燃烧和排放试验研究  

Experimental Study on Combustion and Emissions in an Ammonia-Diesel Dual-Fuel Engine Based on Injection Strategies

作　　者：陈清楚 蔡开源 刘奕[1] 齐运亮[1] 陈虎[1] 王志[1] CHEN Qingchu;CAI Kaiyuan;LIU Yi;QI Yuniang;CHEN Hu;WANG Zhi(School of Vehicle and Mobility,Tsinghua University,Beijing 100084,China)

机构地区：[1]清华大学车辆与运载学院,北京100084

出　　处：《内燃机工程》2024年第4期9-15,28,共8页Chinese Internal Combustion Engine Engineering

基　　金：国家自然科学基金面上项目(52076118);宁波市重大科技任务攻关项目(2022Z151);清华大学水木学者计划。

摘　　要：在一台重型柴油发动机试验平台的基础上改造氨柴双燃料发动机,加装了一套电控喷氨系统,采用氨气进气道喷射、柴油缸内直喷方式,通过柴油喷射策略的变化,在发动机1 200 r/min的中高负荷下50%氨能占比工况,开展了氨柴双燃料的燃烧和排放特性优化研究。试验结果表明:氨柴双燃料燃烧时,由于氨燃料燃烧速度慢、起燃温度高等特性,柴油原机的上止点附近单次喷射策略,使得氨燃烧与柴油燃烧不同步,燃烧放热率呈现“双峰”曲线,氨燃烧效率较低。采用柴油双喷策略,通过提前柴油预喷时刻,可推迟柴油起燃时间,活化活塞凹坑外的氨燃料,促使柴油和氨燃烧趋于同步,将“双峰”放热曲线转变成“单峰”放热曲线,从而加快燃烧速度,缩短燃烧持续期,减少未燃氨排放,提升氨燃烧效率。但过度提前预喷时刻会造成柴油撞壁,对发动机指示热效率不利。A dual-fuel engine using ammonia and diesel was modified,based on a heavy-duty diesel engine experimental platform.A set of electronic control ammonia injection systems was installed,with ammonia injected into the intake manifold and diesel directly injected into the diesel cylinders.By varying the diesel injection strategy,combustion and emission characteristics of the ammonia-diesel dual-fuel engine was optimized under 1200 r/min medium loads with a 50%ammonia energy ratio.Experimental results show that the slow combustion rate and high ignition temperature of ammonia fuel lead to an asynchronous combustion with diesel in the vicinity of the top dead center of the diesel engine’s original injection strategy,resulting in a“double-peak”heat release curve,leading to lower efficiencies in ammonia combustion.By adopting a dual injection strategy for diesel,the ignition timing of diesel can be delayed by advancing the diesel pilot injection timing,which activates the ammonia fuel outside the piston cavity,promoting synchronization between diesel and ammonia combustion.The“double-peak”heat release curve is transformed into a“single-peak”curve,accelerating the combustion rate,shortening the combustion duration,reducing unburned ammonia emissions,and enhancing ammonia combustion efficiencies.However,excessive advancement of the pilot injection timing may cause diesel wall impingement,which is detrimental to the indicated thermal efficiency.

关 键 词：氨–柴双燃料 燃烧 喷射策略 柴油双喷策略 

分 类 号：TK464[动力工程及工程热物理—动力机械及工程]