正丁醇/柴油RCCI尾气颗粒纳观特性的研究
- Study on the nanoscopic characteristics of n-butanol/diesel RCCI exhaust particles
- 摘要：本文基于一台RCCI发动机,在总循环能量(4000J.cyc-1)和发动机转速(1500r.min-1)不变的条件下,研究了不同喷油定时(Start Of Injection ,SOI)对正丁醇/柴油活性控制压燃(Reactivity Controlled Compression Ignition ,RCCI)的尾气颗粒基本碳粒子微观形貌、表面纳观特性特征参数(微晶长度(La)、微晶曲率(Tf)、层间距(Ds))和石墨化程度的影响,并与传统燃烧模式(Conventional Diesel Combustion ,CDC)进行了对比。结果表明,1：在微观形貌方面,两种燃烧模式下基本碳粒子均表现为典型的“外壳-内核”结构,“外壳”类似洋葱状的肉眼可见的微晶碳层；而“内核”则由无定型长度的微晶紊乱的堆积而成。2：对基本碳粒子的La、Tf和Ds的统计数据研究发现,首先,从整体上看,两种燃烧模式下的La、Tf 和Ds统计数据都符合右偏分布。其次,在不同燃烧模式下,La和Tf随SOI提前变化规律相反,在CDC模式下,La、Tf随着SOI的提前总体变小,而RCCI模式则变大；而在同一SOI下,由于上述La和Tf相反规律的存在,两种燃烧模式下的La或Tf 的统计数据特征值大小随燃烧模式的变化并不单调。最后,Ds在两种燃烧模式下随着SOI的提前,总体都在变大,而在同一SOI下,RCCI模式下的Ds的统计数据特征值整体上大于CDC模式。3：用Raman方法分析颗粒物的石墨化程度发现,在两种燃烧模式下,颗粒物石墨化程度随着SOI的提前在变高,此外对比RCCI模式和CDC模式发现,RCCI模式下的颗粒物石墨化程度更高。
- Abstract：This paper is based on a RCCI engine with a constant total cycle energy (4000J.cyc-1) and engine speed (1500r.min-1) to investigate the effects of different Start of injection (SOI) on the microscopic morphology, surface nanoscale characteristic parameters (fringe length (La), fringe tortuosity (Tf), separation distance (Ds)), and graphitization degree of the basic carbon particles in n-butanol/diesel Reactivity controlled compression ignition (RCCI) and Conventional diesel combustion (CDC) and compared them. The results show that: 1: In terms of microscopic morphology, In both combustion modes, the basic carbon particles show a typical "crust-core" structure, and the "shell" is similar to the onion-like crystalline carbon layer visible to the naked eye. The "inner core" is formed by the disordered accumulation of amorphous length microcrystals.2: The statistical analysis of La, Tf, and Ds for basic carbon particles indicates the following findings: firstly, from a comprehensive perspective, the statistical data of La, Tf, and Ds in both combustion modes exhibit a right-skewed distribution. Secondly, the trends of variation in La and Tf with SOI advancement are opposite in the two combustion modes. In CDC mode, La and Tf generally decrease with SOI advancement while they increase in RCCI mode. Thirdly, at the same SOI value, due to the contrasting trends of La and Tf, the characteristic values of La or Tf do not consistently change with changes in combustion mode. Finally, Ds generally increases with SOI advancement in both combustion modes; moreover, characteristic values of Ds are typically larger in RCCI mode compared to CDC mode at the same SOI.3: Using Raman analysis to analyze the degree of graphitization of particulate matter, it was found that the degree of graphitization of particulate matter increased as SOI advanced in both combustion modes, and the degree of graphitization was higher in the RCCI mode compared to the CDC mode.
