正戊醇-柴油混合燃料发动机颗粒物的形貌结构与氧化活性研究  

Morphology and oxidation reactivity of exhaust particles from diesel engine fueled by N-pentanol-diesel blend

作　　者：汪映[1] 王鹏[1] 王小琛 Wang Ying;Wang Peng;Wang Xiaochen(School of Energy and Power Engineering,Xi’an Jiaotong University,Xi’an 710049,China)

机构地区：[1]西安交通大学能源与动力工程学院,西安710049

出　　处：《农业工程学报》2020年第8期48-53,共6页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然科学基金资助项目(51776162);陕西省自然科学基础研究计划(2020JM-044)。

摘　　要：掺混正戊醇能够降低柴油机颗粒物排放,但掺混正戊醇对柴油混合燃料颗粒物的形貌结构和氧化活性的影响规律尚不明确。该研究采用高分辨率透射电子显微镜、拉曼光谱仪和同步热分析仪研究了柴油机中分别燃用不同掺混比的正戊醇/柴油混合燃料时生成颗粒物的形貌、纳观结构和氧化活性。结果表明,正戊醇掺混体积比分别为0、15%和30%的3种混合燃料燃烧颗粒物的微观形貌相似,低倍率时表现为由基本碳粒子聚合而成的团聚形貌,高倍率时呈现出典型的"外壳-内核"结构;随着正戊醇掺混比例的增加,颗粒物的基本碳粒子直径减小,微晶长度减小而微晶曲率增加,D1峰与G峰的峰面积比增加。说明颗粒物结构更为无序,石墨化程度降低。同时,随着正戊醇掺混比例的增加,3种燃料燃烧颗粒物的氧化温度逐渐降低,依次为:616.9、609.9和583.6℃,说明其对应的氧化活性逐渐升高。分析表明,正戊醇/柴油混合燃料燃烧生成的颗粒物高氧化活性与其更为无序的纳观结构相关。The exhaust particles from diesel engine can be reduced by mixing diesel with n-pentanol, however, the effect of n-pentanol blending fuels on the oxidation reactivity and morphology of diesel exhaust particulates has not been well understood. Therefore, this paper aims to design an experiment and then solve this problem. Experiments were conducted in a high pressure common-rail diesel engine, and three fuels were selected, including pure diesel, DP15(15% n-pentanol +85% diesel, by vol.), and DP30(30% n-pentanol +70% diesel, by vol.). In this work, the engine speed and torque were set at 2000 r/min and 0.59 MPa, respectively. Tests were performed without any engine modification, but only with fuels change. In the test, the particulate samples were collected from the exhaust pipe of the engine through a vacuum pump, then the particulate matter(PM) characteristics were analyzed by transmission electron microscope(TEM), Raman spectroscopy(RS) and thermogravimetric analysis(TGA). Results showed that the morphologies of soot particles from three fuels were similar. Soot aggregates with numbers of primary particles were observed at low magnification, while a typical "shell-core" nanostructure was presented at high magnification. The "shell" part is mainly composed of parallel microcrystals, representing the order of basic carbon particles, while the "core" part consists of irregular microcrystals, indicating the disorder of basic carbon particles. With the increase in n-pentanol blending ratio, the oxidation process of soot was promoted due to the oxygen content of n-pentanol, while the mixing of n-pentanol reduced the generation of soot precursor, such as pyrene, and thereby the surface growth of soot decreases. Therefore, the primary particle diameters of soot samples slightly decreased from 21.813 nm to 20.030 nm. Meanwhile, as the n-pentanol blending ratio increased, the fringe length of soot samples decreased 0.025 and 0.051 nm, while the fringe tortuosity increased slightly. The decrease of fringe length and the i

关 键 词：柴油机 正戊醇 颗粒物 纳观结构 氧化活性 

分 类 号：TK464[动力工程及工程热物理—动力机械及工程]