| 废气再循技术对正丁醇/柴油燃烧颗粒结构及分形特征的影响 |
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| 引用本文： | 瞿磊,王忠,赵洋,刘帅,李瑞娜.废气再循技术对正丁醇/柴油燃烧颗粒结构及分形特征的影响[J].农业工程学报,2016,32(1):118-124. |
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| 作者姓名： | 瞿磊 王忠 赵洋 刘帅 李瑞娜 |
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| 作者单位： | 江苏大学汽车与交通工程学院,镇江,212013 |
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| 基金项目： | 国家自然科学基金(51376083)；江苏省2013年度普通高校研究生科研创新计划项目(CXZZ12_0672)；江苏省2014年度普通高校研究生科研创新计划项目(KYLX_1035)。 |
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| 摘 要： | 为深入了解添加含氧燃料和废气再循环技术(exhaust gas recirculation,EGR)共同作用对颗粒结构及分形特征的影响,运用颗粒分级采样装置采集了EGR率分别为0、10%、20%时,柴油机燃用正丁醇质量百分比为10%的正丁醇/柴油混合燃料(N10)的燃烧颗粒(N10EGR0、N10EGR10%、N10EGR20%),通过电镜试验和图像处理技术,开展了不同EGR率对正丁醇/柴油燃烧颗粒的影响研究,分析了颗粒群的微观结构、平均粒径、分形维数,基本碳粒子的层面间距、微晶尺寸等物理结构参数的变化规律,结果表明,N10EGR0、N10EGR10%、N10EGR20%燃烧颗粒群整体呈现团簇状结构,颗粒粒径范围主要集中在30~70 nm之间,呈正态单峰分布;随着EGR率的增加,粒径范围向大粒径方向移动,平均粒径逐渐增大,N10EGR20%与N10EGR0相比,平均粒径增大约为19%;计盒维数逐渐减小,表明颗粒间的团簇程度逐渐减弱。不同EGR条件下的基本碳粒子结构相似,呈指纹状球形碳层结构,随EGR率的增加,基本碳粒子的内核碳层排列无序性和外壳石墨晶体结构无规则性增强,平均层面间距和弯曲度逐渐增大,微晶尺寸逐渐减小。该研究为含氧燃料与EGR共同作用对颗粒的形成机理以及降低柴油机颗粒排放的措施提供理论参考。
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| 关 键 词： | 柴油机 颗粒 微观结构 正丁醇 废气再循环 计盒维数 |
| 收稿时间： | 2015/9/17 0:00:00 |
| 修稿时间： | 2015/11/30 0:00:00 |
Effect of exhaust gas recirculation on structure and fractal characteristics of particulate matters in combustion of n-butanol/diesel |
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| Qu Lei,Wang Zhong,Zhao Yang,Liu Shuai and Li Ruina.Effect of exhaust gas recirculation on structure and fractal characteristics of particulate matters in combustion of n-butanol/diesel[J].Transactions of the Chinese Society of Agricultural Engineering,2016,32(1):118-124. |
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| Authors: | Qu Lei Wang Zhong Zhao Yang Liu Shuai and Li Ruina |
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| Institution: | School of Automobile and Traffic Engineering, Jiangsu University, Zhenjiang 212013, China,School of Automobile and Traffic Engineering, Jiangsu University, Zhenjiang 212013, China,School of Automobile and Traffic Engineering, Jiangsu University, Zhenjiang 212013, China,School of Automobile and Traffic Engineering, Jiangsu University, Zhenjiang 212013, China and School of Automobile and Traffic Engineering, Jiangsu University, Zhenjiang 212013, China |
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| Abstract: | Pollutant emissions of diesel engine are mainly particulate matters, nitrogen oxide(NOx), hydrocarbon (HC), carbon moNOxide(CO), etc.The NOx, sulfide and particulate matters can form aerosol in the atmosphere, which is one of main causes leading to fog and haze.The concentration of small and medium scale particles such as PM2.5 and NOx is increasing with the wide application of diesel engine.The fog and haze weather occurs frequently, which has negative impacts on human health.It is quite necessary to carry out research on reducing particulate matters emitted from diesel engine.The diesel particulate matters and NOx emissions can be effectively controlled by adding the oxygen-containing fuel in the reaction process combined with the technology of the exhaust gas recirculation(EGR), which yet has multiple effects on the microstructure and oxidation behavior of the diesel engine particulate matters.In order to analyze and comprehend the effect of particle structure and fractal characteristics, a particulate matter sampling device was employed to collect the diesel engine particulate matters, which took oxygenated fuels combined with the technology of EGR into consideration.And the effects of different EGR rate (0%, 10% and 20%) on the particulate matters, which were produced in the combustion of N-butanol/diesel blended fuel with 10% N-butanol(N10), were studied with the thermal field emission scanning electron microscope (SEM) and high resolution electron microscopy(TEM), and the results were analyzed by the image technology.To be specific, the changing rule of physical structure parameter including the particulate matter microstructure, the average particle size of particulate matter group and the fractal dimension were analyzed, as well as the fringe separation distance and the fringe length distribution of basic carbon particles.It could be well observed that there was obvious clusters structure of particulate matters formed by combustion under 3 different conditions: N10EGR0, N10EGR10% and N10EGR20%.What was more, the range of particulate matter size was mainly concentrated between 30 and 70 nm which showed the normal single peak distribution.And the size of particulate matters demonstrated the pattern moving to larger figures gradually with the EGR rate increasing.Also the average size of particulate matter of N10EGR20% increased by 19% compared to N10EGR0.The gradual decreasing of box dimension indicated the fact that the intergranular degree of clusters gradually weakened.On the other hand, the basic carbon particles under different EGR conditions presented the similar structures, which looked like spherical carbon layer fingerprints.The basic carbon particulate matters were composed of 2 parts, the basic kernel layer and the shell.The basic kernel layer was the amorphous carbon structure, and the shell was the structure of graphite crystallite.Moreover, with the increasing of the EGR rate, the basic kernel layer was arranged more disorderly and the shell carbon particulate matters presented more irregular graphite crystal structure.To summarize, the average fringe separation distance of basic carbon particles was increased gradually as well as the average tortuosity distribution, and the average fringe length distribution was decreased with the increasing of EGR rate.The oxidation activity of particulate matters was improved with the adoption of EGR.This study can provide a theoretical reference for the formation mechanism of particulate matters and the measures to reduce the particulate matter emission of diesel engine by oxygenated fuel and the technology of EGR together. |
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| Keywords: | diesel engines particulate matter microstructure N-butanol EGR box dimension |
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