Chen Hanyu, Wang Xi, Pan Zhixiang
School of Energy and Power Engineering, Wuhan University of Technology, Wuhan 430063, China; Center for Advanced Powertrain and Fuels (CAPF), Brunel University London, Uxbridge UB8 3PH, UK.
School of Physical Education, Jianghan University, Wuhan 430056, China.
Sci Total Environ. 2021 Jan 1;750:141716. doi: 10.1016/j.scitotenv.2020.141716. Epub 2020 Aug 15.
The aim of present work is to bridge the gap of knowledge concerning crystallite size, graphene layers curvature and inter-layer distance as nanostructure characteristics of soot primary particles, and also to comprehensively characterize the morphology of soot emission in a light hydrocarbon premixed charge compression ignition (PCCI) engine. In this study, the chemical composition, morphology and nano-structure of particulate emissions between conventional diesel and light hydrocarbon PCCI engine were performed with thermogravimetric analysis, gas chromatography mass spectrometry, and high-resolution transmission electron microscopy technology. The results show that the volatile matter content of light hydrocarbon is much higher than that of diesel, and thermogravimetry and differential thermogravimetry curves of light hydrocarbon shift to low temperature regions. The total organic components of particulate matter of light hydrocarbon PCCI engine are less, and the corresponding separation time is shorter. The structure of particles produced in light hydrocarbon PCCI engine is more open, and the size of aggregates is smaller. Fractal dimensions of 1.774 and 1.691 are obtained for soot particles in light hydrocarbon PCCI engine, compared to that of 1.81 and 1.785 in conventional diesel engine. Compared to conventional diesel engine, fringe separation distance and fringe tortuosity in light hydrocarbon PCCI engine are smaller while fringe length is larger. The primary particle nanostructures of light hydrocarbon PCCI engine incline to graphitize and change into the orderly structure. Compared with conventional diesel combustion, the average primary particle diameter of light hydrocarbon PCCI approximately reduces 2.0% at 75% load and 18.2% at 100% load, respectively.
本研究的目的是填补关于烟灰一次颗粒的微晶尺寸、石墨烯层曲率和层间距离等纳米结构特征方面的知识空白，并全面表征轻质烃预混充量压缩点火（PCCI）发动机中烟灰排放的形态。在本研究中，采用热重分析、气相色谱 - 质谱联用以及高分辨率透射电子显微镜技术对传统柴油发动机和轻质烃PCCI发动机的颗粒排放物的化学成分、形态和纳米结构进行了研究。结果表明，轻质烃的挥发物含量远高于柴油，且轻质烃的热重曲线和微商热重曲线向低温区域移动。轻质烃PCCI发动机颗粒物的总有机成分较少，相应的分离时间较短。轻质烃PCCI发动机产生的颗粒结构更开放，聚集体尺寸更小。轻质烃PCCI发动机中烟灰颗粒的分形维数分别为1.774和1.691，而传统柴油发动机中为1.81和1.785。与传统柴油发动机相比，轻质烃PCCI发动机中的条纹间距和条纹曲折度较小，而条纹长度较大。轻质烃PCCI发动机的一次颗粒纳米结构倾向于石墨化并转变为有序结构。与传统柴油燃烧相比，轻质烃PCCI发动机在75%负荷和100%负荷下的平均一次颗粒直径分别约减小2.0%和18.2%。
