Effect of Metallic GPF on the Micro Characteristics of Soot Particles of GDI Engine

High-resolution transmission electron microscopy (HRTEM) was used to observe the soot particles emitted from gasoline direct injection (GDI) engine equipped with metallic particulate filter (GPF). The changes of microscopic morphology and structure of the soot particles at pre-GPF and post-GPF were studied at a fixed speed of 1500 r/min and 25 %, 50 % 75 % and 100 % load, respectively. Furthermore, the micro-parameters of the primary particles that make up the soot particles were analyzed. The results show that the primary particles are approximately spherical, and agglomerate to form irregular shapes such as chains, branches and rings. The load and GPF have no significant influence on the microscopic morphology of the soot particles, the fractal dimension of soot particles at both ends of the GPF increases with the increase of load. Under the experimental conditions of the engine, most primary particles consisting of the soot particles are “shell-core” structure; The fringe length, tortuosity and interlayer spacing of the primary particles at pre- and post-GPF are monomodal. Among them, the average fringe length increases with the increase of load, while both the average tortuosity and average interlayer spacing change the opposite. These indicated that the degree of graphitization of the soot particle increases with the increasing load. Load and GPF only affect the micro-structure parameters of the primary particles and have no effect on its distribution.