Abstract: The particulates in different positions of the exhaust pipe of the 186F diesel engine were collected by using the engine exhaust particle size (EEPS), and the effect of the exhaust transport process on the particle size is analyzed. The fourier infrared spectrometer and X ray photoelectron spectrometer were used to detect the particulates collected at different positions of the exhaust pipe, and the effect of the exhaust transport process on the surface functional groups of the particulates was studied. The results show that the average particle size of the particulates was increased gradually along the flow direction of the exhaust gas in the process of diesel exhaust transportation, and the proportion of the nuclear particulates was reduced gradually. In the process of exhaust transport, the chemical composition of the particulate surface was basically the same. With the process of exhaust transport, the aliphatic hydrocarbon content of the particulates was increased, the content of C=O and C-OH in the particulates was increased, and the oxidation activity of the particulates was increased. The study showed that, along the flow direction of diesel exhaust transportation, the oxidation activity of the particulates was increased which was beneficial to the regeneration of the diesel engine post treatment device DPF

Key words: diesel engine, particulates, transport process, functional group