Study On Particulate Emission Characteristics Of Diesel Engine Based On Lubricating Oil Additives

The emission limits of particulate matter(PM)in the "Six Standards for Light Vehicle Countries" are strictly 33.33% compared with "National Five." The contribution of lubricant additives to particle emission is about 15%.According to different lubricating oils and additives,the particulate size concentration,oxidation process and microphysical morphology of the particulates are studied by means of bench test,thermogravimetric analysis,scanning / fluoroscopy electron microscopy and Raman spectroscopy.The influence of lubricant and additives on the characteristic temperature,characteristic structure and Micromorphology of particulates was discussed.It provides a new idea for the allocation and production of lubricants.And it provides a theoretical reference for diesel particulate matter emission control and post-processing technology.The main research work and conclusion of this paper are as follows:On the model JX493ZLQ3 diesel engine,CF-4 15W40 and CI-4 15W40 lubricating oil were used to investigate the effect of lubricating oil on particulate size distribution and quantity concentration of particulate matter under different operating conditions.The results of the study show that at medium and low torque(100N·m),the particulate size distribution and the concentration of particulate matter increase with the increase of the rotational speed;at high torque(200N·m),the peak particle size of the particulate matter as the rotation speed increases,the number concentration increases as the rotation speed increases.This shows that at high loads(100N·m,2800r/min;200N·m,1200r/min),because of the difference in the quality of lubricating oil,the consumption of CI grade is smaller than that of CF grade,and the particulate size distribution of particles different from the effect of quantity concentration,particulate emissions are better with CI-grade lubricants than with CF-grade lubricants.The lubricating oil antioxidant,detergent and anti-foaming agent with a volume ratio of 1% were respectively added to diesel fuel.Based on the thermogravimetric analysis method,the ignition temperature,the weight loss rate peak temperature,and the burn-out temperature were investigated around the oxidation process of the particulate matter.The variation of the characteristic temperature,combined with the kinetic equation of the oxidation of the particulate matter,studies the effect of the additive on the oxidation activity of the particulate matter.The results show that the characteristic temperature parameters of the three additive particulates show a downward trend as the torque or rotational speed increases.In the case of high torque(250N·m),the anti-oxidant particulates are most easily oxidized with the increase of the rotation speed,and the anti-foaming agent particles are the most difficult;at medium and low rotation speeds(1200 r/min),the resistance increases with the increase of the torque.Oxygen particulates strengthen the antioxidant capacity.As the cetane number of the additive-diesel blended fuel increases,the activation energy of the particulate matter decreases and the oxidation activity becomes better.Among them,the activation energy of antifoam particulates was the lowest,which was 57.89 J·mol-1.The effects of additives on microphysical properties of particles were studied by means of scanning electron microscopy,transmission electron microscopy and Raman spectroscopy combined with Digital Micrograph software.The results show that the average layer spacing,average crystallite size and average curvature of the three kinds of additive particles are between 0.393nm~0.409 nm,1.959nm~2.211 nm,and 1.182nm~1.773 nm,respectively.The influence of CC bond length on the graphite lattice is small;RC-C is about 0.146 nm.As the fuel T90 raises,the average layer spacing of the particles decreases.With the decrease of crystallite size,the degree of graphitization of particulate matter increases,the oxidation characteristic temperature decreases,and the oxidation activity increases.Compared with the curvature and the layer spacing,the variation rule is opposite.