Experimental Study On The Effect Of Lubricating Oil On Particulate Emission Characteristics Of Automotive Diesel Engine

With the frequent haze weather in the country,and more stringent regulations on engine particle emission,the amount of particule emission is also included in the regulation.This article will focus on the influence of the fuel mixed with a small amount of different kinds of lubricants on engine particle emission.It will provide a reference for reducing engine particle emission from the angle of lubricating oil.Four kinds of lubricants with special characteristic parameters were mixed into pure diesel on a four-cylinder turbocharged diesel engine in order to magnify the influence of lubricating oil.This article analysed the influence of the engine load,fuel mixed lubricants and characteristic parameters of lubricants on the performance of combustion and particle emission of diesel engine.Meanwhile the effects of the various factors on the oxidation activity of particles,the content of C₁₀^C₃₁ n-alkanes and metal elements were also analyzed.The results of the study show that:The effect of fuel mixed lubricants on the combustion performance:fuel mixed with a small amount of lubricants will not deteriorate the performance of diesel engine combustion massively;Only CI-4lubricating oil will lead to advance in combustion,and the main spray heat release decreases under low loads.Four kinds of lubricating oil will all lead to reduce the peak value of the combustion characteristic parameters slightly under the condition of large loads.The effect of fuel mixed lubricants on the engine particle emission:For all kinds of mixed fuel,the increase of engine load will reduce the particle emission of the engine;Compared to pure diesel,fuel mixed lubricating oil will change particle size distribution from unimodal logarithmic distribution to bimodal logarithmic distribution,besides,significantly increase the quantitative concentration of particle emission,massively increase the nuclear modal particles,and obviously make the geometric mean particle size much smaller.;Low ash lubricants can reduce the particle emission,which will mainly reduce the emission of nuclear mode particles;The low ash PAO lubricating oil with the base oil IV causes more particulate emissions than the CNG lubricating oil with class II base oil under the low loads,but the opposite of high loads.The effect of fuel mixed lubricants on the large size particle emission:The fuel mixed with lubricants increases the emission of large size particle,but there is no strict corresponding law of quantity between the amount of lubricants and emisson;The type of base oil of the lubricants has a great influence on the large size particle emission.When the other factors are consistent,the large size particle emission of the IV base lubricants is less than the II base lubricants.The effect of fuel mixed lubricants on the oxidation activity of particles:The oxidation activity of particles will decrease with the increase of loads;The fuel mixed with lubricants will significantly change the shape of the weight loss curve and increase the SOF content in the particles,which may reduce the temperature of maximum oxidation rate significantly especially under low loads;When the fuel is mixed with lubricants,the oxidation activity of the particles of II lubricants is higher than that of IV lubricants;When using pure diesel as fuel,the oxidation activity of the particles of low ash content lubricants performs better,while the conclusion is opposite when using the fuel with lubricants.The effect of fuel mixed lubricants on the proportion of elements in particles:The change of loads has little influence on the proportion of elements in particles;The proportion of the main metal elements in the particle emission of the IV lubricant PAO is higher than that of the II lubricant CI-4,while more kinds of metal elements can be detected in the particulate emission of CI-4 lubricant;The proportion of metal elements in the emission of lower ash lubricants is lower.The effect of fuel mixed lubricants on the distribution of C₁₀^C₃₁n-alkanes in particles:C₁₀^C₃₁ n-alkanes in particulate emissions from diesel engines are approximately bimodal distribution;When the pure diesel is used,the n-alkanes of below C₁₉ under low loads are more than those under high load,while the n-alkanes of above C₁₉ is opposite;When the fuel mixed with lubricants is used,the amount of n-alkanes with different carbon number is lower under low loads than that under high loads;Under low loads,the n-alkanes of below C₁₉ when using the fuel mixed lubricants are less than that when using pure diesel,while the n-alkanes of above C₁₉ are opposite.Under high loads,the amount of n-alkanes with different carbon number is lower using the fuel mixed lubricants than that of using pure diesel;When the rest of the variable approaches,there are more n-alkanes than IV lubricants in the particles of II lubricants,and C₁₀^C₃₁1 n-alkanes in particles are less when the lower lubricant is used.