Influence Of Lubricant Characteristic On The Particle Emission Of Diesel Engine

With more and more serious environmental problems,engine particulate emissions controlling requirements become more and more stringent.This paper focuses on the impact of lubricating oil on particulate emissions,in order to reduce the exhaust emissions of vehicles to provide a reference.With the use of lubricating oils of different formulations and physical and chemical characteristics,we changed the working temperature of lubricating oil to investigate the effect of working load,temperature and characteristics of lube oil on engine particulate emission.And the influence of the above factors on the content of C10~C30 n-alkanes and elemental components in the exhaust particles was analyzed.In this paper a distinction on diesel particulate emissions was made: particles in the range of 5~300nm which were affected by fuel are called fuel-level particles,and particles in the range of 300~1000nm which were affected by lubricating oil are called lubricant-level particles.The increase of engine speed results in an increase of fuel-level and lubricant-level particles.Particle emissions rise on heavy load,and size of lubricant-level particles grows on low speed.As the temperature of lube oil rises,fuel-level and lubricant-level particles decreases on light load and increases on heavy load.In the condition of high oil temperature,lube oil with higher content of saturated hydrocarbons intends to less fuel-level and lubricant-level particles.PAO(BASE2)containing higher content of high polymers increases the fuel-level and lubricant-level particles on light load and decreases the particles on heavy load.The results on effect of characteristics of lubricating oil showed that low-ash oil could reduce the particle emission,especially the fuel-level particles on heavy load.Low-ash oil could also enlarge the size of lubricant-level particles.With higher evaporation loss rate of lube oil,the engine ended with more particle emissions.It is worth noting that the effect of evaporation loss rate on particles strengthened with high working temperature.Low Kinematic viscosity oil increases the particles of fuel-level.The mass concentration of C10~C30 n-alkanes in engine particle emissions turns out a regular pattern of two peaks,which happens on C16~C18 and C29,C23 and longer n-alkanes result from lubricants.Shorter n-alkanes than C22 reduce on light load and longer ones go up.Different lube oils intend distinguishing phenomenon.High content of saturated hydrocarbons reduce the content of longer n-alkanes.And high content of high polymers raises longer n-alkanes on light load as well as lessens longer n-alkanes on heavy load.Oil with low ash will decrease the content of medium and long n-alkanes,and high evaporation loss rate ones will increase the content of medium and long n-alkanes.The lower Kinematic viscosity of lube oil is,the more medium and long n-alkanes it will generate.The content of element of Ca,Mg and Al in engine particle emissions rises with heavy load and high temperature of lubricating oil,and content of element Ca occupies a higher role of the three kinds of metal elements.What is more,the change of duty turns out little impact with the content of elements of Ni,Cu,Fe and so on.The purified lube oils like PAO(BASE2)and CNG(low ash),can increase the contents of Ca,Mg,Al.Different oils lead to a similar content of elements of Ni,Cu,Fe and so on.