Influence Of Fuel And Lubricant Characteristic On The Particle Emission Of High Speed Light Duty Diesel Engine

As haze appears frequently,air pollution especially fine particles pollution draws public attention.Vehicle emission regulation is becoming more and more stringent,and starts to limit the amount of particles emission.Therefore,to adapt the emission regulation and meet the demand of environment governance,researches on the factors impacting vehicle particulate emission are quite meaningful.This paper focuses on fuel and lubricant characteristics,studying their effect on particulate emission.This paper firstly investigated how bio-diesel blending and sulfur content influenced the combustion and particulate emission of diesel engine.Then we changed the lubricant and its working temperature,and measured particle amount,oxidation activity,n-alkanes content and metal elements content,to study the effect of lubricant quality and working temperature on particulate emission characteristics.Fueled with diesel,low sulfur diesel and blended fuel which consist of diesel and 20% bio-diesel,the effect of fuel charcteristics on the combustion and particulate emission of diesel engine was investigated.The blend of bio-diesel made the heat release angle of pre-injection fuel in advance,increased the heat release rate of main injection fuel and cylinder pressure.As it improved the combustion,the cylinder temperature rised,together with the accumulated heat release rate.Low sulfur diesel had high cetane number and low aromatic content,which optimized the combustion of engine.It made the heat release angle of pre-injection fuel in advance,and raised the the heat release rate of main injection fuel and cylinder pressure at high load.Both the blend of bio-diesel and the use of low sulfur diesel had positive impact on the decrease of particulate emission.Among three kinds of fuel,D100 had the most particle emission number concentration and the biggest geometric mean diameter,S0 had less and smaller,D80S20 had the least and smallest.Using CNG,PAO and low ash-PAO,the influence of lubricant quality on particle emission of CI engine was investigated.The lower was the ash content of lubricant,the less was the total particle emission number concentration.Besides,lubricant quality had effect on heavy particle number size distribution of diesel engine.Because of their different evaporation loss rate,at most conditions,low ash-PAO had the least heavy particle number emission,CNG had the most.Lubricant quality alse affected the oxidation activity of particle.The oxidation activity of particle was the best,while using low ash-PAO and the worst while using PAO.In the aspect of n-alkanes emission,since low ash-PAO had the lowest ash content and evaporation loss rate,it had the least n-alkanes emission.In addition,with the use of low ash-PAO,the Ca,P,Fe,K content in particles was apparently lower.Changing the working temperature of lubricant,the influence of lubricant temperature on particle emission of CI engine was studied.The result indicated that the higher was the working temperature of lubricant,the more was the total particle emission number concentration,especially at low load.While heavy particle didn’t become more with the increase of lubricant temperature.There were two reasons.One was the increase of lubricant temperature raised the lubricant amount entering the combustion chamber,which would increase particle emission.The other is the increase of lubricant temperature raised the gas mean temperature,which would promote the oxidation of particle.Lubricant temperature affected the oxidation activity of particle,but there was no regularity.Using PAO,the oxidation of particle from diesel engine was the best at 80 degrees centigrade,worse at 90 degrees centigrade and the worst at 85 degrees centigrade.Using low ash-PAO,at high load the oxidation of particle from diesel engine increased with the increment of lubricant temperature;at low load the oxidation of particle from diesel engine was the best at 90 degrees centigrade,worse at 80 degrees centigrade and the worst at 85 degrees centigrade.The particulate n-alkanes emission of diesel engine didn’t have positive correlation with lubricant temperature.Most of n-alkanes had the highest emission at 85 degrees centigrade.