Influence Of Fuel&Oil Characteristic On The Combustion&emission Of Compression Ignition Engine

To meet the demand of environment governance and adapt the limits of increasingly stringent emission regulation,researches on the factors impacting the combustion and emission of engine has become hotspots,such as the experimental research on the effects of fuel&oil characteristic on engines,which can provide some theoretical basis about pollution control.This dissertation mainly investigated how bio-diesel blending and aromatic hydrocarbons blending affected the combustion and emission of CI engine on a diesel engine fueled with different kind of diesel which contained different amount of bio-diesel or aromatic hydrocarbons;during the experiments employing pure diesel as fuel,this paper also studied how oil composition and oil temperature affected the the combustion and emission of CI engine.Fueled with diesel containing different amount of aromatic hydrocarbons,the experimental results indicated that aromatic hydraocarbons had a negative impact on the ignition characteristics of fuel and could affect the process of heat release and the ratio of premixed combustion.With the rise of the aromatic hydrocarbons content,the particle emission of the engine deteriorated,especially the emission of the particle whose radius were above100nm and the GMD of the particle emission increased.Besides,increasing aromatic hydrocarbons content would decrease the NO_x emission under light-duty and increase the NO_x emission under heavy-duty.Furthermore,increasing aromatic hydrocarbons content had complicated impact on HC emission and little effect on CO,and could worsen the effective specific fuel consumption and the thermal efficiency of engine.Fueled with pure diesel,2 blends with different bio-diesel/diesel ratio,and diesel containing different kind of aromatic hydraocarbons,the test result indicated that 2-MN had more negative impact on the combustion than 1-MN,and 2-MN had less AMP emission and smaller GMD than 1-MN because of its worse thermal stability.Besides,2-MN had worse NOx emission,HC emission and CO emission than 1-MN,while performing higher fuel comsuption and lower effective thermal efficiency under some operating conditions.On the other hand,the introduction of bio-diesel could improve the ignition characteristics of fuel,optimize the combustion of engine and increase the temperature in the cylinders.With the increase of bio-diesel blending ratio,the number concentration of accumulation mode particle(AMP)emission and the geometric mean diameter(GMD)of particle emission both decreased,but in some operating conditions,the number concentration of nucleation mode particle(NMP)emission increased,and bio-diesel showed the better particle emission reduction effect under high-speed and heavy-duty;In addition,the blend of bio-diesel could decrease the HC emission,the CO emission and the thermal efficiency of engine,while increasing the NO_x emission and effective specific fuel consumption.The study on the influence of oil composition and oil temperature showed that the rise of the oil temperature could slightly increase the pressure and temperature in cylinders,but would have any effects on combustion and heat release.The increase of the oil temperature could result in the decline of the number concentration of total particle emission and the increase of the number concentration of heavy oil particle emissions whose radius were above 300nm.Furthermore,the study indicated that the number concentration of heavy oil particle emissions was mainly determined by the viscosity-temperature characteristics and evaporation characteristics of the oil,so CH-4 15W40 had higher heavy oil particle emissions than CI-4 15W40and CJ-4 15W40.On the other hand,the viscosity-temperature characteristics,sulphur or sulphate content and metal content of the oil could all have impact on the the number concentration of total particle emission,so CI-4 15W40had higher total particle emission than CH-4 15W40 and CJ-4 15W40,and CJ-4 15W40 had greater feedback to the rising temperature,while CH-415W40 had the less one than 2 other lubricant oil.Moreover,the older lubricant oil can cause higher particle emission.