Study On The Impact Of Oxygenated Fuels On Diesel Particulate Matter Emissions

In order to get out of dependence on non-renewable petroleum fuels and meet the emission regulations,renewable oxygenated fuels will serve as the most promising alternative fuels.In order to study the impact of different oxygenated fuels on engine combustion and particulate matter emissions,from the point of view of the characteristics of oxygenated fuel and combining combustion control conditions in this paper,effects of the different fuels containing different oxygenic functional groups(n-butanol,DMC)and three butanol molecular structures(n-butanol,sec-butanol,iso-butanol)on combustion and particulate matter emissions are investigated by experimental research.By adjusting the intake parameters and injection parameters,the effects of fuel physical and chemical characteristics and combustion control strategy on combustion and particulate matter were determined.In the transient condition,combustion distortion and EGR overshoot increase particulate emissions,this paper studied the extent of improvement of transient particulate emissions from oxygenated fuel.This test is based on a high-pressure common rail diesel engine,the experiment set up a real-time engine combustion and emissions data acquisition and storage system.The development of electric control EGR system can realize the active control and flexible regulation of intake air volume.According to the measurement and analysis system of particle size distribution from steady and transient process,the TSI3090 particle size analyzer and the two stage dilution system were used.The same oxygen content of diesel/n-butanol,diesel/DMC,diesel/sec-butanol and diesel/iso-butanol test fuel were used,the experiment studied the influence of oxygenated fuel on combustion and particulate emissions by adjusting the intake parameters and injection parameters.The results showed that:The physical and chemical characteristics of the fuel are one of the important factors affecting the combustion and emission processes of the engine.In the heavy load conditions,adding n-butanol and DMC can not cause excessive increase of NOx emissions,for other emissions they had more significant reduction effect.Nuclear particulate emissions increased slightly,but accumulated particulate emissions decreased.The butanol isomers were further studied.More branched structure of butanol increased,more difficult to be ignited.The ignition delays of three diesel-butanol blending fuels were sequenced as n-butanol,sec-butanol and isobutanol from short to long while burning duration showed the opposite trend.In the low-load condition,soot was the most,while NO_X was the least for isobutanol.S-butanol had more nuclear particles than n-butanol.In the heavy load conditions,the difference for butanol isomer molecular structure that impact on cylinder combustion and particulate emissions was not obvious.Increasing the injection pressure has a positive impact on reducing particulate emissions.NO_X emissions from diesel,diesel/n-butanol,and diesel/DMC were not significantly different,other emissions had significantly reduced.Butanol and DMC have lower viscosity than diesel,so butanol and DMC helped reduce the need for high injection pressures.The introduction of a certain amount of EGR can help reduce the cylinder temperature and oxygen concentration,achieves the purpose of reducing NO_X emissions.Butanol and DMC combined with EGR strategy reduced soot formation in high temperature hypoxic zones and reduced NOx emissions in high temperature oxygen rich zones,achieved the purpose of reducing NOx and particulate emissions at the same time.The addition of oxygenated fuel created the application conditions for a large proportion of EGR.In the transient process,burning oxygenated fuels helped to improve the engine performance.The addition of oxygenated fuel can reduce the turbocharger's response speed requirements,improve combustion,and reduce ultra-fine particle emissions.Over-regulation of EGR leads to an increase in diesel soot emissions.Diesel/n-butanol and diesel/DMC can effectively improve soot emissions and reduce the number of accumulated particulate matter.It showed that n-butanol and DMC had certain potential to reduce particulate matter emissions in transient load conditions.