Study Of The Combustion And Emission Control Of 2,5-dimethylfuran On A Diesel Engine

Rapid development of industrialization and modernization has led to excessive consumption of fossil fuels,which is found to be the major source of air pollution and makes energy supply extremely emergency.Therefore,it is important to search for alternative and sustainable energy sources in order to reduce the dependency on fossil fuels and lower the emissions of pollutants;in particular,it is highly significant in terms of the transportation industry which consumes one third of the fossil fuels.The bio-fuel 2,5-dimethylfuran(DMF)in this thesis shows excellent adaptability to the current engine because of its unique characteristics,which leads to extensive research boom.The study was carried out on a direct-injection compression-ignition diesel engine fueled with diesel fuel and diesel-2,5-dimethylfuran(DMF)blends.The blended fuels contain 10%,20%,30%and 40%by mass of DMF,called D10,D20,D30 and D40.Firstly,experiments were conducted at various loads ranging from 1.3 to 11.3MPa BMEP at a constant speed of 1800 rpm to investigate the combustion and emissions performance of DMF.The results indicated that diesel-DMF blends produced longer ignition delay and shorter combustion duration.The diesel-DMF blends could lead to higher NOX emissions at medium and high engine loads.But there was a significant reduction of soot emission when fueled with diesel-DMF blends;the CO and HC emissions for tested fuels showed no significant difference at medium and high engine loads.Secondly,the combustion and emissions of diesel,D10 and D30 were investigated when the EGR opening degrees ranging from 20%to 80%at a constant load of 0.38MPa and speed of 1800 rpmThe results shown that with the increase of EGR opening degrees,the maximum in-cylinder pressure and peak heat release rate of diesel,D10 and D30 appeared significant downward trend,and produced longer ignition delay.With the increase of DMF proportion in the blending fuel,the ignition delay also got longer.More,it significantly reduced the NO_X emissions,but increased HC emissions when increasing the EGR opening degree.Finally,the experiment was conducted to investigate the effects of main injection timing,pre-injection timing and pre-injection mass,EGR opening degree,engine loads and speeds on the particle size distribution.The results shown that,it can significantly reduce the soot particle emissions at the same condition when adding DMF into diesel fuel.With the main injection timing advanced,the number of particles of diesel and blending fuels declined and then increased.With the increase of pre-injection timing,the number of particles in nuclei mode significantly increased,but decreased in the accumulation mode;otherwise with the increase of pre-injection mass,the number of particles in nuclei mode and accumulation mode were both decreased.With the EGR opening degree increase,the number of particles in nuclei decreased,but increased in accumulation mode.With the engine loads increase,the number of particles in all modes increased.But with the increase of speed,the particle size distribution of diesel,D10 and D30 shown no significant regular pattern.