Study On Effect Of Diesel/Aviation Kerosene Blended Fuels On Particulate Matter Properties And Unconventional Pollutant Emissions

The physical and chemical properties of the fuel change the formation process of the in-cylinder mixture,which has an important impact on the combustion,emissions and the physical and chemical properties of the particles.At the same time,conventional pollutants have been effectively monitored and controlled,and unconventional pollutants have attracted more and more attention because of their great harm.This paper was based on an electronically controlled,air-cooled and direct-injected diesel engine with unit pump,mixed with different volume ratios of RP-3 aviation kerosene and diesel to form blended diesel/RP3 fuels.Through experimental methods,the influence of RP-3 blending ratio on emission characteristics and particle physical and chemical properties was studied,which provided theoretical basis on DPF design and reduction of unconventional emission technologies when aviation kerosene/diesel blended fuel was used in diesel engines.The main conclusions are as follows:（1）Using cylinder pressure sensors,charge amplifiers and combustion analyzers to collect the combustion process of different blended fuel in the engine.The ignition delay,combustion duration,cylinder pressure and combustion temperature were obtained under different working conditions and different RP-3 blending ratios.Under the same working condition,as the blending ratios of RP-3 increased,the ignition delay was extended,the combustion duration was shortened,the combustion pressure in the cylinder did not change much,the corresponding crankshaft angle was delayed,and the maximum combustion temperature in the cylinder increased slightly.（2）The SESAM-FTIR FTIR multi-component exhaust gas analyzer was used to collect conventional and unconventional emissions pollutants from different blended fuels used in engines,and properties of the conventional emissions（CO,THC,soot,NO_x）and unconventional emissions（C₂H₄,C₃H₆,CH₄,AHC,HCHO,MECHO）under different working conditions and different RP-3 blending ratios were obtained.Conventional emission characteristics:under the same operating conditions,after the diesel was blended with RP-3 aviation kerosene,it could greatly reduce soot emissions and improved the trade-off relationship between NOx and soot,but the THC emission generally was on an upward trend,CO emissions increased at large loads and decreased at medium and small loads.Unconventional emission characteristics:for the same working condition,as the mixing ratio of RP-3 increased,C₂H₄,C₃H₆,CH₄,and AHC emissions increased.HCHO and MECHO emissions increased at large loads and decreased at medium and small loads.For the same fuel,the emissions of C₂H₄,C₃H₆,CH₄,AHC,HCHO,and MECHO decreased as the load increases.（3）Based on transmission electron microscope images and Raman spectra under different working conditions and different RP-3 blending ratio,through fractal dimension method and five-band fitting method,combined with MATLAB and Image J,the overall microscopic morphology,agglomeration degree,average diameter of primary carbon particles and degree of order were analyzed.For the same working condition,with the increase of the RP-3 blending ratio,the shape of the particles did not change much,and the overall shape was chain clusters;The overall fractal dimension of the particles increased slightly,and the fractal dimension was between1.59～1.98,and the particle microstructure was more compact;The average diameter of the primary carbon particles was reduced,and the whole diameter was between24.67～34.71 nm;the graphitization degree of the particulate was increased,the amorphous carbon content was reduced,and the carbon arrangement structure of the particulate was more orderly.For the same fuel,as the load increased,the fractal dimension increased,the degree of particulate stacking increased,the degree of graphitization increased and the amorphous carbon component decreased.（4）Based on thermogravimetric analyzer,TG and DTG curves of particles under different working conditions and different RP-3 blending ratios were obtained.The oxidation characteristic temperature and apparent activation energy of particle were analyzed.The oxidation interval temperature of the particle in different working conditions and different blending ratios was 500-720℃,and the energy required for oxidation was between 98.8～150.6 kJ·mol^-1.For the same working condition,after the diesel was blended with RP-3 aviation kerosene,the Ignition temperature（T_i）,peak temperature of oxidation rate（T_p）,end temperature（T_e）and apparent activation energy increased,For the same fuel,the oxidation characteristic temperature and apparent activation energy increased with the increase of load,and the energy required for oxidation increased.