| In this paper,the research background is in the 2000 m high altitude,atmospheric pressure and low oxygen concentration in plateau area,by mixing biomass oxygen fuel change effective measures the performance of diesel fuel quality is to restore a plateau.Taking D30 type high pressure common rail diesel engine as the research model,first launched the original machine universal characteristic test,to test the performance and emissions D30,and for the external characteristic of diesel fuel mixing biomass burning oxygen(15% biodiesel as D85E15,15% nbutyl alcohol as D85B15,15% poly dimethyl ether as methoxyl D85P15,15% are amyl alcohol as A15)to provide the original machine contrast data.Experiments show that: on the basis of the V diesel fuel,the dynamic performance of diesel engine will be increased with the increase of oxygen mixed fuel is reduced,and the fuel consumption and NOx emissions increased at the same time,under the full load and low speed not pervious to light smoke and CO emissions reduce obviously.The comprehensive analysis of several fuels shows that the diesel engine has a good comprehensive performance in the combustion of low proportion n-butanol and diesel fuel in the high altitude area of 2000 meters.Secondly,the effect of different fuel on the performance,emission and post-processing performance of the diesel engine is carried out in different speed constant torque(50N.M).The experimental results show that the effective thermal efficiency of polymethoxylated dimethyl ether(D80P20)is obviously higher than that in the middle and low speed.At high speed,20% of n-pentanol(D80A20)NOx emission was low,and CO emission was lower at low and middle speed.D80A20 has a significant effect on the conversion efficiency of CO emission after loading and reprocessing of DOC and CDPF,and the emission conversion efficiency of D80A20 in posttreatment DOC+CDPF is relatively higher than that of D80P20.Under high rotation speed,the total pressure difference of the DOC+CDPF after loading was significantly higher than that of the CDPF after loading.At high speed,the total pressure difference of DOC+CDPF after combustion of D80A20 was increased.Combustion of D80P20 at high speed with high back pressure.When the fuel of three different physicochemical properties is at low speed,the exhaust temperature difference of the front end of DOC is not obvious.Only at high speed,the difference between the DOC front end of the three fuels and the end of DOC and the rear end of the CDPF will be greater.However,the exhaust temperature of the back-end of DOC and CDPF is relatively small.The comprehensive performance of D80A20 is better than that of D80A20.The effective thermal efficiency of D80A20 increases sharply with the increase of rotational speed during the regeneration of CDPF at different rotational speeds,while the increase of D80P20 is small,and there is a tendency to decrease when the speed is high.The NOx emission of D80P20 is obviously higher,but the emission of CO tends to 0 with the increase of rotational speed.The NOx emission of D80A20 is significantly lower than that of D80P20,while the CO emission is higher at medium and low speed.The CO conversion efficiency of D80P20 in CDPF regeneration test is basically 100%.The D80A20 and diesel trends are basically the same.D80P20 and D80A20 increase with the speed,and the conversion efficiency of CDPF is gradually reduced.With the increase of rotating speed,the diesel back pressure is larger in the regeneration process of CDPF.When adding oxygen-containing fuel D80P20 and D80A20,the particle regeneration was slow,so the back pressure was small.The exhaust temperature at the front end of the DOC with pure diesel and D80A20 was significantly lower than that of the back end of DOC and CDPF.However,there is a small difference in the temperature trend between the front end of DOC,the end of DOC and the end of CDPF after combustion of D80P20.The comprehensive performance of D80P20 is relatively good in the process of CDPF regeneration.According to D30 main technical parameters,the high pressure common rail diesel engine by coupling CONVERGE simulation software to build mechanism of ethanol/biodiesel,simulation studies different EGR rate(0%,25%,45%),and different blending ratio of compression ignition engine under the influence of the combustion and emission characteristics.Research shows that: under such as EGR rate with the increase of ethanol blending ratio,the maximum explosion pressure in cylinder showed a trend of increase,Soot emissions reduced.When an EGR rate is bigger,NOX emissions of final value is reduced,and the Soot emissions was increased.At the same time,with the increase of the EGR rate,the emission of NOx is gradually increased,and the emission of NOx decreases gradually,and the decrease of NOx emission is significant.EGR rate is fixed at 45%,was studied in different injection time(0 ° CA BTDC,6 ° CA BTDC,12 ° CA BTDC,18 ° CA BTDC,24 ° CA BTDC and 30 ° CA BTDC),two different types of fuel characteristics,with the increase of fuel injection advance Angle makes the combustion period moved forward,the ignition delay period and premixed more even,lead to the instantaneous peak heat release rate in cylinder and cylinder pressure and temperature are increased.According to the products of combustion in cylinder under different injection time of 3 d slice cloud picture shows that with the increase of fuel injection advance Angle,different mixing ratio of mixed fuel in cylinder active free radical(OH,O)concentration and CO increase,Soot generation decreases.As the fuel injection time continues in advance,the fuel characteristics are less affected,so when the temperature and pressure in the cylinder continue to rise,NO emission increases.The comprehensive analysis of the EGR rate was 25% ethanol blending ratio was 20%(E20 EGR25)injection time of 12 ° CA BTDC when the comprehensive performance of diesel engine is relatively good. |
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