Study On Effect Of Biodiesel Ratio On Performance And Emissions Of Light Duty Diesel

With diesel vehicles worldwide trend accelerated,it will be more and more demand for diesel in the future.And with oil resources depleted,the auto industry rapidly developed in recent years and people's awareness of environmental protection has greatly accelerate the pace of development of alternative fuels.Biodiesel,by the superior environmental performance,has attracted all the attention in the word.This paper has investigated the effect of engine's performance and its pollutant emissions that used four biodiesels with different ratio(B0, B10, B20 and B30) on a light duty diesel that meets the EuroⅢemission standards and without its construct and parameters being changed and adjusted. The results of the experiment should has directive significance to the application of Bio-diesel in the engine. The main work is as follows.1. The experiment of studying on engine performance shows that the maximum engine torque reduced and the fuel consumption and fuel consumption rate for the overall discipline gradually increased with the biodiesel fuel content increased on the condition of structural parameters and the electric control system in the engine without being adjusted.Compared with B0, the minimum fuel consumption rate of B10 engine increases 0.2% ~ 1.1%; that of B20 engine increases 1.7% ~ 4.4% and that of B30 engine increases 2.2% ~ 6.2%.2.The analysis of different types of fuel combustion characteristics shows that compared with B0 fuel when the pure bio-diesel fuel is used the main spray combustion starting point,end point and the focus of exothermic all put forward ,the main jet combustion duration shortens, the maximum combustion pressure and the peak of heat release rate decreased, the corresponding phase advances.3.To different ratio bio-diesel fuels added, with an increase in the content of biodiesel fuel, the highest-cylinder engine pressure and the peak of heat release rate gradually lowers,and whose corresponding phase position and the Exothermic focus gradually advances, compared with B0 compared, the phase position of combustion parameters of B30 can put forward 1°CA the most, ignition delay and combustion duration has been shortened. The effect of adding proportion of bio-diesel to the maximum cylinder pressure is little, and to the peak of heat release rate is large. The impact of the peak of heat release rate under the middle-load and large load conditions become more pronounced.Compared with B0, the maximum cylinder pressure of B30 fuels only reduces by 3.8%, while the peak of heat release rate reduces 11.5% at 75% load point.4. According to the test results of the total engine power characteristics, and the universal characteristics (load characteristic) and the emission characteristics comprehensively considered with power, economic and emissions,it's suitable for the engine using bio-diesel hybrid fuels with the addition of biodiesel to 10 percent. 5. Using biodiesel blended fuel, the diesel engine can reduce CO, PM, DS emissions, but the NOx emissions increase. compared with B0 the B30 fuel used can reduce the CO, PM 13 and the DS condition weighted average emissions respectively by 16.6%, 22.0% and 19.5%, while the NOx increased by 10.2%, HC and SOF respectively decreases by 22.0% and 22.0% .6. With the increase of content of bio-diesel fuel blends,the brake specific emissions of CO, PM and DS decrease gradually, that of HC and SOF emissions change little, that of NOx emissions increases gradually. Under different load conditions, bio-diesel content has different impact degree to exhaust pollutants.7. To different proportion of bio-diesel hybrid fuels added, the emission pollutants'weighted brake specific emissions has the similar change law with the overall change law of the brake specific emissions ,and the weighted brake specific emissions of CO, PM and DS decrease larger under the conditions of heavy load. That of NOx emissions has the same increase amplitude under all conditions.8.That the Bio-diesel fuel has the character of oxygen-containing is the main reason causing the low emissions of CO, PM and DS and the emissions increase of NOx.9. A gas chromatography method is established and the GC-2014 gas chromatograph is used to make a qualitative and quantitative analysis of HC emission composition in the low boiling point under the low speed low load condition and the idling condition. The HC emission components of low boiling point under idling condition is composed of methane (CH4), ethane (C2H6), ethylene (C2H4), propylene (C3H6), acetylene (C2H2), isobutane, n-butane and 1-3 Succinimide Triazene. Of these, the ethylene and propylene has the largest proportion and play a decisive role ,and is the focus of control. Under low-speed low load conditions (1943r/min, 25% load), eight components of HC in low boiling point are still measured, including which the methane and ethylene have the largest proportion, but emission levels have declined due to improved combustion.