Study On The Effects Of Fuel Injection Law On Emission Performance Of A Diesel Engine

The influence of nitrogen oxides discharged by shipping power plants on atmosphere andmarine environment is increasingly serious. With the emission regulations is becoming perfectand strict gradually, it brings an unprecedented challenge to the development of marine dieselengine. The diesel engine fuel injection law directly affects the formation, combustion ofin-cylinder gas mixture and the generation of emission. The in-cylinder pressure, temperatureand combustion heat release rate etc. in various fuel injection laws are different, and theseparameters are directly related to the power, economy and emission of diesel engine.Based on the Hiroyasu Model, this paper establishes a modified quasi-dimensionalcombustion model. The mixture of positive cetane and α-methylnaphthalene is used toreplace diesel oil, fully considering the influence of boiling point and critical point of fuel onevaporating process and the influence of forced convection and strong Stephen flow on theliquid drop surface of hot environment on the regulation of heat transfer and mass transfer.Through numerical simulation method, the comparative optimization is made to different fuelinjection law.This paper researches on the influence of multiple fuel injection laws on the emissionperformance of a certain high-middle speed diesel engine, including single injection(rectangle, trapezium oil injection law)、pre-injection、post injection, meanwhile, consideringthe influence law of fuel injection timing and inflection point of trapezium oil injection curveon combustion process. Through simulation contrast, the conclusions are gained in thefollowing: the effect of NO emission in rectangle fuel injection law is the best, but carbonsmoke emission is somewhat worsen; with the delay of fuel injection timing, NO emissionamount is reducing but carbon smoke emission is increasing; with the delay of prophaseinflection point in trapezoid fuel injection law curve, NO emission amount is increasing butcarbon smoke emission is decreasing with a small variation; for pre-injection technology,when its amount is2%and main-pre injection interval is20℃A, the emission effect is thebest; for post injection technology, when its amount is15%and post injection interval is16℃A, the emission effect is the best.Through simulation calculation of diesel engine, this paper effectively improves theemission performance of engine and gets a relatively ideal effect of emission. The research results of this paper provide an improvement diesel performance and pollutants emission.