Comparasion Study On Spray And Combustion Characteristics Among Ethanol-diesel,Water-emulsified Diesel,and Pure Diesel

With the development of Chinese automobile industry, emissions of the internal combustion engine have become one of the main sources of environmental degradation in our country. Appropriate alternative fuels, which have become a research hotspot, can greatly reduce the soot and NOx emissions of internal combustion engine with less changing diesel engine structure. While ethanol-diesel fuel and emulsified-diesel considered to be the suitable common alternative fuels.In this paper, a constant volume combustion bomb and the high speed digital schlieren method system have been used to study the characteristics of cold-spray, evaporation and combustion under different conditions. The fuel injection pressure ranged from 100 MPa to 200 MPa, the environmental density ranged from 7.5 kg/m3 to 15 kg/m3, the ambient temperature was set from 800 K to 1200 K, and the ambient gas oxygen concentration ranged from 15% to 21%. At the same time, doing comparasion study on cold-spray, evaporation and combustion characteristics among ethanol-diesel fuel(E10), pure diesel(E0) and water-emulsified diesel(W10). Try to make a better Understanding of the effects when diesel blending with ethanol and water.In the cold-spray experiments, the results showed that higher the injection pressure is, longer the spray penetration is, greater the spray area and spray volume are, and better atomization effect is. Higher the ambient gas density is, short the spray penetration is, bigger the spray cone angle is, while poor the overall atomization effect is, smaller the atomization area and volume are. In the evaporation experiments, the results showed that development law of evaporation characteristics and cold-spray characteristics are almost the same. In the combustion experiments, the results showed that, higher the environment temperature, the ambient gas density and the ambient gas oxygen concentration are, shorter the ignition delay period is, higher the peak INFL is, and higher the flame combustion temperature is. So that the Soot generation is greater, and so does the luminosity of smoke radiation. The flamer lift-off length is closer to the nozzle. While the combustion process near the end, the Soot oxidation speed is faster under high combustion temperature. So as the increase of environment density, environment temperature and oxygen concentration, the final Soot emission reduced. With the spray injection pressure increasing, better the fuel atomization effect is, lower peak INFL is, and less Soot generated, faster the oxidation rate of Soot is, so it can conclude that the spray injection pressure can effectively reduce final Soot emission. What’s more, this article also compares the spray, evaporation and combustion characteristics among ethanol-diesel fuel, pure diesel and water-emulsified diesel. The results showed that, there is little difference in cold-spray and evaporation characteristics among E10, E0 and W10. While has an opposite conclusion on combustion characteristics. obvious effects on combustion flame synthesis brightness, comprehensive combustion It turned out that the INFL value from high to low in sequence is E10 > E0 > W10, which can be concluded that diesel blending with 10% ethanol or 10% water can have a positive function on combustion process, reducing the final Soot emission.