Simulation Studies of the Effect of Fuel Injection Pattern on NO and Soot Formation in Diesel Engines

Up to now, diesel engines with direct fuel injection are the propulsion systems with the highest efficiency for mobile applications. Future targets in reducingCO2-emissions with regard to global warming effects can be met with the help of these engines. A major disadvantage of diesel engines is the high soot and nitrogen oxide emissions which cannot be reduced completely with only engine measures today. The present paper describes two different possibilities for the simultaneous in-cylinder reduction of soot and nitrogen oxide emissions. One possibility is the optimization of the injection process with a new injection strategy the other one is the use of water diesel emulsions with the conventional injection system. The new injection strategy for this experimental part of the study overcomes the problem of increased soot emissions with pilot injection by separating the injections spatially and therefore on the one hand reduces the soot formation during the early stages of the combustion and on the other hand increases the soot oxidation later during the combustion. Another method to reduce the emissions is the introduction of water into the combustion chamber. Emulsions of water and fuel offer the potential to simultaneously reduceNOxand soot emissions while maintaining a high-thermal efficiency. This article presents a theoretical investigation of the use of fuel-water emulsions in DI-Diesel engines. The numerical simulations are carried out with the 3D-CFD code KIVA3V. The use of different water diesel emulsions is investigated and assessed with the numerical model.

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Multidimensional Modeling of Impinging Sprays on the Wall in Diesel Engines

Applied Mechanics Reviews ◽

10.1115/1.3098930 ◽

1999 ◽

Vol 52 (4) ◽

pp. 119-138 ◽

Cited By ~ 18

Author(s):

J. Senda ◽

H. G. Fujimoto

Keyword(s):

Diesel Engines ◽

Formation Process ◽

Fuel Injection ◽

Soot Formation ◽

Film Formation ◽

Combustion Process ◽

Interaction Process ◽

Droplet Breakup ◽

Wall Surface ◽

Wall Interaction

This article summarizes model analysis of the dispersion process of a Diesel spray on the wall surface in order to simulate the spray-wall interaction process in Diesel engines. The mixture formation process near the wall of the piston cavity affects the combustion process and the hydrocarbon or soot formation process through the quenching of the mixture and flame at the wall surface. In particular, mixture burning occurs mainly near the cavity wall through the whole combustion period in the case of high pressure fuel injection. In this article, representative modeling approaches on spray-wall interaction process including the film flow formation are summarized briefly. Then, our models of spray impingement for low/high-temperature models including the process of fuel film formation, film breakup, wall-drop/film heat transfer, and droplet breakup owing to the solid-liquid interface boiling are introduced with the comparison of experimental results. This review article includes 83 references.

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