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Reducing NOx tailpipe emissions is one of the major challenges when developing automotive Diesel engines which must simultaneously face stricter emission norms and reduce their fuel consumption/CO2 emission. In fact, the engine control system has to manage at the same time the multiple advanced combustion technologies such as high EGR rates, new injection strategies, complex after-treatment devices and sophisticated turbocharging systems implemented in recent diesel engines. In order to limit both the cost and duration of engine control system development, a virtual engine simulator has been developed in the last few years. The platform of this simulator is based on a 0D/1D approach, chosen for its low computational time. The existing simulation tools lead to satisfactory results concerning the combustion phase as well as the air supply system. In this context, the current paper describes the development of a new NOx emission model which is coupled with the combustion model.

Diesel engines are being more commonly used for light automotive applications, due to their higher efficiency, despite the difficulty of depollution and extra associated costs. They require more accessories to function properly, such as turbocharging and post-treatment systems. The most important pollutants emitted from diesel engines are NOx and particles (in conventional engines), being difficult to reduce and control because reducing one increases the other. Low temperature combustion (LTC) diesel engines are able to reduce both pollutants, but increase emissions of CO and HC. Besides HCCI and EGR systems, one method that could achieve LTC conditions is by using multiple injections (pilot/main, split injection, etc.). However, understanding multiple diesel injection is no easy task, so far done by trial and error and complex 3D CFD models, or too simplified by 0D models. Therefore, a numerical 1D model is to be adapted to simulate multiple injection situations in a diesel engine.

Unsteady flow in the inlet and exhaust systems of Internal Combustion Engines can be simulated with multi-dimensional simulation codes. Due to their computational time, other methods are widely used and give the opportunity of coupling it with a model of the complete engine. This paper reports on an investigation undertaken to compare the accuracy of the method of inertia, the acoustic method and the one-dimensional method for modeling the gas flow in pipe systems. Results of this study give the advantage and disadvantage of each approach. The comparison shows good agreement between one-dimensional and experimental results while the calculation time is kept acceptable.

Diesel engines are being more commonly used for light automotive applications, due to their higher efficiency. However, pollutant emissions can be higher than their gasoline counterparts, being difficult to reduce and control because reducing one pollutant increases another. One way to reduce emissions is by using multiple injection strategies. However, understanding multiple injections is no easy task, so far done by trial and error and experience. Therefore, a numerical 1D model is to be adapted to simulate multiple injection situations in a diesel engine. In a previous paper by the authors, an existing model was adapted with a thermal dilatation model to consider both radial and axial dilatations in the diesel spray. The base model used is that of Ma et al (based on the Eulerian model of Musculus and Kattke for inert diesel jets).