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The dramatic change in terms of pollutant constraints for diesel engines, with future Euro-6 regulations for example, will probably require the improvement of alternative combustion modes such as homogeneous combustion (Homogenous Charge Compression Ignition - HCCI). These new concepts allow the reduction of NOx and particulate emissions to very low levels for low loads thanks to a high level of external Exhaust Gas Recirculation (EGR) while maintaining CO2 emission advantage of diesel engines. Nevertheless, due to a resultant low combustion temperature, HC and CO emissions rise significantly, especially at low load when the catalyst bed temperature is not sufficient for their aftertreatment. This paper describes three considered ways to potentially overcome this barrier thanks to HCCI combustion improvement.

Modern diesel engines are equipped with an increasing number of actuators set to improve human comfort and fuel consumptions while respecting the restricted emissions regulations. In spite of the great progress made in the electronic and data-processing domains, the physical-based emissions models remain time consuming and too complicated to be used in a dynamic calibrating process. Therefore, until these days, the calibration of the engine's cartographies is done manually by experimental experts on dynamic test bed, but the results are not often the best compromise in the consumption-emissions formula due to the increasing number of actuators and to the nonlinear and complex relations between the different variables involved in the combustion process. Recently, neural networks are successfully used to model dynamic multiple inputs - multiple outputs processes by learning from examples and without any additional or detailed information about the process itself.

An experimental study of diesel spray / wall interaction is conducted in a pressurized bomb using Phase Doppler Anemometer and high speed shadowgraphy. The instantaneous droplet sizes and velocities are measured in the impingement region, without combustion, in the plane located at 3 mm from the wall, for four wall temperatures 20, 200, 300 and 400 °C. A droplet wall interaction model has been developed and incorporated in the Kiva II code. The model accounts for droplet atomization and heat transfer. The computed spray penetration, the shape contour and the SMD are compared respectively to spray photographs and PDA measurements.