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This paper presents an experimental study of a water injection (WI) application where water fog is added in the intake of a common rail High-Speed Direct Injection (HSDI) automobile Diesel engine in order to reduce pollutant emissions Nitrogen Oxides and Particulate Matter (NOx and PM) for future emissions standards. Also studied are the physical parameters of the engine (in-cylinder pressure, air inlet temperature, air mass flow, specific fuel consumption etc). The results are compared with those obtained with low-pressure dry Exhaust Gas Recirculation (LP EGR) on the same engine. Tests performed with the water injection system show that a much better NOx / PM trade-off (reduced NOx emission levels at constant PM emission levels) is obtained than with EGR especially at points of high engine loads. In addition, tests are performed with EGR in parallel with water injection to investigate the reduction of NOx emissions while potentially reducing water consumption.

The tightening restrictions, in terms of fuel consumption, have pushed the vehicle manufacturers and equipment suppliers into searching for innovative ways to reduce the carbon dioxide emissions. Along with the ameliorations added to the engine itself, additional systems are grafted to the engine in order to keep up with the ever-changing laws. Isolating the impact on the fuel consumption of an added system, by on board testing, is a complicated task. In this case, using simulation modeling allows the reduction of delays related to prototyping and testing. This paper presents modeling of various thermal systems in a vehicle and their interactions to evaluate the fuel consumption using AMESim software. As means to reduce the CPU cost of the model (calculation time), without decreasing its predictability, engine modeling has been done by two steps: high frequency model and mean value model.