A phenomenological model is presented that predicts NO emissions from a conventional heavy-duty diesel combustion process. As the model is intented for application in the field of engine control, modeling activities have aimed at limiting the computational effort while maintaining a sound physical/chemical basis. The main inputs to the model are in-cylinder pressure data and trapped in-cylinder conditions together with basic fuel spray information. For its validation measured concentrations of respectively in-cylinder and exhaust gas NO from two different engines have been used. Relative changes in NO for a variation in fuel injection timing and for a variation in exhaust gas recirculation rate are well captured by the model. However, absolute emission levels are significantly overpredicted. Observed deviations are evaluated and possible explanations are suggested.
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