In the present study, a semiempirical, zero-dimensional multizone model, developed by the authors, is implemented on two\nautomotive diesel engines, a heavy-duty truck engine and a light-duty passenger car engine with pilot fuel injection, for various\noperating conditions including variation of power/speed, EGR rate, fuel injection timing, fuel injection pressure, and boost pressure,\nto verify its capability for Nitric Oxide (NO) emission prediction.The model utilizes cylinder�s basic geometry and engine operating\ndata and measured cylinder pressure to estimate the apparent combustion rate which is then discretized into burning zones\naccording to the calculation step used. The requisite unburnt charge for the combustion in the zones is calculated using the\nzone equivalence ratio provided from a new empirical formula involving parameters derived from the processing of the measured\ncylinder pressure and typical engine operating parameters. For the calculation of NO formation, the extended Zeldovich mechanism\nis used. From this approach, the model is able to provide the evolution of NO formation inside each burned zone and, cumulatively,\nthe cylinder�s NO formation history. As proven from the investigation conducted herein, the proposed model adequately predicts\nNO emissions and NO trends when the engine settings vary,with low computational cost. These encourage its use for engine control\noptimization regarding NOx abatement and real-time/model-based NOx control applications.
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