Experimental and theoretical investigation of the effect of heat release rate on nitrogen oxides

Diesel engine powered vehicles are gaining importance due to the advantage of thermal efficiency. Vehicle induced pollution is one of the primary problem which has not been solved today. Nitrogen oxides are regulated pollutants and have to be reduced in diesel engines according to upcoming Euro-6 legislation. Investigation and modelling the effect of the rate of heat release on engine-out nitrogen oxides are the main aim of this PhD thesis. A zero-dimensional and multi-zone cylinder model was developed for estimation of the effect of the rate of heat release on performance parameters of diesel engine. Double-Wiebe rate of heat release global model was used to describe fuel combustion. Extended Zeldovich mechanism and partial equilibrium approach were used for modelling the formation of nitrogen oxides. A multi-cylinder, commercialized common-rail diesel engine was selected for the calibration process of model. Engine performance outputs and exhaust emissions were measured for different pre-injection quantities and injection advances. Rate of heat release was obtained by analysing the in-cylinder pressure data. Multi-zone cylinder model showed good relevancy, which is higher than 97% with respect to experimental in-cylinder pressure data, after the model calibration process. Also it was seen that the NOx formation model greatly predicted the engine-out NOx emissions.