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A non-linear transient engine cycle simulation software has been integrated to a versatile quasi two-dimensional multi-zone combustion-emissions model in order to predict exhaust emissions under transient operating conditions. The basic engine and exhaust emissions models are outlined with special reference to the requirements of engine transient operation. The predictive capability of the simulation is demonstrated through comparison of measured and predicted performance and emissions for several engine transients.

Experimental data and analytical techniques are used to study the trade-offs between emissions and performance for a turbocharged, intercooled HSDI diesel engine equipped with an electronically controlled exhaust gas recirculation (EGR) system. Measured data are used to support a thermodynamically based cycle simulation comprising a multi-zone combustion and emission model. The simulation is used to investigate the effects of various key parameters including fuel injection equipment (FIE) on engine performance and emissions.

A model for the prediction of combustion and exhaust emissions of DI diesel engines has been formulated and developed. This model is a quasi-dimensional phenomenological one and is based on multi-zone combustion modelling concept. It takes into consideration, on a zonal basis, details of fuel spray formation, droplet evaporation, air-fuel mixing, spray wall interaction, swirl, heat transfer, self ignition and rate of reaction. The emission model uses the chemical equilibrium, as well as the kinetics of fuel, NO, CO and soot reactions in order to calculate the pollutant concentrations within each zone and the whole of cylinder. The accuracy of prediction versus experimental data and the capability of the model in predicting engine heat release, cylinder pressure and all the major exhaust emissions on both zonal and cumulative basis, is demonstrated.

A microprocessor fuelling controller, which limits engine maximum fuelling in proportion to cylinder-trapped mass during transient operation, is used to examine the effect of fuelling control on engine transient performance. Results obtained under various transient schedules including acceleration, load application and a combination of the two, with alternative fuelling control strategies and a number of injection timing settings are presented and discussed, together with a full analysis of the effect of fuelling control on engine performance. It is shown that exhaust smoke may be reduced to low levels during most engine transients, particularly during acceleration, by the use of a fuelling controller. However, the choice of a proper control strategy is essential in order to optimize response versus smoke during acceleration and ensure stall-free operation of the engine during load acceptance.