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Measurements of the soot emissions and engine operating parameters from a diesel engine during transient operation were used to investigate the influence of transient operation on the soot emissions, as well as to validate a realtime mean value soot model (MVSM, [1]) for transient operation. To maximize the temporal resolution of the soot emission and engine parameter measurements (in particular EGR), fast instruments were used and their dynamic responses characterized and corrected. During tip-in transients, an increase in the soot emissions was observed due to a short term oxygen deficit compared to steady-state operation. No significant difference was seen between steady-state and transient operation for acceleration transients. When the MVSM was provided with inputs of sufficient temporal resolution, it was capable of reproducing the qualitative and, in part, quantitative soot emission trends.

A mean value soot model (MVSM) was developed and validated for the realtime prediction of the raw, engine-out soot emissions from common rail diesel engines. Through the consideration of five representative states during the combustion cycle, the developed MVSM determines the engine out soot emissions based on the soot formation and oxidation processes, using only parameters available from a standard engine control unit. 16 model parameters are used to describe the engine, fuel, and combustion characteristics, and must be determined for each engine and fuel combination. The MVSM was parameterized and validated using the measured soot emissions from two different engines operating with a total of three different fuels. After parameterization, the MVSM was capable of qualitatively and quantitatively reproducing the soot emissions for operating points throughout the entire operating map, including for operating regimes not considered during the parameterization.