Modeling of soot emission for heavy-duty diesel engines in transient operation

Sammanfattning: The soot emissions from diesel engines are much higher in transient operation than during steady state operation. In this thesis, a method for estimating the soot mass flow emission in transient drive cycles is presented. The proposed method uses stationary emission maps in combination with step responses. Bandpass filters are used to filter the engine torque/power to provide transient detection and quantification. The final estimation method combines the stationary emission map and the bandpass filtered signals with correction parameters determined by the step responses. Good results were obtained for the World Harmonized Transient Cycle (WHTC). Black box modeling was also conducted for the soot mass flow emission. The fitted models take two inputs: injected fuel mass per cycle and equivalence ratio. Linear models as well as nonlinear models were identified with the best results obtained for a nonlinear (Wiener) model. The best model had a fit of 95 % in accumulated soot mass emitted as a function of integrated power in the WHTC cycle. The system identification was performed using data from the first half of a WHTC cycle and validation was conducted using the whole cycle.