Estimation of deviations in NO and soot emissions between steady-state and EUDC transient operation of a common-rail diesel engine

The study measured Mass Air Flow, (MAF), Manifold Absolute Pressure, (MAP), and emissions of NO and soot during fourteen transients of speed and load, representative of the Extra Urban Drive Cycle (EUDC). The tests were conducted on a typical passenger car/light-duty truck powertrain (a turbocharged common-rail diesel engine, of in-line 4-cylinder configuration). The objective was to compare NO and soot with corresponding steady-state emission results and propose an engine measurement methodology that will potentially quantify deviation (i.e. deterioration with respect to steady state optimum) in emissions of NO and soot during transients. Comparison between steady state, quasi-steady-states (defined later in the paper) and transients indicated that discrete quasi-steady-state engine operation, can be used for accurate prediction of transient emissions of NO and soot. Furthermore, quasi-steady-state engine characterisation quantified NO and soot deterioration that may occur due to MAF and MAP deviations from their optimised (steady-state) values. Therefore, the results from quasi-steady-state can be used to estimate deterioration in emissions during transients. These results are potentially of use in modelling with a view to assess component to engine compatibility during the engine development phase and minimise emissions deterioration (due to component ageing and production variability) during the life-time of engine.