Browse Publications Technical Papers 2001-24-0076
2001-09-23

Modelling of transient influences on HDV Emissions 2001-24-0076

As passenger car exhaust emissions are becoming less pollutant, the share of Heavy Duty vehicle (HDV) emissions to the overall air pollution (local and regional) is increasing, especially for NOx and particles. However, adequate methodologies to model the emissions of a HDV in real world conditions do not yet exist. The main problems for generating accurate emission factors for HDV are
  1. 1)
    Since measurements on HDV engine test beds and/or HDV chassis dynamometers are rather expensive most national projects are based on small data bases. This makes it difficult to model fleet average emission bahvior.
  2. 2)
    Most emission models are based on steady-state measurements. Consequently, they are not properly equipped to make accurate predictions of emissions for the transient driving conditions that occur on the road. The influence of these transient conditions is for most of the driving cycles not negligible.
For these reasons the EU-projects ARTEMIS (Work Package 400) and COST 346 have been started at the beginning of 2000. Both projects have the objective to develop a commonly agreed European model for generating transient HDV emission factors.
The ARTEMIS model will be based on a broad database of steady-state emission maps, as well as a set of correction functions to account for the transient conditions in real world driving conditions. The actual power demand and speed of the engine are calculated on a second-per-second basis from the driving resistances and a driver/gear-shift model for any given vehicle driving cycle. This results in so-called ‘quasi-stationary emissions’, that are obtained by interpolation from the stationary emission maps. The correction functions translate these into transient emissions. Since the difference between transient and stationary emissions can be quite substantial, the elaboration of these correction functions is an important and challenging task of the projects.
The paper presents two different approaches for the simulation of HDV emissions under transient conditions, and compares the model results with measurements on both the engine test bed and a HDV chassis dynamometer.

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