5.4 Regulated engine emissions – background and data sources
Regulated emissions (i.e. NOx, HC, PM (particles) and CO) are difficult to calculate since the formation of these substances are related to the combustion process inside the engine. There are a number of ways to estimate these emissions, e.g. use typical emission data presented by vehicle manufacturers, usually derived from certification tests
- use data generated by on-board diagnosis equipment available (as option) in newer vehicles
- use information from laboratory tests of engines and vehicles, available from literature (e.g. research projects and open tests)
- use maximum emission values as defined by legal requirements.NTM presents emission data for the following diesel engine ‘generations’: Pre Euro/Euro ’0’, Euro I, Euro II, Euro III, Euro IV and Euro V. The table below shows EU emission standards for heavy duty diesel vehicles Euro I – VI:
EU emission standards for heavy duty diesel engines (www.dieselnet.com)
One of the aims with the NTM method is to encourage the user to substitute the presented default data with situation-specific operational data. Since fuel consumption is one key operational data often available, the NTM emission calculation is based on vehicle fuel consumption. On-line measurement/calculation data on emissions are only available from the most advanced trucks, while fuel consumption data is readily extracted or measured from most trucks in operation.
All emission factors and fuel consumptions for road vehicles are taken from the European road emission model HBEFA 3.1 where Euro 5 and 6 and onwards will be taken from 3.2.
The emission factors and fuel consumptions are in HBEFA presented as grams pollutant per vehicle kilometre and grams fuel per vehicle kilometre.
To obtain fuel consumptions in grams per liter, the fuel consumptions from HBEFA were divided with the fuels density (Europe diesel, 0,830 kg/l). The emission factors from ARTEMIS were then divided with the volumetric fuel consumption to obtain grams pollutant per liter fuel burnt for each vehicle type and engine/fuel combination.