Browse Publications Technical Papers 2020-01-2091

The Impact of the Fleet Age Structure on the Cold-Start Emission. Case Study of the Polish Passenger C and Light Commercial Vehicles 2020-01-2091

Road transport sector is significant source of the air pollution in Poland. The total exhaust emission from particular vehicle is estimated as the total mass of the selected air pollutant released into the air during the vehicle’s trip. In the context of the thermodynamic conditions, the total exhaust emission can be split into two parts: hot emission, when the engine achieves the normal operating temperature, and cold-start emission - produced during the thermally unstable engine’s operating conditions.
The aim of the paper is to present results of mathematical modelling of the influence of the fleet age structure used in Poland on the cold-start emissions which are released into the air shortly after the engine’s start. There are considered emissions from the passenger cars, and the light commercial vehicles.
The emissions of enumerated pollutants are estimated basing on the official projections of the fuel consumption for the period 2025 - 2040 (with the 5 years intervals), and the changes in the fleet’s average age considering the progress in the environmental properties of the engines (the Euro standards).
Presented analysis does not consider parameters that can impact the cold-start emissions such as e.g. ambient temperature, and trip length.
The presented result of modelling show that with the change of the structure of vehicles (replacement of old vehicles with lower Euro standards with new vehicles with higher Euro standards), it will reduce cold-start emissions and total emissions.
The modelling is carried out using the COPERT software, which is widely applied for purposes of the national emission inventories compilation.
The contribution of the cold-start emission to the total emission generated by the road transport is negligible in case of NOx and PM2.5 particulates. In case of CO, CH4, and NMVOCs this contribution is substantial, nearly 50% (CO and CH4,), and close to 40% (NMVOCs).
In case of majority of the pollutants (excl. NOx) it can be noticed that the contribution of the cold-start to the total emission will be decreasing after 2020.


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