Modelling of the air pollutants’ cold-start emissions depending on average vehicles’ speed

Abstract

The aim of the study is to present the results of mathematically modeled influence of the average speed on the pollutant released in the air during the cold-start process. There were taken into consideration the emission from the passenger cars (PCs) for the different fuel types, vehicles’ segments (including hybrid), and the Euro standard. In the article the simulations was performed using the COPERT software, as well as WLTP-based research. The modelling results there are presented show that the change in average speed has a significant effect on air pollutant (CO2, NOx, NMVOC, CO) emissions released in cold-start process. Furthermore, the results show that pollutants’ emissions are sensitive to average speed fluctuations.

The problem of cold start emissions from vehicles

“…This program makes use of the "Tier 3" methodology, which computes the complete exhaust emissions by separating between emissions released during the thermal engine operation ("cold start emissions") and those emitted when the engine reaches its regular operating temperature ("hot emissions"). The equation for the 'Tier 3' methodology is provided [15].…”

“…where: E Totaltotal emissions [g] of any pollutant for the spatial and temporal resolution of the application, E Hotemissions [g] during stabilized (hot) engine operation, E Cold emissions [g] during transient thermal engine operation (cold-start) [15].…”

“…These emissions can be compared to the hot emissions released when the engine is running normally. The distance travelled before reaching stabilized emissions is known as l trip [15].…”

“…It is commonly assumed that the majority of cold start emissions originate from urban driving, with rural driving as the second largest contributor. This is due to the fact that highway conditions are not usually the starting point for many trips [15].…”

“…The release of these substances into the air can lead to a high level of air contamination and can have a damaging impact on both the health of people and the environment [1]. The release of these substances can create smog and tiny particles, which can result in illnesses related to the lungs and heart, in addition to contributing to global warming [1,15]. It is essential to take action to solve the issue of cold start emissions in order to reduce the amount of emissions from vehicles and enhance air quality.…”