Particle number emissions from standard and hybrid SI passenger cars

This paper presents the PN (Particle Number) and some gaseous emissions results from a group of SI (Spark Ignition) passenger cars including HEV (Hybrid Electric Vehicle), PFI (Port Fuel Injection) and GDI (Gasoline Direction Injection) vehicles. The PEMS (Portable Emission Measurement System) was used for on-board emission measurements. The vehicles were driven using the routes complying with the EU Real Driving Emissions (RDE) test procedures required in the European Commission Regulation (EU) 2016/427, i.e. starting in an urban driving mode and then continuing into a rural driving mode and ending with motorway driving mode part. The percentage of these three segments is approximately 33%, 33%, 33% respectively. The total test time was between 90 to 120 minutes.

The vehicles’ driving parameters such as road speed, tailpipe exhaust temperatures and energy consumption were recorded and their correlations with emissions were investigated. The results show that most of the PN spikes were related to acceleration, deceleration and engine restart events. Comparing accumulated PN from different vehicles, total PN from the hybrid car was the lowest, even though this hybrid car is the oldest among all the six cars being tested. Correlations between PN and v*a, VSP and CO2 emissions rates were investigated. A strong correlation was observed between the common logarithm of PN and CO2 emission rates.