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The latest generation of internal combustion engines may emit significant levels of sub-23 nm particles. The main objective of the Horizon 2020 “DownToTen” project was to develop a robust methodology and provide policy recommendations towards the particle number (PN) emissions measurements in the sub-23 nm region. In order to achieve this target, a new portable exhaust particle sampling system (PEPS) was developed, being capable of measuring exhaust particles down to at least 10 nm under real-world conditions. The main design target was to build a system that is compatible with current PMP requirements and is characterized by minimized losses in the sub-23 nm region, high robustness against artefacts and high flexibility in terms of different PN modes investigation, i.e. non-volatile, volatile and secondary particles.

In the future, similar to passenger cars, newly registered European heavy duty vehicles shall be labelled with the fuel consumption in typical driving cycles, determined at standardised conditions. This shall improve the comparability of the vehicles and motivate manufacturers to apply more fuel-saving technology. Therefore, a multi-stage certification procedure has been developed by a consortium of European laboratories under the leadership of the Institute for Internal Combustion Engines and Thermodynamics of TU Graz. It is based on a simulative approach and consists of: On-road measurement of driving resistances; determination of drivetrain losses; power demand of engine auxiliaries and other consumers; generation of an engine fuel consumption map from the engine's type approval tests; development of several driving cycles, typical for different vehicle applications; and a proposal for a calculation method of fuel consumption.

Diesel engines are widespread in both passenger car and heavy duty truck applications. However, despite that the combustion concepts are similar in the two cases, the engine calibration required for compliance with the different emission standards leads to distinct particle emission behavior from the two categories. This paper compares the exhaust particle emissions from heavy duty engines with typical diesel passenger cars of similar emission standard and/or emission control technology. Measurements were conducted with the same sampling system and sampling protocol to avoid interferences induced by the sampling methodology. A range of particle properties were studied, including mass, number of solid and total particles and total particle surface. For comparability, the results are expressed per unit of exhaust volume, per unit of fuel consumed and per unit of distance driven.