Real Driving Emissions Measurement of Brake Dust Particles 2019-01-2138

The measurement of brake dust particles is a complex challenge owing to its open system configuration; indeed, the emitted particles are directly spread into the environment. Measurements on the inertia brake dyno feature controllable and reproducible environmental and operational parameters. Although Real Driving Emission (RDE) measurements enable the detection of brake dust particles emitted in real driving conditions (i.e. traffic condition, driving style, air humidity, vehicle components’ wear and ageing, etc.), they are complex and not reproducible due to external, continuously changing parameters (e.g., flow conditions, changing traffic conditions, particulate matter from other sources). The motivation lies in developing a real driving emission sampling system for brake particle emissions, which meets the quality requirements of the measurements, as well as the prevention of particle losses and contamination, thereby supplementing and reviewing laboratory-based procedures. On the basis of knowledge from the computational fluid dynamics and experimental investigations, an advantageous concept of a sampling system for mobile application is presented. The chosen methodological approach shows that the transport efficiency and the uniformity of the number concentration depend on the design, the associated flow conditions and process parameters. In addition, the Particle injection and particle spreading behaviour, influence of disc ventilation and the variable particle properties over the cycle are to be implemented into the evaluation. As a result, an optimized design of a sampling system for mobile applications is derived. Furthermore, the results express the influence of different test environments, test cycles and test setups. The experimental study shows fundamental differences and similarities between laboratory and real-road test environments.