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The particulate emissions of two brake systems were characterized in a dilution tunnel optimized for PM10 measurements. The larger of them employed a fixed caliper (FXC) and the smaller one a floating caliper (FLC). Both used ECE brake pads of the same lining formulation. Measured properties included gravimetric PM2.5 and PM10, Particle Number (PN) concentrations of both untreated and thermally treated (according to exhaust PN regulation) particles using Condensation Particle Counters (CPCs) having 23 and 10 nm cut-off sizes, and an Optical Particle Sizer (OPS). The brakes were tested over a section (trip-10) novel test cycle developed from the database of the Worldwide harmonized Light-Duty vehicles Test Procedure (WLTP). A series of trip-10 tests were performed starting from unconditioned pads, to characterize the evolution of emissions until their stabilization. Selected tests were also performed over a short version of the Los Angeles City Cycle.

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.