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The characterization and accurate measurement of non-exhaust brake emissions address sustainable cities and communities from the United Nations Sustainable Development Goals. Multiple health studies correlate particulate matter (PM) with respiratory illness and the impacts on societies and economies in different ways. Even though the fate of PM from braking and the causality of direct health effects remains elusive, road transport is responsible for generating PM. The braking system has many nuances, making it challenging to establish overall targets for reduction without extensive measurements under controlled laboratory conditions. Some factors influencing PM generation include vehicle running mass, brake size, friction couple design, customer driving modes, and vehicles-in-operation.

There is vast literature and peer-reviewed methods to estimate losses1 during aerosol sampling. However, there are no current published models for transport losses during laboratory measurement for brake emissions. This paper presents an open source (Microsoft® Excel) Macro using three different models (Particle Loss Calculator - PLC - from the Max Planck Institute [1]; AeroCalc [2] from the United States Center for Disease Control and Prevention; and SAE AIR6504™:2017-10 [3] for calculation of non-volatile particulate matter penetration). The fourth model (LINK) provides the average value from the three initial models. The LINK PALS2 Microsoft® Excel Macro (or ‘Macro’ for short version) also includes calculations for isokinetics not included on any of the three initial models.

The investigation and measurement of particle emissions from foundation brakes require the use of a special adaptation of inertia dynamometer test systems. To have proper measurements for particle mass and particle number, the sampling system needs to minimize transport losses and reduce residence times inside the brake enclosure. Existing models and spreadsheets estimate key transport losses (diffusion, turbophoretic, contractions, gravitational, bends, and sampling isokinetics). A significant limitation of such models is that they cannot assess the turbulent flow and associated particle dynamics inside the brake enclosure; which are anticipated to be important. This paper presents a Design of Experiments (DOE) approach using Computational Fluid Dynamics (CFD) to predict the flow within a dynamometer enclosure under relevant operating conditions. The systematic approach allows the quantification of turbulence intensity, mean velocity profiles, and residence times.

Emissions of particulate matter, or PM, due to brake wear, are not well quantified in current air pollutant emission inventories. Current emission factor models need to be updated to reflect new technologies and materials and to incorporate the effects of changing driving habits and speeds. While emission regulations drive technical innovations that are significantly reducing PM emissions in vehicle exhaust, non-exhaust automotive emissions remain unregulated. Current emission factor models need to be updated to reflect the changes caused by new technologies, materials, and speed-dependent vehicle usage. Most research regarding brake emissions relies on a laboratory setting. Laboratory testing has allowed researchers, application engineers, data modeling engineers, and environmental agencies to generate large datasets for multiple vehicle configurations and friction couple designs.