Estimation of Transport Efficiency for Brake Emissions Using Inertia Dynamometer Testing

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 results include additional factors (aerosol and air properties) to better estimate losses during: a) conceptual design and assessment of the feasibility of the initial system layout, with emphasis on the influence of duct design, dimensions and isokinetics; b) validation (prior to actual testing) of a given system; and c) actual testing, with proper corrections for cooling air conditions. The methods proposed are agnostic to the brake dynamometer design, brake type or size, or the specific particle measurement system. In order to cover meaningful ranges for duct size, airflow in the duct, and airflow in the sampling lines, the assessments follows a Renard series according to ISO 3:1973 Preferred numbers - Series of preferred numbers [4]. This work contributes to the industry efforts (UNECE/GRPE/PMP and led by the JRC [5]) to develop a robust and harmonized test method to characterize and report automotive brake emissions using inertia dynamometer testing.