Assessing Brake Emission Performance Across New, Upgraded, and Retrofitted Test Bed Infrastructures

Brake wear particle emissions are a significant source of traffic-related particulate matter, prompting increasing regulatory attention through frameworks such as UN GTR No. 24 and the forthcoming Euro 7 standard. To address the demand for accurate and reproducible measurement solutions, a comparative study was conducted using an identical ventilated cast-iron disc brake across different test bed infrastructures. Three AVL solution configurations were assessed: (1) a newly built brake emission test bed, (2) an engine test bed upgraded with brake emission measurement equipment, and (3) a simulated third-party brake test bed (e.g., originally used for performance or NVH testing) retrofitted with brake emission measurement equipment. In the third configuration, the UN GTR No. 24 test sequence was automated and executed by the AVL System Control in coordination with the existing test bed infrastructure. The testing infrastructure included a CFD-optimized brake enclosure and sampling tunnel designed to minimize particle losses, as well as highly dynamic dynamometers. Advanced PM10 and PM2.5 samplers with automated filter changers for consecutive tests, along with particle counters for solid (SPN) and total (TPN) particle number measurement, were employed. Results demonstrated excellent agreement across all configurations, with emission factor variations within ±10%, confirming the reliability, reproducibility, and infrastructure independence of the measurement approach. Integration into third-party test beds operated seamlessly, achieving full UN GTR No. 24 process automation, including data acquisition and compliant reporting, even without taking full control of the test bed operation. With research on non-exhaust emissions across diverse test environments, we will continue to contribute to the development of regulatory procedures and the refinement of brake emission measurement methodologies within international working groups.