Identifying Factors that Affect Brake Wear PM Emissions during Real-World Test Conditions

Particulate Matter (PM) is one of the world’s most problematic pollutants in terms of harm to environment and human health. It has been found out that PM emission levels are very high during traffic congestion and thus, PM is considered as the primary pollutants in city areas. Many literatures suggested that PM emitted during braking sequence from both internal combustion engines and electrified vehicles are considered high and could be the major cause of this issue. Many studies regarding to PM from brake wear were done in the pin disc laboratory setup with a brake dynamometer that might not represent real-world driving scenarios. Various studies of on road non-exhaust PM measurement were mostly focused on driving cycles. Parametric studies to identifying factors that affect brake wear during real-world driving scenarios are still needed for more investigations. The current study focuses on identifying factors that affect brake wear particle emissions from a vehicle in real-world test conditions. A PM sampling device is attached on the left front wheel of the tested vehicle. This device is specifically designed to mimic PM sampling setup in the laboratory environment. PM measurements including mass and number of size distributions are monitored during the braking sequence. Parametric studies including driving behavior, temperature of brake pad, and payloads (weight of additional mass on vehicle) are observed. Based on experiments, it is found out that the pattern of PM emissions observed by number of size distributions from brake wear is consistent with driving behavior as suggested in many literatures. PM emissions are also observed to be significantly increased at the brake temperature of 130°C. In addition, increasing payloads results in higher amounts of PM emissions. Based on PM size distribution from brake wear, 84% of total PM emissions are considered as PM₁.