PM₁₀ prediction for brake wear of passenger car during different test driving cycles

PM₁₀ emissions generated from the brake wear of passenger car per braking event during three test driving cycles (WLTP, LACT, and WLTP-Brake) were studied using a finite element analysis (FEA) approach in combination with the relationship among the mass emitted rate of airborne particles versus local contact pressure and sliding speed. In addition, PM₁₀ emissions were measured per braking event during the WLTP-Brake cycle on a brake dynamometer using an electrical low-pressure impactor (ELPI+) to validate the proposed FEA approach. The simulated and experimental results for WLTP-Brake illustrated that the proposed simulation approach has the potential to predict PM₁₀ from brake wear per braking event, with an R² value of 0.93. The FEA results of three test driving cycles showed that there was a gradient rise in pad wear on both sides from the inner to outer radii. The simulated PM₁₀ emission factors during the WLTP, LACT, and WLTP-Brake were 7.9 mg km^-1 veh^-1, 9.8 mg km^-1 veh^-1, and 6.4 mg km^-1 veh^-1, respectively. Among three test driving cycles, the ratio of PM₁₀ to total brake wear mass per braking event was the largest for the LACT, followed by WLTP and WLTP-Brake. From a practical application perspective, reducing the frequency of high-speed braking may be an effective way to decrease the generation of PM₁₀ emissions.