The effective reduction of particulate emissions from modern vehicles has shifted the focus to tire, brake, road wear and re-suspended particulate emissions. To meet future EU air quality standards and even stricter WHO targets for PM2.5, a reduction in non-exhaust particulate (NEP) emissions seems to be essential. For this reason, the EURO 7 emissions regulation contains limits for PM and PN emissions from brakes and tire abrasion. Graz University of Technology develops test methods, simulation tools and evaluates technologies for the reduction of brake wear particles and is involved in and leads several international research projects on this topic. The results are applied in emission models such as HBEFA (Handbook on Emission Factors).
In this paper, we present our brake emission simulation approach, which calculates the power at the wheels and mechanical brakes, as well as corresponding rotational speeds for vehicles using longitudinal dynamics equations integrated in the simulation tool PHEM (Passenger Car and Heavy duty Emission Model). This simulation model is applicable for both LDV and HDV in the case of NEP. The brake wear emissions, including PM10, PM2.5, PN23, and PN10, are interpolated from characteristic brake emission curves that depend on braking power and vehicle speed. These characteristic curves are generated from a database containing data from literature, partners, and measurement campaigns conducted by our team. Additionally, the effects of brake energy recuperation in hybrid and battery electric vehicles, as well as retarder use in HDVs, are taken into account. The physical approach enables the simulation of all propulsion systems in various driving cycles for all vehicle categories. Furthermore, we will present the projected development of PM and PN emissions for European PC, LDV and HDV traffic through 2050, considering different propulsion technology scenarios including also exhaust particle emissions for comparison.