Beitrag zur analytischen und experimentellen Untersuchung des Reifen-Fahrbahnkontaktes in Bezug auf partikelförmige Emissionen

Im Zuge eines ständig wachsenden Umweltbewusstseins werden anthropogene Schadstoffemissionen zunehmend kritisch begutachtet. Dies betrifft insbesondere auch Emissionen, die mit dem Individualverkehr in Verbindung stehen. In der Vergangenheit hat besonders das Schädigungspotential von Abgasemissionen einen hohen Bekanntheitsgrad erlangt. Infolge der gesetzlichen Festlegung von Abgasgrenzwerten und den daraus resultierenden technischen Abhilfemaßnahmen, konnte die Schadstoffbelastung der Außenluft, trotz erheblich gestiegenem Fahrzeugaufkommen, deutlich reduziert werden. Abgasferne Feinstaubemissionen, die durch den Abrieb von Bremsen, Reifen und der Fahrbahn erzeugt werden, unterliegen hingegen keiner Regulierung. Es wird jedoch angenommen, dass diese bereits die größte fahrzeugbezogene Feinstaubquelle darstellen. Hieraus folgen Regulierungsbestrebungen, die in Bezug auf Bremsstaubemissionen bereits ein fortgeschrittenes Stadium erreicht haben. Die Regulierung von Reifenemissionen wird, aufgrund der Vielzahl der Einflussgrößen, gegenwärtig als zu komplex eingestuft. Im Zuge der Elektrifizierung des Antriebstranges ist damit zu rechnen, dass Abgas- und Bremsstaubemissionen an Bedeutung verlieren werden. Folglich könnte der Reifen als letzte fahrzeugbezogene Schadstoffquelle verbleiben. Der Reifenabrieb gilt zudem als insgesamt größte Mikroplastikquelle. Aufgrund dieser Vorrausetzungen ist mit einem erheblichen medialen und politischen Druck zu rechnen, der in Richtung einer Regulierung abzielt. Die vorliegende Arbeit leistet einen Beitrag zur Identifikation und Beschreibung von Einflussgrößen, die mit dem Emissionsprozess von Reifenpartikeln in Verbindung stehen. Dies umfasst die Entstehung und Messung von Reifenemissionen sowie deren Ausbreitung in der Umwelt. Hierfür wurden Methoden erarbeitet, die eine prozessübergreifende Einflussgrößenbewertung ermöglichen. Die Arbeit ist in drei Themenkomplexe untergliedert. Der erste Themenkomplex ist der Analyse der Partikel-Strömungs-Interkation gewidmet. Das Verständnis des Partikelverhaltens in Abhängigkeit der Partikelgröße und den Strömungseigenschaften ist insbesondere für die Bewertung der Messfähigkeit von Reifenemissionen sowie deren Ausbreitung in der Umwelt von Relevanz. Der zweite Themenkomplex behandelt die Messung von Reifenemissionen im Fahrversuch, wobei der Zusammenhang zwischen dem Fahrzustand und der Partikelentstehung im Vordergrund steht. Abschließend wird eine Simulationsmethode beschrieben, die es erstmalig erlaubt, die Entstehung von Reifenemissionen vorherzusagen und deren Ausbreitung in der Umwelt nachzuvollziehen. Das Ziel der Arbeit bestand darin, die wichtigsten Einflussgrößen, die sowohl die Emission von Reifenpartikeln als auch deren Immissionswirkung betreffen, qualitativ zu beschreiben.Due to a permanently growing environmental awareness, anthropogenic emissions are being now a subject to increasing criticism. This is relevant in particular for traffic related emissions. In the past, exhaust emissions have gained a high degree of public attention. As a result of the legal regulation efforts, exhaust after-treatment systems were introduced. Consequently, a significant reduction of ambient air pollution was achieved while traffic volume increased at the same time. In contrast, non-exhaust emissions such as brake, tire and road wear particles are not yet subject to legal regulation. It is assumed that non-exhaust sources already exceed exhaust emissions. Regulatory efforts for brake particle emissions have already reached an advanced stage. Tire and Road Wear Particles (TRWP) have a similar impact. However, eventual regulations on TRWP are currently considered to be too complex due to the high number of influencing variables. In view of the trend towards electric powered vehicles, exhaust and brake emissions may become irrelevant in the future. Tire emission may ultimately occur as the final vehicle related emission source. Taking into account that the tire wear was identified as the biggest source of micro-plastic emissions, serious political pressure will accelerate regulatory efforts in the near future. This thesis aims to identify and to describe the most important variables influencing the tire emissions. The content includes the particle generation and measurement as well as the dispersion in the environment. The work was subdivided into three main parts. The first part is dedicated to the analysis of the particle-flow interaction. Proper understanding of the particle behavior as a function of particle size and flow properties is especially relevant for the interpretation of tire particle measurements as well as the particle dispersion in the environment. The second part is focused on the tire emission measurements based on driving tests. In particular, the relationship between the parameters of the driving dynamics and the tire emissions was investigated. Within the third part, a novel simulation method for virtual emission prediction and environmental tracking is introduced. The aim was to describe the tire particle formation process as well as the related immission effect in a qualitative manner

Comparison of methods for sampling particulate emissions from tires under different test environments

Traffic-related emissions are strongly criticised by the public because they contribute to climate change and are classified as hazardous to health. Combustion engine emissions have been regulated by limit values for almost three decades. There is currently no legal limit for non-exhaust emissions, which include tire wear particle emissions and resuspension. As a result, the percentage of total vehicle emissions has risen continuously. Some of the particles emitted can be assigned to the size classes of particulate matter (≤10 µm) and are therefore of particular relevance to human health. The literature describes a wide range of concepts for sampling and measuring tire wear particle emissions. Because of the limited number of studies, the mechanisms involved in on-road tests and their influence on the particle formation process, particle transport and the measuring ability can only be described incompletely. The aim of this study is to compare test bench and on-road tests and to assess the influence of selected parameters. The first part describes the processes of particle injection and particle distribution. Based on this, novel concepts for sampling and measurement in the laboratory and in the field are presented. The functionality and the mechanisms acting in each test environment are evaluated on the basis of selected test scenarios. For example, emissions from external sources, the condition of the road surface and the influence of the driver are identified as influencing factors. These analyzes are used to illustrate the complexity and limited reproducibility of on-road measurements, which must be taken into account for future regulations

Analysis of TRWP particle distribution in urban and suburban landscapes, connecting real road measurements with particle distribution simulation

This article deals with methods and measurements related to environmental pollution and analysis of particle distribution in urban and suburban landscapes. Therefore, an already-invented sampling method for tyre road wear particles (TRWP) was used to capture online emission factors from the road. The collected particles were analysed according to their size distribution, for use as an input for particle distribution simulations. The simulation model was a main traffic intersection, because of the high vehicle dynamic related to the high density of start–stop manoeuvres. To compare the simulation results (particle mass (PM) and particle number (PN)) with real-world emissions, measuring points were defined and analysed over a measuring time of 8 h during the day. Afterwards, the collected particles were analysed in terms of particle shape, appearance and chemical composition, to identify the distribution and their place of origin. As a result of the investigation, the appearance of the particles showed a good correlation to the vehicle dynamics, even though there were a lot of background influences, e.g., resuspension of dust. Air humidity also showed a great influence on the recorded particle measurements. In areas of high vehicle dynamics, such as heavy braking or accelerating, more tyre and brake particles could be found

Methodology for Virtual Prediction of Vehicle-Related Particle Emissions and Their Influence on Ambient PM₁₀ in an Urban Environment

As a result of rising environmental awareness, vehicle-related emissions such as particulate matter are subject to increasing criticism. The air pollution in urban areas is especially linked to health risks. The connection between vehicle-related particle emissions and ambient air quality is highly complex. Therefore, a methodology is presented to evaluate the influence of different vehicle-related sources such as exhaust particles, brake wear and tire and road wear particles (TRWP) on ambient particulate matter (PM). In a first step, particle measurements were conducted based on field trials with an instrumented vehicle to determine the main influence parameters for each emission source. Afterwards, a simplified approach for a qualitative prediction of vehicle-related particle emissions is derived. In a next step, a virtual inner-city scenario is set up. This includes a vehicle simulation environment for predicting the local emission hot spots as well as a computational fluid dynamics model (CFD) to account for particle dispersion in the environment. This methodology allows for the investigation of emissions pathways from the point of generation up to the point of their emission potential