Physical Characterization of Brake-Wear Particles in a PM10 Dilution Tunnel

Mamakos, Athanasios; Arndt, Michael; Hesse, David; Augsburg, Klaus

doi:10.3390/atmos10110639

Cited by 42 publications

(24 citation statements)

References 23 publications

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“…Several different approaches for sampling and measuring brake particle emissions have been proposed. These include studies at the brake component level on a pin-on-disc configuration [7,8], at the brake couple level on a brake dynamometer [9][10][11][12][13][14][15], and at full vehicle level both in the laboratory [16,17] and on-road [18,19]. Mathissen et al [17] summarised in detail the different setups applied for studying brake particle emissions.…”

Section: Introductionmentioning

confidence: 99%

Statistical Assessment and Temperature Study from the Interlaboratory Application of the WLTP–Brake Cycle

Grigoratos

Agudelo²,

Grochowicz

et al. 2020

Atmosphere

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The relative contribution of brake emissions to traffic-induced ambient Particulate Matter (PM) concentrations has increased over the last decade. Nowadays, vehicles’ brakes are recognised as an important source of non-exhaust emissions. Up to now, no standardised method for measuring brake particle emissions exists. For that reason, the Particle Measurement Programme (PMP) group has been working on the development of a commonly accepted method for sampling and measuring brake particle emissions. The applied braking cycle is an integral part of the overall methodology. In this article, we present the results of an interlaboratory study exploring the capacity of existing dynamometer setups to accurately execute the novel Worldwide Harmonised Light-Duty Vehicles Test Procedure (WLTP)–brake cycle. The measurements took place at eight locations in Europe and the United States. Having several dynamometers available enabled the coordination and execution of the intended exercise, to determine the sources of variability and provide recommendations for the correct application of the WLTP–brake cycle on the dyno. A systematic testing schedule was applied, followed by a thorough statistical analysis of the essential parameters according to the ISO 5725 standards series. The application of different control programmes influenced the correct replication of the cycle. Speed control turned out to be more accurate and precise than deceleration control. A crucial output of this interlaboratory study was the quantification of standard deviations for repeatability (between repeats), sample effect (between tests), laboratory effect (between facilities), and total reproducibility. Three critical aspects of the statistical analysis were: (i) The use of methods for heterogeneous materials; (ii) robust algorithms to reduce the artificial increase in variability from values with significant deviation from the normal distribution; and (iii) the reliance on the graphical representation of results for ease of understanding. Even if the study of brake emissions remained out of the scope of the current exercise, useful conclusions are drawn from the analysis of the temperature profile of the WLTP–brake cycle. Urban braking events are generally correlated to lower disc temperature. Other parameters affecting the brake temperature profile include the correct application of soak times, the temperature measurement method, the proper conditioning of incoming cooling air and the adjustment of the cooling airspeed.

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Section: Introductionmentioning

confidence: 99%

Statistical Assessment and Temperature Study from the Interlaboratory Application of the WLTP–Brake Cycle

Grigoratos

Agudelo²,

Grochowicz

et al. 2020

Atmosphere

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“…Thus, BWPs are a complicated mixture of metal and plastic. BWP emissions depend on the bulk friction material 23,26 , on the frequency and severity of braking 27 , speed, weight, condition and maintenance of the automobile 28 and the environmental conditions 23,29,30 .…”

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confidence: 99%

Atmospheric transport is a major pathway of microplastics to remote regions

et al. 2020

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In recent years, marine, freshwater and terrestrial pollution with microplastics has been discussed extensively, whereas atmospheric microplastic transport has been largely overlooked. Here, we present global simulations of atmospheric transport of microplastic particles produced by road traffic (TWPstire wear particles and BWPsbrake wear particles), a major source that can be quantified relatively well. We find a high transport efficiencies of these particles to remote regions. About 34% of the emitted coarse TWPs and 30% of the emitted coarse BWPs (100 kt yr −1 and 40 kt yr −1 respectively) were deposited in the World Ocean. These amounts are of similar magnitude as the total estimated direct and riverine transport of TWPs and fibres to the ocean (64 kt yr −1). We suggest that the Arctic may be a particularly sensitive receptor region, where the light-absorbing properties of TWPs and BWPs may also cause accelerated warming and melting of the cryosphere.

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“…Similarly, the 3h-LACT yielded the same levels of PM 2.5 but distinctly higher PM 10 emissions, with the PM 10 /PM 2.5 ratio increasing from 3 to 3.6. Tests with other brake systems suggested that PM emission varies with the size of the brakes, with PM 2.5 over the last section of WLTP ranging between 1.5 mg/km and 4.1 mg/km, for two systems having an effective disc radius of 113 mm [32] and 144 mm [17], respectively. The PM 10 to PM 2.5 ratios for both brake systems (~2.7) were similar to what was observed in the present study.…”

Section: Discussionmentioning

confidence: 99%

“…As a reference, the inertial losses of 10 µm particles in a 90 • bend for the above duct sizes and flows would be 15% to 23% for 80 mm ducts and 8% to 11% for 175 mm ducts. In fact, a single 90 • bend is the major source of losses in the small tunnel [32], while the larger tunnel employed here incorporates two 90 • bends resulting eventually in similar losses. Overall, the effect of flow on particle losses is expected to be small at the conditions tested as confirmed by the gravimetric PM measurements.…”

Section: Discussionmentioning

confidence: 99%

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Particle Emissions and Disc Temperature Profiles from a Commercial Brake System Tested on a Dynamometer under Real-World Cycles

et al. 2021

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The particle emissions from a commercial brake system utilizing copper-free pads have been characterized on a brake dynamometer under two real-world driving cycles. These included a novel cycle developed from analysis of the database of the World Harmonized Test Procedure (WLTP-Brake) and a short version of the Los Angeles City Traffic cycle (3h-LACT) developed in the framework of the European LowBraSys project. Disc temperature measurements using an array of embedded thermocouples revealed a large temporal and spatial non-uniformity with the radial temperature distribution depending also on the test procedure. Averaging over the duration of the cycle, it effectively reduced the influence of thermocouple positioning, allowing for more reliable quantification of the effectiveness of convective cooling. Particulate Matter (PM) emissions were similar for both cycles with PM2.5 averaging at 2.2 (±0.2) mg/km over the WLTP-Brake and 2.2 (±0.2) mg/km over the 3h-LACT, respectively. The corresponding PM10 emissions were 5.6 (±0.2) mg/km and 8.6 (±0.7) mg/km, respectively. The measurements revealed the formation of nanosized particles peaking at 10 nm, which were thermally stable at 350 °C under both cycles. Volatile nanoparticles were observed over the more demanding 3h-LACT cycle, with their emission rates decreasing with increasing the tunnel flow, suggesting nucleation of organic vapors released during braking as a potential formation process.

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Physical Characterization of Brake-Wear Particles in a PM10 Dilution Tunnel

Cited by 42 publications

References 23 publications

Statistical Assessment and Temperature Study from the Interlaboratory Application of the WLTP–Brake Cycle

Statistical Assessment and Temperature Study from the Interlaboratory Application of the WLTP–Brake Cycle

Atmospheric transport is a major pathway of microplastics to remote regions

Particle Emissions and Disc Temperature Profiles from a Commercial Brake System Tested on a Dynamometer under Real-World Cycles

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