TYRE PARTICLE CAPTURE
Exhibition day
TYRE PARTICLE CAPTURE
UNDERGRADUATE RESEARCH PROJECT - TEST RIG DESIGN
Tyre wear particles (TWPs) are a type of non-exhaust emissions (NEEs) produced by frictional processes during vehicle use. TWPs, also known as tyre and road wear particles, are released when a tyre is abraded against the road and can contain microplastic particles. These particles can become suspended in the air and leach toxins into waterways, posing a risk to human health and the environment. In fact, a recent report by Eunomia found that automotive tyres are the largest source of microplastic pollution in the UK, generating over 13,000 tonnes per year. This is more than the combined total from cosmetics, paints, and clothing.
As exhaust emissions from road transport have decreased, the proportion of emissions that are NEEs has increased. Data from the UK National Atmospheric Emissions Inventory (NAEI) shows that NEEs from road transport now exceed those from the tailpipe, and this trend is expected to continue as vehicles become increasingly electrified and heavier. Data from the European Environmental Agency also found that, despite stricter regulations on exhaust emissions, primary PM2.5 (fine particulate matter) from road transport increased by 22% between 2000 and 2017, with the NEE component rising from 18% to 46%. The increase in NEEs was even more significant in the PM10 category, with the proportion of NEEs increasing from 32% to 63% in the same period. To achieve air quality targets for PM2.5 and PM10, it is essential to reduce both exhaust and NEEs.
For our undergraduate research project, my team challenged ourselves in designing a test rig to facilitate research on TWPs emitted during driving. By better understanding TWPs and their impact, we can work towards finding ways to reduce their release and improve overall air quality.
As part of the Particle Capture and Environment Control subgroup, our team has focused on designing and developing a particle capture mechanism for recovering a high percentage of particles emitted during the interaction between a go-kart tyre and a rolling road. Through a process of iterative design, testing, and analysis, we were able to create a mechanism that is capable of recovering 85% of all emitted particles.
This report outlines the various stages of our project, including the development of three potential redesigns and the conduct of two formal tests on critical elements of our final design. Our goal is to contribute to ongoing research efforts on tyre wear particles and their impact on air quality, with the aim of finding ways to reduce their release and improve overall air quality.
From the outset of the project, it was decided that a combination of vacuum suction and mechanical removal via brushes would be the most effective and reliable method for collecting particles. Our project deliverables statement (PDS) outlined specific goals for this approach, including:
• Ability to capture at least 85% of particles
• Ability to capture both airborne particles and residual particles on the road surface
• Ergonomically Designed (<5 minutes setup and <5 minutes retrieval of particles)
• Ability to increase temperature sufficiently to simulate higher wear conditions
• All with a budget of £1000
Throughout the development and testing phase, various design modifications were made to improve the effectiveness of the particle capture mechanism. For example, initial suction head tests led to the incorporation of a supporting wire mesh and rebates, as well as changes to the head insert to improve uniformity and the rear collection to improve brush efficiency. Ergonomics were also a key consideration in the design process, with amendments such as the installation of the rear collection and the adjustment of the head bracket aimed at making the subassembly as user-friendly as possible. The total cost of prototyping, materials, parts and finishes came to £821.72, within our budget of £1000.
Based on our calculations, the current iteration of the suction head and rear collection subassemblies is capable of achieving a capture rate efficiency of 92% for a single tyre. The redesign section of this report identifies potential improvements to the subassembly as well as potential barriers to implementation. To address the temperature adjustment criterion, we tested the use of a simple heat lamp and found that it was capable of comfortably providing a 30°C temperature increase, in addition to the inherent temperature increase caused by friction between the tyre and road. This allows us to simulate high wear conditions similar to those encountered during motorway driving at low speeds while minimising health and safety risks.
Testing of the final design revealed the effectiveness of our suction head design, as well as areas for improvement. The first test focused on the uniformity of suction across the filter surface and found that modifications to the head and insert design resulted in a 37% reduction in the normalized standard deviation across the face. The redesign section recommends further testing of the next iteration of the insert to further improve performance. The second test evaluated the performance of several different filters and concluded that filter paper was the most suitable option due to its high capture efficiency and ease of post-processing.
The future of the project development would be focused on providing real-time data on particles and filter saturation management. The former could be in the form of using photo imagery to acquire details on size, spatial distribution, and temporal distribution. One approach to saturation management is pressure transducers and relating pressures to associated saturation levels (which would need to be found using detailed additional testing).
