Abstract
The formation characteristics and the reduction of nanoparticles emitted from wheel–rail contacts at subway-train velocities of 73, 90, and 113 km/h under dry and water-lubricated conditions (using tap water) were studied using a twin-disk rig. The resulting number concentration (NC) of ultrafine and fine particles increased with train velocity under both conditions. Particle generation varied with slip rate under both conditions in both the particle categories. Furthermore, the formation characteristics at 113 km/h under dry conditions showed a notable deviation from those under water-lubricated conditions in three aspects: (i) The maximum NC of ultrafine particles was higher than that of fine particles, (ii) the predominant peak diameter was in the ultrafine particles category, and (iii) the proportion of ultrafine particles was much higher than those of the fine particles. Applying water decreased the NC of ultrafine and fine particles significantly at all tested velocities (by 54–69% and 87–91%, respectively). Adding water increased the NC of particles ≤ 35 nm in diameter, possibly owing to the increase in water vapor and mineral crystals from tap water. Overall, this study provides a reference for researchers aiming to minimize nanoparticle formation at the wheel–rail contacts by applying a lubricant.
Highlights
The formation characteristics and the reduction of nanoparticles emitted from wheel–rail contacts at subway-train velocities of [73, 90], and 113 km/h under dry and water-lubricated conditions were studied using a twin-disk rig
Under dry conditions at each studied velocity, the number concentration (NC) of ultrafine and fine particles increased with the slip rate up to approximately 1%
The total NC of fine particles was higher under dry conditions, whereas that of ultrafine particles was higher under water-lubricated conditions
Summary
The formation characteristics and the reduction of nanoparticles emitted from wheel–rail contacts at subway-train velocities of [73, 90], and 113 km/h under dry and water-lubricated conditions (using tap water) were studied using a twin-disk rig. The underground subway system emits airborne wear particles (AWPs) at various contacts, such as the wheel–rail and brake-pad–disk contacts. These AWPs deteriorate the air quality of the subway environment because they are trapped within the tunnels and transported to stations. AWPs are generated by both the brake system and the wheel–rail contact during mechanical braking[10]; the wheel–rail contact is the only source of AWP formation during electrical b raking[11], which. The AWPs formed at wheel–rail contacts are the focus of this study
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
