Brake Particle Emissions From Freight Trains

Sammanfattning

This research has been conducted to measure the brake particle emission from freight trains drag braking operation. It only focuses on mechanical brakes by using two different brake pad material one is sintered, and another one is composite, in combination with grey cast iron brake disc. All the materials have been collected from real time braking operations from Green cargo. This research is an example of a joint collaboration within academia and industry. Lund university performs as the academic partner and Green Cargo ab has been the logistics and finance contributor for this study. This experimental work was conducted using a pin-on-disc tribometer under controlled laboratory conditions. Particle number concentration and size distributions were measured by using a condensation particle counter (CPC) and a mini wide-range aerosol spectrometer (MiniWRAS). In this study a K-type thermocouple has been installed in the disc of the pin-on-disc tribometer to monitor the surface temperature of the sliding operation between the friction materials. The wear mechanism and surface morphology of the tested pads were investigated using scanning electron microscopy (SEM) and material characterization was done by energy-dispersive X-ray spectroscopy (EDXS). The results showed that sintered pads indicate more stable friction and temperature increase in the repeated drag braking than composite pads. The wear rate of sintered pad is 34% higher than composite pad, which also showcasing the stability of CoF of the sintered pad. Both brake pads show almost similar particle number concentration in the repeated drag braking tests, whilst sintered pads have doubled PM10 than composite pads in the repeated drag braking tests. Sintered pads showcase wider mass-weighted size distribution and coarser particle sizes than composite pads in the drag braking runs. While the mass concentration of PM2.5 for sintered pad is slightly higher than the composite pad material. Worn surfaces of sintered pads are mainly composited of metallic elements whilst composite pads exhibited a certain amount of non-metallic elements besides metals on their worn surfaces. This research contributes valuable insights to the understanding of non-exhaust emissions from rail transport and supports future efforts toward greener and safer braking technologies in alignment with EU sustainability goals.