Researchers at the Korea Institute of Machinery and Materials (KIMM) have built a vehicle system that cleans roadside air while driving and captures brake dust before it escapes. The technology uses the vehicle’s existing structure, turning ordinary cars into mobile air purifiers for city streets.
A team led by Dr. BangWoo Han of KIMM’s Department of Urban Environment Research built three systems. They are a grille-type electrostatic precipitator, a caliper-type brake dust collector and a wireless power transfer system for purifying air while parked. Engineers installed them on vehicles including a Kia Carnival and a Hyundai Sonata to verify performance.
Electrified grille traps dust
The grille system electrically charges fine particles entering through it and attracts them to collection plates. Carbon fibers far thinner than a human hair enable efficient collection at low electrical current while minimizing ozone generation.
While driving, it relies on the airflow created by the vehicle’s motion instead of a separate high-power blower. When the car is parked in a space with wireless power, its existing radiator fan can purify the surrounding air.
At 18.6 mph (30 km/h), the grille system removed at least 95% of PM2.5 and at least 99% of coarser PM2.5–10 particles. It held the same performance at 31 mph (50 km/h) and purified about 63,600 cubic feet (1,800 cubic meters) of air per hour per vehicle. Fuel efficiency changed by no more than 1% in either the Carnival or the Sonata after installation.
Stopping brake dust early
Brake dust is captured at its source by a collector behind the brake caliper. Friction between pads and discs naturally charges the particles, so the system needs no separate particle charger or suction fan.
Under the Worldwide harmonized Light vehicles Test Cycle (WLTC), the collector captured 22.2 milligrams of brake wear particles per kilometer per vehicle, about 35.7 milligrams per mile. That equals roughly 0.35 ounces (10 grams) over 280 miles (450 km).
Beyond the tailpipe
Conventional automotive pollution controls have focused mainly on engine exhaust. Non-exhaust particles from brakes and tires also come from electric and hydrogen-powered vehicles, and brake particle emissions are now regulated under Euro 7.
Electrostatic precipitation offers low resistance to airflow and fits into spaces and components already on the vehicle, which minimizes added power and structural changes, the researchers said.
Next: Real-world testing
Han said a key feature is that vehicles can clean roadside air while also cutting brake wear particles directly at the source. Senior researcher Gun Hee Lee said using the vehicle’s structure and driving airflow “minimized the need for additional power.”
KIMM plans to further validate performance and long-term durability under real-world driving conditions. It is a key achievement of AirFive, one of KIMM’s Five Flagship Brands, and the institute plans to expand its application to help improve urban air quality.
The project, “Mutually Beneficial Cooperative Air Purifying Automobiles Against Atmospheric Fine Particles,” was supported by the Automotive Industry Core Technology Development Program. Findings have been published in Tribology International and Atmosphere, and patent applications have been filed in Korea, the United States and Germany. The brake study is titled “A charger-free electrostatic precipitator for collecting triboelectrically charged brake wear particles.”