Volkswagen is the introduction of a gasoline particulate filters (GPFs) for its gasoline-powered cars as part of a wider plans to improve the emissions across its range and provides for reductions of particulate emissions in some models up to 95%.
Up GTI earned GPF technology at the beginning of this year, but the device was already used on the manual-transmission variant of the Tiguan 1.4 TSI in Germany and has been launched through the brand, the other cars.
The measures follow a commitment on the part of VW in 2016 to mount particulate filters for gasoline engines, as the company has tried to recover by 2015 the Dieselgate scandal.
Other manufacturers equip their cars with gasoline with GPF systems. Mercedes-Benz, for example, for several S-Class derivatives, such as VW, plans to roll it out more widely across its fleet. Ford has the new Mustang, among other models.
Petrol cars have been the subject of particulate emissions, legislation beginning with the introduction of the EU5 standard in 2009. The last phase, EU6c, was introduced in September 2017, forcing the gasoline engine particulate emissions to be reduced by 10 times the previous level.
VW diesel particulate filter doubles as a three-way catalytic converter, the device normally equipped with gasoline exhaust gases of motor vehicles to reduce the emission of toxic gases. Conventional three-way catalytic converters contain a ceramic honeycomb structure called a substrate, through which the exhaust gases flow on their way to the exhaust. The substrate has a catalyst coating dramatically cuts the levels of the three main toxic gases exhaust gases: unburnt hydrocarbons (HC), nitrogen oxides (NOx) and carbon monoxide (CO).
Traditionally, the focus of big size, the diesel particulate matter up to 10 microns in diameter (PM10) or smaller PM2.5. In comparison, a human hair is about 70 microns in diameter. But already in 2001, a new threat has come to light in the form of nanoparticles, which are more than 100 times smaller than PM10.
A report commissioned by the Swedish National Road Administration revealed that, under certain conditions, some of the gasoline vehicles were to emit the same number of nanoparticles, such as diesel.
The amount of particulate matter in the exhaust gas was previously measured by weight, but for the awareness of the nanoparticles is increased after the use of alternative measurement techniques. Even if the nanoparticles weighed little, were present in large numbers and can cover a large surface area. The concern was that the nanoparticles can penetrate deeper in the lungs than larger particles. As particulate filters, GPF has been designed to capture all sizes of particles, including nanoparticles.
However, different types of fine dust are produced from a variety of sources, including the brakes, tyres and road dust. According to a study conducted by DEFRA, these sources can produce the same amount of particulate matter to that of a road vehicle exhaust gas.
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Like petrol, diesel particulate filter works:
The new filter is tucked behind the engine a few inches from the turbo, it heats up very quickly and is effective in seconds after the cold start. On the inside, the exhaust gas is forced through the walls of the channels blocked at alternative ends. The particulate matter trapped are hot, CO2 reduction and, at the same time, the unwanted HC, NOx and CO are also converted to small amounts of CO2, nitrogen and water.
After leaving the filter, the exhaust gases pass through a second conventional three-way catalyst mounted under the floor. This ensures that the exhaust is compliant with the latest level of EU6c emission standards, even when the engine is running flat out. Until the GTI is subject to the new WLTP (Worldwide Harmonised Test Procedure) and RDE (Real Driving Emissions) test standards. As EU6c, WLTP applies to all new types of car introduced after September 2017. WLTP should ensure that the mentioned emissions are much closer to the real world outputs.
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