VW Equips Its Petrol Powered Vehicles With Gasoline Particulate Filters
Volkswagen will equip all its petrol powered vehicles with gasoline particulate filters (GPF), which, as the company assures, will reduce particulate emissions on some models by 95%, according to the Autocar.
The Up GTI has already received the technology this year, earlier such filters were installed on the variant of Tiguan 1.4 TSI with a manual transmission in Germany. VW is going to equip with them other petrol models in the range.
The measures are carried out to follow a commitment VW made in 2016 after the diesel scandal broke out in 2015. Other automakers do the same. In particular, the GPF system is mounted on some S-Class (other Mercedes models will have it too), as well as a new Ford Mustang.
Petrol-powered vehicles have been subject to the particulate emissions legislation since the introduction of the EU5 standard in 2009. More stringent EU6 norms are in force since September 2017, they require to reduce particulate emissions by 10 times the previous level.
Particles in diesel car exhausts were traditionally considered the ones up to 10 microns in diameter (PM10) or even smaller PM2.5. For comparison: human hair has a diameter of up to 70 microns. In 2001 nanoparticles were revealed. They are a hundred times smaller than PM10.
According to the report of the Swedish National Road Administration under certain conditions some petrol engines emitted the same amount of nanoparticles as diesel ones.
The number of particles in exhaust was previously measured by weight, but awareness of nanoparticles grew after the use of alternative methods of measurement. Although nanoparticles weigh very little, there are plenty of them, and they are able to cover the surface of a large area.
It turned out that nanoparticles could penetrate the lungs deeper than large particles. Like diesel particulate filters, the GPF is designed to capture particles of all sizes, including the smallest.
The filter is installed behind the engine a few centimeters from the turbo, heats up quickly and becomes effective in a matter of seconds after the engine starts. Harmful HC, NO, CO from the heated particles captured by the filter are converted into carbon dioxide, water and nitrogen.
After leaving the filter, the exhaust gases pass through a second, conventional three-way catalytic converter installed beneath the floor. This ensures that the exhaust pipe meets the latest EU6 standard.
Since September 2017, a new WLTP (World Harmonized Test Procedure) is being applied to all new cars, which is considered closer to real results.