Petrol Particle Filter
The research of the Max Planck Institute for Chemistry, which guarantees somewhat confidence-inspiring figures, looks at additional polluters, too: 35,000 deaths per year in Germany from particulate matter, of which
15,750 (45%) by agriculture. There are 7,000 by traffic burdens, but less than half are accounted for by exhaust fumes, more by car and road abrasion. By the way, one should count the particles instead of weighing
them, because they catch the much more dangerous smaller ones, which penetrate the body very far.
Since the vast majority of Diesel cars have been using particulate filters for more than 10 years and if you count instead of weighing, there are many gasoline direct-injection engines emitting even more than the majority
of diesel engines. After the expiry of a three-year special regulation, the petrol engined cars must now comply with the same limit values.
Hence the rather widespread introduction of the gasoline particulate filter now. We have already reported on a possibility of the gasoline particulate filter: the
four-way catalyst, installed e.g. in the Mercedes S-Class.
We are dealing here with an installation as shown on the picture above. It is astonishing that the 3-way catalytic converter additionally occurs in the housing together with the particle filter. Presumably it has here
similar to the oxidation catalyst at the Diesel engine a temperature-increasing function, although the exhaust gas temperatures are generally higher in the gasoline engine and the particulate filter is located close to the
engine.
| Rarely occurring, active regeneration possible without additional hardware. |
Also unlike the Diesel it regenerates here constantly with its higher temperatures. This is also called passive regeneration, because over long distances no additional measures, such as the late injection of the Diesel
engine are necessary. The mineral used in the particulate filter is cordierite, a Mg-Al-Si compound which, according to Wikipedia, has a continuous mixed crystal structure.
There are suppliers who promise a filtering effect for particles PM 2,5 and smaller. Although the passageways through the filter material are larger, the movements of the molecules at these temperatures are expected
to interfere with unobstructed passage. PM 2.5 means a diameter of 2.5 µm (microns).
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