The truck fleet, vans and buses emit – as they are today – more than 50 percent of the nitrogen oxides in German inner cities. The savings potential there is therefore much greater than that of diesel cars, which cause only December 2018 Blank Calendar one third of the nitrogen oxides. Franz Rohrer © RESEARCH CENTER JÜLICH / TOBIAS CASTLES (CUTTING) Franz Rohrer | Franz Rohrer is an Atmospheric Chemist at Forschungszentrum Jülich.
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Since 1984 he has been intensively involved in nitric oxide chemistry. Since 2006, he has been head of the “Energy-related emissions” department at the IEK-8 troposphere. They speak of laboratory values. Do you mean the official readings from the test benches that were cheated and that caused the diesel scandal, no, we use values that come from the lab, but correspond to real traffic.
The diesel scandal has arisen because in the passenger cars the catalytic converters on the road have been deliberately switched off for various reasons. This is not the case with trucks. There is no scandal. In general, the SCR catalysts that absorb the nitrogen oxides work there. But that is valid only if constantly a osche engine power is required, as is the case on the highway. The exhaust system under the truck is then very warm and the removal of nitrogen oxides by the SCR-Kats works reliably.
But on the streets in the city center there is often stop-and-go. Red lights, buses stop at stops, garbage trucks stop at garbage cans. As a result, the catalyst cools down and stops working. In city centers, the exhaust gas cleaning of trucks and buses has a temperature problem. Does that mean that trucks drive through the city center as if they had no cat? That’s the way to describe it. It depends on how well the exhaust gas post-processing works. In the city center, a truck drives very little, but it emits a lot.
At 25 kilometers per hour, a truck emits five times more nitrogen oxides than on average on the motorway. 90 percent of the truck fleet is still Euro 5, which almost all have the temperature problem. Then come quickly to the fact that trucks and buses in the city center play a dominant role. Why is so little compared to the cars spoken? I can not tell you that.
The problem has been known for a long time. This is taken into account in the latest catalysts; since you try to keep the catalyst active even when driving through the city. Recently, there are test cycles that are similar to downtown driving. In order to comply with the emissions regulations, the manufacturers themselves have to improve on most modern Euro 6 vehicles. That sounds very theoretical.
How safe are the bills? The power a truck needs to drive through a city can be accurately calculated: mass, air resistance, frontal area of the car, average load, all these factors are well known. The engine has a known December 2018 Blank Calendar efficiency. You need such assumptions in order to extrapolate statistically significant values for the medium-sized truck in the German city.