Volkswagen: Clean Evo diesel in the Passat
VW has developed an extension to the SCR exhaust gas aftertreatment system. This is known as the twindosing process. In this process, Adblue is injected upstream of two SCR catalytic converters arranged in series. Reduction of nitrogen oxide values The new 2.0 TDI Evo engines with the Twindosing process are expected to reduce nitrogen oxide values by around 80 percent compared to the previous generation of the respective models. Volkswagen will gradually introduce the new technology for all models [...]
Reduction of nitrogen oxide levels
The new 2.0 TDI Evo engines with twindosing process are expected to reduce nitrogen oxide levels by around 80 percent compared with the previous generation of the respective models.
Volkswagen will gradually introduce the new technology for all models with the Evo engines. Following the 2.0 TDI Evo with 150 hp currently used in the Passat, the new Golf will also rely on Twindosing in a similar form in all TDI variants.
Second catalyst in the underbody
The process requires a second SCR catalyst, which is located in the vehicle underbody. The greater distance from the engine means that the exhaust gas temperature upstream of the second catalytic converter is up to 100 degrees Celsius lower.
Even at exhaust gas temperatures close to 500 degrees Celsius, the overall system can still achieve high conversion rates. A barrier catalytic converter downstream of the SCR system also prevents the slip of excess ammonia.
