Volkswagen's Touareg has one of the cleanest diesel engines in the world. Its BlueTDI engine with SCR catalytic converter reduces nitrogen dioxide (NOx) emissions by up to 90 percent. Touareg BlueTDI delivers 165kW/225 PS and meets even the strictest "Tier2 Bin5" exhaust emissions standards implemented in the US states particularly in California, Massachusetts, New York, Vermont, and Maine.
In the USA economical turbo-diesels like the V6 BlueTDI more than any present day powertrain technology can help in reducing oil consumption and the generation of climate-impacting greenhouse gases. Volkswagen will offer the Touareg with the SCR catalytic converter starting 2008 first in the US as part of its BlueTec alliance with DaimlerChrysler and Audi. The BlueTec alliance was started by the three carmakers last year.
Volkswagen has also scheduled the launching of a smaller Jetta in America in 2008. It will also be equipped with NOx storage catalytic converter that eliminates up to 90 percent of nitrogen oxides. Both the Touareg BlueTDI and Jetta are scheduled to debut in Europe. The Euro 4 standard currently specifies a NOx limit of 0.25 g/km while the US standard which Volkswagen Touareg BlueTDI satisfies specifies a NOx limit of 0.043 g/km or 0.07 g/mile. Aside from the remarkable NOx catalytic converters that Touareg and Jetta have, they are also equipped with heavy duty VW axles.
It should be noted that the Touareg TDI had successfully towed a Boeing 747 and was made possible by its especially modified VW axle. By towing the 155 ton Boeing 747, Volkswagen Touareg has displayed not only the prowess of its engine but also the durability and power of every component.
The SCR (Selective Catalytic Reduction) Catalytic Converter
SCR is short for "Selective Catalytic Reduction". Its main function is to selectively convert the nitrogen oxide or NOx exhaust components to nitrogen and water without producing any undesirable byproducts. Volkswagen's Touareg BlueTDI which will debut at the Geneva Motor show will also feature an oxidation catalytic converter and a diesel particulate filter.
Water-based urea solution like AdBlue is used in converting the nitrogen oxides. The urea solution is stored in an auxiliary tank on the Touareg BlueTDI. It is in the auxiliary tank wherein the 32.5 percent urea is continuously sprayed into the exhaust stream before the SCR catalytic converter. It is measured based on the mass flow of the exhaust. An engine management system after obtaining information from a Nox sensor located after the SCR catalytic converter makes sure that everything is correctly regulated.
The urea solution is atomized into fine spray by a screen and transformed in the hot exhaust has stream upstream of the catalytic converter. It is in the SCR catalytic converter where the nitrogen oxide is split into nitrogen and water. The water-based additive AdBlue is an odorless, non-toxic and biodegradable solution.
The AdBlue is consumed at an average rate of about 0.1 liter per 100 kilometers. The tank and consumption are measured so that the AdBlue supply can last up to the next scheduled service.