The double AdBlue injection arrives for TDI engines

Volkswagen presents a new system to reduce NOx emissions from its TDI engines by up to 80%, thanks to the double injection of AdBlue.

The increasingly strict emission regulations are forcing manufacturers to implement more sophisticated technologies to reduce the harmful gases that come out of their engines’ exhausts. Among them, one of the most widely adopted is AdBlue injection into the exhaust for TDI engines.

If your diesel uses AdBlue, you should know this. In the article from the previous link you will learn a little more about this additive, what it is, and its advantages and disadvantages. Above all, because now the second evolution of selective catalytic reduction (SCR) technology has arrived, which is how these systems that require the AdBlue additive to work properly are known.

And it is that diesel engines have an advantage over petrol engines in terms of lower CO2 emissions, because diesel has a higher energy density and the combustion process is more efficient. But since combustion in diesel engines takes place with excess air, and the main constituent of air is nitrogen, diesel engines produce higher emissions of nitrogen oxides (NOx). You can see a more detailed explanation here about which pollutes more, a diesel or a petrol engine.

The double AdBlue injection will debut on the new VW Passat

The new system doubles the elements needed in the exhaust to eliminate up to 80% of nitrogen oxides. Thus, instead of one SCR catalyst, two are needed. And the AdBlue additive is injected selectively into the exhaust gas stream as it passes through these two catalysts.

Since the second SCR catalyst is farther from the engine than the first, the exhaust gas temperature there can be around 100 degrees lower than at the first catalyst. The main advantage is that the operating range for the post-treatment of exhaust gases is widened in this second catalyst, with higher conversion rates from cold start up to when the exhaust gas temperature exceeds 350 degrees. It also prevents the possible slip of ammonia generated when AdBlue comes into contact with the exhaust gases.

Volkswagen will debut the double AdBlue injection technology in the 2.0 TDI Evo engine of the new Passat.

Volkswagen will fit the new dual SCR system in the new Volkswagen Passat, initially in the 2.0 TDI Evo engine. It will later also be used in the new generation of the Volkswagen Golf, and will be gradually introduced across the rest of the range.