How Diesel Exhaust Fluid (DEF) Works and Is It Urine? The Chemistry of Cars [Video]

Diesel Exhaust Fluid UREA
Class is in session with TFLcar’s Charlotte Roadcap.

TFLcar’s Chemistry of Cars, Ep. 1 – What is Diesel Exhaust Fluid?

TFLcar’s Charlotte Roadcap lays out why diesel engines emit nasty NOx molecules and how diesel exhaust fluid, more commonly known as UREA works.

In a nutshell, she points out that diesels run at higher temps and pressures than gasoline engines. And they run lean, therefore, they produce more NOX emissions. And she explains how those NOx particles reek havoc on the environment and atmosphere.

To mitigate the problem auto manufacturers sent UREA to the rescue. The UREA tank connects to the vehicle’s exhaust and sprays the rough mix of 2 parts water to 1 part ammonia onto the hot exhaust. This causes a chemical reaction which splits the NOx molecules apart to produce nitrogen gas and water vapor.

Simple right? Well, Charlotte does a much better job of putting this chemistry into plain English. She also unravels the myth that UREA essentially repurposed cat pee. You’ll have to watch Charlotte’s video to find out her answer.