German oil manufacturer LIQUI MOLY has recently introduced a new product to the market that addresses a prevalent issue with the AdBlue reagent. The additive, known as DEF Anti Crystal Additive Concentrate, is designed to protect the Selective Catalytic Reduction system from damage.
The SCR system, familiar to most hauliers, is a crucial component in modern diesel-powered vehicles. In addition to diesel fuel, these vehicles require AdBlue to meet the nitrogen oxide emission standards applicable in Europe. The SCR system converts nitrogen oxides generated during the combustion process in a diesel engine into elemental nitrogen and water in the catalytic converter.
However, the reliability of this system can be compromised due to the crystallisation of the urea contained in AdBlue.
“Urea crystals form in the lines or in the dosing valves. This happens when the water in the pipes evaporates,” explains David Kaiser, Head of Research and Development at LIQUI MOLY. In extreme cases, this can lead to blockages in the AdBlue system, potentially causing damage to the pump and injectors or triggering an error message in the engine control unit.
LIQUI MOLY claims to have found a solution to this problem.
“The AdBlue reagent additive, called DEF, is injected into the hot exhaust system in appropriate doses through a separate tank. The solution evaporates there. Residues may form because a coating forms on the surface of the exhaust pipe, where water evaporates faster than the urea can decompose,” says Kaiser.
According to Kaiser, the additive lowers the temperature to obtain the so-called Leidenfrost effect. This phenomenon promotes the residue-free decomposition of the AdBlue solution and limits the formation of a film on the exhaust surface.
Another challenge of the SCR system is the sensitivity of the reagent to cold. To protect the system from freezing, vehicle manufacturers use heaters. However, they are only activated when the engine is started. “AdBlue freezes at temperatures below -11.5 degrees C. Thanks to our additive, the freezing point can be reduced to approximately -16 degrees C,” explains Kaiser.
The DEF Anti Crystal Additive Concentrate can be used for all SCR systems powered by a 32.5% urea solution, providing a practical solution to common issues faced by hauliers using modern diesel-powered vehicles.
