What is the purpose of adding urea to trucks?

[VivianAnn]

Trucks use urea primarily to reduce harmful nitrogen oxides in exhaust gases into nitrogen and water. Below is a detailed introduction to vehicle urea: 1. Principle: The main harmful substances in exhaust are nitrogen oxides and particulate matter. While particulate emissions can be reduced through technical means inside the engine, nitrogen oxides remain predominant in the exhaust. By injecting urea into the exhaust after-treatment device, the urea decomposes into ammonia gas under high temperatures. In the presence of a catalyst, the ammonia reacts with nitrogen oxides to produce harmless nitrogen and water. This system is called the SCR (Selective Catalytic Reduction) after-treatment system. 2. Urea consumption: Vehicles are equipped with a dedicated urea tank. As long as the vehicle is running, urea will be consumed, so it needs to be replenished regularly. Generally, about 4 liters of urea are consumed per 100 liters of diesel. The exact consumption depends on factors such as engine displacement, model, manufacturer, etc. Different road conditions and varying loads can also affect urea consumption.