What is the purpose of automotive urea?
4 Answers
Automotive urea is a liquid used in SCR (Selective Catalytic Reduction) technology to reduce nitrogen oxide (NOx) pollution in diesel vehicle exhaust. It is composed of 32.5% high-purity urea and 67.5% deionized water. Automotive urea is synthesized by blending high-quality agricultural urea with ultrapure water in specific proportions. According to national standards, there are strict requirements for the density, refractive index, alkalinity, metal ion content, and impurities in automotive urea. The primary harmful substances in diesel vehicle exhaust are nitrogen oxides and particulate matter. While particulate emissions can be reduced through technical means within the engine, the remaining exhaust mainly consists of nitrogen oxides. By injecting automotive urea into the exhaust after-treatment device, the urea decomposes into ammonia at high temperatures, which then reacts with nitrogen oxides in the presence of a catalyst to form harmless nitrogen and water. This process is known as the SCR after-treatment system.
Automotive urea? Simply put, it's a 'cleaning agent' for diesel vehicles to purify exhaust. My diesel pickup truck needs this stuff, mainly working in conjunction with the SCR system onboard. The exhaust from diesel vehicles contains severe nitrogen oxide pollution. When urea is injected into the exhaust pipe, it produces ammonia gas, which can convert most nitrogen oxides into harmless water and nitrogen. If you don't add it or use inferior quality, not only will the car alarm, but over time it may also clog the exhaust pipe, and the power will suffer as well. Most crucially, many places check this environmental indicator during annual inspections.
I didn't understand it before either, but later a friend who drives heavy trucks told me this is crucial for diesel vehicle exhaust treatment. The exhaust gas from diesel engines needs to pass through the SCR system (Selective Catalytic Reduction system). After the urea is injected and reacts, it can basically decompose all the harmful nitrogen oxides. If you don't add urea or the concentration is incorrect, the vehicle will either limit power or directly trigger a fault light. Some places even check this indicator during annual emissions inspections. You need to be careful not to spill it when refilling, as it's corrosive to the skin. Oh, and it's best to use certified urea for different vehicle brands, as off-brand products can easily crystallize and clog the nozzles.
After driving a diesel SUV for several years, I finally understood that this blue urea (scientifically known as AdBlue) is the environmental assistant for diesel vehicles. It is injected into the SCR system, where it decomposes into ammonia, specifically neutralizing the irritating nitrogen oxides in the exhaust. If you don't add it, the vehicle's system will definitely light up a warning, and it will also fail the annual inspection. For long trips, it's best to carry two barrels, especially in northern winters where you need to switch to the winter-grade antifreeze version in advance. Its consumption is linked to mileage, averaging about 1-1.5 liters per 100 kilometers.
