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So which wide-body light passenger brands have national five models?
At present, wide-body light passengers on the market are: all models of SAIC Chase V80, JMC New Generation Transit, Nanjing Iveco, Dongfeng Yufeng, Fukuda Tuiano
First of all, what is the urea solution for cars?
The urea solution for vehicles is a colorless, transparent and clear liquid with a concentration of 31.8% -33.2%, which is used to reduce nitrogen oxides. The urea solution for vehicles was first used in Europe, called Adblue, and the North American term was DEF (Diesel Exhaust Fluid), which is called the vehicle urea solution or "vehicle denitrifier" in China.
The currently used vehicle urea solution is generally composed of 32.5% high-purity urea and 67.5% deionized water. The concentration of urea directly affects the reduction rate of nitrogen oxides and the crystallization point of the urea solution. Too high or too low concentration will not only improve the conversion efficiency of nitrogen oxides, but will also cause secondary pollution caused by the remaining ammonia. The concentration of 32.5% was chosen because the urea solution of automotive has the lowest crystallization point at this concentration (freezing point -11 ° C).
So why use a urea solution for cars?
With the continuous improvement of China ’s diesel engine emission standards, modern diesel vehicles, whether they adopt EGR [exhaust gas recirculation technology] or SCR [catalytic reduction] and other technologies in the treatment of exhaust gas, have become the automobile after-treatment equipment or application technology. Necessary for the development of the times. China's upgrade of the fourth line is the SCR line, that is, the use of selective catalytic reduction technology. The operation process is shown in the figure. Generally, the exhaust gas comes out of the turbine and enters the exhaust pipe. A urea metering injection device is installed on the exhaust pipe to inject urea aqueous solution. The nitrogen oxides in the urea solution and the exhaust gas are in the SCR reaction tank. A redox reaction occurs, and nitrogen and water are generated and discharged.
Nitrogen and oxygen compounds in automobile exhaust are not only one of the causes of acid rain, but also directly harm the human body. The role of the urea solution is to chemically react with nitrogen oxides in the car exhaust to generate non-toxic nitrogen and water, thereby reducing the emissions of toxic gases in the car exhaust and reducing pollution.
The optimal transport and storage temperature should be kept between -5 ° C and 25 ° C. In addition, urea for vehicles will crystallize when the temperature becomes low, and the volume expansion will increase to 7%. If the urea is too full, it will be kept below 90% of the storage volume ratio. High temperature will cause the decomposition of urea. Generally, the storage temperature of urea is related to the storage time of urea.
Therefore, the technology of combustion optimization + SCR also has certain shortcomings. It requires the construction of urea supply infrastructure, the need to prevent ammonia gas excretion technology, the requirement to reduce the consumption of lubricating oil by the engine, and the requirements for the system layout space (requires the addition of a urea tank). ).