What is the device that can reduce nitrogen oxide emissions from the engine?
4 Answers
The device that can reduce nitrogen oxide emissions from the engine is the Exhaust Gas Recirculation (EGR) system. Exhaust Gas Recirculation is a technology used in small internal combustion engines for automobiles, where a portion of the exhaust gases is redirected back to the intake side to be re-breathed after combustion. There are various forms and control methods for EGR systems. Based on the actuator control form, they can be categorized into mechanically controlled EGR systems and electronically controlled EGR systems. The basic principle of Exhaust Gas Recirculation: Since the specific heat of triatomic gases such as CO2, H2O, and NO2 in engine exhaust is relatively high, when fresh air-fuel mixture is mixed with exhaust gases, the heat capacity increases accordingly. Heating this exhaust-diluted mixture requires more heat to raise the temperature by 1 degree, which means that with the same total heat release from fuel combustion, the maximum combustion temperature is reduced. Additionally, the dilution effect of exhaust gases on the fresh air-fuel mixture lowers the oxygen concentration, thereby inhibiting the formation of nitrogen oxides.
When it comes to devices for reducing nitrogen oxide emissions from engines, I think the most reliable one is the Exhaust Gas Recirculation system, or EGR system. This thing works by recirculating a portion of the exhaust gas back into the engine for re-combustion, which lowers the temperature and thus reduces the formation of nitrogen oxides. All the cars I've driven before were equipped with this system, and it's quite common in both gasoline and diesel vehicles. If the system fails, emissions will exceed the standard and may also affect engine performance. Additionally, in diesel vehicles, there's the SCR system, which uses a urea solution to convert nitrogen oxides, making the emissions much cleaner. During maintenance, you need to check these devices for blockages or leaks, replace filters, and so on, to ensure the car remains environmentally friendly and durable. Overall, these designs help minimize the vehicle's impact on the air and meet regulatory requirements.
To reduce nitrogen oxide emissions, I have to mention the SCR system, mainly used in diesel vehicles. It's like installing a chemical filter for the engine, requiring AdBlue liquid to be sprayed in to treat exhaust gases, and the effect is excellent. I've noticed that modern vehicles basically all have this device. If you drive a diesel car, remember to refill the urea regularly; otherwise, the system will trigger an alarm, and emissions won’t meet standards. Additionally, the EGR device is also quite important—it cools the combustion process, reducing pollution sources. During my last car maintenance, the technician reminded me to clean the EGR valve to prevent carbon buildup from affecting performance. These kinds of devices make vehicle exhaust emissions cleaner, the air fresher, and give peace of mind while driving.
Nitrogen oxide emission control devices include SCR systems for diesel vehicles, three-way catalytic converters for gasoline vehicles, and EGR systems which can be used in both. SCR uses urea to convert exhaust gases, catalysts employ chemical reactions for purification, and EGR reduces temperature by recirculating exhaust. I find these devices relatively easy to maintain, but it's important to prevent dirt from affecting functionality. Regular inspections can prevent major issues.
