How does the Exhaust Gas Recirculation (EGR) system work?

[VivienneDella]

The working principle of Exhaust Gas Recirculation (EGR) is a specific application of the heat capacity theory. Since triatomic gases such as CO2, H2O, and NO2 in engine exhaust have relatively high specific heat, when fresh air-fuel mixture is mixed with exhaust gas, the heat capacity increases accordingly. Heating this exhaust-diluted mixture requires more heat for each degree of temperature rise. With the total heat released by fuel combustion remaining unchanged, the combustion temperature is thereby reduced. The primary purpose of EGR is to reduce nitrogen oxides (NOx) in the exhaust gas and improve fuel economy under partial load conditions. There are various forms and control methods for EGR systems. Based on the actuator (EGR valve) control mechanism, they can be classified into mechanically controlled EGR systems and electronically controlled EGR systems.

[IsabellaRose]

The Exhaust Gas Recirculation system, or EGR, is something I'm quite familiar with in terms of how it works. Essentially, it redirects a portion of the exhaust gases from the exhaust pipe back into the intake, mixing them with fresh air before sending the mixture into the engine's combustion chamber for burning. This mixing process lowers the combustion temperature, reducing the formation of nitrogen oxides (NOx) under high-temperature conditions, which is particularly effective in cutting down tailpipe emissions. I've seen many older vehicles suffer from severe carbon buildup due to aging EGR systems, leading to engine misfires or power loss. That's why regular maintenance, including cleaning the EGR valve to prevent clogging, is crucial. During high-speed driving, the system activates more frequently, while in city traffic jams, it may occasionally remain inactive without affecting daily driving. Overall, this is a common eco-friendly technology in modern vehicles, helping us comply with emission standards, and it works even better when paired with a catalytic converter.

[White]

I think exhaust gas recirculation is a clever little trick in automotive eco-design, with a pretty straightforward principle: it takes a portion of the exhaust gases emitted by the engine and sends them back to the intake via a valve, where they mix with oxygen before being burned again. The key role is to lower combustion temperatures, suppressing the production of harmful nitrogen oxides, which helps improve urban air quality. I recall that new car designs often emphasize this feature, especially under the China VI emission standards, as it reduces the vehicle's environmental impact. However, I should remind everyone that long-term use of the system can lead to soot buildup, affecting valve operation and potentially increasing fuel consumption or reducing power. But regular maintenance can easily prevent these issues. Overall, it strikes a good balance between performance and environmental friendliness—quite practical.

[McAriel]

I once experienced an issue with the exhaust gas recirculation (EGR) system in my own car, which triggered the engine warning light. The principle involves recirculating a portion of exhaust gases back into the combustion chamber to lower combustion temperatures and control pollution. Simply put, it functions like a small recirculation system, using a valve to regulate the flow of exhaust gases and prevent excessive nitrogen oxide emissions at high temperatures. During my repair, I found that the valve was stuck, affecting the engine's smooth operation, and the car returned to normal after the fix. This technology is beneficial for reducing smog and health risks, but without regular maintenance, carbon buildup can clog the valve, leading to idle instability issues.