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Exhaust Gas Recirculation (EGR)

Exhaust Gas Recirculation (EGR) is an emission control technology used in internal combustion engines to reduce nitrogen oxide (NOx) emissions. It works by redirecting a portion of the engine’s exhaust gases back into the combustion chamber, where they mix with the incoming fresh air-fuel mixture.

Reducing Nitrogen Oxide Emissions

Nitrogen oxides, primarily composed of nitrogen dioxide (NO2) and nitric oxide (NO), are harmful pollutants that contribute to air pollution and have adverse effects on human health and the environment. EGR plays a crucial role in mitigating these emissions by employing the following mechanisms:

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Lowering Combustion Temperatures: By recirculating exhaust gases, EGR reduces the amount of oxygen available in the combustion chamber. This leads to lower peak combustion temperatures, as oxygen is a key factor in promoting high-temperature reactions that generate NOx. Consequently, the formation of nitrogen oxides is significantly reduced.

Diluting the Air-Fuel Mixture: The recirculated exhaust gases act as an inert gas, diluting the incoming air-fuel mixture. This dilution effect lowers the concentration of oxygen in the combustion chamber, further suppressing the formation of nitrogen oxides during combustion.

Reducing Flame Front Speed: EGR also slows down the flame front speed, which is the rate at which the combustion process propagates through the air-fuel mixture. Slower flame front speed allows for more complete combustion and reduces the formation of nitrogen oxides.

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By combining these mechanisms, EGR effectively reduces nitrogen oxide emissions, helping to meet stringent emission standards and promoting sustainable development in the transportation sector.

Keywords: combustion, nitrogen, exhaust, emissions, mixture, oxides, chamber, reduces, oxygen