How does cooled EGR reduce NOx emissions?
• Cummins utilizes cooled EGR to effectively control NOx emissions. Cooled EGR works by re-circulating a varying proportion of the exhaust gas back to the cylinder. This reduces the oxygen content to a lower combustion temperature resulting in a reduction of NOx formation. The exhaust gas is cooled as it flows through an EGR cooler, and then is mixed with the compressed fresh air from the turbocharger before entering the intake manifold. EGR is introduced to reduce the amount of in-cylinder oxygen available forcombustion while maintaining the same amount of flow through the engine. Exhaust gases present during the start of combustion are very stable and have a very slow reaction rate. They absorb heat during combustion, resulting in lower in-cylinder peak flame temperatures, and therefore, lower NOx emissions.
