UENR4490-01 21 Engine Operation Illustration 17 g02467360 Typical example The NOx Reduction System (NRS) operates with the transfer of the hot exhaust gas from the exhaust manifold to the exhaust cooler (8). The hot exhaust gas is cooled in the exhaust cooler (8). The now cooled exhaust gas passes through the assembly of the exhaust gas valve. As the demand for more cooled exhaust gas increases the electronically controlled valve opens further. The further opening of the valve increases the flow of cooled exhaust gas from the exhaust cooler. As the demand for cooled exhaust gas decreases, the electronically controlled valve closes.
This decreases the flow of cooled exhaust gas from the exhaust cooler. The reed valves that are located in the exhaust gas valve (NRS) has one main function. The one main function is to prevent the reverse flow of charge air from the inlet side of the engine to the exhaust side of the engine. Exhaust gases from the exhaust manifold enter the inlet of the high-pressure turbocharger in order to turn the high-pressure turbocharger turbine wheel. The turbine wheel is connected to a shaft that rotates. The exhaust gases travel from the high- pressure turbocharger.
The exhaust gases then travel through the duct on the turbine side into the turbine inlet of the low-pressure turbocharger in order to power the low-pressure turbocharger. The exhaust gases pass from the low-pressure turbocharger through the following components: exhaust outlet, back pressure valve, Clean Emissions Module and exhaust pipe. As the electronically controlled valve (9) starts to open the flow of cooled exhaust gas from the exhaust cooler (8) mixes with the air flow from the charge air aftercooler. The mixing of the cooled exhaust gas and the air flow from the charge air aftercooler reduces the oxygen content of the gas mixture.
This results in a lower combustion temperature, so decreases the production of NOx.