UENR4490-01 25 Engine Operation Illustration 22 g03690232 Typical example (1) Exhaust outlet connection (2) Diesel Oxidation Catalyst (DOC) (3) Selective Catalytic Reduction (SCR) system (4) Diesel Exhaust Fluid (DEF) injector (5) Exhaust intake connection The Clean Emissions Module (CEM) for the engine consists of the following components. A flexible exhaust pipe connects the engine to the Clean Emissions Module (CEM). Refer to Disassembly and Assembly for the correct procedure to install the flexible exhaust pipe.
Diesel Oxidation Catalyst (DOC) Selective Catalytic Reduction (SCR) system After the DOC, the exhaust gases are injected with a Diesel Exhaust Fluid (DEF) by a Diesel Exhaust Fluid (DEF) injector. The exhaust gases and the DEF are mixed in a mixing chamber. The mixture decomposes to form ammonia and carbon dioxide. The mixture passes to the main Selective Catalytic Reduction (SCR) reaction chamber. The DOC oxidizes the carbon monoxide and the hydrocarbons that are not burnt in the exhaust gas into carbon dioxide and water. The DOC also acts on the oxides of nitrogen to increase the nitrogen dioxide fraction for improved efficiency of the SCR system.
The DOC is a through flow device that will continue to operate during all normal engine operating conditions.