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Christian Libby
2nd hour
Auto Tech 1
Tech Report on Diesel Exhaust Fluid
Diesel trucks could be run with a lean air-to-fuel ratio, to ensure the full combustion of soot and to prevent the exhaust of unburnt fuel. The excess of oxygen necessarily leads to nitrogen oxides (NOx), which are harmful gases, from the nitrogen in the air. Selective catalytic reduction (diesel exhaust fluid) is used to reduce the amount of NOx released into the atmosphere.
Diesel exhaust fluid (from a separate DEF tank) is injected into the exhaust pipeline, the aqueous urea vaporizes and decomposes to form ammonia and carbon dioxide. Within the SCR catalyst, the
NOx are catalytically reduced by the ammonia (NH3) into water and nitrogen (N2), which are both harmless; and …show more content…
DEF is clear and colorless, and looks exactly like water. It has a slight smell of ammonia, similar to some home cleaning agents.
DEF is used in by Selective Catalytic Reduction (SCR) technology to remove harmful NOx emissions from diesel engines.
In January 2010, the U.S. Environmental Protection Agency
(EPA) brought in new emissions standards requiring medium- and
heavy-duty vehicles to significantly reduce engine emissions, particularly NOx and particulate matter (PM). Vehicle manufacturers use SCR to meet these standards. DEF is sprayed into the exhaust, breaking down NOx gases into nitrogen and water using an advanced catalyst system. As a result most new diesel trucks, pickups, SUVs, and vans are now fitted with SCR technology and have a DEF tank that must be regularly refilled.
EPA set the emissions standards to improve air quality. NOx and PM emissions are associated with a wide range of health problems including respiratory and cardio diseases, aggravation of asthma, acute respiratory symptoms, chronic bronchitis and decreased lung function. The EPA estimates that the emission standards will prevent 8,300 premature deaths, more than