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NO x gases are usually produced from the reaction between nitrogen and oxygen during combustion of fuels, such as hydrocarbons, in air; especially at high temperatures, such as in car engines. [ 1 ] [ 2 ] [ 3 ] In areas of high motor vehicle traffic, such as in large cities, the nitrogen oxides emitted can be a significant source of air pollution.
SCR systems are now the preferred method for meeting Tier 4 Final and EURO 6 diesel emissions standards for heavy trucks, cars and light commercial vehicles. As a result, emissions of NOx, particulates, and hydrocarbons have been lowered by as much as 95% when compared with pre-emissions engines. [2]
The main drawback of lean-burning is that a complex catalytic converter system is required to reduce NOx emissions. Lean-burn engines do not work well with modern 3-way catalytic converter —which require a pollutant balance at the exhaust port so they can carry out oxidation and reduction reactions—so most modern engines tend to cruise and ...
Selective non-catalytic reduction (SNCR) is a method to lessen nitrogen oxide emissions in conventional power plants that burn biomass, waste and coal.The process involves injecting either ammonia or urea into the firebox of the boiler at a location where the flue gas is between 1,400 and 2,000 °F (760 and 1,090 °C) to react with the nitrogen oxides formed in the combustion process.
Cummins Inc. (NYSE: CMI) is testing the same technology that boosts fuel economy in passenger vehicles to see whether it can dramatically reduce smog-forming oxides of nitrogen (NOx) emissions ...
The California Air Resources Board found in studies that 50% or more of the air pollution in Southern California is due to car emissions. [citation needed] Concentrations of pollutants emitted from combustion engines may be particularly high around signalized intersections because of idling and accelerations. Computer models often miss this ...
The term NO x represents several forms of nitrogen oxides such as NO (nitric oxide), NO 2 (nitrogen dioxide) and N 2 O (nitrous oxide, also known as laughing gas).In a gasoline engine, NO is the most common form of NO x at around 93%, while NO 2 is around 5% and the rest is N 2 O.
[53] [54] In reality, the system failed to combine lower fuel consumption with compliant NO x emissions, and Volkswagen chose around 2006 [60] to program the Engine Control Unit (ECU) to switch from lower fuel consumption and high NO x emissions to low-emission compliant mode when it detected an emissions test, particularly for the EA 189 ...