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Diesel exhaust fluid (DEF; also known as AUS 32 and sometimes marketed as AdBlue [3]) is a liquid used to reduce the amount of air pollution created by a diesel engine. Specifically, DEF is an aqueous urea solution made with 32.5% urea and 67.5% deionized water .
British Rail Class 55 Deltic diesel locomotive with their characteristic dense exhaust when starting a train. Diesel exhaust is the exhaust gas produced by a diesel engine, plus any contained particulates. Its composition may vary with the fuel type, rate of consumption or speed of engine operation (e.g., idling or at speed or under load), and ...
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 reduced by as much as 95% when compared with pre-emissions engines.
To meet EPA Tier 4 emission standards for nitrogen oxides , manufacturers rely on one of two methods: exhaust gas recirculation (EGR), where exhaust gases are cooled and recirculated back through the combustion cycle, or selective catalytic reduction (SCR) using urea-based diesel exhaust fluid, which converts NOx in the catalytic converter to ...
The structure of the molecule of urea is O=C(−NH 2) 2.The urea molecule is planar when in a solid crystal because of sp 2 hybridization of the N orbitals. [8] [9] It is non-planar with C 2 symmetry when in the gas phase [10] or in aqueous solution, [9] with C–N–H and H–N–H bond angles that are intermediate between the trigonal planar angle of 120° and the tetrahedral angle of 109.5°.
Emissions from all non-road engines are regulated by categories. [49] In the United States, the emission standards for non-road diesel engines are published in the US Code of Federal Regulations, Title 40, Part 89 (40 CFR Part 89). Tier 1–3 Standards were adopted in 1994 and was phased in between 1996 and 2000 for engines over 37 kW (50 hp ...
Euro 6 and US Tier 2 emission compliance is achieved via NOx adsorber-based system for smaller size vehicles or urea-SCR system for larger vehicles. Other features included low-friction bearings for the camshaft and balancer shafts, piston rings that have less pre-tension, a two-stage oil pump with volumetric flow control. [6] [7]
BlueTEC is Mercedes-Benz Group's marketing name for engines equipped with advanced NO x reducing technology for vehicle emissions control in diesel-powered vehicles.The technology in BlueTec vehicles includes a selective catalytic reduction (SCR) system that uses diesel exhaust fluid, and a system of NOx adsorbers the automaker calls DeNO x, which uses an oxidizing catalytic converter and ...