File Name: exhaust gas recirculation advantages and disadvantages .zip
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- How Exhaust Gas Recirculation (EGR) system works
- EGR Systems & Components
For more details about why EGR is needed on an internal combustion engine, how it works and what components an EGR system contains, read also the following articles:. Exhaust Gas Recirculation EGR systems are widely used in diesel engines with the purpose of reducing the formation of nitrogen oxides NO x , by lowering the combustion temperature and the amount of oxygen into the cylinders. Depending on whether the exhaust gas is recirculated before or after the turbocharger , there are two types of EGR systems:. This architecture is the most widespread and has been used on diesel engines starting with Euro 2 pollutant emission limits. In a high pressure EGR system, the exhaust gas is taken before the turbine and reintroduced into the intake manifold after the compressor, thus in the high pressure zone of both exhaust and intake manifolds.
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In many countries around the world, the emissions of NOx from diesel and gasoline vehicles are restricted by legislation. NOx is formed in the combustion chamber of engines, when high temperatures cause oxygen and nitrogen both found in the air supplied for combustion to combine. This involves recirculating a controllable proportion of the engine's exhaust back into the intake air. A valve is usually used to control the flow of gas, and the valve may be closed completely if required. The substitution of burnt gas which takes no further part in combustion for oxygen rich air reduces the proportion of the cylinder contents available for combustion. This causes a correspondingly lower heat release and peak cylinder temperature, and reduces the formation of NO x.
How Exhaust Gas Recirculation (EGR) system works
Revision This is a preview of the paper, limited to some initial content. Full access requires DieselNet subscription. Please log in to view the complete version of this paper. Exhaust gas recirculation EGR is an emission control technology allowing significant NOx emission reductions from most types of diesel engines: from light-duty engines through medium- and heavy-duty engine applications right up to low-speed, two-stroke marine engines. While the application of EGR for NOx reduction is the most common reason for applying EGR to modern commercial diesel engines, its potential application extents to other purposes as well.
EGR Systems & Components
Oxides of nitrogen NOx are one of the major hazardous pollutants from diesel engine emission. Various control technologies exist for its control but each technique has advantages and disadvantages. At present, there is no single optimal technique that can control NOx without other side effects.
Revision This is a preview of the paper, limited to some initial content. Full access requires DieselNet subscription.
External Exhaust Gas Recirculation EGR has been used on diesel engines for decades and has also been used on gasoline engines in the past. It is recently reintroduced on gasoline engines to improve fuel economy at mid and high engine load conditions, where EGR can reduce throttling losses and fuel enrichment. Fuel enrichment causes fuel penalty and high soot particulates, as well as hydrocarbon HC emissions, all of which are limited by emissions regulations.