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- By closing the VGT vanes, the exhaust pressure builds up, higher than the intake pressure, which allows the exhaust gas to flow into the intake. By using a throttle in the intake manifold, the pressure after the throttle drops, below the exhaust gas pressure, which also triggers the exhaust gases to flow into the intake manifold.
x-engineer.org/exhaust-gas-recirculation-egr-introduction/Exhaust Gas Recirculation (EGR) complete guide – introduction
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In order to have an exhaust gas flow into the intake manifold, the exhaust gas pressure must be higher than the intake air pressure. On a turbocharged diesel engine this can be achieved either by using the geometry of the turbine vanes (VGT) or by fitting a throttle on the intake manifold.
Exhaust gas recirculation (EGR) is the most common technology to reduce nitrogen oxides (NOx) emissions on diesel internal combustion engines (ICE). EGR takes exhaust gases from the exhaust manifold and reintroduces them into the intake manifold, mixing them with fresh air.
Exhaust gas recirculation (EGR) has proven to be a successful method of emission control. In the case of conventional highpressure EGR, exhaust gas is removed immediately after the cylinder and mixed with the intake air.
- High Pressure EGR
- Low Pressure EGR
- Hybrid (Combined), Dual Loop EGR
- Dedicated EGR
High pressure EGR, compared with a low pressure EGR system, is referred to as the “classic” EGR architecture. This architecture is the most widespread and has been used on diesel engines starting with Euro 2 pollutant emissionlimits. In a high pressure EGR system, the exhaust gas is taken before the turbine and reintroduced into the intake manifold...
Euro 6 standard reduced the NOxemissions limit to only 80 mg/km in the NEDC cycle, compared with 180 mg/km for Euro 5. This significant drop has imposed an increase of the EGR rates and the introduction of low pressure EGR systems. In a low pressure EGR system, the exhaust gas is taken after the turbine and reintroduced into the intake manifold bef...
Hybrid (combined) EGR system integrates both high pressure EGR and low pressure EGR on the same engine. This type of EGR architecture is also called dual loop EGR system. The advantage of this architecture is that combines the benefit of both low and high pressure EGR systems, switching between them depending on the operating point of the engine (s...
In spark ignitions engines, high levels of EGR rates (more than 15%) increase fuel efficiency and reduce pollutant emissions. The drawback is that high EGR rates can cause incomplete combustion and increased hydrocarbons (HC) emissions. To overcome this, the combustion stability can be improved by supplementing the air charge with either pure hydro...
Mar 17, 2023 · High-pressure EGR – This system recirculates exhaust gases back into the engine at high pressure, typically just before the intake manifold. Exhaust gas cooling – This system cools the exhaust gases before they are recirculated back into the engine, which further reduces the formation of NOx.
Nov 11, 2020 · As part of the combustion process, air enters the combustion chamber through the intake manifold and mixes with the fuel. As it is compressed or ignited (depending on the system), the pressure forces the piston down to power the engine and exhaust gas comes out through the exhaust manifold .
Oct 3, 2019 · The EGR system reduces the combustion temperature by diverting a small portion of the exhaust gases back into the intake manifold. How does it work? Exhaust gases are no longer combustible.
