Exhaust gas recirculation system

About the exhaust gas recirculation system

1. Presentation on Exhaust Gas Recirculation System

2. Contents Intro Formation of Nox . How can Nox be Reduced Exhaust Gas Recirculation Basic Parts of EGR Working Principle Advantages Disadvantages Conclusion

3. Introduction Major problem environmental pollution is faced by today’s world. For which, vehicular traffic is a major contributor.  Exhaust gases from vehicles includes CO,CO2,HC,Noxs etc. Of these NOx is particularly very harmful. These are one of the chief constituents of smog, which have an adverse effect on ecological systems. They are also contribute to the formation of acid rain.  NOx also cause breathing illness in human beings

4. Formation of NOx The factors that cause diesel engines to run more efficiently than gasoline engines also cause them to run at higher temperature. This leads to the creation of Nitrogen Oxides (NOx). Fuel in any engine is burned with extra air and some of the OXYGEN is used to burn the fuel. When the peak temperatures are high enough for long periods of time, the NITROGEN and OXYGEN in the air combines to form NITROGEN OXIDES.

5. How can Nox be Reduced In order to reduce NOx an engine should run at a lower temperature than the normal temperature. Reduced cylinder temperatures can be achieved in three ways. Enriching the air fuel mixture Lowering the compression ratio and retarding ignition timings Reducing the amount of Oxygen in the cylinder

6. Exhaust Gas Recirculation Exhaust Gas Recirculation is an efficient method to reduce NOx emissions from the engine . It works by recirculating a quantity of exhaust gas back to the engine cylinders . Recirculation is usually achieved by piping a route from the exhaust manifold to the intake manifold. A control valve within the circuit regulates and times the gas flow.

7. Basic Parts of EGR There are 3 basic parts of EGR EGR Valve EGR Cooler EGR Transfer Pipe

8. EGR Valve

9. EGR Cooler

10. EGR Transfer Pipe

11. EGR Engine

12. Working Principle In internal combustion engines,  exhaust gas recirculation  ( EGR ) is a nitrogen oxide ( NO x )emissions reduction technique used in petrol/gasoline and diesel engines. EGR works by recirculating a portion of an engine's exhaust gas back to the engine cylinders. This dilutes the O 2  in the incoming air stream and provides gases inert to combustion to act as absorbents of combustion heat to reduce peak in-cylinder temperatures. NO x  is produced in high temperature mixtures of atmospheric nitrogen and oxygen that occur in the combustion cylinder, and this usually occurs at cylinder peak pressure. Another primary benefit of external EGR valves on a spark ignition engine is an increase in efficiency, as charge dilution allows a larger throttle position and reduces associated pumping losses.

13. Advantages It reduce Nox and save the environment. It decreases the engine temperature. Improve Engine life through reduced cylinder temperature.

14. Disadvantages As EGR reduce O2 so it is difficult to combust the fuel. Continues reduction of O2 reduce the peak power required for the engine. EGR valves can’t responds all the time and it will take time to flow the EGR gases. As the amount of recirculated gas is less so for multi-cylinder engine the EGR gas is not reach in proper ratio.

15. Conclusion Using Exhaust Gas Recirculation Technique in engines, the emissions are vary much controlled due to lesser amounts of NOx entering the atmosphere. Exhaust Gas Recirculation is a very simple method. It has proven to be very useful and it is being modified further to attain better standards. This method is very reliable in terms of fuel consumption .

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