This document provides an overview of exhaust gas recirculation systems. It discusses how nitrogen oxides (NOx) form in diesel engines due to high combustion temperatures. Exhaust gas recirculation reduces NOx by diluting the oxygen in incoming air with inert exhaust gases, lowering in-cylinder temperatures. The basic components of an EGR system include an EGR valve, cooler, and transfer pipe to recirculate a portion of exhaust back to the intake manifold. By reducing oxygen levels and peak combustion temperatures, EGR decreases NOx emissions while improving engine efficiency and life. However, EGR can also reduce power output if oxygen levels are decreased too much.

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
1. EGR Valve
2. EGR Cooler
3. 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 (NOx)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 O2 in the incoming air stream and provides
gases inert to combustion to act as absorbents of combustion heat to reduce
peak in-cylinder temperatures.
 NOx 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.

16. Thank You