27-05-2013, 01:06 PM
SEMINAR ON EXHAUST GAS RECIRCULATION
EXHAUST GAS.ppt (Size: 4.69 MB / Downloads: 135)
INTRODUCTION
IC engine is a major source of pollution.
Exhaust gas includes CO2,CO,HC,NOx … …
NOx are important family of air polluting compound
Effects are acid rain, smog, breathing illness etc.
Formation of ground level ozone.
Exhaust can have 2000 ppm of NOx.
Exhaust gas recirculation(ECR)
FORMATION OF NOx
N2 breaks down into N (monoatomic)
Max. Temp occur at Stoichiometric f/a ratio (φ=1)
High Combustion duration.
Maximum NOx forms at φ=.95
Excess O2 combines with nitrogen.
EXHAUST GAS RECIRCULATION
It works by recirculating a quantity of exhaust gas back to the engine cylinders.
Intermixing the recirculated gas with incoming air reduces the amount of available O2 to the combustion and lowers the peak temperature of combustion.
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
EGR THEORY OF OPERATION
The purpose of the EGR system is to precisely regulate the flow under different operating conditions.
By integrating the fuel injection & amount of air entered control with the EGR metering system, engine performance and the fuel economy can be enhanced
For this an ECM (Electronic Control Machine) is used to regulate the EGR flow. When EGR is required ECM opens the EGR valve.
CONCLUSION
Using EGR Technique in engines, the emissions are very much controlled due to lesser amounts of NOx entering the atmosphere.
EGR is a very simple method. It has been proven to be very useful and it is being modified further to attain better standards.
EGR is the most effective method for reducing the nitrous oxide emissions from the engine exhaust.