Exhaust Gas Recirculation
Exhaust Gas Recirculation
(OP)
I understand that it is used in automotive engines to reduce the NOx emissions of the engine. What happen to the carbon dixiode as it going through another combustion cycle? Does it become something different? Does it do anything beside take up volume in the cylinder chamber that could be better filled by oxygen?





RE: Exhaust Gas Recirculation
In effect the exhaust (which is largely nitrogen by the way) dilutes the reaction and gives the fixed quantity of fuel more stuff to heat up, so it reduces the combustion temperature. NOx forms at high temperatures.
Cheers
Greg Locock
RE: Exhaust Gas Recirculation
Less O2 means less heat.
RE: Exhaust Gas Recirculation
RE: Exhaust Gas Recirculation
http://www.damek.kth.se/~borje/Artiklar/SAE%20982476.pd...
http://www.damek.kth.se/~borje/Artiklar/SAE%201999-01-3...
My real interest in both of these papers is whether or not EGR is really just an alternative type of water injection since steam is a primary component of the exhaust gas.
Though I am interested in following this thread for any information on the possibility of induction charge displacement from the other inert gases in the EG that is being recirculated.
Ed.
www.turboice.net
RE: Exhaust Gas Recirculation
The biggest effect seems to be the decreased oxygen decreases peak flame temperature.
RE: Exhaust Gas Recirculation
Recently, throttled Diesel engines have been tested: using an electronic controlled throttle valve (ETC), it's possible to lower the intake manifold pressure and increase the fraction of recirculated gases, being their mass flow related to the exhaust/intake pressure ratio. This, in future, can contribute to the NOx reduction in Diesels, always a critical emission of these engines. To increase volumetric efficiency is also widely used an EGR cooler, a gas/liquid heat exchangers using engine's cooling water.
RE: Exhaust Gas Recirculation
Any throttling of the diesel inlet gases would eat into their efficiency, better to displace the air with inerts.