/ Kubota Interim Tier IV Motor Oils #11
- Apr 21, 2001
- Rural mountains - Colorado
- Kubota M59, JD530, JD310SG. Restoring Yanmar YM165D
Exhaust Gas Recirculation (EGR) is often misunderstood.
Exhaust is introduced into the combustion chamber,which dilutes the oxygen level in the chamber.
This results in a lower combustion chamber temperature,thereby reducing NOx emissions.
Thank you for participating. What is it that you think is misunderstood? How to explain it better?
Let me add that the EGR gas is first cooled by engine coolant in a heat exchanger, and then mixed with more heated turbo-pressurized air in the intake manifold before going on to the combustion chamber.
So although lack of oxygen reduces combustion temperatures, the intake air is still heated above ambient.
Retarding the timing further reduces combustion temperatures.
Lower temperatures plus the lack of oxygen reduces NOx emissions, but increases the soot emissions.
In a nutshell, the increased soot is the problem with using EGR to meet Interim Tier IV regulations. The whole Interim regulations is a poorly designed stopgap that met the regulations but missed the point.
Some of us with Interim engines who would like to reduce the soot as well. Anyone who wants please jump in. It would be better for the operator, the world, and of course it would be better for the engines. Soot is not only a poison, it is abrasive.