> Exhaust contains carbon dioxide and inert gases. Those gases cool the
> combustion process thus reducing chamber temperatures and in the process
> reduces the chance of preignition. Exhaust temperature has nothing to do
> with it, it's the affect the gases in the exhaust have in the combustion
> chamber.
>
> Read all about it: http://www.motorage.com/edindex/129614.htm - ABCs of EGR
I guess that is true in a way, but in that respect, cooling or heating
really has nothing to do with it. Ive taken the class, done the math, and
worked the complete chemical equations for combustion (really, Ive taken a
graduate class on internal combustion engines, lots of thermodynamics,
hear transfer and chemistry) and the EGR gasses in no way cool anything,
if you want to talk temperature, they heat things up. What the EGR does,
and does fairly well, is introduce residual gasses into the combustion
process. What this effectively does is slow down the combustion process a
bit, and this helps to prevent preignition becuase it is harder for the
combustion process to start. Combustion with the EGR is more complete
though becuase of the raised temperatures in the combustion chamber, the
particles have more potential energy to combust, and do so more readily.
The problem is when you add TOO much EGR to the combustion, then it can
hinder combustion for multiple reasons. (like when an EGR goes south and
your vehicle runs like ca ca!)
Clay
This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 11:47:02 EDT