Quote:
Originally Posted by mwebb
EGR does reduce combustion temperature
because the INert gases take up space in the combustion chamber and act like a cushion reducing
COMBUSTION PRESSURE which ultimately is what actually reduces
COMBUSTION TEMPERATURE and since NOX does not form below a certain temperature the formation of NOX is reduced by reduction in combustion temperature which was reduced by reduction in
COMBUSTION PRESSURE which was reduced by the addition of an INert gas to the combustion event by Exhaust gas recirculation, EGR.
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I find it hard to accept that the change in burn temperature is solely (or even mainly) down to pressure.
A realistic way to check this would be to create synthetic air for the engine to run off (obviously without EGR) - The 'air' would be 80% CO2 and 20% Oxygen. In this experiment the charge drawn in would be at ambient pressure - so negating any sort of increased 'filling' of the cylinder. Rem: CO2 at 1 bar contains less molecules of gas than nitrogen (80% of normal air) at ambient.
I am fairly sure - due to Chemistry NOT Pressure the burn would be considerably cooler under such conditions, but I am not saying 'I'm right'; I just feel that's what my gut tells me :O