Quote:
Originally Posted by maxc
So separate the water and the HC's out of the exhaust then flash it back too steam for egr. Steam be will be more effective than exhaust gas that will displace O2.
|
Steam displaces O2 just like EGR. The steam does participate in the combustion sequence when used in relatively small mass percentage quantities as water always has a small measure of dissociated molecules (measured as pH). However, EGR has steam already inherent in it's composition and CO2 and N2 are capably active participants in combustion if the EGR volume is small. Thus, there is no advantage to using steam alone over EGR for fuel efficiency gains. EGR has it's virtues that extend beyond simply being readily available.
In 1980, I worked to replace the EGR system on a Dodge 360 Cubic Inch engine with a digital feedback water injection system. It helped to avoid detonation at full load, but we also programmed in a variable constant flow to replace the EGR flow. It worked well enough, but we would use 7 gallons of water for every 40 gallons of fuel just cruising on the freeway. It wasn't worth the bother, and the EGR system was reconnected and the water injection was only used for full load.
I cannot see a condenser, moisture trap, pump and filter being any less bothersome, though I am sure it could be made to work. EGR is just more convenient.