Quote:
Originally Posted by Isaac Zachary
I don't understand how cooled EGR works better than air, but water I can understand since it changes phases and reduces temperatures that way. But that is interesting.
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I think it's because EGR has a substantial amount of water vapor which will absorb a lot of combustion heat energy and lower temperatures. Water vapor has a very high thermal capacity, though its heat capacity ratio is low.
Liquid water offers extra cooling that EGR doesn't since EGR is gaseous, hence its popularity in turbocharged applications.