RE: Water Cooling

[Randy McCall <randym@schiller.com>]

Scott,

Since I am just talking from my experience in the energy project world and 
haven't done this job yet, I can't give you a definitive answer.  But, that 
said you are absolutely correct about the phase change happening with a 
finer mist.  There are some other things to consider (probably) such as the 
thermal cooling of water when in contact with the IC (non-phase change), 
atomized water steaming from the engine compartment just when you are 
trying to impress someone at a stoplight (heh-heh)

As for achohol/H2O mix I would have to agree that phase change is easier - 
I would be a bit cautious about the fire hazard for too high a proof on the 
mix though.  Any chemical engineers out there to comment on volatility and 
flash points?

The bottom line for IC indirect cooling is to evaporate as much liquid as 
you can from the surface - that way the great majority of the heat is 
actually extracted from the IC and not the surrounding air stream.  The 
principle is pretty simple - phase change of water takes on the order of 
1025 BTU/lb of water evaporated at 120 deg.F while simple extraction of 
heat through non-phase change process is describe by the definition of one 
(1) BTU as the amount of heat required to raise one pound of water one 
degree F(at a reference temp that I have forgotten).  Big difference!

I still thing there is a lot more to gain from direct injection of atomized 
liquid water into the air stream so that compressor heat evaporates the 
liquid resulting in lower compressed air temps.  Once again, no experience 
building anything like that, but it sure works in other applications like 
my house with a two stage direct/indirect A/C system!

-Randy
Also evaporatively cooled! (the house, not the car)



-----Original Message-----
From:	scott miller [SMTP:macatawa@hotmail.com]
Sent:	Tuesday, December 07, 1999 5:13 PM
To:	quattro@audifans.com
Cc:	randym@schiller.com
Subject:	RE:Water Cooling

Ideally, shouldn't the mist evaporate while on the IC and before leaving 
it?
  Does it matter how small the droplets are as long as they phase change?
Finer droplets have a higher surface to mass ratio, wouldn't they phase
change more readily, before exiting the IC?  A finer mist might cover a
larger area too, for the same amount of coolant.  How about a water/alcohol 
mix?  Really officer, the keg is for the intercooler.....

Scott (evaporative cooled)
'90 200tqw  (cool enough)

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