Ed Anderson wrote:

I guesss, I don't understand this search for a different coolant medium.
So far as I know, no commonly available liquid has a higher specific

heat

value than water.  Even mixing antifreeze with water effectively lowers

the

amount of heat the coolant can absorb as anitfreeze does not have as

high a

specific heat value as water.  So regardless of the boiling temp of the
cooling liquid, if the specific heat value is lower then less heat is
transported from the metal into the liquid per unit volume. While a

higher

boiling temp does permit more heat to be transfered to the cooling

medium

before it boils, this does not necessarily mean that it transfers heat

more

efficiently than water.  There may be some applications where the higher
boiling temperature is critical, but for ours?? What am I missing??

Ed Anderson

Ed,

Water is an excellent coolant and also refrigerant with the one small
problem; it will become a solid below 0C. The ethylene glycol and other
things are added to prevent corrosion, lubricate the water pump, increase
boiling point, and most importantly prevent freezing. If you have a car in
North Dakota in the winter time with a cooling system that was designed for
Death Valley with the air conditioner cranking, the thermostat will stay
closed most of the time just to keep the engine at operating temp. The
coolant in the radiator (if only water) can easily freeze under these
conditions, the engine will then paradoxically overheat. You see the same
type of situation in an airplane flying at high altitude that took off in a
Florida summer. The thermostat will cycle open and closed, subjecting the
engine to repeated temperature shocks. Aside from the freezing problem, this
is not good for head gaskets and other things. This is another good argument
for using variable geometry exits or cowl flaps on your system rather than a
thermostat only.

Monty

Many thanks to ED, Paul, Monty and Bill,
I had planned to use a mixture of water/EG that would be maximized for cooling (maybe 70-80% water) because our climate in Arkansas is HOT in the summer but not to bad in the winter (we may have a few days in the teens) but I had not given much thought to corrosion protection - shame on me.  Guess that I will use a 50/50 mix.  I had also planned to use cowl flaps AND a thermostat; again, the shock cooling mentioned by Monty had not occurred to me.  I may still use this setup but levelized cooling is what I wanted the thermostat to do for me.  I definitely need to give this some more thought!

 > 

Ken Powell
kenpowell@aristotle.net

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