>If this is true- then why do anti-freeze variants
>specifically designed for water cooling work?
I'm not sure I follow your reasoning. But this is physics, not philosophy, so I'll try to be more clear.
All materials have some thermal capacity, also called specific heat. This is a measure of how much heat a measure of material contains at a given temperature. Said another way, it is a measure of how much heat must be added to the mass of material to raise its temperature by a given amount.
Here are some links for the specific heat of <A HREF="http://www.electro-optical.com/material_props/water_thermal_prop.htm" target="_new">Water</A> and <A HREF="http://www.electro-optical.com/material_props/liquids_thermal_prop.htm" target="_new">Ethylene Glycol</A> (the principal component of automotive antifreeze).
At 0 deg. C:
Water: 4.225E+3 J/kg-C
Ethylene Glycol: 2.261E+3 J/kg-C
The units here are Joules (a measure of heat) per Kilogram - degrees Celsius. As you can see, the number for water is nearly twice that for the Ethylene Glycol. The ratio is actually 1.87 to 1
What this means:
Say you have 1 Kg of water, and 1 Kg of Ethylene Glycol.
If you add 4.225E+3 Joules of heat to the water, you will raise its temperature 1 degree celsius.
But to raise the temperature of the Ethylene Glycol by 1 degree celsius, you only need to add 2.261E+3 joules of heat.
Flipping the problem around:
Say you add 4.225E+3 Joules of heat to each sample. The temperature of the water will increase by 1 degree celsius, and the temperature of the Ethylene Glycol will increase by 1.87 degrees celsius.
This is all about heat capacity (specific heat). The boiling point of the material is a seperate matter.
Something else to consider is the thermal conductivity of the material. From the same links as above:
Water: 0.566 W/m-C
Ethylene Glycol: 0.242 W/m-C
This means that water conducts heat about 2.3 times better then Ethylene Glycol. Water is much more effective at absorbing/transferring heat then Ethylene Glycol.
So why use it?
It does raise the boiling temperature somewhat. But in an auto cooling system, the boiling point is substantially raised because the system operates under pressure.
It reduces the freezing point substantially.
It is a corrosion inhibitor.
Why use it in a CPU cooler? Corrosion is the only reason I can see.
>If this is true- then why do anti-freeze variants
>specifically designed for water cooling work?
Do they work?
I'd be interested to see a benchmark with pure water as the coolant, and another with pure Ethylene Glycol antifreeze (or a mix). Also, water with a wetting agent only.
<i>Cognite Tute</i>
(Think for Yourself)