Water Cooling

[Brian Donaldson]

Don't even consider using anything less than pure teflon tubing and silver hose clamps

[E. Pardaans]

You can even do without the waterpump if the waterpipes are sufficiently large enough.

Warm water is lighter then cold water, so if you can place the radiator in the top of your house or outside you can use this characteristic of water for natural circulation.

you should place your amplifier as low as possible, and the pipes of the warm section of the sink should go straight up (a few decimeters horizontal will not harm if the diameter of the pipe is large enough).

If the amplifier warms up the water warms up allso.
This way the warm water will be lighter then the cold water and starts to flow to the top of the sink.
The cold water will take the place of the warm water, and so the natural circulation starts.

This is an old technique used in old central heating systems.


Edwin

[Brian Donaldson]

it's also used in old tractors

[GRollins]

I think you'll find that heating systems and tractor engines are somewhat more robust than the average semiconductor...

Grey

[E. Pardaans]

Grey,

You are right about the robustness of heatingsystems and tractors, but if your radiator is big enough and is capable to create a difference of more then 5 degrees celcius between the cold and warm waterpipes there will be no problem.

If the difference in temperature between the cold and warm pipes are bigger, the water will flow faster.

I agree it is much easier to implement a pump in the system
Natural circulation must be well calculated and therefore are more difficult to implement.

Edwin

[BrianDonegan]

I started a thread about this in the solid state forum, but since I am now planning on building a water cooled Aleph30 (possible 5 channel, depending on how well the water cooling works out), I'll jump on this thread.

I just bought a piece of copper 1/4" x 4" x 36" ($30) that I will chop up and use GRollins' method for the heatsink/spreader (1/2" copper pipe soldered to a 1" copper plate).

I will be using about 6' of copper/aluminum baseboard pipe for the radiator. This will be 6 - 1' pieces arranged in two layers of 3, all linked by 3/4" pipe fittings (the radiator pipe is 3/4"). The change from 1/2 to 3/4 should slow the flow rate while the water is disapating heat, then speed back up a bit as it reenters the 1/2 pipe. The pump and radiator will be mounted in a second case (that looks like my amp case hopefully), with fully vented top and bottom panels to allow for convection through the radiator.

For the pump, my brother asked his "pump guy" what to use. He did a quick analysis of the design volume and heat characteristics and came back with the Iwaki Walchem WMD-15RT. It's a magnetic drive pump, meaning that the impeller is driven magnetically by the motor, so there are no seals that can leak. Supposedly very very quiet. It has the proper flow, head and heat resistance to last a long, long time. My brother can get one for $80USD, but that's a good deal. Need to think about it as it's more than I wanted to spend.

A few other comments on other posts I saw:

Using straight anitfreeze is a really bad idea. Antifreeze is not a very good coolant. It is added to cars primarily to keep the water in the cooling system from freezing. It also has some additives to prevent corrosion. If you add straight antifreeze to your car with no water, your car will overheat. Ideal mixture is said to be 50/50. My system will be copper/poly (no aluminum contact) so I will use straight water. Race cars use straight water, then empty it out after each race.

Water is a better cooling medium for this type of cooling project. Oil is better if temps will exceed the boiling point of water. Oil is better in open systems, where pressure is not such a big deal. Remember, oil expands when heated. Water contracts when heated, until it boils, then it expands a lot. In a sealed low temp system, water is the way to go. The fact that oil disappates heat more slowly will be a problem unless you have active cooling on your radiator, or a really really big radiator. Similar to using cast iron for a heat sink. It takes a long time to heat up its large mass, but stays hot for a long time. I think we want this to cool very quickly. Machinists use oil for cooling metal during machining, but it's a full-loss system, constantly pumping fresh cool oil.

[E. Pardaans]

WorkingAtHome,

You are not correct about water contracting when heated.
Water has its highest density at 4 degrees celcius.
When water is heated above, and cooled below this temperature it will expand.

If your water cooled system contains a large amount of water the pressure in the system will rise.
A solution to this is a damper ( i don't know the correct word) used in watersystems to absorb the expanded water.

Edwin

[BrianDonegan]

Ah, thanks, you are correct.

I am thinking of a small air damper, which is basically a little capped piece of pipe connected to a T and sticking striaght up. Air in that piece of pipe absorbs the expanding water volume. Pretty simple, as my system will not have too much volume.

[E. Pardaans]

Yes this will work perfectly, and does not wear like a damper with a rubber membrane.

Edwin.

[E. Pardaans]

WorkingAtHome.

If i understand it correctly you will make your own radiator out of tubes.
You have to consider that tubes has verry little surface area.
If you make your radiator out of tubes he must be verry big.

I advise you to search for an old airconditioner and use its radiator, or an old waterchilled cooler used in offices like i found recently.
The last one has a fan to suck air thrue the radiator, and can dissipate a lot of heat.

Maybe you can do without a fan with the above mentioned radiators if the case which houses the radiator is high enough.
This way you create a chimney with more volume of warm air.
And becouse of the mass differences between warm and cold air the air will flow faster thrue the radiator.

Hey this sounds again like natural circulation.

Another thing you have to think about is the speed of water thru the tubes.
In drinkingwater systems with a central boiler, the warm watersystem has a circulation system with pump.
The speed of water thrue this system is not allowed to go beyond 0.7 meters per second maximum, preferably 0.5 meters per second.
If the speed of water goes beyond this point the tubes will wear becouse of erosion.
In our amplifiers this may be a lesser problem as they are not working 24 ours a day.

Edwin