Liquid cooling with Peltier

[No One]

I've seen plenty of setups where liquid cooling is used to cool a
Peltier attached to a CPU, but has anyone ever used a peltier to cool
the liquid in a liquid cooling system? Say replace the large radiator
with a Peltier heat exchange system. Would this cool the liquid too much?

 

[Adam Webb]

I've seen plenty of setups where liquid cooling is used to cool a Peltier

attached to a CPU, but has anyone ever used a peltier to cool the liquid
in a liquid cooling system? Say replace the large radiator with a Peltier
heat exchange system. Would this cool the liquid too much?

cooling liquid this way doesnt really work too well. 2 or more 220watt TEC's
will cool water down nicely, but they would cool the CPU better if they was
in direct contact.

 

[Phil Weldon]

:
| I've seen plenty of setups where liquid cooling is used to cool a
| Peltier attached to a CPU, but has anyone ever used a peltier to cool
| the liquid in a liquid cooling system? Say replace the large radiator
| with a Peltier heat exchange system. Would this cool the liquid too much?
_____

Yes, Peltier arrays can be used to cool liquid.

Peltier arrays are very inefficient, and generate a lot of waste heat while
pumping a much smaller quantity of heat. Peltier arrays also become less
efficient as the cold side temperature drops. Also the temperature
differential between the cold side and the hot side decreases as the
quantity of heat rises. A good rule of thumb for cooling with a Peltier
array is that the electrical power consumed by the array is about three
times the heat power pumped

Peltier arrays are used in cascade to cool sensors, but this is only
practical when the original amount of heat is small because of the waste
heat generated. If the original heat to be pumped is 1 watt, then the first
Peltier array generates an additional 3 watts, so the second array must pump
4 watts, and the third array must pump 15 watts. The results would be
cooling the first cold side to about 35 C + 25 C + 15 C = 75 C below the
last hot side in a three stage cascade.

Intel and AMD CPUs have now reached heat generation levels that make Peltier
cooling impractical compared to phase change cooling (refrigeration by
compression and expansion of freon, for example.) A CPU that dissipates 80
Watts of heat (also the amount of electrical power consumed) would require a
first stage Peltier array that consumed 240 Watts of power, and the second
stage would require an array that consumed 960 Watts, and the third stage
would require 3800 watts of power and then the total amount of heat would
need to be dissipated; not an easy task.

Not only would the waste heat and power become very large, but the area of
each Peltier array would need to grow by four times in each stage. For this
reason, at high power levels cooling a fluid would be a good way to move
heat from a small surface to a larger surface. At this point, however, the
only advantage of Peltier arrays begins to be lost - piping and pumping
would be required.

Years ago, in the Pentium III era I built a cooling system that used three
80 watt Peltier arrays to cool a water/antifreeze mixture and then pumped
the water over a fourth 80 watt Peltier array that used a copper spreader
plate in contact with a CPU chip. I didn't make progress quickly, and CPU
power dissipation climbe very quickly with the Pentium 4. What was
practical (barely) with a 30 Watt dissipation became impractical with an 80
Watt dissipation.

Until a new, more efficient material is found for Pelitier arrays they will
not be a practical cooling choice for current CPUs.

You can find good information on Peltier arrays at
http://www.tellurex.com/ .

Phil Weldon

| I've seen plenty of setups where liquid cooling is used to cool a
| Peltier attached to a CPU, but has anyone ever used a peltier to cool
| the liquid in a liquid cooling system? Say replace the large radiator
| with a Peltier heat exchange system. Would this cool the liquid too much?

 

[No One]

cooling liquid this way doesnt really work too well. 2 or more 220watt TEC's
will cool water down nicely, but they would cool the CPU better if they was
in direct contact.

So the Peltier cannot cool down the liquid via a cold plate?

 

[No One]

Am I understanding that in a Peltier array as you mention that each
Peltier cools the previous? I was thinking of using two in parallel,
than as a stack.

 

[Adam Webb]

cooling liquid this way doesnt really work too well. 2 or more 220watt

So the Peltier cannot cool down the liquid via a cold plate?

it can cool, its just not as good as direct contact

 

[Phil Weldon]

:
| Am I understanding that in a Peltier array as you mention that each
| Peltier cools the previous? I was thinking of using two in parallel,
| than as a stack.

_____

Try the http://www.tellurex.com web site.
The advantage of cooling a liquid is that the hugh amount of heat generated
by the Peltier arrays can be moved outside the system case. But that loses
the advantage of Peltier arrays ... no pumps or liquid. Current CPUs just
dissipate too much power to be a good candidate for Peltier array cooling.
A single stage of Peltier array cooling can make the cold side no more than
about 35 C lower than the hot side.

Phil Weldon

| Am I understanding that in a Peltier array as you mention that each
| Peltier cools the previous? I was thinking of using two in parallel,
| than as a stack.
|

 

[spr]

I've seen plenty of setups where liquid cooling is used to cool a Peltier
attached to a CPU, but has anyone ever used a peltier to cool the liquid
in a liquid cooling system? Say replace the large radiator with a Peltier
heat exchange system. Would this cool the liquid too much?

Another thing to consider, unless you have the latest and greatest cpu and
memory already(no way to go up), the price of phase change, refrigeration
systems and the high speed memory needed for high overclocks could instead
be spent on a faster core speed cpu and a water cooling setup. And the power
would be half that needed for a phase change or pelt system.

You also have to consider the cooling of the room itself. As stated in other
threads, a peltier box will dump much more heat into a room.

 

[No One]

Another thing to consider, unless you have the latest and greatest cpu and
memory already(no way to go up), the price of phase change, refrigeration
systems and the high speed memory needed for high overclocks could instead
be spent on a faster core speed cpu and a water cooling setup. And the power
would be half that needed for a phase change or pelt system.

You also have to consider the cooling of the room itself. As stated in other
threads, a peltier box will dump much more heat into a room.

Well, I already have a P4 3.4 Prescott and 533-DDR2 memory, but no dual
core. I also have a $100 liquid cooling system that has dropped the CPU
temp 40 deg F under load. I was just wondering if a Peltier could heat
exchange with the liquid better than a copper radiator and a 8 cm fan.

 

[Caporali]

Besides power, another thing that would be a problem with using a pelt
with water cooling is condensation. Very cool water, running over hot
components will definitely cause consensation on your board.
Pelts are also expensive and for the most part a waste, stick with a
decent water cooling setup, Corsair is readying a 500W cooler called
the Nautlius 500, which moves 500w of heat.....for about $150....very
nice little setup
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