Heat pipe cooling

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ian_krase
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Real name: Ian Krase

Heat pipe cooling

Post by ian_krase »

Recently I've been messing around with heat pipes -- specifically, trying and failing to replace the water coolant charge in the standard heat pipes with acetone, which would work at much lower temperatures.

(This would work better if I used, oh, I don't know, vacuum, but I would need to get cryogens and rig up a vacuum adapter to the pipes).

These are familiar to anyone who has ever built their own computer since they are very common in laptop and higher performance desktop cooling systems -- but until now I had never encountered them on their own. As it turns out, you can buy them from Digikey -- and they're inexpensive -- anywhere from 3mm to 12mm diameter, various lengths, prices $5 to $15 depending on size. Once the hot end heats up to around 40-60 C, they begin conducting heat at several orders of magnitude over a copper rod, with no moving parts.

It occurs to me that they might be interesting as fusor stalks -- you would not need to deal with the typical issue of having to electrically isolate a liquid cooling system, or for that matter, of having to seal one -- you just need to be able to accommodate a nearly unsolderable copper rod.

Pictures of my failed re-charged pipes to come later. I'm not sure what the most practical way of sealing these are -- I wonder if annealing and Vise-grip pinch off is actually capable of making a hermetic seal.
Dan Knapp
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Re: Heat pipe cooling

Post by Dan Knapp »

I don’t think vise grips are the answer. Pinch off seals are normally made with more of a cutter type tool. Try using large diagonal cutters.
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Rich Feldman
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Re: Heat pipe cooling

Post by Rich Feldman »

We use tons of heat pipes at work, about the size of pencils.

An easy demonstration to do with a loose heat pipe:
try stirring a mug of very hot coffee or tea or chocolate.
The handle end gets too hot to touch within a couple of seconds.

Hmm ... what would be a good working fluid for heat pipe at 500 to 700 °C?
Stir a pot of molten aluminum and see the handle end soon become red hot.

Looks like annular heat pipes can be used as Isothermal Furnace Liners. Tube furnaces with 0.1 °C uniformity are practical.
Non-hermetic Pressure Controlled heatpipe systems can help when 0.005 °C regulation is needed.
ifl.jpg
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All models are wrong; some models are useful. -- George Box
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Rich Feldman
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Real name: Rich Feldman
Location: Santa Clara County, CA, USA

Re: Heat pipe cooling

Post by Rich Feldman »

Before today I didn't know that pinch-off seals could be made with nothing but tube metal.
Found out lots from one maker of tools for the job, starting with
pinchoff.gif
pinchoff.gif (32.22 KiB) Viewed 3445 times
http://www.pinchofftool.com/node/5

They mention importance of annealing, and mechanical cleaning of the surfaces to be welded. How 'bout something like a Q-tip made with steel wool, or a wire brush made for cleaning gun barrels?
.
Could you use hard steel dowel pins as pinching dies with well controlled shape?
pinchoff2.jpg
pinchoff2.jpg (24.61 KiB) Viewed 3445 times
All models are wrong; some models are useful. -- George Box
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