Author Topic: Any thoughts about water cooled tube for transformer, instead of wire?  (Read 3796 times)

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Offline Superscan811

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Had an idea and probably not a good one,
BUT
Seeing that the main limiting factor for a transformer is heat, why couldn't you use copper tubing, instead of wire, in a transformer?
When the "coils" start to get a bit too warm, circulate a bit of water through them.
You would need to replace the standard fan with a fan/radiator/pump, to cool the tubes during use but it would make for a more compact transformer you would think.
Also, you could get away with the minimal amount of primary windings, as the tube wouldn't be getting as hot.

Thoughts???

Offline noneyabussiness

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Re: Any thoughts about water cooled tube for transformer, instead of wire?
« Reply #1 on: February 28, 2019, 11:02:25 pm »
If it were possible, the cooling potential would be awesome

Offline Pete

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Many years ago I worked on water cooled electric motors. They were cooling water pumps for power stations. They were wound with pvc coated wire, stranded to be flexible. Water was circulated through the motors and windings to cool them. For their size they were very powerful.
Also some air conditioners  in large buildings circulate refrigerant gasses through the windings to cool them, same thing small motor large horsepower. One I saw and worked on would have been around 60 to 100 hp if it were air cooled but was actually 500 hp because of having freon cooling.
Your idea of tube would work, winding the transformer would be problematic. Possibly just the low voltage side could be tube which would also cool the hv side.
Have fun
Pete

Offline bj

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   They also make water cooled TIG equipment.  Water cools the power cable, then torch head, then returns to rad/fan
via a separate tube.
   Used to use one to weld aluminum
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Offline solarnewbee

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I think a cooling system made for desktop cpu coolers and wrap the outside of the xfmr, wrapping through the hole in the center May invite trouble damaging wires and characteristics of the xfmr, wrap with 5/16-3/8” copper tubing. Find some heat sink adhesive compound (eBay, Amazon)so that the tubing makes positive contact. The adhesive does not set up hard but is flexible and should be able to allow you to remove it later if necessary. Maybe wraps some Mylar tape first.  Make sure that the copper tubing connections are made outside the inverter just in case of oops!

The cpu cooling kits are closed loop so I think that’s best really. Another recommendation would be to make your tubing coils on a metal can or piece of wood the same diameter thus avoiding possible damage. I do this with refrigeration coils when I need a consistent coil wrap.

Good luck!
SN

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Offline rossw

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The really big ones they just immerse in an oil bath. Crude but very effective.

Some of the hydroelectric installations I did a bit of work at, used hydrogen for cooling. Its low density meant it didn't impede the machine (probably helped!), but evidently hydrogen can carry away a lot more heat than air.

Offline MadScientist267

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The hydrogen is primarily about drag, while leaving everything "submersed in a cooling fluid". It's not particularly efficient per se vs air, just has better heat transfer to viscosity characteristics, and of course doesn't create as much heat of its own in turn.

And yes, agreed on the oil. Mineral oil has very good characteristics for this. Cheap, readily available, excellent electrical insulation, thermal conductivity, boil/freeze/smoke/non-toxic/etc qualities, and is a go to for anywhere heat needs to be taken away efficiently from electrical equipment that is sensitive to air contaminants and requires near zero maintenance.

Hit Big G images up for "aquarium computer" for how this concept can manifest in the DIY department... Half of them even leave the fans in there in some form as "pumps"  ;D

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Offline rossw

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The hydrogen is primarily about drag

Well, not really...

"Air, water and oil have all been used for cooling. But hydrogen's low density, high specific heat and thermal conductivity make it a superior coolant for this application."
and
"Hydrogen gas is 7 times more effective as a heat transfer medium than air"

(Also 1/14th the density, which is an added bonus!)

Offline MadScientist267

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Ah yep you're right on that Ross. Mix of 2 ideas got me here... Confusing sp heat of hydrogen/helium combined with having been told however long ago it was mostly because it put up next to no fight for moving parts...

That said, I'm still twitchy about the idea ever since first hearing about it... I'm not a fan of having hydrogen around in any quantity... And I guess neither are they but it obviously has advantages or they wouldn't use it lol... It's only even for these reasons that it even stuck with me as a concept  :o

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Offline sunnypower46

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I had thoughts of water cooling a transformer a while back, too.  Heck, just dip the whole thing in a big bucket of water and fire her up.  Bring the wiring out the top.  Pump the heated water over to a radiator of sorts, release the heat and recirculate it back.

Yeh, yeh I know, crazy right?  But wait.  What if I said let's use distilled water -- a non conductor.  One problem I saw was the need to keep the water from the metal core material (rust).  Maybe encapsulate the whole transformer in epoxy?

Offline Pete

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Re: Any thoughts about water cooled tube for transformer, instead of wire?
« Reply #10 on: March 06, 2019, 02:09:13 am »
Hi Sunnypower, Transformer oil is a much better option.
No problems with rust.
Doesn't conduct electricity
Can use convective cooling. Just look at large transformers the pipes up the outside are so that the warm oil will cool as it rises through the tubes.
Been around a long time and works a treat
Cheerio
Pete

Offline sunnypower46

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Re: Any thoughts about water cooled tube for transformer, instead of wire?
« Reply #11 on: March 06, 2019, 10:25:50 am »
>Pete:  I certainly agree that oil-filled utility/industrial transformers have proven themselves in the field.  In such an environment, water cooling, in any form, would be impractical.

On a smaller scale (inverter torroid), water cooling an epoxy capsulated transformer seems practical and relatively inexpensive.

Has anybody out there actually tried it?  I believe water is a better, faster conductor of heat than oil; meaning the system could be more efficient and smaller in size.  I question whether oil cooling would react fast enough to control heat build-up in an inverter torroid that is suddenly pushed to its limit.

Offline solarnewbee

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Re: Any thoughts about water cooled tube for transformer, instead of wire?
« Reply #12 on: March 07, 2019, 11:38:43 am »
Hey Sunny

Mineral oil is not much diffufrom transformer oil and fairly inexpensive. I just wouldn’t want to find out that some worker had made a mistake with the epoxy or the epoxy has cracked. Just find an inexpensive cpu radiator, pump and hoses, put the tranny in a large Tupperware with mineral oil. Not baby oil, it has thing added that may conduct electricity. You might even get creative and make it so you can fit a lid on it and put it back in the inverter. Use 2 miniature radiators or peltier setups I’ve seen lately. By the way the radiators come with fans if you didn’t know. If you can run an extremely fast hot running desktop In an aquarium full of mineral oil for weeks and the only problem encountered was a leak in the glass that’s a winner to me.

My 8000w will run 3200w-ish for several minutes and the tranny never gets “hot” your going to have to trick it into giving you more watts. I believe now they have some pots on the board so you can adjust voltage and maybe wattage. Otherwise it’s bypassing the CT so it will give more watts.

Good luck
SN

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Offline MadScientist267

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Re: Any thoughts about water cooled tube for transformer, instead of wire?
« Reply #13 on: March 08, 2019, 03:41:55 pm »
Yes, you're putting so much at risk with water with no practical gain.

Also, if the containment scheme is large enough, you don't even need radiating elements. I've even done this with air in smaller equipment, circulating internally, sealed to the outside. Your primary goal (other than the obvious) is to simply increase the cooling surface area with a suitable medium, in this case a liquid. If your transformer isn't marginal, you don't need anything but a liquid tight box to put it in.

Also, any "potting", epoxy was mentioned, would only serve to work against your goal if it was thick enough to make me comfortable enough to use water. Just go oil and save the headaches.
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Offline sunnypower46

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Re: Any thoughts about water cooled tube for transformer, instead of wire?
« Reply #14 on: March 09, 2019, 04:37:31 pm »
OK.  Some interesting and informative material being offered. 

To continue, a couple of follow up points, whether it be oil or water:  I'm not sure immersing a typical OEM PowerJack style torroid into either oil or water is a good idea.  It was never designed for that environment (think glue, adhesive, wire coating).  In theory, either distilled water or mineral oil could serve as a safe, non-conducting medium, though.  Off the top of my head, I'm thinking an epoxy coating (2-3mm) should be a decent thermal conductor; so probably not a design impediment.

Then it occurred to me, why aren't we using mineral oil as a coolant in our cars.  Doesn't deteriorate, no problem with metal rusting, won't freeze.  Long term thermal transfer OK, short term, not so much.  Given how quickly these small torroids can heat up, I would think oil is not the best choice.  Just a guess, offering no proof.

I personally have no need for liquid cooling, but as to practical info on enhanced air cooling - - read on.

I've been using two PJ8000-24s (2016 version) 24/7 for the past two years where I modified the cooling via enhanced airflow.

Opened up the torroid core to let it breathe, tilted it on to its short side, added a 235 cfm fan to blow through the core in wind tunnel fashion.  No need to change any wiring lengths, just some careful bending of the primary wiring.  Needed to add a 2 x 18" metal piece on each side to support increasing the case height.  The torroid sits on two short lengths of thick wall 1/2" id silicone tubing, currently unsecured; but gravity is my friend.

Heat be gone!  This behaves like it could run for hours at 3500-4000 watts, if you've got the continuous 165A to spare from your batteries.  I tried 20 minutes at 100A and was then able to grab on to the torroid and hold on for 5 seconds before having to let go.  So, pretty scientific measurement . . . . .

Bought a third PJ8000-24 as a spare (late 2018, the new look case with replaceable daughter boards).  They added a top mounted fan mostly centered over the torroid.  Unfortunately, the torroid core is still is still blocked by the mounting solution they use.  From their standpoint, its the only practical way to do it for shipping reasons. 

If you need more cooling, though, it's easier to do with this new model.  Just remove the mounting bolt and top/bottom core cover pieces to open up the center.  To go a step farther, fashion some metal air deflectors to enhance the airflow pattern around and through the torroid.  While not as effective as my wind tunnel design, I'd expect you'd see noticeable cooling improvement.

At some point I want to try supplying the inverter air input with cooled air via an evaporative pad during my hot, dry summer season.  Could cool moist air be the reasonable compromise in this discussion?