High Power water capacitors 2

[fusion2022]

Distilled water has a great breakdown voltage, a great Er=80 and is cheap, but has great power losses due electrolitic current. It is possible to avoid it by placing a thin polietilene layer on plates surfaces or icing it?

 

[cbarn24050]

No.

 

[rwstowe]

Hello fusion2022,
Thank you for your question.

Without knowing the specifics of your application, is deionized water a possibility?

Deionized water, as the name suggests, is water with ions stripped out of it by a continual filtration process such as a bed of resin beads. A company like Culligan might still be in the business of providing these tanks of resin beads for deionization of water.

Here is a Wikipedia link about deionized water:

http://en.wikipedia.org/wiki/Deionized_water

Bob Stowe
President,
Foundation R&D, Inc.

http://www.frd-inc.com

 

[nbucska]

Old electrolytic caps worked with one fan-folded Al electrode immersed in a borax solution - but the dielectric
was Al2O3

Plesae read FAQ240-1032
My WEB: <

http://geocities.com/nbucska/>

 

[fusion2022]

It is possible using deionized water.

My idea is to build a powerful and little capacitor for pulse application. The problem is that electrolisys of a big capacitor make impossible to manage great capacity because great currents and dangenous hydrogen appears.

I would need a 1 kjoule cap and 1 megavolt would be 2.8m3 but losses would be 100 megawatts

If made with transformer oil it would be 100m3 and losses would be about 16kW

Water data:
Er=80
Breakdown voltage: 1e8 V*m
Resistivity: 182 ohm*m (A friend measured 6000)

Transformer Oil data:
Er=2.2
Breakdown voltage: 4e7 V*m
Resistivity: 1E13 ohm*m

 

[nbucska]

1 KJ at 1 MV = 2 nF ;
2nF 1 MV will be )*^&$&%#$# BIG !!!!

Plesae read FAQ240-1032
My WEB: <

http://geocities.com/nbucska/>

 

[waross]

2.8m3 but losses would be 100 megawatts.

100 megawatts losses dissipated in a 2.8m3 package?
This sounds like an explosion which has found a place to happen.
respectfully

 

[fusion2022]

Yes it is.
1kjoule is serious. Now I am building a very little 50 joule capacitor bank (with 4 electrolitic 470uF 311V only. They are rated for 22A, 100Hz, I am not sure they support short cut discharge. It begins to be serious.
I am now looking for lowest priced and volume to stored energy for next capacitor bank for pulse testing. There are some possibilities: a compulsator and oil capacitors (it seems water ones does not work)
I think that water has a very big energy store capability due charge is transferred with ions instead of electrons

Note, I had a typing error, theorical water resistivity is 182kohm, nor 182 ohm.

 

[cbarn24050]

You need to look at photo flash rated capacitors, 50 joules would be about half the size of 20 Marlborough. I thought from your earlier posts you were looking to use high voltage but now your not. It would help if you outlined your project.

 

[CarlPugh]

Water capacitors were researched many years ago and there were papers written on using water capacitors.
The secret to using water capacitors was to charge the capacitors up fast and immediately discharge them.
If the capacitors were charged too long an explosion would result as mentioned by waross.

 

[jimkirk]

If you do this, be sure to make a video to upload!

 

[rwstowe]

I agree with CarlPugh about using water for capacitor dielectric applications.

Even deionized water resistivity is poor compared to the resistivity of capacitor oil. So, for any high voltage application except for short uS pulses with very low duty, the resulting power dissipation would quickly boil the water resulting in gas expansion.

However, in non-capacitor applications involving high voltage,
deionized water can be effectively used for cooling of high voltage equipment since the surfaces at high and low potential are not close together.

Bob Stowe
President,
Foundation R&D, Inc.

http://www.frd-inc.com

 

[fusion2022]

Thank you to all. I will see photoflash for first designs and then I will shift to oil or bitumen caps