Using hydrogen for cooling armature 1

[frankiee]

Why do some generators use hydrogen for cooling of the armature windings.

 

[alehman]

It has very good heat transfer properties.

 

[TestBeforeTouch]

In addition to having far better heat transfer (8x vs. air) hydrogen reduces windage losses, eliminates oxidation of the insulation, and requires a higher voltage to produce a corona discharge than air.

Unfortunately, a fatal accident happened on Jan. 8, 2007 involving hydrogen cooling at an AEP (American Electric Power) plant. I think it is way too early to draw any conclusions from this newspaper article.

http://www.newsandsentinel.com/News/articles.asp?articleID=12554

 

[jraef]

Although I know that this is done all over, the first guy to implement that on a motor must have had some big brass ones!

 

[edison123]

Advantages of hydrogen cooling:
1. Reduction of windage loss by 90%
2. Increase in machine output
3. Lower oxidation of insulation

Disadvantages
1. Since Hydrogen-air mixture of between 5/95 to 75/25 is explosive, the hydrogen content inside the casing must over 95%
2. Sealing system to prevent air ingress
3. Explosion proof stator frame (though this doesn't seem to work in many cases)

GOLF - Gentlemen Only Ladies Forbidden

 

[dpc]

thread238-19339

As mentioned it's primarily due to the much better heat transfer capability of hydrogen versus air.

Also, pure hydrogen actually reduces the fire hazard inside the machine since no oxygen is present.

 

[byrdj]

I believe GE's first utility unit was back in 1937 (recall that date from sales GEK). I beleive WH had one earlier.

 

[cuky2000]

In addition of the above, increasing the hydrogen pressure could help to increase the power capacity of the generator.

Also the friction at high rotating speed is significantly less than air.


Paraphrasing Yogi Berra, engineering is 90% technical and the other half is administrative.

 

[swn1]

Because hydrogen is less dense than air it is not centrifuged out of the rotor as much as air. Helium also has good thermal properties and is inert, but it is twice as dense as hydrogen.

Is density the determining factor?

 

[byrdj]

swn1, concerning "...centrifuged out of the rotor..."

There are a lot of air cooled units too.

The surface of the rotor ( the blocks that retain the copper bars) have inlet and outlet scoops that pump cooling gas into the passages in the copper bars to the center of the rotor and back out. Then there is a fan at either one end or both that circulates the heated gas from the gap space through coolers to remove the heat.

 

[Bekza]

h2 is the good removal of heat due to losses, it is also to keep h2 purity to accepatable levels. h2 purity of less than 90% contribute or increase losses by 10%. So at higher pressures h2 performs removes heat efficiently.

 

[dpc]

Bekza,

This thread is five months old, so probably not much point in adding to it.