Coloring resin for stator casting

[imsmooth]

I am close to casting my stator, so I was thinking about this one night.  If I color the resin black it will absorb more radiation from the sun and get hot.  However, black objects are better at radiating heat as a black body object.  If I color the resin white it will not absorb much radiation from the sun, but it might internally reflect radiation and not radiate the heat outward.  Since I plan to use marble dust to improve heat conduction, I was planning on going with white.

Does the color, other than for aesthetics, really make a difference?  Has anyone ever looked into this?

[Flux]

If you live in a climate where you see the sun it may be an issue, here in UK it would make no difference.

I think black things absorb significantly more heat than white ones but in terms of radiation I think the reflectivity of the surface may have more effect than the colour. A polished black surface may be worse than a matt white one. Probably natural marble coloured would be fine.

No I haven't done any scientific tests,

Flux

[prasadbodas2000]

cooling of heat generated in coils is more by conduction in the resin material outwards and supported by convection at the outer suraface of the stator disc. This convection is augmented by rotary movement of the disk rotors which makes the air flow. Compared to heat generated in coils, heat absorbed from sun will be much less since the equivalent perpendicular area of stator exposed to sunlight is very less. I feel that resin color is in-significant, except for hiding the coils :-)

[imsmooth]

I have made my mold to allow the center of the coils to be open to air for better cooling. See the last picture on this page.  The inner surface of the coils will have a small rim of resin protecting it.

http://www.mindchallenger.com/wind/axial8.html

[Ungrounded Lightning Rod]

"next" goes to the same page.  B-)

= = = = =

I looked at your F&P design while I was there.  One thing that struck me was the faraday cage over the genny.

Nice idea.  But lightning is pernicious.  Don't be surprised if, should your mill get hit, the lightning goes down a blade and jumps across to the genny at the hub.

If you're going to do a "shield" like that I'd recommend continuing it (with a SMOOTH CURVE) over the front of the genny and down toward the shaft, like the outer skin and end bell of a motor.

Of course this won't work all that well for an axial flux genny with the blades bolted to the front rotor...  But it might be interesting for a conversion of a (more mundane than an F&P) electric motor.

[imsmooth]

Thanks for the comment.  The NEXT goes to the same page because this is as far as I have gotten.

It should work as well for the Axial.  I am trying to protect the stator, which is connected by the wires to the inverter in the home.  Something is better than nothing; but, if a storm was to come I will take the tower down.

[Capt Slog]

I had a look at your page and noticed that you were bringing the coil wires out as 'tails'.  I considered this a weakness when I made mine and was worried that I would easily snap them off where they met the casting, thus ruining it.

So I made these......

which when cast into the mold and finished off looked like this.....

I've found it a much more robust fixing.

[imsmooth]

I like it.  As Yul Brenner sort of said, "So it is shown; so it will be done."

[Capt Slog]

I'm pleased that you found it useful :-)  

The details are here in a diary entry..... http://www.fieldlines.com/story/2007/5/8/10251/45688

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