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Tiny Steam Turbine | 15 comments (15 topical, editorial)

Re: Tiny Steam Turbine (3.00 / 0) (#10)
by spinningmagnets (velmis1450bc(at)aol(dot)com) on Wed Jan 16th, 2008 at 05:36:40 PM MST
(User Info)

I'm always interested in the projects you post! Can you drop a hint about the configuration and rough specs on the PMA you plan on using?

I recall a company called Capstone using a gas turbine (jet) made from turbocharger parts to spin a generator. Their biggest customers were off-shore methane drilling rigs that had used diesel gens for power. The gas turbine could burn fairly "wet" methane with minimal filtering. I was curious what a small ultra-high-RPM PMA would look like.

Re: Tiny Steam Turbine (3.00 / 0) (#11)
by WXYZCIENCE on Wed Jan 16th, 2008 at 06:11:33 PM MST
(User Info)

Spin..., the major problem I have found about high speed PMA's is the heat built up in the coils. My tests with different coils showed that I could remove all of the heat by the use of litz ( multiple strands) wire, this coil is one that is used in my 12000 rpm unit.

The one's that I will be using in the 100k will probably have 10 strands of 40 guage and very few windings. I worked today on the mounts that will hold the turbine and alternator square to each other. I hope to post some more pictures this weekend. Joseph

[ Parent ]

Re: Tiny Steam Turbine (3.00 / 0) (#12)
by Nothing40 (phattymo (at) gmail (dot) com) on Sat Feb 16th, 2008 at 08:07:07 AM MST
(User Info) http://www.users.qwest.net/~ptaylor/

Hmm,Maybe "skin effect" has something to do with the wire heating up?

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

[ Parent ]

Re: Tiny Steam Turbine (3.00 / 0) (#13)
by joestue on Sat Feb 16th, 2008 at 08:46:32 AM MST
(User Info)

Nope, at 12000 rpm and say 4-6 poles the frequency is 800 to 1200 hz.
A 5.8 mm diameter wire would have its resistance increased by 10% at 1200hz.

EDDY CURRENT is the problem.
We ignore it at 300 rpm because it scales with the square of the frequency.
WXYZCIENCE is dealing with 400 to 900 times the effect at 300 rpm.
those numbers may be off by a factor of 2, but you get the idea.

[ Parent ]

Re: Tiny Steam Turbine (3.00 / 0) (#14)
by WXYZCIENCE on Sat Feb 16th, 2008 at 09:45:21 PM MST
(User Info)

joestue, Yep I also agree with your logic. By using several strands I can reduce the eddy current considerably.
Joseph.

[ Parent ]

Tiny Steam Turbine | 15 comments (15 topical, 0 editorial)

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