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Using heat engines for MHD power generation

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Posted by Morris Dovey on June 26, 2011, 8:53 pm
[ posted to alt.solar.thermal and alt.energy.homepower ]

Daniel Connell, an NZ on Facebook who's been aware of my interest in
fluid piston heat engines suggested that, since I had a solar-powered
oscillating column of water, I investigate magnetohydrodynamic (MHD)
power generation.

A quick look was enough to convince me that this stuff was way beyond
anything (and everything) that I now understand, but I'm intrigued by
some of the possibilities.

I'm fairly sure that I can build something like a water-only (no air)
inline fluidyne with a cold head at each end, solar heat the water
between until it becomes supercritical, and have the supercritical
water oscillate vigorously with the cold heads 180 out of phase with
each other, and 90 out of phase with the main flow.

I'd imagined a double-ended configuration before and it had seemed
interesting (because there would actually be 2 power strokes per cycle)
but useless because there didn't appear to be any reasonable way to
extract the mechanical energy. It'd never occurred to me to extract it
as electrical energy, and that's the possibility MHD appears to offer.

Supercritical water appears to have a number of interesting properties
different from subcritical water/steam, and is alleged to be a
super-solvent, which should make it easy to add agents to enhance
ionization for the MHD process.

*I'd really like to hear from anyone who has experience with MHD.*

Everyone else who's interested might enjoy seeing:


Morris Dovey
DeSoto Solar

Posted by somebody on June 27, 2011, 3:58 pm

My high school senior science project, back over forty years ago, was
an attempt to build an ionized steam MHD generator.  I was never able
to get above the parity of the electrical flow going in.  I discovered
that a lot of the dynamics are very similar to the ones in the old
vacuum tubes.  The Russians were big proponents of MHD.  It didn't go

Posted by Morris Dovey on June 27, 2011, 4:48 pm
 On 6/27/11 10:58 AM, somebody@somewhere.com wrote:

Interesting! I'm inclined to think that achieving parity might be a
rather significant accomplishment for a high school student, especially
if you designed and built your own apparatus.

Do you recall what pressures and steam velocities you used? What seemed
to work well and, forty years later, would you suggest to your younger
self (or me) to improve project outcomes?

If you're willing to share sketches, notes, recollections, (anything)
about what worked (or didn't work) I'd be grateful.

It's been fascinating to watch where my web site hits have been
originating since I first started talking about working with superfluids
and (later) MHD power generation - at first there was a flurry of
activity from the Russia, but since then there's been a growing amount
of traffic from (in decreasing order) France, Switzerland, the UK, and
China that's pushed the RF back to fifth place, followed by Italy. WTF?
This is crazy - I'm not a physicist!

Regrettably, none of those (presumably more knowledgeable) folks have
shared any of whatever they know.

Morris Dovey
DeSoto Solar
http://www.iedu.com/DeSoto/  (slowly migrating to
http://www.iedu.com/DeSoto/Solar/  )

Posted by Morris Dovey on July 18, 2011, 12:49 pm
 On 6/27/11 11:48 AM, Morris Dovey wrote:

<all snipped>

New web address for solar stuff: http://www.iedu.com/Solar/  or you can
just use the URL in my signature. Enjoy!

Morris Dovey

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