MHD generators

This topic was inspired by another thread related to High Temperature Mechanisms. The following is a trackback from that thread.

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comment by Jeremy Holmes

Hi all,

Tiskenderian has indeed created an interesting thread here.

I would like to direct your attention here-

[www.physicsforums.com]

Now... this forum (SACA) is obviously more advanced than the latter.

Some interesting quotes from the link.

Quote
physicsforums
I'm going to be entering into that (^^^) competition with one other person. We are going to be doing it on an MHD generator and its use for automotive transportation and as a home generator, amoung other uses.

Also-

Quote
physicsforums
My purpose of this is project is to prove that a low heat MHD generator can be efficiently used for residential use. Basically, right now the only MHD generators that are out there are used in coal power plants where they use very hot liquid metal and on a grand scale of a power plant. Just think the benefits of a MHD generator for use in a car, in a household generator or any other application.

I stumbled across this thread/our, doing a (rough google search for) EXPH12.

Im in the process of wrapping up a pat-pend application, and the MHD dc generator came up... The reality of the situation is that, the projected performance of the generator is relative to the combustion plasma's velocity... [in the external combustion chamber]

In any event, the electrode's will decompose under the exposure to the combustion plasma, so they are water cooled, then inturn, used as a heatexchanger source. So any-type of steam cycle established a "combined heat cycle" as the MHD system is a "topping cycle" and the electrodes serve as a bottoming cycle's primary heat exchanger.

Oh and heres some new tunes-

1977 Classic from Kraftwerk "We are the Robots"
[www.youtube.com]

RED MARTIAN - MEGANE (FENDER BASS IV)
[www.youtube.com]

Best

Jeremy

Edited 1 time(s). Last edit at 06/07/2010 09:15PM by Jeremy Holmes.
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comment by LAquaker
I've spent the last few years designing a four-stage external firebox NH3+lithium closed cycle steam -electric generator.
With a total ammonia charge of less than a gallon and an external propane-butane/ & air radiator re-condensing circuit on the outside of a 900 gallon containment vessel.
MHD, -3inch turbine wheel, -5inch turbine wheel, -single Sullair ammonia "screw" pump/impeller, exhausting on the inside of the containment to condense for injection back into boiler tubes.
Because my donor vehicle is presently all aluminum and 40 feet long, a 60"x96" 150psi steel containment is plausible.

Thanks for your topic; high temperature rotation in an outlandish ambient condition. Thanks.

Years ago, I designed a short term Venus "Lander" and six separately ejected (during Lander descent) monochrome mechanically scanned video cameras with a single element detector, since (excepting early plum-icon and image-orthicon) no unmanned space probes had ever been allowed by the DOD to use multi-element arrays. The screenplay gave Lander a life of just a few days because some of the successful Russian landers had a useful life of closer to an hour with 1970's technology and a pre-release cryogenic chill-down. The mid-1980's joint French-Soviet-American Haily's/Venus balloon atmospheric descents were also much longer than minutes. The expiration time of all this hardware was dependent on shells that gradually failed because i used their skins as batteries.
The kinetic energy (fuel) is low and the number of launch windows is high, the "Einstein" delay can be so much shorter, why JPL chose "The God of War" and ceded "The Goddess of Love" to the Russians.....
The question made me into a Quaker.
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comment by Jeremy Holmes
[spacescience.spaceref.com]

Notice at the bottom of the linked page the Magellan Misson link does no longer work, I find this disappointing...

With regards to the MHD, the closest that Nasa ever got to MHD in space is the RTG's used on Cassini...

Its funny, since if the electrode's [for an MHD unit] were even cooled to 500 degrees F., it would work great with regards to thermal differental in space or on earth, with regards to Carnot efficiency. Also, the electrodes could be used [for an MHD unit] as a boiler thus cooling them, in order to minimize electrode thermo decomposition, a piggyback steam engine system, could be driven by such an arrangement.. The same should apply to Cassini's RTG's. If im correct with respect to Carnot, MHD use in space, was driven by the starwars program, since very high power generators are needed for the application to drive lasers.

you can find a picture of an RTG used by the Cassini Spacecraft here.
[www.astroengine.com]

Just a great song-

Pi - Super bon bon
[www.youtube.com]


[saturn.jpl.nasa.gov]

Best

Jeremy
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Comment by Jeremy Holmes
Ive taken sometime to ponder what LAquaker said;

Quote

MHD, -3inch turbine wheel, -5inch turbine wheel, -single Sullair ammonia "screw" pump/impeller, exhausting on the inside of the containment to condense for injection back into boiler tubes.

Im sure some here, will question the merit of this dialog, perhaps I can offer some insight.

If your going to build a "small-scale" MHD unit your going to need a steam engine for two reasons. The electrodes need cooling hence the reference to a "boiler" also you either need to use a permanet magnet or an electro magnet, permanent magnets dont like heat... The electromagnet can tollerate some heat and it has to be energized somehow, and what better way, than a steam "piggy-back" cycle that cools the electrodes.

So this could be done using a 3inch turbine wheel (depending on capacity) or a piston steam engine. Its only fitting, that steam guys like us : ) recognize this. This is something I have been experimenting with for years, unfortunitly there are so many variables, that development of such a thing may eclude a patent. -edit- :ie it most likely would be a "cluster" of inventions, although a patent would go a long way to describe a useable system-

Jeremy

Edited 1 time(s). Last edit at 07/28/2010 07:04PM by Jeremy Holmes.
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comment by LAquaker
The concept is to convert as much kinetic energy as possible thus re-condensing NH3+Li with the four stages, and hopefully ending up with less than 1Bar in the 900gallon containment tank..
The fast hot MHD is a spiral path within a copper wound solenoid, electrodes are inner shell and innermost shell.
The hard part is the ceramic constant radius, expanding pitch bulkhead separating the shell (pipe) electrodes. i suppose ablation will force constant replacement.
Ammonia can not touch copper,silver, Al, zinc et al, but routing NH3 for cooling might be feasible.
PM magnets with wound stater for both contracting and expanding turbine impellers may need cooling since 100C is close to the Curry point for any magnet i can buy.
Bringing cold propane used for cooling or for fuel inside a "containment" tank is not going to be safe.

My father invented the patent numbers
2,852,727 2,909,096 2,933,008 2,988,953 3,010,024 3,049,588 3,397,859 3,049,588 3,157,882 4,164,677 et al...
He was a genius, but a "patent" gives you only the right to sue someone.
At 63 he gave up and got a job, got laid off because he turned 81.
I owned the best blood formula in Hollywood for a few years, sold 30 gallons at a time, when my main customer filched a copy of the complex formula... he swamped the market for veinus, arterial, scabs and all.
Patents are part of the body of our Federal Constitution in order to move invention into the public commons as fast as possible, to build "progress".
My goal is to push anhydrous ammonia as the Carbon free liquid fuel for today's cars, trucks and air travel. If i succeed in any way, please steal it, i won't starve.



Edited 1 time(s). Last edit at 08/03/2010 05:13AM by LAquaker.
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LAquaker,

Those are some interesting patents your father invented

Quote
LAquaker
My father invented the patent numbers
2,852,727 2,909,096 2,933,008 2,988,953 3,010,024 3,049,588 3,397,859 3,049,588 3,157,882 4,164,677 et al...

2,852,727 MECHANICAL MEMORY
[www.freepatentsonline.com]

2,909,096 PULSE OPERATED CAMERA
[www.freepatentsonline.com]

2,933,008 APPARATUS FOR CONTOUR PLOTTING
[www.freepatentsonline.com]

2,988,953 APPARATUS FOR CONTOUR PLOTTING
[www.freepatentsonline.com]

3,010,024 MISSILE TRACKING SYSTEM
[www.freepatentsonline.com]

3,049,588 QUALITY CONTROL SYSTEM
[www.freepatentsonline.com]

3,397,859 ELECTROMECHANICAL TRANSDUCER AND VALVE OPERATED THEREBY
[www.freepatentsonline.com]

3,157,882 PULSE OPERATED CAMERA
[www.freepatentsonline.com]

4,164,677 ANODE ASSEMBLY FOR HIGH POWER ELECTROM BEAM LASER
[www.freepatentsonline.com]



The type of MHD device im reffering to is a linier combustion plasma type. Yours seems more complex.

Best

Jeremy

What is an MHD? Magneto Hydro Dynamic is what comes to my mind, but you don’t mean that? Are you thinking of a Stirling RTG ? I don’t spend time in the Phorum, I’ve got a job. We are using RTGs on the next Mars rover, MSL.

[marsprogram.jpl.nasa.gov]

I don’t understand about “screenplay” and “orthicons”, I started my career in 1984 and I’m mechanical. Our modern technology won’t give us too much more than 1 hour on Venus, and we are still taking the slow boat down. The atmosphere is so viscous you would have to power your way down to go fast!

Hi Tiskenderian,

The MHD im refering to is indeed Magnetohydrodynamics. More specifically a MHD type generator. Here's a link to help clear any confusion.
[www.buzzle.com]
htp://www.buzzle.com/articles/how-do-mhd-generators-work.html

The main reason this is relevant to your thread "High Temperature Mechanisms" is because the electrodes in the combustion plasma stream will erode or decompose under the very high temperature's encountered from contact with the combustion plasma stream.

"I don’t understand about “screenplay” and “orthicons”, "

Ok, so you dont like acronym's : )

You would be suprised, at the machinery I work with[build] as a process engineer.(day job) I get your point, so im not going to go any further with that.

" I don’t spend time in the Phorum"

I do, and quite frankly it can be some fun. None of us "need" to be here, perhaps because most of us do have good jobs. You should lighten up a bit. Even thou sometimes it can be(the forum) a release from everyday stress, and we have some good fun at times, Scott keeps us inline(admin).

I have waited for a long time for this part of the forum (Misc Tech) to take off, seems as though were off to a good start, with this section and I couldnt be happier.

By the way, I apologize for not recognizing that you work with JPL on your first posting, I used to live in Huntsville AL. You mentioned your interest in steam cars your in the right place,

Happy Friday and Cheers

Best

Jeremy Holmes
[www.flashsteam.com] [what im doing with flashsteam is not my dayjob, yet...]



Edited 1 time(s). Last edit at 08/06/2010 01:10PM by Jeremy Holmes.

Just to let everyone know that im NASA "friendly" here are some pictures and the link to my u/tube account, yes I produced that...

http://www.youtube.com/user/crispset



best

Jeremy



Edited 1 time(s). Last edit at 08/06/2010 08:41PM by Jeremy Holmes.

" Closed cycle MHD" can look very different, as can direct thrust sea water MHD, MHD space craft propulsion, and last, but not least; MHD as a major energy transfer dynamic in interstellar space. Maxwell & Lorentz seem to play well in any venue.

Small scale development of MHD electricity for vehicles, home or for commercial use is almost never addressed since the 1960's Russian coal and nuclear electrical generation experiments: centralized mega watt electricity is the only goal in most published literature on the subject in the last 40 years.

A rare exception is a 1990's patent on a closed cycle shipboard electric generator with a helical channel inside a solenoid coil.
When this patent's legal restraint runs out, we can all prosper

My father's 1979 4,164,677 ANODE ASSEMBLY patent was tested by the AirForce & Boeing just last year.
That laser's "cover story" was Livermore's never ending tritium pellet fusion experiment, first tested just two years ago.

Heating a small quantity of NH3+Li mixture to high pressure, and than sending that mixture through four cascading slower and larger devices, each stealing kinetic energy (and eletricty) until the NH3+Li condenses.
A little more than a back yard experiment, but as children we spent our time in the 'hood (Granada Hills) building bombs. My buddy next door hand built a 1917 Sopwith Camel in his garage, sold it to the USNavy. Go Figure.

Sorry, to much bla bla

Topic is finding a successful way to build machines that have a useful service life, running in untested corrosive ambient environments, at out-land-ish pressures and fast rising temperatures.
Sullair successfully built positive displacement rotary "screw" pumps for gaseous ammonia/water at 25 atmospheres at 400F, for decades.
Exhaust driven superchargers on IC engines work at very high temperatures and put up with hot exhaust gasses with a well understood chemistry, useful but with deal-breaking differences.
The "jet" engine business is way out of my experience.

My earlier post refers to a film screenplay i finished writing decades ago, that supposedly "solved" the survival problems of landing a short lived group of large and small robotic devices on Venus and transmitting back useful data before they expired. (I got a job working on the movie star wars in 1975, at $5/hour)

Isolating hot and cold NH3+LI from a required copper solenoid magnet, lubricating high speed shafts without any brass or pressurized oil, and controlling gross temperatures.....

thanks for ideas

TIskenderian,

For that Venus lander, Is it possible that instead of a parachute one could use instead an auto gyro? This could set the thing down easy enough and the rotation of the gyro could be used to power some cooling. A thermo cooler could cool the main body of the thing and the whirling blades could shed the heat.

Best, ------ Bill G.

Cool idea, hopefully such rotating wings could also serve as a hi-gain radio antenna and magnetometer array.
Perhaps their skin would react with the Venus atmosphere in a endothermic reaction, sort of an ablative heat sink.

If you study the 8 Russian landers, [www.mentallandscape.com] the problem is that there is nowhere to put the incoming heat that will stop most all rotational devices man builds today.
Delta-T drives heat into your machine. The Russians used, inside Venera's pressure exclusion "dewar"..... "A large thermal accumulator of lithium nitrate trihydrate and a circulating fan distributed and absorbed excess heat. This lithium salt has a high specific heat of fusion, like ice, but melting at 30° C".

Back at earth, i have a 5ft. x 5ft. x 5inch thick steel radiator, with a built in mechanism to control its angle-of-attack, or frontal area, to adjust the cooling rate of the contraption. With a slipstream at less than 35C, I am assuming this pumped propane external cooling loop can condense a working charge of 1 gallon NH3+Li. within a 900gallon tank.
Perhaps ugly will be to nice a word.

Ive actually am working on this MHD generator using my corn burner what has to serve as the plasma. Orientation of the magnetic field has to be perpendicular to the flame stream. Also seeding the flame stream with nickel acts as a catalyst its considered a consumable. The screen eroded pretty fast several hundreds of pounds corn burned.

This is it...

Ride like the wind

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