MHD

James Snover

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Magnethydrodynamics, aka thermomagnetohydrodynamics as a form of power production is an idea that just won't die.

The idea is pretty simple: any charge-bearing material passing through a field of magnetized coil will produce an electric current. It doesn't matter if it is the magnets on an electric motor, or the hot gas of a fire. Yes: pass a flame through a tube lined with a field coil, and you convert the heat energy of the flame into an electric current. That is TMHD, or MHD, as it is referred to for short. At the end you still have a fairly hot, fairly high velocity gas which you can run through a turbine and skim off a few more Watts.

The idea is simple, but there are a host of problems that go with it. The hotter and faster the flame, the more energy you get out of it. So you need a rocket nozzle and as hot a fire as you can get. The problem is rockets are short-duration items that require the utmost in quality parts, materials, design, machining and maintenance.

And then you need to line the tube with something like Inconel to last. Very expensive. You could use glass, and it would last longer, but it is very susceptible to thermal and physical shock, and it has to be thin. So, no luck there.

And then, if you add salt to the fuel for the fire, you get a huge boost in generated current. But now you've got a plasma that will chew right through that Inconel, IF your rocket engines don't burn-through first.

And of course, to get the most Watts out of it you have to use superconducting field coils. So now you have a fire in expensive equipment being corroded like mad, running through a tube that has to be cryogenically cooled, and you have to also have a supply of salt in addition to the fuel, and so far, what we know for certain is two things: there is no faster setup to get more watts of power, and there are no materials to make the damn thing long-term practical. They've been at it since the '70's.
 

buffalosoldier

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when I was a kid i read in popular mechanics about twisting a copper wire and a steel wire together and make a thing like a flower and putting it over a candle and it made enough juice to run a small radio. that was over 50 years ago. it was in common use in india.

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DaleM

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Magnethydrodynamics, aka thermomagnetohydrodynamics as a form of power production is an idea that just won't die.

The idea is pretty simple: any charge-bearing material passing through a field of magnetized coil will produce an electric current. It doesn't matter if it is the magnets on an electric motor, or the hot gas of a fire. Yes: pass a flame through a tube lined with a field coil, and you convert the heat energy of the flame into an electric current. That is TMHD, or MHD, as it is referred to for short. At the end you still have a fairly hot, fairly high velocity gas which you can run through a turbine and skim off a few more Watts.

The idea is simple, but there are a host of problems that go with it. The hotter and faster the flame, the more energy you get out of it. So you need a rocket nozzle and as hot a fire as you can get. The problem is rockets are short-duration items that require the utmost in quality parts, materials, design, machining and maintenance.

And then you need to line the tube with something like Inconel to last. Very expensive. You could use glass, and it would last longer, but it is very susceptible to thermal and physical shock, and it has to be thin. So, no luck there.

And then, if you add salt to the fuel for the fire, you get a huge boost in generated current. But now you've got a plasma that will chew right through that Inconel, IF your rocket engines don't burn-through first.

And of course, to get the most Watts out of it you have to use superconducting field coils. So now you have a fire in expensive equipment being corroded like mad, running through a tube that has to be cryogenically cooled, and you have to also have a supply of salt in addition to the fuel, and so far, what we know for certain is two things: there is no faster setup to get more watts of power, and there are no materials to make the damn thing long-term practical. They've been at it since the '70's.
Would sapphire work instead of glass for durability? I know expense but it seems viable. If synthetic or lab developed diamonds could be mass produced, some amazing things could be do e for us all.

OK Bozos, stop clowning around.
 

EatonEggbeater

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The problem with diamond would be isolation from oxygen. Interesting too is as James says, the hotter the gas the greater the return. Your best results would bump up against the melting point of whatever material you'd decided on.


Would sapphire work instead of glass for durability? I know expense but it seems viable. If synthetic or lab developed diamonds could be mass produced, some amazing things could be do e for us all.

OK Bozos, stop clowning around.
 

James Snover

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Would a fluid with metallic particles or similar ionization to meyal inside the hardened material work, obviously a closed system

It would work but you couldn’t vent that the atmosphere and there is a lot of volume of gasses created to be dealt with!


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James Snover

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01svtL

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My wife is a materials scientist with an expertise in molten salts and nuclear energy. She’s one of two on Earth doing what she does. I edit her papers for spelling and grammar. Beyond that, I have no input on this conversation.
 

SonicDTR

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What would prevent the use of a cheap material solid fuel rocket such as this one?

 

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The problem with diamond would be isolation from oxygen. Interesting too is as James says, the hotter the gas the greater the return. Your best results would bump up against the melting point of whatever material you'd decided on.

Diamond is like the hardest metal. 1 gram of diamond weighs like 15 grams
 

EatonEggbeater

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Diamond is like the hardest metal. 1 gram of diamond weighs like 15 grams


I can't disagree, but with the presence of oxygen and temperature; diamond is the same as coal.

Not really disagreeing with Dale, he's suggested a closed system (and that's the only way James' idea could work) more on the thinking that diamonds are any kind of panecaea. Diamond has its own properties, and they're formidable...
 

James Snover

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I can't disagree, but with the presence of oxygen and temperature; diamond is the same as coal.

Not really disagreeing with Dale, he's suggested a closed system (and that's the only way James' idea could work) more on the thinking that diamonds are any kind of panecaea. Diamond has its own properties, and they're formidable...
Just to clarify, MHD is not my idea! And it does work. It's actuially a big effect in tyhe interaction between a white dwarf and a neighboring star still on the main sequence. But, you know. Stars. End of discussion right there. Big magnetic fields, don't have to worry about anything melted because it's all already plasma.
 

xblitzkriegx

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They aren't talking perpetual motion, it is still consuming a fuel to make electricity.

I'm well aware of what they're talking about. You misunderstand my point.

It's not a viable source of energy because of the energy investment required up front is too great. That's why nuclear fuel and fossil fuels are still dominant.
 

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