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Author Topic: I think I've found Maxwell's Demon, however the demon is quite large...  (Read 37771 times)

DreamThinkBuild

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Yes that was exactly my thought, this is why you could put the entire "power plant" into a "box", isolate it from the environment and have a wire coming out, giving you free electricity. In the heat pump scenario you would have two wires, one input and one output, with the out wire giving more than you put in because of the heat pump's extreme efficiency of separating heat into temperature potential.

All that is needed is two extremes. I found this interesting motor made of muscle wire on youtube.

http://www.youtube.com/watch?v=CR2f_NE6j4I

One side contracts when hitting the cold water while the other expands when hitting the warm water.

Nabo00o

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All that is needed is two extremes. I found this interesting motor made of muscle wire on youtube.

http://www.youtube.com/watch?v=CR2f_NE6j4I

One side contracts when hitting the cold water while the other expands when hitting the warm water.

Hmm I've never seen that one before, and I like the rpm it gets even when it is loosely put together  :)
But like a sterling engine it is possible to use at a not too extreme temperature, and this might be less complicated to make also. Do you know how it works? I thought muscle tissue was exited by signals of electricity in the body?

DreamThinkBuild

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Muscle wire is wire that expands when a current passes through or heat is applied. Neat stuff for small robotic projects. It contracts when it gets cold, although the drawback is the slow return. With the motor in the video using ice quickly contracts the metal. I'm assuming in the video that if the other tank is boiling water then as the wire expands on one side it pushes up on the wheel which feeds the wire into the cold tank which pulls the wheel. Pushes on the warm side pulls on the cold side then loops back.

Here's some more info on the wire.
http://en.wikipedia.org/wiki/Shape_memory_alloy

Nabo00o

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Seems activity dropped down somewhat.....

Anyway, I just wanted to add that if a thin pipe is used, like the one we just have discussed, the inner wall should actually as well be isolated from the working fluid. I think it matters a whole lot if we use water, and a little less if we use air, this is because air doesn't transfer its heat as fast as the water does to the inner wall material (plastic, metal or anything).  The problem is that even though the fluid is isolated from its outside environment, a relatively good heat conductor such as PVC would constantly work against the creation of a temperature gradient inside the pipe by transmitting heat from the top to the bottom, thereby severely limiting the efficiency.

I believe that this is a real problem with the design, and does probably make it necessary to increase the width slightly, just to compensate for the volume taken by isolation.
Do any of you know of an insulator that would fit this task, to be thin, water proof (or at least capable to withstand water) and at the same time be a good insulator?

Naboo

Nabo00o

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Re: I think I've found Maxwell's Demon, however the demon is quite large...
« Reply #34 on: November 07, 2009, 06:05:33 PM »
I know its been awhile since anything happened on this tread, partly because I have focused on other projects for the last months. Still I just want to inform you that the phenomena which cause the temperature to change is a called a temperature inversion.

You can check out the wiki page on it, at least they have some information regarding the process:
http://en.wikipedia.org/wiki/Inversion_(meteorology)

broli

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Re: I think I've found Maxwell's Demon, however the demon is quite large...
« Reply #35 on: August 03, 2010, 10:05:12 PM »
1 year later and I still think this concept has merit. I just remembered it and wondered why it died off. It would be very easy to confirm.

You would be right about choosing a bad thermal conductor as the container. PVC in itself is a bad thermal conductor but some companies actually make tube shaped polyurethane like seen here:

http://www.coolag.co.za/products/

This could be inserted in the PVC pipe to get the thermal conductivity further down.

But I do have one question relating to the concept. You say that without buoyancy the fluid in the container will take the temperature of the bottom coil. And this is where it gets a bit confusing for me. So let's say the temperature is 20°C uniformly distributed. Now you introduce buoyancy, wouldn't the temperature become lower than 20°C at the bottom and higher at the top? Because the total sum has to become 20°C? In your explanation you prorpose that the lower temperature would match the environment.
Of course if this is true it wouldn't change much in fact I think it would aid the concept more.

broli

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Re: I think I've found Maxwell's Demon, however the demon is quite large...
« Reply #36 on: August 03, 2010, 10:33:50 PM »
I also forgot to mention the test. You don't need a whole array, just one long isolated tube would do. You keep one temperature probe at the top and one at the bottom, if the latter goes from bottom to top it has to preferably be non metal or it might act as a short circuit for the gradient and defeat the purpose. This experiment would show the feasibility and give some numbers on how much temperature difference arises using x m height. Luckily buoyancy only needs hight so the tube doesn't have to be large in diameter but I think using less volume would make the gradient appear quicker but it would also be easier to disrupt.
This is what they would call a proof of concept.

lumen

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Re: I think I've found Maxwell's Demon, however the demon is quite large...
« Reply #37 on: August 03, 2010, 10:46:20 PM »
I also forgot to mention the test. You don't need a whole array, just one long isolated tube would do. You keep one temperature probe at the top and one at the bottom, if the latter goes from bottom to top it has to preferably be non metal or it might act as a short circuit for the gradient and defeat the purpose. This experiment would show the feasibility and give some numbers on how much temperature difference arises using x m height. Luckily buoyancy only needs hight so the tube doesn't have to be large in diameter but I think using less volume would make the gradient appear quicker but it would also be easier to disrupt.
This is what they would call a proof of concept.


I did build such a test device!

I placed a 3" diameter pvc pipe inside a 4" diameter pipe and used a vacuum pump to evacuate the cavity between the tubes to work as an insulator.

I had installed temperature probes in each end (digital cooking thermometers) to see the results.

After leaving it in the shed, standing on end for a few days, the probes checked exactly the same temperature.

I thought it was working at one point when the upper was a few degrees higher, but it was the result of an increase in the ambient temperature near the ceiling.

It does seem the results should have been better, but I am convinced that you would probably get more energy by raising a large weight  when the moon is overhead, and extracting the energy when the moon is on the other side of the earth. ;)

broli

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Re: I think I've found Maxwell's Demon, however the demon is quite large...
« Reply #38 on: August 03, 2010, 10:50:59 PM »

I did build such a test device!

I placed a 3" diameter pvc pipe inside a 4" diameter pipe and used a vacuum pump to evacuate the cavity between the tubes to work as an insulator.

I had installed temperature probes in each end (digital cooking thermometers) to see the results.

After leaving it in the shed, standing on end for a few days, the probes checked exactly the same temperature.

I thought it was working at one point when the upper was a few degrees higher, but it was the result of an increase in the ambient temperature near the ceiling.

It does seem the results should have been better, but I am convinced that you would probably get more energy by raising a large weight  when the moon is overhead, and extracting the energy when the moon is on the other side of the earth. ;)

Interesting but you didn't mention the two most important parameters. What was the height of the tube and what fluid or gas did you use? Also how could the temperature probe be affected by the ceiling if it was supposed to be inside the insulated tube? And finally, what was the accuracy of your thermometers?

And don't be so hasty with debunking it  ;D . Only a fool would conclude final results after one test.

Nabo00o

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Re: I think I've found Maxwell's Demon, however the demon is quite large...
« Reply #39 on: August 03, 2010, 11:26:51 PM »
Hey Broli, yeah it has been a while, actually also a while since I have been on the forum.

First I think something like the insulator you proposed would work very well, as long as it is thin enough to allow some water or other fluid left inside.

Second, here is how I see it. If there were no buoyancy, then the temperature should have remained at whatever it was to begin with, and probably equally distributed all inside the volume.
When we then introduce heat exchangers like the coils, the temperature inside and outside should equal with enough time, so no gradients there.

Okey, to the confusion. With buoyancy, but 'without' the heat exchanger, the bottom would be colder then the otherwise average inside temperature, and this would also keep the inside temperature as a total conserved. But since we have a heat exchanger at the bottom, it will fight that change and keep the bottom at the outside temperature, given its heat conductive capacity is higher than the inside buoyancy forced temperature separation, which it probably is.....

So the bottom will stay at the outside temperature, but there should at the same time be created a gradient, and the top of that gradient must be at some value higher than the original temperature, because of the methods here used. At least I strongly believe so.


And from here it is a simple task of connecting the top high temperature of one tube to the bottom low temperature of the next tube, thus helping the heat to flow, and kinda works like connecting two or more batteries in series. If we want this heat to be transferred at a fast rate, something called a heat pipe would aid this process tremendously, but it is probably not cheap at a bigger scale than the one found in my laptop's cpu.

Also...... I have had some new ideas about this concept, partially inspired by the vortex tube.
Since gravity decides the power of buoyancy, what about replacing that force with centrifugal force, which can be much much higher....

Julian

Nabo00o

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Re: I think I've found Maxwell's Demon, however the demon is quite large...
« Reply #40 on: August 03, 2010, 11:45:06 PM »
Interesting but you didn't mention the two most important parameters. What was the height of the tube and what fluid or gas did you use? Also how could the temperature probe be affected by the ceiling if it was supposed to be inside the insulated tube? And finally, what was the accuracy of your thermometers?

And don't be so hasty with debunking it  ;D . Only a fool would conclude final results after one test.

Hmm, if he used the well idea he talked about earlier it is many many meters.
Otherwise there might also be some holes in my theory about water's ability to do this, although I think I have heard mention of it in other situations. I would believe air could work better, but give less capacity, maybe.....

Actual temperature inversion means that air for example will create a very thin layer between hot and cold air which keeps them separated, but my idea doesn't exclusively rely on it....

Julian

broli

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Re: I think I've found Maxwell's Demon, however the demon is quite large...
« Reply #41 on: August 03, 2010, 11:45:54 PM »
Hey Broli, yeah it has been a while, actually also a while since I have been on the forum.

First I think something like the insulator you proposed would work very well, as long as it is thin enough to allow some water or other fluid left inside.

Second, here is how I see it. If there were no buoyancy, then the temperature should have remained at whatever it was to begin with, and probably equally distributed all inside the volume.
When we then introduce heat exchangers like the coils, the temperature inside and outside should equal with enough time, so no gradients there.

Okey, to the confusion. With buoyancy, but 'without' the heat exchanger, the bottom would be colder then the otherwise average inside temperature, and this would also keep the inside temperature as a total conserved. But since we have a heat exchanger at the bottom, it will fight that change and keep the bottom at the outside temperature, given its heat conductive capacity is higher than the inside buoyancy forced temperature separation, which it probably is.....

So the bottom will stay at the outside temperature, but there should at the same time be created a gradient, and the top of that gradient must be at some value higher than the original temperature, because of the methods here used. At least I strongly believe so.


And from here it is a simple task of connecting the top high temperature of one tube to the bottom low temperature of the next tube, thus helping the heat to flow, and kinda works like connecting two or more batteries in series. If we want this heat to be transferred at a fast rate, something called a heat pipe would aid this process tremendously, but it is probably not cheap at a bigger scale than the one found in my laptop's cpu.

Also...... I have had some new ideas about this concept, partially inspired by the vortex tube.
Since gravity decides the power of buoyancy, what about replacing that force with centrifugal force, which can be much much higher....

Julian

That's a very good idea. The force can be easily made 10,000 time stronger than gravity. But it would be much more complex than the array solution. I believe lumen's experiment could be successful if the height was raised more and insulated better. This would give use a good constant as to the delta of temperate compared to acceleration of gravity. But like he suggested I believe it's small. If for instance it's 0.001°C per meter then we would need many kilometers  :P . But making it 10,000x bigger would result in perhaps 10°C per meter in radius. Which is much more interesting.

But to be honest this is the kind of research requiring some big funding.

lumen

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Re: I think I've found Maxwell's Demon, however the demon is quite large...
« Reply #42 on: August 03, 2010, 11:50:27 PM »
Interesting but you didn't mention the two most important parameters. What was the height of the tube and what fluid or gas did you use? Also how could the temperature probe be affected by the ceiling if it was supposed to be inside the insulated tube? And finally, what was the accuracy of your thermometers?

And don't be so hasty with debunking it  ;D . Only a fool would conclude final results after one test.

@Broli,

I was mostly trying to avoid all the details, but the test ran for about 3 months because I was so disappointed I just left it there and every time I went out to the shed, I would look at it.

The cooking thermometers are only accurate to one degree F, but they read exactly the same. In fact they were so well matched, I could unplug them from the thermocouple and swap them and they would still read the same, or the same difference.

The tube was built from full length 10 foot tubes, and I had a fill plug on one end. I originally started with warm water and shook it up to make everything equal at the start, and it was.

I did see about a two degree change with the top warmer shortly after starting and thought it was going to show some good results, but it just went down hill from there.

I also bought a vacuum gauge to mount on the tube to monitor the vacuum status but the test showed poor results and I never installed the gauge.

The gauge would have been important since I knew the starting vacuum was about 23in Hg using a refrigeration vac pump, but the final vacuum when I finally dismantled the device was zero.

So given that in the end the main insulator was missing, and that I have no way to know when it went dead, the final results are inconclusive.
 
I thought this is important since I don't want to discourage anyone from doing their own testing by showing the results are conclusive when they are not.

Nabo00o

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Re: I think I've found Maxwell's Demon, however the demon is quite large...
« Reply #43 on: August 04, 2010, 01:05:25 AM »
@lumen
I am very glad that you actually built a test unit to see if it could work. It sounded very tempting and easy, but maybe it wasn't that simple  :)

In any case I should as well try to make a simple setup and see if it could register at least a little bit.
But yeah, this is one of those experiments primarily about proving a point, rather than doing something useful..., which again might be a bad goal.

@Broli
When I first thought of using rotation, I thought of a big wheel rotating with fluid inside, and somehow tap the temperature gradient inside it, but it would be very complex.
Then, what if we instead have a stationary wheel-shaped storage with fluid inside, where a single and simple propeller accelerates the fluid to very high speeds. It would be much easier to collect the heat from such a device, and in a way it resembles the vortex tube.

Julian

broli

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Re: I think I've found Maxwell's Demon, however the demon is quite large...
« Reply #44 on: August 04, 2010, 01:37:55 AM »
@lumen
I am very glad that you actually built a test unit to see if it could work. It sounded very tempting and easy, but maybe it wasn't that simple  :)

In any case I should as well try to make a simple setup and see if it could register at least a little bit.
But yeah, this is one of those experiments primarily about proving a point, rather than doing something useful..., which again might be a bad goal.

@Broli
When I first thought of using rotation, I thought of a big wheel rotating with fluid inside, and somehow tap the temperature gradient inside it, but it would be very complex.
Then, what if we instead have a stationary wheel-shaped storage with fluid inside, where a single and simple propeller accelerates the fluid to very high speeds. It would be much easier to collect the heat from such a device, and in a way it resembles the vortex tube.

Julian

Julian, you're always one step ahead. In my head I had this monstrous device stacked, connected with others and filled with water. But your solution is much more elegant. It's funny I didn't even think about that seeing I built magnetic stirs to make water vortices.

This puts it back in the world of the garage tinkerer. Good thinking  ;) .