Tesla's "Ambient Heat Engine" Experiment

Discussion on Stirling or "hot air" engines (all types)
Tom Booth
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Tesla's "Ambient Heat Engine" Experiment

Postby Tom Booth » Wed Apr 11, 2012 8:52 am

According to an article by Nikola Tesla some of the HEAT passing through a heat engine is CONVERTED into some other form of energy (mechanical motion, momentum etc.) and so never reaches the "sink". He envisioned that given a heat engine running on Ambient heat with great enough efficiency - so little of the heat would reach the sink (ice as a heat sink for example) that the power produced by the engine could be used to remove what little heat actually reached the sink allowing the engine to operate indefinitely.

My question is, does the Ambient heat running a heat engine actually get converted as Tesla imagined or is the heat just intercepted in its passage but continues on its way like the water over a water wheel?

I thought up an experiment which could demonstrate the theory one way of the other.

Take two identical LTD type Stirling Engines and set them on top of two identical insulated Styrofoam or perhaps wooden pans full of equal amounts of ice. (Something non-heat conducting at any rate) so that the Ambient heat can only reach the ice by passing through the engines (predominantly anyway). Have a small hole in the bottom of each pan with a water glass underneath.

Now set the engine on the left running but leave the other engine idle or disabled.

Image

If Tesla was right, the ice in the pan on the left with the running engine on top should melt more SLOWLY than the pan on the right with a non-operational engine since the running engine is converting some portion of the heat trying to reach the ice into another form of energy.

If this does not happen, then I would have to conclude that there is something wrong with Tesla's theory and possibly something wrong with our general understanding of how a heat engine operates.

At this point I do not have a couple of identical engines to run this experiment immediately but I thought someone else here might.

Tesla wrote:

"...Heat, though following certain general laws of mechanics, like a fluid, is not such; it is energy which may be converted into other forms of energy as it passes from a high to a low level.... If the process of heat transformation were absolutely perfect, no heat at all would arrive at the low level, since all of it would be converted into other forms of energy.... We would thus produce, by expending initially a certain amount of work to create a sink for the heat to flow in, a condition enabling us to get any amount of energy without further effort. This would be an ideal way of obtaining motive power.

"We do not know of any such absolutely perfect process of heat-conversion, and consequently some heat will generally reach the low level, ...But evidently there will be less to pump out than flows in, or, in other words, less energy will be needed to maintain the initial condition than is developed by the fall, and this is to say that some energy will be gained from the medium. What is not converted in flowing down can just be raised up with its own energy, and what is converted is clear gain. Thus the virtue of the principle I have discovered resides wholly in the conversion of the energy on the downward flow."


If Tesla's assumptions were correct, then in this experiment, the ice in the pan with the engine RUNNING on top should melt more slowly than the one with an engine not running. The running engine, to one degree or another, according to its efficiency, acting somewhat like a refrigeration unit keeping the ice cold or converting a portion of the heat into mechanical motion.

At lest there should be some measurable difference in the amount of melt-water accumulated in each water glass regardless of the efficiency of the engines used.

I have pondered this question for some time. Is the heat passing through a heat engine actually converted or is it merely intercepted? Energy can be derived from water passing over a water wheel, but the water itself is in no way changed or converted into something else.

Tom Booth
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Re: Tesla's "Ambient Heat Engine" Experiment

Postby Tom Booth » Wed Apr 11, 2012 1:48 pm

There is, perhaps, something Tesla overlooked.

My intuition seems to tell me that although some of the heat is being converted, due to the action of the engine, the heat may be getting drawn in at a faster rate due to the continual agitation and turbulence as the air is shuttled up and down.

In that case, the ice with the running engine may melt at the same rate or even faster regardless of whatever conversion might be happening as the heat is being drawn in more quickly than it would be otherwise, thus rendering Tesla's idea unrealizable.

At any rate I think it is an experiment that would be worth carrying out. Whatever the outcome.

Ian S C
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Re: Tesla's "Ambient Heat Engine" Experiment

Postby Ian S C » Thu Apr 12, 2012 3:56 am

The experiment is worth trying, but my bet would be that the ice would melt fastest under the left hand engine, the working engine is actively converting heat into energy, and in the prosess transfering the unused (90% +) heat to the cold side. Ian S C

Tom Booth
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Re: Tesla's "Ambient Heat Engine" Experiment

Postby Tom Booth » Thu Apr 12, 2012 8:43 am

Ian S C wrote:The experiment is worth trying, but my bet would be that the ice would melt fastest under the left hand engine, the working engine is actively converting heat into energy, and in the prosess transfering the unused (90% +) heat to the cold side. Ian S C


I tend to agree. I'm still not 100% sure which way it would go though. At any rate, to realize Tesla's idea, I think the efficiency of the engine would have to be above 50%, probably more just to break even. Like the "drinking bird" it might keep running but would have no real practical value in terms of power output as all the power generated would be used just to get rid of the excess heat with little or nothing left over.

Here is another idea though that I think would be worth trying. It is somewhat different from Tesla's idea in that it does not passively use "Ambient Heat" but rather first concentrates that heat by compressing the air.

The more I think about this, the more I think that this "Ambient Heat Engine" could probably be built using "off the shelf" components. Here is how, and why.

I've worked in a lot of engine shops with air compressors. The compressor head on a regular shop air compressor gets hot enough to cook an egg despite having cooling fins, fan and being exposed to the open air. All that heat is not coming from the compressor itself, from friction, but rather from the air that is being compressed and giving off heat (solar/ambient heat stored in the air). This is how any refrigeration system works, with a compressor to compress a fluid to drive off the heat. It works just the same with ordinary air. When you compress air the heat gets "wrung out".

After the compressed air sits in a tank and returns to room temperature, an ordinary air tool, like an air motor or impact wrench when running will emit bitter cold exhaust air. I know this because someone I worked with went to the hospital and had to go out on disability because he was taking some head bolts out of an engine with an air powered impact wrench and his finger got frozen solid to the tool and actually broke off because he had his finger over the exhaust port.

Ice formation on an air tool is a common and well known problem. They sell antifreeze for the purpose of preventing these tools from becoming clogged with ice at the exhaust port.

So here we have, in spite of precautions taken to prevent it, an enormously large temperature differential that has been created with nothing more than an ordinary shop compressor and shop air tool.

Now imagine we lubricate the compressor with something like PTFE (Teflon or "Slick 50") and INSULATE the compressor head and pipe. Take the pipe off of the tank and extend it. Wrap this extremely hot pipe around the hot side of a Stirling engine. Allow the pipe to continue from there through some cooling coils with fins exposed to the air to cool it back down to ambient, or even send it through a tub of water or radiator or both.

Now release the cool compressed air through an air motor coupled to an electric generator for power output. Now insulate the air motor and its cold air exhaust to prevent it warming up to ambient. Run that pipe back to the cold side of the Stirling Engine.

Now have the Stirling engine coupled to the compressor so that the Stirling engine can run the compressor.

First we can run the compressor with its electric motor until it gets hot. Then we turn on the air motor and let it run until it gets cold. We now have the temperature differential to run the Stirling Engine. Start up the Stirling Engine and shut off the electric motor.

Now the whole apparatus is running on heat extracted from the air. It is also delivering power via the air motor to the generator. At the same time it is continually drawing in more warm ambient air as "fuel".

This would not be "perpetual motion". It would be running on solar energy. The heat trapped in the air.

The only real problem I see with this is that a conventional compressor is not designed to operate at extremely hot temperatures. To operate for an extended period of time the compressor would probably have to be made out of some high tech ceramic or something, but an ordinary shop compressor should probably run long enough to prove the concept before it overheats. Another problem would be water vapor in the air condensing and freezing at the air motor and clogging up the lines. But again, it should probably run long enough to prove the concept before that happens. It could also probably be run in a closed loop using DRY air with the addition of a heat exchanger between the cold exhaust and the compressor intake.

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Re: Tesla's "Ambient Heat Engine" Experiment

Postby Tom Booth » Thu Apr 12, 2012 12:59 pm

One thing I want to emphasize is that the air-motor or turbine or whatever is used for power output would require a load in order for the heat to be converted into work.

In some air-cycle cooling systems and similar systems that use an expansion turbine the expansion turbine just powers a "dummy load" like a water cooled break, but it could just as easily power an electrical generator (with the generator powering some external load like a heating element).

The heat coming from the remote load (like lights or a heating element or whatever) represents heat removed from the system so as to create your cold "sink" and provide the required temperature differential to run the Stirling Engine. Without the load on the air-motor or turbine you wouldn't be converting the heat into work. That heat has to be dissipated somehow via a remote load.

In other words, if this has any chance of working, it probably would not work unless it was actively producing power to run something. It couldn't just sit there and idle or it would likely loose the temperature differential and quit running.

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Re: Tesla's "Ambient Heat Engine" Experiment

Postby Tom Booth » Thu Apr 12, 2012 10:18 pm

Well, I called around today to manufacturers advertising "High temperature air compressors" for "severe conditions" but when I called none had anything that could run without a cooling system.

I guess no air compressor makers ever considered using a compressor as a heat collector where you want to retain all the heat generated.

Maybe an old cast iron air compressor off an old truck used for air breaks or some other rugged old air compressor could be got from a salvage yard.

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Re: Tesla's "Ambient Heat Engine" Experiment

Postby Tom Booth » Wed Jan 21, 2015 1:05 am

I find this interesting: There are several sources stating that as much as 100% of the electrical energy used to compress air in a conventional air compressor is lost as heat and that most of that heat is recoverable.
" as much as 100% of the electrical energy used by an industrial air compressor is converted into heat and 96% of this energy is available for recovery"

http://us.kaeser.com/Products_and_Solut ... efault.asp

How is that possible?

The compressed air is used to run air tools and air motors and such. If as much as 100% of the energy used to compress the air in the first place is lost as heat, then where is the extra energy to power the air tools coming from?

Also, if nearly all that waste heat can be recovered to say... run a Stirling Engine... It seems to me that there is a surplus of energy coming from somewhere. I would say that the "waste" heat from an air compressor is not coming from the electricity used to compress the air but from the latent heat in the air being compressed.

If the compressed air is then used to power an air tool which exhausts very cold air, could not this waste heat and cold possibly be used to create a temperature differential to run a Stirling Engine?

Aviator168
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Re: Tesla's "Ambient Heat Engine" Experiment

Postby Aviator168 » Wed Jan 21, 2015 7:42 am

Because energy is present everywhere (except when it is absolute zero). Heat is only one form of it. Keep in mind, they are saying almost 100% is lost through heat, but not 100%. The rest stored in the form of entropy. When you release the gas, the gas gets back some of the lost heat from the container/environment.

Ian S C
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Re: Tesla's "Ambient Heat Engine" Experiment

Postby Ian S C » Fri Jan 23, 2015 2:27 am

Sorry, I would tend to take a good bit of Tesla's work with a "grain of salt".
Ian S C

Tom Booth
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Re: Tesla's "Ambient Heat Engine" Experiment

Postby Tom Booth » Fri Jan 23, 2015 1:35 pm

Aviator168 wrote:Because energy is present everywhere (except when it is absolute zero). Heat is only one form of it. Keep in mind, they are saying almost 100% is lost through heat, but not 100%. The rest stored in the form of entropy. When you release the gas, the gas gets back some of the lost heat from the container/environment.


This is, apparently, not necessarily true.

If a gas is compressed and cooled while under pressure and then released it will get "cold" as it expands. At the same time it will pick up heat from the surroundings.

If it is released through a turbine or pneumatic device, such as an air motor or turbine it will do the same thing but also turn the turbine in the process.

If the turbine is put under a load, that is, coupled to an electric generator the gas will get colder as it expands. At the same time it will pick up heat from the surroundings.

If however the turbine or whatever is kept insulated from the surroundings so that the gas being released from under compression through it CANNOT PICK UP HEAT FROM THE SURROUNDINGS the turbine will still turn. The generator will still make electricity. The gas however, will get even colder. It will still get cold as it expands, but because it can't pick up any additional heat from the surroundings, due to the turbine or whatever being thermally insulated from the surroundings, the gas will get EXTREMELY COLD as a consequence.

This is because the gas can still draw on its internal "latent heat" to do the expanding, even though it is thermally insulated from the surroundings.

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Re: Tesla's "Ambient Heat Engine" Experiment

Postby Tom Booth » Wed Aug 17, 2016 11:34 pm

I will be continuing research on Tesla's theory and I will be building a prototype. Hopefully a WORKING proof of concept model, but I can't give any guarantee of that at this point of course. I do think that there is a chance of it actually working or, naturally I wouldn't bother.

If anyone would like to help out of just follow along I will be posting updates to my gofundme page and to Facebook.

https://www.gofundme.com/2fsahck

https://www.facebook.com/tom.booth.31508

Hopefully this won't come across as "spam". I consider it a rather serious, potentially world-shaking world-saving project, (if it works) but It should also be kind of FUN!

Tom Booth
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Re: Tesla's "Ambient Heat Engine" Experiment

Postby Tom Booth » Fri Aug 18, 2017 1:40 am

I think this is a significant update. I submitted the idea discussed here in this forum to a recent National Geographic Magazine contest. It got through the initial screening process. I've purchased a metal lathe, drill press and other tools and just recently got lucky in finding a place where I can set up shop to work. The prize money though would really help move things along and free up my time to work on this project.

Look for "The Air Juicer". (My girlfriends name for the engine, she also sent me the link to the contest, She's a MENSA genius herself and she has confidence this idea will work, though she gets tired of hearing me talk about Stirling engines sometimes.)

Feel free to log on and make comments or ask questions. The contest only allowed a 60 second video, which doesn't provide enough time to really explain the idea.

http://www.natgeochasinggenius.com/videos

Tom Booth
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Re: Tesla's "Ambient Heat Engine" Experiment

Postby Tom Booth » Fri Aug 18, 2017 2:07 am

Here is why I think this can possibly work.

Take a lamina flow type Stirling. Lets say at point "a" of the cycle, air in the cylinder is expanding and pushing the piston out. At some point pressure inside the cylinder and atmospheric pressure outside the cylinder will equalize. But the piston still has momentum. That momentum will carry the piston further through the cylinder and in the process it will be expanding the air in the cylinder. Mechanically expanded air cools down instantly and so also contracts. In other words, for that brief instant when the air in the cylinder is fully expanded there is a momentary refrigerating effect which I believe is what suddenly causes the piston to reverse direction. And it will reverse direction even without a flywheel, as in a free piston Stirling. I don't know how else to explain that except that under certain conditions or at a certain point in the cycle a Stirling engine acts for a brief instant as a Stirling cooler.

If I'm on the right track then I think that this could be exploited and with a little engineering in that direction the ice in the above experiment really could be prevented from melting. Possibly by simply extending the throw of the piston and adjusting the timing of the displacer so as to maximize the cooling effect when the displacer is in the UP position. (in the above illustration, with ice on the bottom)

Tom Booth
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Re: Tesla's "Ambient Heat Engine" Experiment

Postby Tom Booth » Fri Aug 18, 2017 7:08 am

OK, so lets say you CAN get a Stirling engine to run on ice with NO or VERY LITTLE waste heat reaching the cold side of the engine. I'm theorizing that a Stirling can possibly be designed in a way where it might not contribute much if any heat to melting the ice,.. might even contribute to keeping the ice cool.

But if the engine is using any power produced while running on ice to also compressing a bit of air, even a very slight or tiny amount of air, the compression and expansion of air can cause an additional heating and cooling effect. That is, the temperature difference could be augmented by whatever power is produced by initially running on ice. If that is done then possibly the ice not only would not melt but the ice could be made colder while the ambient (Hot) side grew hotter from the heat and cold generated by the additional compressed and expanded air.

Then as Tesla wrote: "We would thus produce, by expending initially a certain amount of work to create a sink for the heat to flow in, a condition enabling us to get any amount of energy without further effort. This would be an ideal way of obtaining motive power."

The problem in Tesla's day was that "Heat Engine" meant primarily: STEAM ENGINE and the only way to run a steam engine in such a way would be to liquefy the air and then use the liquid air in the boiler. A much more difficult and costly proposition I think.

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Re: Tesla's "Ambient Heat Engine" Experiment

Postby Ian S C » Sat Aug 19, 2017 3:32 am

Tom I have run my LTD motor on ice, the ambient temperature was 20*C, so there was a 20* (a little less) temperature differential. The but is the amount of energy required to make the ice.
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