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Author Topic: Tesla's Ambient Heat Engine Theory - Right or Wrong ?  (Read 95295 times)

DaS Energy

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #75 on: April 19, 2015, 01:31:11 AM »
Question?  The engine fuel source being compressed air, where does the energy come from to compress the air?

memoryman

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #76 on: April 19, 2015, 02:04:59 AM »
Question?  The engine fuel source being compressed air, where does the energy come from to compress the air?
Whatever drives the compressor (for example a standard shop air compressor) supplies the energy, usually in mechanical form (electric motor for example).

Tom Booth

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #77 on: April 19, 2015, 02:51:08 AM »
Tom, compressing gas partially converts energy from the compression process to heat;

I agree, but I don't believe that that is all that happens. That is, not all the heat comes from the energy of the compression process, (work done on the gas). At least some of the heat released is due to the gas being restricted in a smaller space so it gives up some of its internal kinetic energy (heat).

That is just my opinion I suppose but the conclusion seems unavoidable to me.

Tom Booth

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #78 on: April 19, 2015, 03:09:11 AM »
Question?  The engine fuel source being compressed air, where does the energy come from to compress the air?

If you are referring to Tesla's "Self Acting"engine, the energy to run the engine is derived from ambient heat or indirect Solar Energy.

The fuel source is not compressed air (not the pressure of compressed air) as such but the heat driven off by compressing the air. The fuel is the heat.

But primarily the cold produced by throwing heat away is what creates the temperature difference to run the engine. It is a kind of heat engine. The "fuel" is heat, ambient heat, not compressed air. Compressing the air is just a means of establishing a temperature differential.

You might say then that the fuel is not heat so much as the cold produced by removing the heat which gives the freely available ambient heat something to flow into. once established the engine intercepts that flow.

I look at it more or less like a kind of siphoning action. In this case Heat is being siphoned out of the air not by a heat sink but by converting the heat into electricity which leaves a "cold hole" for more heat to flow into.




Tom Booth

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #79 on: April 19, 2015, 03:34:54 AM »
In other words, the whole idea is to first establish a "cold hole" for the ambient heat to flow into. As Tesla wrote:

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"Could we produce artificially such a "sink" for the energy of the ambient medium to flow in? ... can we produce cold in a given portion of the space and cause the heat to flow in continually?"

Once a flow is established a heat engine can be used to intercept it. Tesla reasoned that since the heat engine converts heat into another form of energy, such as electricity "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." So the excess unconverted heat needs to be dumped somewhere. The ideal place to dump it as far as possible is back into the heat engine thus: "What is not converted in flowing down can just be raised up with its own energy, and what is converted is clear gain."

Tom Booth

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #80 on: April 19, 2015, 03:47:55 AM »
Tesla was talking in principle. He was a bit vague as to exactly how all this is to be accomplished. For example he states: "Conceive, for the sake of illustration, [a cylindrical] enclosure T, as illustrated in diagram b, such that energy could not be transferred across it except through a channel or path O, and that, by some means or other, in this enclosure a medium were maintained which would have little energy, and that on the outer side of the same there would be the ordinary ambient medium with much energy.  Under these assumptions the energy would flow through the path O, as indicated by the arrow, and might then be converted on its passage into some other form of energy."

"By some means or other" is not very specific, but IMO Tesla is clearly talking about a heat engine here. A Stirling Engine fits the bill. "little energy" (cold) on one side "the ordinary ambient medium with much energy" relatively hot on the other side. "the energy would flow through the path O, as indicated by the arrow, and might then be converted on its passage into some other form of energy" This describes exactly the function of a Stirling type Heat Engine.

Tom Booth

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #81 on: April 20, 2015, 09:40:09 AM »
Another attempt at a concept drawing:


Tom Booth

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #82 on: April 20, 2015, 10:16:33 AM »
If there is any chance of something of this sort working at all, it would, of course, require some sort of auxiliary starting mechanism to run the compressor until a temperature differential is established.

Also, it should be noted that in this illustration ALL the heat and cold generated in the air-cycle system is used to run the Stirling engine - which in turn, will take over running the compressor. Power output (if any) would come from the re-expanding of the air through the turbine which would turn an electrical generator.

The job of the whole air-cycle system is mainly to produce COLD. Extreme Cold. The colder the better. That low grade ambient heat is turned into high grade heat in the process is almost incidental.

I think this is in harmony with the principles Tesla outlined, though I'm not sure it is exactly what he had in mind. In a way it is a reversal of what he described in that he talks about removing the excess heat from the "cold hole". Here the heat is removed by flushing out the "cold Hole" with the cold air expanded through the turbine.

As I said, Tesla was talking in the abstract. This is my own idea how it could be done, based on what I know about air-cycle heat-pumps, Stirling engines, compressed air... etc.

It may seem that it is counterproductive to cool the compressed air before it is expanded through the turbine. The idea there is to cool the expanding air as much as possible. That expanding the air through a turbine reduces the temperature dramatically (much more than throttling alone) because energy is being removed, is almost incidental. The main purpose of expanding the air through a turbine is to cool it. not power production, but as power production is a necessary byproduct of an air-cycle cooling system, it is there for the taking.

The idea here is simply to have something working. A "Self-Acting" engine. To start with... with some power output at least.

if that much can be accomplished, then it can be modified to maximize power output later.

But IMO, even if we just end up with something that sits and runs on a coffee table as a conversation piece that would be a marvel.

memoryman

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #83 on: April 20, 2015, 05:02:42 PM »
Tom, a very interesting topic. At the moment i am dealing with some serious personal matter, and have little time to spend on posting. Find a video wit Daniel Sheehan on 'challenges to the second law of thermodynamics'; give me you thoughts on that.

Tom Booth

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #84 on: April 21, 2015, 08:25:59 AM »
Tom, a very interesting topic. At the moment i am dealing with some serious personal matter, and have little time to spend on posting. Find a video wit Daniel Sheehan on 'challenges to the second law of thermodynamics'; give me you thoughts on that.

Certainly Tesla was well aware of the second law and was going head to head with it in his discussion regarding his "Self Acting Engine". He wrote:

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I read some statements from Carnot and Lord Kelvin (then Sir William Thomson) which meant virtually that it is impossible for an inanimate mechanism or self-acting machine to cool a portion of the medium below the temperature of the surrounding, and operate by the heat abstracted.  These statements interested me intensely...

He then goes on to describe various possible loopholes so-to-speak in this second law. Primarily this idea of creating an artificial heat sink for the ambient heat to flow into so that energy could be extracted from that flow. Perhaps there was some flaw in his logic but I am not aware that his idea has ever been tested in any practical way, by building some such engine as he proposed. Personally I think he was right and I think it would be worth the investment to build such a device and see what happens.

Beyond that I've been round and round about the second law on various forums. To me it seems quite like an article of faith for some and quite slippery when it comes to definitions. Just for example, If a Heat Pump has a COP > 1 is that because the second law doesn't apply because it is an "open system" or what ? What constitutes an "open system" anyway ?

The little "Drinking Bird" appears to violate the second law. But we can get around that by redefining what is or isn't an open system.

In my mind the bird is simply a heat engine extracting energy from the ambient air and using some of that energy to drive it's own simple refrigeration system. My argument is simply that a drop of water on a toy birds felt beak is not much of a "cold hole" and that the same principle could be used to drive a larger more practical heat engine with a more effective cooling system and from which some real usable energy could be derived, violation of the second law or not.

memoryman

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #85 on: April 21, 2015, 06:34:12 PM »
here is the video I was referring to: https://www.youtube.com/watch?v=bBp_SPJAOJc
Note that he is collecting charge - not heat.
A heat pump TRANSFERS heat; it does not generate it. Energy has to be supplied for the transfer. That transferred heat is available to do work.

lightend

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #86 on: June 27, 2016, 10:32:40 PM »
Got to page 2. Thought I would just chip in. will keep reading but wanted to suggest a couple of things.
Ambient temps drop at night.
this sterling type motor heats up the cold box.

(see awesome art work attached)
If we can do it with just a couple of degrees, how about this?
Why not have the 'cold box' cold during the day, as the box warms up due to heat being exchanged it will become ambient, around this time the sun goes down and the outside air plummets, now the box hows the heat and exchanges with the cooler outside temperature, running the thing in reverse.


second thought, is its just a couple of degrees,
why not have the hot sink in ambient temps but have a cold sink underground spread about in the soil where it can dissipate any heat fairly easily.

sorry if I jumped the gun here, just intrigued by this and the prospect of possibly using low heat nitinol.

dieter

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #87 on: June 27, 2016, 10:55:38 PM »
The drinking bird is actually a good example for a demonstrated 2nd law breakdown.

Open system or not, is splitting hairs.

Tesla mentioned a similar idea, in which a liquid substance with a boiling point at ambient temperature is used, instead of water as in a steam engine. Wether boiling or just expanding, like eg. carbo-hydroxides such as eg. gasoline, which are performing high volume chanches under small temperature diffrences. It certainly is possible to convert thermal environment energy into mechanical force. Cooling can always be achieved by evaporation. And where there is cooling, there's a temperature diffrence and hence an opportunity for a heat engine.

pomodoro

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #88 on: June 29, 2016, 02:27:43 AM »
The drinking bird is actually a good example for a demonstrated 2nd law breakdown.

Unfortunately , it may look like it is but isn't actually braking the 2nd law at all. The increase in entropy from the water going into vapor is enough to offset the heat required from the system, so the water cools down. Pretty funky still.

dieter

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #89 on: June 29, 2016, 04:12:31 AM »
I consider the atmosphere with the energy of the sun as a closed system in equilibrium.

See water evaporation as the same as microscopic turbulences, such as brownian motion.

And in Maxwells demon, brownian motion is allowed. At least as long as it cannot / does not have to think ^^

Ok, maybe you say  now then combustion of fuel would be the same. Maybe it is, for me the only point is: it must be clean and freely available.

But ok, I probably miss the point here.