Tesla's "Ambient Heat Engine" Experiment

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

Postby Tom Booth » Sun Aug 20, 2017 9:43 pm

Ian S C wrote: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.


You certainly make a valid point. Energy is required to make ice in the first place of course. As quoted above, Tesla's reasoning was:

"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."


In otherwords, Yes it requires energy to make ice and ice is needed to get the engine started, but once started, the engine is then being powered by, not the ice, but the surrounding ambient heat.

A "Real" Stirling Engine has a regenerator, which apparently can be very efficient at preventing heat loss to the sink (the ice).

Most people, I mean YouTube videos I've seen, make no effort to insulate the ice from the surrounding ambient heat to prevent it from melting. I'm wondering what would be the result if the LTD Stirling (Preferably with a regenerator) were placed on top of a dewar type thermos full of ice. (As illustrated in the above experiment).

Ideally the engine should be running some kind of generator so as to be converting the ambient heat energy into some other form of energy, - electricity or mechanical output ("work").

Could that energy output then be used to actively remove heat from the ice as necessary so as to keep it cold and prevent it from melting and so allow the engine to keep running on the supplied ambient heat, which is really indirect solar energy.

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

Postby Tom Booth » Sun Aug 20, 2017 10:00 pm

Removing heat from the ice is really not a correct statement. If you study how a heat pump or refrigerating system actually works, it is more like the heat is removed during compression of the gas refrigerant. In those days refrigeration was accomplished by compressing air. The old "Cold Air Machines" worked by compressing air and removing the heat from the air during compression (which also made compressing the air easier. If heat is removed DURING compression of the air the air tends to contract naturally as it is cooled).

The relatively cool compressed air, having had the heat removed from it is then allowed to expand. This air is then extremely cold. Much colder 6than what would be needed to make ice. Air compressed cooled and expanded in such a way, especially if made to do work as it expands, can reach cryogenic temperatures.

If heat were water, then this cold air is like a dry sponge to soak up heat from the ice.

If you are continually squeezing heat out of the air to get the heat energy to run the Stirling engine then returning the cold "Dry" air back to the atmosphere to absorb more heat, then you only need to allow this cold air to kind of "mop up" any excess heat on its way back to the outside atmosphere.

I would say that the 2nd law of thermodynamics does not apply as this is an "OPEN SYSTEM" and it is not "Perpetual Motion" it is just an indirect use of solar energy.

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

Postby Tom Booth » Mon Jan 08, 2018 7:20 am

I thought I might mention something I've been working on recently and am also curious to know if anyone else here has ever heard of it or done anything with it.

https://en.m.wikipedia.org/wiki/Vuilleumier_cycle

This "heat pump" is quite interesting. I think the patent is quite facinating and informative.

Apparently the concept works and is quite efficient from what little I've been able to find out about it.

Anyway I THINK I've worked out a way of combining an ordinary small LTD type Stirling engine with a Vuilleumier heat pump so as to create a very simple and relatively easy to build realization of Tesla's Ambient heat engine that could "run on ice" that never melts.

The basic concept is to add a second regenerative displacer to the bottom half of an ordinary LTD Stirling and have the movement of this displacer timed in such a way that it should absorb some heat from the ice that the stirling is running on.

In otherwords the Stirling running on ambient heat comming in from above will simultaneouly use some very little of its energy gained from the ambient heat to move a second displacer/regenerator that acts as a Vuilleumier type heat pump.

Put another way the engine will have two regenerators. One drawing heat from the warm ambient air above and the other drawing heat from the colder ice below. (Ice itself still contains a great deal of heat in actuality)

A. Vuilleumier heat pump itself functions in much the same way. Using two seperate regenerators to draw heat in from both ends.

The major difference is that a Vuilleumier heat pump outputs only heat and cooling but has no power output. So the idea in some respect is to take a Vuilleumier heat pump with two regenerators and incorporate a piston so that the heat is converted and output as "work" instead of heat.

I'm quite enthusiastic about this Vuilleumier heat pump.

I've designed some engines on the principle Tesla described before. Basically on the order of a Stirling engine being used to run a vapor-compression type heat pump using air as a "working fluid". That is, a Stirling engine running an air-cycle refrigerator to keep itself cool.

The main problem I've run into with that is, building such a thing, a combined Stirling engine and what amounts to a refrigerator combined required quite a bit of precission engineering and macine shop work for things like compressor piston & cylinder and an expansion turbine.. So I've been spending a lot of time and money trying to set up a machine shop. Which in itself has cost me thousands of dollars. Not only for the equipment but also for some space to set it all up.

Using a Vuilleumier heat pump for cooling as an alternative to an air-cycle system is, I think, much more straightforward, as well as much simpler and a whole lot easier to construct. All that is needed that would not be needed to build a little model LTD Stirling is a little extra steel wool for the additional regenerator.

That is, it can be constructed without a machine shop and without precision tooling. No compressor. No turbine. Just a second displacer/ regenerator added to what would otherwise be an ordinary LTD Stirling. And well... Some additional linkage.

The important thing of course is the timming of the two displacers so as to have them working in phase to effect both Stirling engine power output and Vuilleumier cycle cooling simultaneously in the one selfsame device.

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

Postby MikeB » Wed Jan 10, 2018 6:13 am

So, if no heat ever goes into the ice, what effect does it have on the system????

I think what Tesla was really getting at, (probably incorrectly) was that if the engine was 100% efficient (no chance) then the _output_ of the engine could be used to cool the ice/cold end. Which sounds to me rather like blowing on the sail of a yacht - works fine if you are outside, but has no effect when onboard.

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

Postby Tom Booth » Fri Jan 12, 2018 4:38 am

I think the question hinges on what actually goes on in the inner workings of a heat engine.

The predominant view had always been and to a great extent still is: for a heat engine to operate heat entering the engine must pass through the engine and out the other side, much like water passing through a turbine or over a water wheel.

Tesla recognized that this is not actually true. Heat passing THROUGH an engine Drawn by some external force, as water is drawn down by the external force of gravity is not what powers the engine. Fundamentally it is a question of the nature of heat itself and also how a heat engine utilizes heat.

A heat engine does not need to be 100% efficient for the idea to work. Far from it. Infact it could be extremely ineficient.

A 100% efficient engine would need to operate at absolute zero on the cold side. That is clearly unnecessary aside from being entirely impossible.

If we start out with a cold engine, then introduce heat, the heat expands the air which drives the mechanism that converts the heat to momentum or "work" as some form of mechanical output. As a result, the conservation of energy requires that the work performed by the heated gas causes the gas to lose the heat temporarily loaned to it, which has gone out as work. So the heated air becomes cold again and the cycle is complete. Now the air can be reheated to perform another cycle of work.

This should work with or at any temperature difference with any source of heat but if the engine is first cooled below ambient then ambient heat can be the source. Since the heat entering the engine is converted rather than just pasing through there is no necessity for the heat to ever be transfered to whatever provided the initial cooling.

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

Postby Wellington » Fri Jan 12, 2018 2:46 pm

Tom Booth wrote:According to an article by......



hello tom. can you provide a link to the material you reference. thanks.

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

Postby Ian S C » Sat Jan 13, 2018 2:59 am

I only have one thing to say on this type of technology, build it, and demonstrate the proof.
Ian S C

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

Postby Tom Booth » Sat Jan 13, 2018 9:29 pm

Wellington wrote:
Tom Booth wrote:According to an article by......



hello tom. can you provide a link to the material you reference. thanks.



http://www.unz.org/Pub/Century-1900jun-00175

The relevant sections start around page 200:

"A DEPARTURE PROM KNOWN METHODS—POS-SIBILITY OF A "SELF-ACTING" ENGINE..."


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