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

Post by Tom Booth »

Nobody wrote: Sun Nov 21, 2021 10:03 am Okay. It is not Tesla. Tesla probably knew that it takes as much energy to create a "Cold Hole" as you get back out by filling it. You are the one that thinks it doesn't need to be filled. It takes energy/Work to create a temperature difference when there is none.
You obviously have not bothered to read Tesla's article, or even the relevant passages quoted at the start of the tread, or are incapable of comprehending the concept of converting heat into work.

My not responding to your other ramblings here or elsewhere does not mean I agree with any of it. From the start of your recent appearance here you've done nothing but try to discredit me for "soapboxing", being "disruptive", making off-topic posts, apparently, it would appear, to justify my being banned from that science/physics forum, which I can only assume you followed me here from. Are you the moderator there?

In any case, there is nothing to be gained by my wasting time trying to untangle your objections and what seem like intentional "misunderstandings", and straw-man arguments.
Nobody

Re: Tesla's "Ambient Heat Engine" Experiment

Post by Nobody »

No. Not a moderator anywhere. This is the only place I comment. I'm here to help. Mostly to help you. But also to apply basic engineering to the reasoning being explored here.

I ran across a video where someone put together a multilayer panel that when pointed up, even in the sun, it gets cold. SkyCool Systems.

http://www.ammonia21.com/articles/9334/ ... uter_space

https://m.youtube.com/watch?v=7a5NyUITbyk

I don't think this material is what you are talking about here. If what the inventor is claiming is true. There is potential for a Low Temperature Differential Stirling to use these on the cold side, and ambient on the hot side.

Similar to what you are looking for. Of course it is a Ted Talk.
Tom Booth
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Re: Tesla's "Ambient Heat Engine" Experiment

Post by Tom Booth »

Nobody wrote: Sun Nov 28, 2021 2:35 am
I ran across a video where someone put together a multilayer panel that when pointed up, even in the sun, it gets cold.

I don't think this material is what you are talking about here.
That is, of course, not Tesla's heat engine, but somewhat related.

This radiant cooling technology has been under discussion here before.

viewtopic.php?f=1&t=2097&p=10107#p10104

As well as more recently:

viewtopic.php?f=1&t=2133#p16469

How is it possible that you could be unaware of this, since you've made reference to the "burnt pancake" thread repeatedly, including a few posts back in this same thread. Made critical comments, quoting from there... ?

Anyway, yes, that is one of the materials I made reference to. Starlite, reportedly, was supposed to have similar radiant properties, as does any so-called "black body" emitter.

If you are coming around to realizing that maybe these things are not so mythical or impossible after all, I guess that's a good thing.
Nobody

Re: Tesla's "Ambient Heat Engine" Experiment

Post by Nobody »

No.
Tom Booth
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Re: Tesla's "Ambient Heat Engine" Experiment

Post by Tom Booth »

Some good news, some of the long awaited scraps of Aerogel blanket I ordered finally arrived. Unfortunately this is not pure Aerogel. That seems to be unobtainable in anything but tiny 1" squares at a price that is through the roof, and I'm not sure it's any better than some DIY mock "Starlite"- like material, or homemade pyrolyzed carbon foam.

Anyway, it's a start.

IMG_20211130_165123896_20211130165732614.jpg
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While I'm over here changing the igniter on the furnace to get some heat going again in this place, I thought I'd show off the future work space.

I've had this sawmill lumber stacked up to dry for a heavy duty workbench so I can finally set up a bench top metal lathe, drill press, and whatnot I bought a long time ago but never had room in the house to set up anywhere.

I'll be utilizing this enormous basement in a commercial building in the downtown area for future engine work and experiments.but it needs to be cleaned up, work benches made, equipment moved, some lights, outlets, maybe a small fridge, coffee maker, video recording area. I have to bring down the big kiln and get that set up (for pyrolyzing carbon foam, making ceramic engine parts, and teaching Nitinol how to behave. etc. etc.

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There is also a nice creek out back that might come in handy for cooling a Stirling engine running on compost or something. Lots of fun on the horizon.
Nobody

Re: Tesla's "Ambient Heat Engine" Experiment

Post by Nobody »

If you are having trouble with the kilns igniter you could light some paper and toss it in?
Tom Booth
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Re: Tesla's "Ambient Heat Engine" Experiment

Post by Tom Booth »

Nobody wrote: Fri Dec 03, 2021 4:32 am If you are having trouble with the kilns igniter you could light some paper and toss it in?
The igniter was on the furnace. That is, the heating system (oil burner) for the building.

The kiln is electric.
Tom Booth
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Re: Tesla's "Ambient Heat Engine" Experiment

Post by Tom Booth »

I had plans to go to considerable trouble to build an all acrylic LTD Stirling engine. All, except for the bottom that is.

The idea being, heat could be conducted into the engine through the metal bottom but since the sides and top are all plastic, the heat would be trapped inside with no outlet.

According to the current prevalent interpretation of the 2nd law of thermodynamics, 80% or more of the heat entering through the bottom of the engine would need to be rejected to the cold reservoir (out the top, conducted to the surrounding air).

In other words, with no outlet for the heat, it would be "impossible" for such an engine to complete a cycle.

Before I got a chance to build such an impossible plastic engine however, I found this one for sale on Amazon:


https://youtu.be/lx1tet8aHJU

As can be seen, it ran quite well, completing more than one cycle, in spite of the 2nd law, and continued running steadily in the same way for another 20 minutes after my phone ran out of video storage and the video ended.

The top and sides of the engine remained cool to the touch the entire time, (on the outside at least).

I think this engine was intended as a solar engine, meant to be operated by sunlight entering through the clear plastic top and being converted to heat inside the engine (like a greenhouse) the heat passing through by being transfered to the cold metal "sink" at the bottom.
Tom Booth
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Re: Tesla's "Ambient Heat Engine" Experiment

Post by Tom Booth »

To further eliminate heat transfer to the top (cold sink) I was thinking of trying something like this:

Resize_20220409_130652_2416.jpg
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The power cylinder would be extended down and a diaphragm would isolate the lower heat input side from the upper unheated side.

My theory is that the pressure from compression will expand the diaphragm upward allowing the air from the cylinder to be heated as it comes into contact with the bottom hot plate.

The air trapped under the diaphragm will expand and drive the piston upward, the air will cool, the piston return etc. etc.

Actually, open atmosphere could be above the diaphragm. The top plate would really only serve as structural support. Possibly as "buffer" space.

Some experimenting should reveal what works best, if something along these lines could work at all.

Anyway, it is a fairly simple modification.
matt brown
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Re: Tesla's "Ambient Heat Engine" Experiment

Post by matt brown »

Tom - this diaphragm scheme is the same I eluded to in a hot potato response, but mine was 'inverted' with ported 2 stroke cylinder on bottom with diaphragm (from gas regulator) on top, scheming towards solar. I often scheme low tech Otto and worry more about specific power than efficiency. Otto nixes regen issues, ported inlet & outlet nix any cooling issues, and specific power could be increased via pressurized low pressure reservoir ('between' ports). However, heating remains a major challenge, and remembering that Otto will have constant volume heating vs Brayton will have constant pressure heating illuminates many failures...from Brayton & Ericsson thru Tailer thermal lag. As drawn, your diaphragm scheme (as per mine) has a minimal dead volume in 'heater' area, whereupon compression forces gas into heater area.

Unfortunately, if we slow this down a bit, and consider what is really happening, we find that as gas enters heater area, it increase temperature AND pressure which increases Wneg AND retards gas entering heater area until end of stroke. In effect, the cool gas 'pools' under pressure equalization like a collie herding sheep. The only good news here, is that, more or less, such a scheme is simple gas spring with whatever heat makes it into gas increasing Wpos without other cycle types Wneg.

I think any such scheme where the gas enters & exits heater from the same location will suffer similar result, and that the trick remains passing the gas thru the heater via uniflow vs counterflow scheme. Any such schemes must consider various heater volume issues, but this is the only issue for Otto vs a horde of issues for any real Stirling. I still like your hot potato idea since it varies the heater space, I just don't think the counterflow (as drawn) will work, and why I favor a transfer tube from cylinder top to heater top for uniflow scheme.
Tom Booth
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Re: Tesla's "Ambient Heat Engine" Experiment

Post by Tom Booth »

I think you may be imagining problems that aren't actually problems.

"as gas enters heater area, it increase temperature AND pressure which increases Wneg AND retards gas entering heater area until end of stroke. In effect, the cool gas 'pools' under pressure equalization like a collie herding sheep"

The piston is doing work to compress the gas while forcing it into the heating space.

Such work performed on the gas is not "negative work". At least, the work is not lost. The gas the work is being done on is compressed and heated by this work, which work BTW is contributed "for free" by atmospheric pressure driving the piston home after expansion/work output/cooling.


"...AND retards gas entering heater area until end of stroke."

Well, I guess, but that is precisely what is wanted, isn't it?

At near full compression, just before TDC. Bam!

The compressed heated air enters the heat input area, is further heated, just as the piston crosses TDC.

The piston, like a pitched baseball colliding with a swung bat, driven by atmospheric pressure collides with the sudden heat input at TDC and, home run. Is driven back out. Adiabatic bounce.

The heat and work are not lost, they are compounded.

Because this all happens very fast (adiabatic, without heat loss) each cycle adds a bit more energy to the dynamic.
Tom Booth
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Re: Tesla's "Ambient Heat Engine" Experiment

Post by Tom Booth »

Interestingly, after some "breaking in", the little acrylic engine is running better, and much longer on less of a ∆t as the water cools off.

Today it ran for nearly three hours on a mug full of hot water. (The mug is double wall vacuum insulated)

At first the acrylic power cylinder seemed to have a lot of drag, causing some binding, but it seems the longer it runs, the acrylic becomes impregnated with graphite.
Tom Booth
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Re: Tesla's "Ambient Heat Engine" Experiment

Post by Tom Booth »

I debated for a few seconds; should this go here or in the thermodynamics thread ?

Well Tesla emphasized the fact that heat is not a substance, not a fluid, but rather a form of energy, so he argued that a heat engine sending heat to a sink was not an absolute requirement and a heat engine might be constructed where no heat at all would pass through, but rather all the heat entering the engine could be converted to work.

In my various experiments to test this idea, one thing I found to be consistently true and measurable (so far) is that insulating the unheated side of the engine causes the engine to run better, faster, stronger.

This is the opposite of what most people probably would expect. If heat is flowing through the engine from the hot to the cold side, and this FLOW of heat, like a river turning a water wheel, is what makes the engine run, then insulation anywhere in the path would cause a blockage. The heat would build up inside the engine and it would be unable to run.

So insulating the cold side should at least cause the engine to slow down, even if the insulation is not perfect, the flow would be reduced to one degree or another.

It crossed my mind recently however, while conversing with John Corey that if heat is kinetic energy, the impact of fast moving air molecules, then, as far as a heat engine is concerned, insulation on the cold side of the engine is functionally equivalent to making the cold side colder, increasing the temperature difference because fewer energetic "hot" air molecules would be making contact with that side of the engine (from the outside).

Here is a sketch to help illustrate what I mean:

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The top picture is an LTD type displacer chamber without insulation, showing the "heat" or number of hot air molecules or atoms randomly crashing into the engine.

The bottom illustration is the same engine with the cold side insulated. It seems obvious that fewer hot air molecules will impact the cold side. Less ambient heat will be able to reach the engine from that side.

As far as the air inside the engine knows, the cold side is now even colder!

A consequence of the actual nature of heat as kinetic energy and not some kind of fluid held in "reservoirs" and compelled by some mysterious force akin to gravity to flow from hot to cold.

Heat in a gas, like air is simply random motion. It is not "flowing" anywhere. The insulation prevents this kinetic energy from impacting the engine, effectively making it seem colder. Fewer impacts over a given time period.

So, theoretically, perfect insulation might be the effective equivalent of a cold side at absolute zero.

At absolute zero ALL the heat entering the engine would be converted to work, so there would be no heat remaining to "flow" through to the sink.

Perfect insulation would consequently have the same effect as the cold side being at absolute zero.

No heat crossing the boundary.

I'll be interested to hear (or rather read) the response to this idea/theory, but I don't think he had read that particular message as yet. So far he has categorized my experiments as "anecdotal".

Some of the videos of experiments he said he could not watch due to "too much advertising".
Tom Booth
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Re: Tesla's "Ambient Heat Engine" Experiment

Post by Tom Booth »

Well, I received a response, very patiently explaining how a Stirling engine operates, and why my theory(ies) don't hold water.

Nothing I haven't heard perhaps a half dozen times before on the various physics forums I've mostly been banned from.

Anyway, we sent for some so-called "Hy-Tech" thermal blocking paint intending to paint the ceiling in the attic, to save on the heating bill.

https://hytechsales.com/

Apparently based on methods used to protect the space shuttle on reentry. Dust like ceramic hollow (vacuum) microspheres, that can be added to paint.

I also have a few gallons of the raw material, hollow microspheres, both ceramic and glass a company that manufactures the stuff was kind enough to send me samples of.

Anyway, if my theory is correct, and this paint actually works, similar to a Dewar bottle on a paint brush, the inside of the cold side of the engine could be painted with the stuff.

See what effect that has
Tom Booth
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Re: Tesla's "Ambient Heat Engine" Experiment

Post by Tom Booth »

Another thought occurs to me.

The argument has been put forward several times that; when the flywheel is removed from a Stirling engine so there is no stored energy in a flywheel that could force the piston to return (against the residual pressure caused by imperfect conversion of heat into work); the reason the piston returns is due to stored energy put into the atmosphere so that the atmosphere acts as an "air spring".

This kind of makes sense, but something about that explanation has nagged at the back of my mind saying this was just rather silly and wrong but I was never able to formulate a coherent argument.

In a sealed engine with a "buffer space" this explanation makes some sense. The pressure in the buffer space increases when the gas in the power cylinder expands. Atmosphere then is just a big "buffer space" acting as an air spring. Pretty cut and dry.

The flaw in that argument, however, I think now, is that the atmosphere is so vast, it has a virtually infinite capacity and pushing a tiny thimble full of air out into the outer atmosphere from the power cylinder of a model engine does not increase the pressure of this vast "buffer space", Earth's entire atmosphere, one iota.

The larger the buffer space the less it acts as any kind of "air spring" and the atmosphere is effectively infinitely large and completely open to outer space, not a sealed confined container that can build up pressure so as to STORE mechanical energy and then return it, like a substitute for a flywheel.

No, when the gas expands in the power cylinder and the piston pushes the air in the cylinder out into the atmosphere, the atmosphere does not "store" some of that energy and then return it, "like an air spring" or as a substitute for a flywheel. That's just not happening.

I'm not saying atmospheric pressure does not push the piston back to TDC, I'm just saying that it does not do so as a result of any "stored energy" that originally came from the expansion of the gas in the engine, or from the piston causing an increase in pressure of the infinitely vast atmospheric "air spring".

Whatever energy the motion of the piston might contribute to the outside atmosphere is like a drop of warm water put into the ocean. That energy is lost and dissipates. No way it can ever return like the momentum stored in a flywheel.

So how can the piston possibly return all the way back to TDC?

Something happens to the gas INSIDE the engine EXCLUSIVELY. The outer atmosphere does not change, does not increase in pressure, does not store any energy to return it later, "like a flywheel".

Sorry, but that atmospheric "air spring" substitute flywheel explanation does not hold water IMO.
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