Stirlingengineforum.com

Recently I've been looking into automotive turbochargers as a means of compressing air to create heat.

It seems also, that a turbocharged engine includes some regulators to limit the pressure and reduce the heat.

Blowout valve, waste gate, and intercooler.

So, could these regulating mechanisms be modified, adjusted, or utilized in a different way?

In a car, the heat produced by a turbocharger/compressor is just thrown away as nuisance heat, an unwanted byproduct of compressing air with a turbine.

At a minimum, this use of an intercooler to reduce the amount of heat produced gives me some hope that an off-the-shelf turbocharger could be used to compress air and produce heat for running a heat engine.

At any rate, I found this rebuilt turbocharger for $75 and will be seeing what if anything I might be able to do with it.

Here is a video with some basic info about the turbo:

https://youtu.be/zenMEj0cAC4

And my recent acquisition:
Exhaust gas from a tailpipe seems to me to be a rather low source of energy input. Holding ones hand over the tailpipe of a running car is as likely to stall the engine as anything.

Well, the "rebuilt" turbocharger, after testing it with a shop vacuum cleaner blower to mimic a car exhaust, turned out to be in need of rebuilding at best. The chance taken buying things via Facebook marketplace and/or you get what you pay for.

Tomorrow I'll be trying again though. This time a forced air "positive displacement" supercharger, rather than a turbo.
I may be wrong, but from my limited research, this one is from a Buick Regal and has a twin screw compressor that works at low RPM.

It seems I may have been wrong about the turbocharger needing rebuilding.

Apparently most turbochargers have "floating bearings" that require a cushion of oil.

My turbocharger has no more play in it than the one in this video, described as "acceptable".

https://youtu.be/02fPvE_YP-Q

https://www.buyautoparts.com/blog/turbo ... haft-play/

Or this video:

https://youtu.be/VS1qsTJDo1A

Also, the seemingly meager output at the speed that can be achieved just using a vacuum cleaner is apparently also quite typical.

https://youtu.be/Xe7ITt9ZuOQ

The supercharger also seems to be in good working order, though for my purposes, both have numerous parts that are prabably not needed.

Just as a reminder of what this thread is about, it stems from this passage from Tesla's 1900 article on "Increasing human energy"

"...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."

It has been considered, for the past 100 years or more, completely "impossible" to have a heat engine running a heat pump which supplies heat to the heat engine to provide power to run the heat pump. etc. etc.

So Tesla, who apparently did not believe in the word impossible, set his mind to work and came up with the above solution, simply put, run the heat engine on ice.

As ambient heat is used by the heat engine to produce work to run the heat pump, the heat is diverted, away from the ice, so there is little work for the heat pump to keep the ice cold.

Just last night, I had an idea to take one of those "twin" Stirling model engines and see if it is not possible, in some way, to modify the linkage system so that one of the engines operates as a Stirling cooler.

I think all that might be necessary is to cross over the piston and displacer linkage on one side, (for one of the engines that is) which I think will have the effect of making each engine run in reverse of the other, as far as the phase difference between displacer and piston.

https://youtu.be/8lsPBWGVC9I

Your turbo might need a pressurized oil line to make the bearings work correctly.

What was the outcome of the acrylic LTD Stirling Engine test?

Nobody wrote: ↑Sat Oct 16, 2021 5:34 am Your turbo might need a pressurized oil line to make the bearings work correctly.

Automotive turbochargers do require oil, unfortunately. Though I think I read somewhere that a gravity fed line is sufficient for the purpose. i'd have to find the reference, may have been a video.

What was the outcome of the acrylic LTD Stirling Engine test?

The acrylic top I was making ended up cracking when I tried attaching the cylinder, which was too tight a fit.

Instead of trying to make another, I ended up sending away for some additional manufactured "solar" engines, nearly identical but with clear acrylic top instead of aluminum.

Like this:
Solar Low Temperature Stirling Engine
https://www.amazon.com/dp/B018YQE3ZO/re ... Y2CG81JPZJ


I haven't had time to do any extensive experimenting, but I did put one engine together with an acrylic top, covered the top with additional insulation, with an access window. Mostly to test a new regenerator.

The modified engine ran about the same as with an aluminum top, but took longer to get going and ran rather slow, though I never used this regenerator with an aluminum top plate, so I can't really make a comparison without additional testing.

https://youtu.be/cR31i09PnNQ

I thought, during this test, that the infrared thermometer was measuring the INSIDE temperature of the engine, but by doing some experiments, it became apparent that infrared cannot penetrate acrylic, so the temperature reading is only the temperature of the outside surface of the acrylic.

It would seem the regenerator was quite effective at retaining heat. Though without some INTERNAL temperature probe, it's hard to say what the temperature of the air inside under the acrylic might have been.

The upper part of the acrylic at least did not appear to be getting hot under the insulation.

I have not yet done any other tests with the acrylic, but I'm satisfied it is possible for a Stirling engine to operate with a "sink" that does not conduct much heat, or rather, with no "sink" whatsoever, other than the internal heat sink of the regenerator itself. That heat trapped by the regenerator, though, does not pass through or leave the engine. Not in the brief span of this one test anyway.

My next test will likely be to use a complete vacuum to insulate the "sink".

To that end, I picked up this vacuum pump:
Fabricating a kind of thermos bottle engine body will be a future project, though I don't know as it would be much of an improvement over the acrylic sides and top especially if it has to be fabricated out of metal which would probably conduct/radiate more heat than the acrylic, even through a vacuum, as acrylic does block infrared as well as being a very poor conductor.

The cup holding the hot water was a vacuum insulated double wall stainless steel thermos type.

Apparently more heat was radiating through the vacuum and/or around, over the upper lip of the flask, than was reaching the top of the engine through the regenerator and acrylic.

Tom Booth wrote: ↑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.

The Vuilleumier heat pump is not very efficient. It's one nich is when there is an ample supply of waste hot heat, and free ambient cool or cold.

The mechanical work into it is much less than for a standard heat pump for the same amount of cooling. However the heat supply's to the hot side is more than the heat removed from the even colder side. Furthermore, the heat delivered to the ambient cold side is even greater than both those heats.

The device is similar to two Stirling Machine connected on a common crank. One is an engine and turns the crank. The other would operate as a cooler and requires something to turn the crank.

There are three bodies with three different temperatures. Hot, ambient, and cold.

Heat moves into the engine from the hot body. Some is converted to work turning the crank. A smaller amount is rejected to the ambient body

Heat moves into the cooler from the cold body. Some work is converted to heat. The larger amount of heat is rejected into the ambient body.

It will work to drive a refrigerator pump with a Stirling. It will move more heat out of the hot body than comes out of the cold body. More heat will be absorbed by the ambient body than the heat supplied by both hot and cold bodies combined.

If you were to use the cold body to run the Stirling it would melt the ice faster.

First and Second laws of thermodynamics. Claiming you can break either of those laws doesn't demonstrate it. I see the mistakes. Trying here to explain them. Thanks.

Nobody wrote: ↑Sun Oct 24, 2021 2:26 pm

First and Second laws of thermodynamics. Claiming you can break either of those laws doesn't demonstrate it. I see the mistakes. Trying here to explain them. Thanks.

I don't think I've ever "claimed" anything one way or the other.

But when, for instance, I'm told that 80% or more of the heat used to run a heat engine not only should, but absolutely must, under any and all circumstances, pass through the engine as "waste heat" to the sink, and I see by direct experiment that a simple model Stirling engine appears to conduct ZERO heat to the "sink", under certain circumstances, by actual measurement, I don't just dismiss the cumulative evidence of dozens of objective experiments off hand on the basis that someone thinks the second law says that is "impossible".

Something is wrong somewhere.

I think that warrants further investigation.

Tesla suggested that if heat is energy that can be converted, a sink is not a necessity. In actuality, even Carnot, who basically established the second law in it's earliest form came to the same conclusion, though that fact is almost universally ignored.

I'm not out to prove anything, but I don't consider established scientific opinion sacrosanct or infallible either.

Tesla was a rather smart guy. Smarter than me, probably, so I'm not going to assume he was wrong.

I don't personally see any good reason why heat energy has to be any less efficient than any other form of energy.

Nobody cares if an electric motor gets up to 99% efficiency, but for a heat engine running on a cup of hot water to get better than 18% efficiency some people think all science would have to be overturned and the world would come to an end.

To me that seems rather silly.

I'm not going to deny experimental results I see with my own eyes in an experiment I conducted myself.

For instance, this is not a "claim". it's an experiment.


https://youtu.be/fFByKkGr5bE



I tried first, replacing the heat conducting steel bolts with non-heat conducting nylon bolts. Insulated the sides of the engine so all of the 80% of the "waste heat" should, theoretically, pass through to the top of the engine.

The bottom of the engine was scalding hot.

But after running for some time, the top of the engine remained cool to the touch.

Nevertheless, I thought if I blocked the heat sink path with insulation, the engine should overheat and stall, or at least slow down.

Surprisingly, instead, the engine ran a little faster.

Other people make the claim that there is some flaw in my experiment, so I take suggestions and modify the experiment. Add more, thicker insulation. Plug all the gaps. The engine still runs faster.

https://youtu.be/Iq6snxiXbGg


That is not a claim.


So far, I have been completely unable to prove Tesla wrong. It looks like a "sink" may not actually be necessary.

If you have any suggestions for modifying or improving the experimental methodology, can point out some flaw or whatever, I'm all ears.

Historically, people keep asserting Tesla was wrong with zero empirical evidence to back up that claim.

In the past century, I can find no record of any experiment conducted to prove Tesla wrong. I'm just trying to be objective and do some experiments that should have been done 100 years ago

My main issue is with the dictum that:

the second law of thermodynamics has a third form:

A Carnot engine operating between two given temperatures has the greatest possible efficiency of any heat engine operating between these two temperatures

.

The quote is lifted from this page directly:

https://courses.lumenlearning.com/physi ... -restated/

But any one of thousands of other citations making the same claim will do.

This assertion, I would offer, has absolutely no empirical foundation whatsoever. First of all, a "Carnot engine" is a theoretical construct. It is not a real engine, so no actual experimental comparison is possible to conclusively demonstrate the claim.

Second of all, the so-called "efficiency" of this theoretical Carnot engine was based on the known fallacy that heat is an "indestructable fluid".

Further, the mathematics for calculating "Carnot efficiency" were originally derived using the same flawed theoretical foundation, namely; that a heat engine derives power from heat in the same way a mill wheel derives power from a fall of water. A mill wheel takes in a quantity of water, which results in the turning of the wheel to output useful work and ALL the water is let out at a lower level. Likewise a heat engine takes in heat and the heat engine turns and produces useful work and the heat is let out at a lower temperature.

We shall ignore mill wheels that use the undershot method, as there the analogy breaks down.


https://youtu.be/-JXLPRVkW24


No water is "lowered down" in this case (though some is raised) The water remains horizontal. Somewhere the water had been lowered, so it can now impart kinetic energy to the wheel, but it is not lowered by, or through the wheel. Similarly the sun imparted some energy to the atmosphere. That is now kinetic energy, not a "fluid".

This "lowering" of heat was not considered an analogy, though, it was considered an exact correspondence.

Carnot believed, at first, that heat was actually a fluid and that it was actually "let down" and just like water ALL of it let out at the lower temperature.

The power output of a mill wheel depends on the distance the water travels in being lowered, so the reasoning goes, or went, so, likewise the "efficiency" of a heat engine:

"depends only on the temperature difference"

On the basis of that reasoning, we have the formula:

Efficiency = (Qh - Qc)/Qh

From what exactly is that formula derived?

A completely "ideal", or in other words IMAGINARY engine that operates on a fallacious theory of heat.

For a little toy Stirling engine running on a cup of hot water that works out to, at best, somewhere around 20% "Carnot efficiency". And we are informed again, Carnot efficiency represents the efficiency of a "perfect" Carnot engine and that this "perfect" Carnot engine:: "has the greatest possible efficiency of any heat engine"

In reality then, the toy Stirling cannot hope to approach anywhere near 20% efficiency.

So again, how was this formula derived?


Efficiency = (Qh - Qc)/Qh


Is that equation based on any experimental work? Was it calculated on the basis of actual measurements? Temperature readings from actual engines? How was it proven? How was it verified? How was this "LAW" actually established as FACT?

What does it mean anyway?

Well, the "h" in the equation is the hot temperature, the "c" is the cold temperature. So we take the hot temperature and subtract from that the cold temperature and we get the temperature difference.

Wait a minute. The temperature difference? You mean, Carnot's original fallacious theory about the distance the bucket of water is lowered down by a water wheel?

Well, actually yes.

The heat is lowered from Th down to Tc and supposedly Qc/Qh=Tc/Th for reasons that are never explained but anyway, if we want to rewrite this temperature difference as an efficiency it needs to be in the form of a percentage so we take the temperature difference and divide that by the high temperature (or "all the heat" on the absolute scale)

So, this supposed "efficiency" is just the same old "height of the fall" or temperature difference written as a percentage of the absolute temperature scale.

So, we have gone directly from a fallacious theory of heat as a fluid to an equation based on the same known fallacy with ZERO experimental evidence to back it up.

On what basis exactly is this accepted as a "LAW".

Well.

Historically, nobody has ever succeeded in building a perpetual motion machine, so,...

So what?

So, in spite of being wrong in every other respect, heat is not a fluid, he SOMEHOW got it right.

Looking at this, I can only shake my head in disbelief.

20% of "all the heat" down to absolute zero is not the same thing as 20% of the heat required to bring a cup of water to a boil. Is it?

How do we equate "efficiency" with the temperature difference anyway? The one has nothing whatsoever to do with the other.

But, for arguments sake, let's try a few simple experiments.

How much of the actual heat in the cup of hot water is traveling up and out through the top of the engine?

Where is this 80% (or theoretically much more as this is no "perfect" Carnot engine) of the heat put to the engine actually going?

According to the prevailing theory, nearly all the heat, 80% or more, should be "rejected" by the engine to the "sink" or "cold reservoir" as waste heat.

But, experimentally, the top of my toy engine running on scalding hot boiled water for an hour remains cold to the touch the entire time.

With all that heat "rejected" to the "sink", the top of the engine, shouldn't the top of the engine be getting noticeably warmer?

So let's add some insulation anyway, just for laughs. Subjective experience about how something "feels" to the touch, warm or cold is meaningless.

Insulation results in the engine running faster.

Explanation?

The insulation actually increased the surface area so heat is actually dissipated faster.

Again, I can only shake my head in disbelief at the abject absurdity of it all.

Needless to say, I do not find the explanation that insulation conducts heat to air faster than aluminum very convincing.

What about acrylic?

As far as the Vuilleumier heat pump, I don't know where you may be getting your information but from what I've read about it, it is more efficient than any kind of Stirling engine.

It is also not intended for any sort of work or power output. It's a heat pump, so when you say "Furthermore, the heat delivered to the ambient cold side is even greater than both those heats." That is it's intended purpose when used for heating. It provides more heat than the heat required to run it, because it pulls heat from both hot and cold ends. None of that incoming heat is intended or used for mechanical power output.

Suppose, however, if the Vuilleumier heat pump were redesigned to use all that heat to be output as mechanical work.

IMO, that is very close to what some Stirling engines are already doing. Pulling heat from both heat source and "sink" and converting both into work output.

I'm not claiming there are no loses to friction and parasitic heat dissipation.

Tom Booth wrote: ↑Thu Oct 28, 2021 9:35 am As far as the Vuilleumier heat pump, I don't know where you may be getting your information but from what I've read about it, it is more efficient than any kind of Stirling engine.

It is also not intended for any sort of work or power output. It's a heat pump, so when you say "Furthermore, the heat delivered to the ambient cold side is even greater than both those heats." That is it's intended purpose when used for heating. It provides more heat than the heat required to run it, because it pulls heat from both hot and cold ends. None of that incoming heat is intended or used for mechanical power output.

Suppose, however, if the Vuilleumier heat pump were redesigned to use all that heat to be output as mechanical work.

IMO, that is very close to what some Stirling engines are already doing. Pulling heat from both heat source and "sink" and converting both into work output.

I'm not claiming there are no loses to friction and parasitic heat dissipation.

It works with three different temperatures. Hot body, cold body and ambient. Ambient is between the two body's.

Spinning in one direction, heat is taken from the cold body making it colder. Heat is taken from the hot body, but is replenished by waste heat from some other source (A propane torch would also work.) Those two heats, one pulled in at cold body temperature, one pulled in at hot body temperature are exhausted to the ambient at approximately the ambient temperature. That wasted heat is larger than both the heats pulled in added together.

Work is also pushed into the cooler, (If you'd like: electricity running the displacers with a motor.) But it doesn't enter into the cycle process. That work doesn't act to transfer more heat.

The amount of work put in is potentially way less than a standard heat pump. However the overall thermodynamic efficiency is way less than the Carnot cycle law. Shortcutting efficiency proclamations are one way advertisers deviously try to baffle their own customers. They forget to tell you, that you need a lot of waste heat in addition to the electric motor. And you will heat up the ambient, air, river, lake...

But when, for instance, I'm told that 80% or more of the heat used to run a heat engine not only should, but absolutely must, under any and all circumstances, pass through the engine as "waste heat" to the sink, and I see by direct experiment that a simple model Stirling engine appears to conduct ZERO heat to the "sink", under certain circumstances, by actual measurement, I don't just dismiss the cumulative evidence of dozens of objective experiments off hand on the basis that someone thinks the second law says that is "impossible".

That is a claim which violates the laws of thermodynamics. Specifically "conduct ZERO heat to the "sink",".

Think about it this way, a hot body is completely surrounded by a colder ambient environment. Hot travels to cold. No amount of insulation will stop that. It may slow it, but it won't stop it. An engine running between those two, will not stop that. A heat pump could pump heat back up into the hot and out of the ambient faster than it comes out of the hot body, but it takes more work than the work produced from the heat lost from the hot body.

A LTD Stirling, as you've purchased, probably doesn't even generate a watt of power. So running it wouldn't tend to pump much heat at all. Like trying to heat a gallon jug with a paper match.

An electric motor dumps it's electrons at zero voltage and therefore doesn't violate Carnot's cycle laws. Again the advertiser is baffling us with bs. Those figures don't include wires or source losses, or off peak performance.

A Carnot engine running between 10K and 1500K could have an efficiency of 1490/1500 = greater than 99% . Living on Pluto would make this more possible. Stirlings are more efficient in the Arctic, or winter.

Why do you need a heat difference? What happens internally to require a heat difference?

If insulation does cut off heat transfer, the zero heat transfered to the cold body should dictate that it will run continuously in an oven. With oven heat supplying the heat, and insulated cold body supplying the cold for your temperature difference.

Suppose, however, if the Vuilleumier heat pump were redesigned to use all that heat to be output as mechanical work.

The the cooling effect would be way less. The cooling process requires input energy in the form of heat to cool the cold body. That will be in opposition to any work you would be trying to gain.

Nobody wrote: ↑Fri Oct 29, 2021 6:32 pm.

It works with three different temperatures. Hot body, cold and ambient. Ambient is between the two body's.

That statement is, to say the least, a little misleading.

A refrigerated space, like the freezer compartment of your refrigerator is not a "cold body". To say "ambient is between the two bodies" makes it sound as though the heat pump requires a cold reservoir or "cold body" to operate, the way a Stirling engine requires a hot side and a cold side. The cold end of a cryogenic freezer is not a "cold body", it is a refrigerated space created by the heat pump.

The cold side of the Vuilleumier heat pump will pull heat from whatever it may be in contact with, hot cold or ambient, the same as your kitchen freezer. It is not a "cold body". The Vuilleumier heat pump does not "work between three different temperatures". It works by a heat input. The cold side is at ambient at the start then is made cold by the heat pump, the cold produced by the heat pump is not what drives the heat pump.

Spinning in one direction, heat is taken from the cold body making it colder. Heat is taken from the hot body, but is replenished by waste heat from some other source (A propane torch would also work.) Those two heats, one pulled in at cold body temperature, one pulled in at hot body temperature are exhausted to the ambient at approximately the ambient temperature. That wasted heat is larger than both the heats pulled in added together.

As I said before. Your so-called "wasted heat" is not wasted if it is being used to heat your house.

If you put a gas flame to the Vuilleumier heat pump, it can then pull heat from the cold outdoors to heat your house in winter. That "waste heat" at "ambient" as you say, is more heat than what you would get by heating your house with the same gas flame directly.

Work is also pushed into the cooler, (If you'd like: electricity running the displacers with a motor.) But it doesn't enter into the cycle process. That work doesn't act to transfer more heat.

The amount of work put in is potentially way less than a standard heat pump. However the overall thermodynamic efficiency is way less than the Carnot cycle law. Shortcutting efficiency proclamations are one way advertisers deviously try to baffle their own customers. They forget to tell you, that you need a lot of waste heat in addition to the electric motor. And you will heat up the ambient, air, river, lake...

A Vuilleumier heat pump does not require any work input. It operates on heat input. It is a heat driven heat pump. It does not require an electric motor or any other outside work input. The COP is > 1.

Nobody wrote: ↑Fri Oct 29, 2021 7:37 pm
Why do you need a heat difference? What happens internally to require a heat difference?

Good question.

If insulation does cut off heat transfer, the zero heat transfered to the cold body should dictate that it will run continuously in an oven. With oven heat supplying the heat, and insulated cold body supplying the cold for your temperature difference.

Now we're getting somewhere.

But, we already have an oven. The heating element is the sun. The oven is Earth's atmosphere.

Returning to the first post in the thread, quoting Tesla: "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."

That is, as you describe, an insulated ice cube in an oven with a Stirling engine on top. Lots and lots of really good insulation and no other way for any heat to get to the ice except by passing through the engine, converted to work output in the process.

The experiment is far from perfect but IMO it failed to prove Tesla wrong, and, to me, at least, gave some indication he may have been right.


https://youtu.be/-7zntz8kwIk