I'd like to recreate Tom's experiment

[Jack]

As per title, I'm curious and have some time available.
(...)

I have easy access to this Stirling engine from a local ebay variant.
Screenshot_20240722_170123_Lazada.jpg

Would this be sufficient?

Not to be critical of your apparent interest but "Tom's experiment" is too vague, considering I've done dozens of different experiments.

"Would this be sufficient?" Is not answerable. Sufficient for what?

What experiment specifically are you interested in replicating?

I've done many different experiments using different setups for different purposes to test different things over the course of several years of research.

Presumably you are talking about a video recorded experiment posted to YouTube. If you are genuinely interested, that would be the logical and sensible place to start.

Post the video of the experiment you intend to recreate so everyone, including me, can have some actual idea what you're talking about.

I don't know the full extent of what it is you experimented with, but I thought it was pretty self explanatory as there's one idea that's continually contested and argued about here.
The experiment where you claim to prove that a stirling engine doesn't need a cold plate. Or at least a running engine keeps it cold longer than one that isn't running.

In the end, what I would like to experiment with, is the Tesla cold hole theory. And I think proving your claims would be a first stab at it.

My thinking is that we might be overfeeding the stirling engine with heat in the way it's normally operated. Hence the reason it seems to run better when you insulate both sides.

The reason I'd like to do this is because the idea or claim comes close to what I'm trying to achieve with my own machine. And I'll have to set up the test equipment anyway. I'm also very curious.

Is this clear enough for you?

[Tom Booth]

(...)
The experiment where you claim to prove that a stirling engine doesn't need a cold plate.

Just to be clear, none of my experiments "claim to prove" anything.

Also, there is no experiment where the engine "doesn't need a cold plate". There is always a temperature difference.

My "claim" overall, for the most part is that contrary to what is claimed or generally believed the "Carnot efficiency limit" equation (actually simply the temperature difference) does NOT have absolute control or sets some hard limit "by nature" or "by law" on how much heat the engine takes in or how efficiently the engine utilizes that heat.

An "ultra" LTD engine, for example, pretty obviously takes in MORE heat do to the design using a very large diameter hot plate with a huge amount of surface area for heat exchange. As a consequence an ultra LTD engine can operate in spite of only having a 0.5°F temperature difference (though it can also run on a high heat as well)

I think it is also obvious heat utilization can be improved in other ways. Exotic working fluids like helium and hydrogen as well as pressurization. Having textured surfaces for heat exchange, improved air flow etc

"Height of the fall" (temperature difference) claimed to be the ONLY limiting factor on efficiency is a complete misconception based on a fallacy regarding the very nature of heat.

I do not "claim" that a Stirling engine can operate without a cold plate. At least initially for start-up.

After startup, it appears that a Stirling engine may be able to operate, and possibly operate better with the lower temperature side insulated instead of having an external application of cold, because the engine itself is creating its own temperature difference internally, by converting the heat input into work (if indirectly by energizing the working fluid molecules to impact the piston with greater force so as to transfer energy to the piston, rather than sending "heat" through to a "sink" which is useless).

Judging by the general absence of detectable "waste heat" it appears that the "Carnot Limit" estimates in that regard are not accurate. At least as far as direct heat transfer to the cold plate. I discount "work" converted back into friction at bearings, power piston etc. IMO that is not "waste heat" in the sense of unconverted heat. The heat had to be converted to work before producing friction, and friction could always be reduced anyway with frictionless magnetic bearings or air bearings.

Or at least a running engine keeps it cold longer than one that isn't running.

Relatively easy:

https://youtu.be/DmkVR7hF14Y

That video shows more about insulating the ice cube itself, so it doesn't melt rapidly by the surrounding ambient heat, which insulation may not even be necessary just for comparative testing rather than insulating the engine.

I'd recommend reading the video description and 1st comment in that video.

This was the "control" (not running engine).

https://youtu.be/fuWzV4ijAoE

Rewatching the video just now, I noticed a potential flaw in this experiment.

The "control" ice cube broke in half while dislodging it from sticking to the bottom of the double walled vacuum insulated cup. The "running" engines ice did not break. Breaking the ice exposed more surface area which could have resulted in the non running engines ice cube melting more quickly.

This was the end of the "control" (engine on 1 ice cube and ice water not running)

https://youtu.be/ykN0SOQsMQw

This next video just gives more detail of how the engine was insulated, between all the bolts to reduce convective air flow between the plates:

https://youtu.be/fwWTfyoq9rk

Again, I think the experiment could be simplified, especially if you have access to several identical engines.

For comparison alone, just to see which ice cube melts faster, insulation should not really be necessary. The ice would mostly melt from surrounding ambient heat, but since the engine controls the heat flow on one side, some difference in melting time should still be apparent Maybe just not as much.

Another possible improvement might be to use clear glass containers for the ice and ice water.

Without insulation in the way, you could have a visual on the rate of melting without having to interfere with anything to see what is going on.

After one run, I'd switch roles and use the running engine as the not running control and vice versa to help eliminate any influence from slight differences in the "identical" engines. There could be all kinds of minor differences.

If possible, I'd also have multiple controls (not running engines) to see if ice melts faster with displacer up, down or in the middle, and

Another test I'd like to do is to have an engine that had the displacer lifted up and down by a small motor. Possibly with the piston disconnected from the crank, just to see what influence the displacer motion alone might have by circulating the working fluid up and down in a non-operating engine. Will the ice melt just as fast as in a non operating engine where there is no displacer movement.

The main reason for the insulation was to simply have the engines running as long as possible which might make a slight difference over an extended period of time more apparent vs. no insulation where presumably all the ice would melt rapidly just due to the surrounding ambient heat.

After numerous experiments, all with the same results: the ice taking measurably longer to melt when the engine is running, I'm pretty confident there would still be a difference even without insulation and you would have the benefit of the visual access and actually produce more rapid results, since maybe the ice would not take so many hours to melt. More experiments could be run in the same time frame.

Running simultaneous experiments also helps eliminate variations in time of day, ambient temperature, humidity etc. though it does introduce possible variations between "identical" engines.

If I were to run this experiment again I'd leave off the insulation and use clear glass or simply plastic cups to have a view of the ice as it melts.

In the end, what I would like to experiment with, is the Tesla cold hole theory. And I think proving your claims would be a first stab at it.

My thinking is that we might be overfeeding the stirling engine with heat in the way it's normally operated. Hence the reason it seems to run better when you insulate both sides.

I don't insulate both sides.

I haven't ever insulated the hot side, for obvious reasons. There has to be a way to let the heat in. Though you could, by putting a heating element under the insulation. I'm not sure what purpose that would serve though.

The reason I'd like to do this is because the idea or claim comes close to what I'm trying to achieve with my own machine. And I'll have to set up the test equipment anyway. I'm also very curious.

Is this clear enough for you?

It helps.

I'm still not sure if the ice melting thing is what you had in mind, but that's probably the easiest way to show "a running engine keeps it cold longer than one that isn't running".

Or, it might prove that my experiments were a fluke, and you may get different results.

[Tom Booth]

To answer your other question, for a simple comparative test of the rate of ice melt type experiment, as described above, in a running vs. not running engine, I think those small models you have at your disposal should be adequate.

[Fool]

Insulate the hot side? That would show, if heat is getting out the cold side through the insulation, wouldn't insulating the hot side show if heat is getting in through the insulation to the hot side? It sounds like an awesome control.

[Tom Booth]

Insulate the hot side? That would show, if heat is getting out the cold side through the insulation, wouldn't insulating the hot side show if heat is getting in through the insulation to the hot side? It sounds like an awesome control.

Heat, where there is a high ∆T going through insulation, slowly, sooner or later is inevitable, as no known insulation is 100% perfect.

Heat, "flowing OUT of the engine" (on average) where there is zero, or a negative ∆T (with or without insulation) is impossible.

That heat gets through on the hot side, insulated or not, says nothing about what is going on on the cold side.

If you think that would be "an awesome control" I look forward to your doing your own experiments.

On the other hand, if Jack has enough engines, redundant "controls" don't hurt anything and might show something interesting, but not what you suggest.

The purpose of insulation on the cold side is not so much to stop heat, but to slow it down enough so that even a very small amount of "heat rejection" from the cold side should build up under the insulation over time so as to be measurable.

In my LTD with regenerator and increased throw, that didn't happen. No heat build up (temperature increase) at all on the cold side even under the best insulation available. (Silica Aerogel). Instead, there was a temperature decrease even after 3 hours of steady operation.

That however, would be a more involved experiment requiring rather extensive modifications to the engine, adding a regenerator, eliminating heat conducting bolts and modifying the crankshaft.

But no, absolutely not. Some heat getting through insulation on the hot side (high ∆T) would be expected and does not prove heat is also leaving the cold side.

As usual, fool, your suggestions for experiments are idiotic. It's hard to believe you can actually be as stupid as you seem. The alternative is malicious interference and intentional distraction.

As nonsensical suggestions for experiments from you are a pattern and overall, you seem far from stupid, I chalk it up to intentional malice and your ongoing campaign to derail and discredit this research.

[Fool]

Jack, set and LTD on a block of foam at room temperature. Put an insulated calibrated ice cube on top so the ice touches the engine. See how long it takes to melt. Running and not running. See if it cools off the hot side fast enough to stop running, or slow way down.

[Tom Booth]

Jack, set and LTD on a block of foam at room temperature. Put an insulated calibrated ice cube on top so the ice touches the engine. See how long it takes to melt. Running and not running. See if it cools off the hot side fast enough to stop running, or slow way down.

That might actually be interesting. My apologies "fool".

Personally, depending on how well you insulate the bottom hot plate, if no part around the edges is exposed, I don't think the engine would run long because you are actually blocking off the heat source and the cold from the ice would tend to pool inside the bottom of the engine like an ice chest .

No heat input sufficient to run the engine.

Blocking off the NECESSARY heat input is different from blocking the UNnecessary and virtually non-existent heat "rejection".

Of course, those models appear to have metal bolts. If they are Stainless steel they shouldn't conduct much heat.

If the engine stops or has difficulty running, or will not run at all, I'd say that is further evidence the Carnot theory is false, since it would show that the insulation IS actually effective at blocking heat transfer.

If it blocks the heat INPUT so the engine will not run then it should also block the heat "rejection", if any, so the engine would not run.

Again, my apologies. That would be an interesting variation.

[Jack]

My idea was to insulate the entire engine with a controlled way of adding heat. And then measure the work output and cold plate temperature.

[Tom Booth]

My idea was to insulate the entire engine with a controlled way of adding heat. And then measure the work output and cold plate temperature.

I'm not sure in what way you would set all that up and that is not anything I have done so....

Not really recreating "Tom's experiment".at all.

[Fool]

Tom. I finally got out one good idea. LOL. Sorry. LOL. It had to happen, I suppose, with all the posts I've been making. LOL.

Thanks.

Jack, I like your insulation idea. Senior year in college some of my classmates insulted a plywood box inside with foam sheets like 4" thick, an internal cavity had lightbulbs for a heat source. I don't remember what they were measuring, temperatures, yes, maybe infrared camera. They ran it for several days. The inside got hot enough to severely melt some of the foam.

The lesson I learned would be to control the temperature inside not the power, volts amps, delivered. Temperature is what drives thermodynamics, temperature and work. Pressure and force are what drive work. Good luck.

[Tom Booth]

Well, I have two brand new, very well made, rather expensive KontaX engines of this type:

Compress_20240505_221454_4707.jpg (16.32 KiB) Viewed 2760 times

You've inspired me to try rerunning my ice melt experiment as described above using transparent cups so we can watch the ice as it melts.

The way I look at it, the heat from friction lost at the power piston generated from "work" is effectively heat taken away from the vicinity of the ice.

The running engine will be converting the ambient heat in the air directly above the ice.

The heat will mostly reappear at the power piston due to friction, but from there should rise up and away from the engine and the ice.

The ice under the running engine should therefore take a little bit longer to melt.

These style engines are perfect for such a test as the PP is remote from the cold side of the engine so the heat generated from friction should not influence the ice at all, and the piston should not be affected by condensation.

In previous tests the engine ran over four hours on one ice cube, but that was with the ice very well insulated in a double wall vacuum insulated cup nestled inside additional insulation.

These tests should go much quicker I imagine.

But I still only have one of the engine kits actually assembled.

[Jack]

My idea was to insulate the entire engine with a controlled way of adding heat. And then measure the work output and cold plate temperature.

I'm not sure in what way you would set all that up and that is not anything I have done so....

Not really recreating "Tom's experiment".at all.

Fair enough. But it's based on the same principle and trying to prove the same idea while trying to exclude as many variables as possible.
So yeah, not exactly copying the experiment, but trying to do it in a way that satisfies everyone so the results can be accepted by everyone.

[Tom Booth]

My idea was to insulate the entire engine with a controlled way of adding heat. And then measure the work output and cold plate temperature.

I'm not sure in what way you would set all that up and that is not anything I have done so....

Not really recreating "Tom's experiment".at all.

Fair enough. But it's based on the same principle and trying to prove the same idea while trying to exclude as many variables as possible.
So yeah, not exactly copying the experiment, but trying to do it in a way that satisfies everyone so the results can be accepted by everyone.

That's great. Not trying to be discouraging or anything. The main difficulty or disagreement, or shall we say difference in opinion or point of view is over what constitutes "work" and how to measure it.

A little model LTD does not generally produce any "useful" work output that can be easily measured, and the myriad of other energy outputs, friction at multiple points, vibration, sound, air resistance etc. would be a nightmare to try and account for.

From my studies on the subject, there seems to be a general consensus that there are two, and only two possible outputs, WORK or Waste Heat.

What is not "waste heat" is the result of "work". So, if you measure waste heat, the remainder must be work.

No "waste heat" at all = 100 minus zero = 100% efficiency.

IMO that is the true and sensible and logical approach. All the little outputs, friction, vibration, air resistance, displacing atmosphere etc. are a result of WORK done by the engine and do not result in any direct "waste heat".

Yet, there is not a universal consensus. Not only is there disagreement on the forum here, there is just as much disagreement in the literature.

Several sources consider FRICTION in general as producing "waste heat" and only consider "useful work" as "work".

The whole topic is a muddle and not well defined. The whole subject of the Carnot Limit seems largely a matter of opinion and INTERPRETATION by academics with little knowledge of mechanics, engineering or science generally

The actual results make no impression on the "Carnot Limit" believer.

In the same way a heat pump can be shown to have an efficiency of 300% in violation of the "Carnot limit". No matter. We will just exempt heat pumps from consideration by redefining "efficiency" and call it COP.

In the end, I have no doubt the same principle will be applied to Stirling engines. If it is proven they violate the Carnot limit, one more exemption will be written into the second law, or "efficiency" will once again be redefined or it will be argued that a Stirling engine is not an engine at all but another form of heat pump or "energy converter" so the Carnot limit does not apply, or maybe we can say it is an "open system" or whatever rationalization is necessary to preserve the sacred "Carnot limit" and maintain the 2nd LAW inviolable

I personally could care less about all that, or I guess I'm supposed to say I could not care less.

I was never out to disprove the 2nd Law or Carnot, or to prove Tesla.

My intention was simply to build a Stirling engine to run on my wood stove. Something with useable power output, which seemed to suggest that improvements in Stirling engine design would be needed.

So I worked to design a better more efficient Stirling engine

Upon someone in charge of reviewing my design for a friend who is a military contractor I was told the design "violated the second law of thermodynamics".

That was the first I ever heard about it. This "second law of thermodynamics".

So, having no funding to build my engine, I began posting my general design ideas or concept online, including this forum and was then informed about the "Carnot Limit".

So these objections to my design came after the fact.

What the hell is this "second law"????

Well, my conclusion is, the Carnot limit is crap. A bunch of nonsense based on obsolete theory that does not hold up under experiment.

At any rate it has no bearing on the workability of my original design concept, which only coincidentally corresponds with Tesla's, so I can carry on.

As I said, I was never out to "prove" Tesla correct or Carnot wrong. These things were brought to my attention after I already had a design worked out

I was working from the point of view of an engine repair mechanic and appliance/refrigerator repairman.

I had taken 2 years of small engines and appliance repair in high school, but there was very little Theory. It was almost all entirely hands on repair work. After school I opened a repair shop in my parents garage. Then mostly worked in engine repair shops until I retired, though I've done work in many trades.

My only concern is the feasibility of my engine design, I could care less if it is considered a violation of Carnot or the second so-called "law".

Anyway, good luck in trying to satisfy everyone or get results that can be accepted by everyone.

[Fool]

What is not "waste heat" is the result of "work". So, if you measure waste heat, the remainder must be work.

No "waste heat" at all = 100 minus zero = 100% efficiency.

There is talk of several laws of thermodynamics. They are:

Zeroth, Temperature is measurable.
First, Conservation of energy.
Third, Heat energy won't flow from cold to hot. Reversibility.
Fourth, Absolute zero temperature.

Etc.

It's not mentioned, but can be observed in nature and derived from those laws, I think there should be, a minus one law spelled out so everyone gets it.

Fools minus one law, All heat going into a heat engine becomes waste heat. This is through all the losses of heat transfer and heat leakage to the cold atmosphere, friction, windage, sound, etc., and the heat coming out of the cold plate however small. In addition the useful work coming out of the engine wether it is directly applied to the cold atmosphere, or carried away on power lines to heat up the atmosphere elsewhere. All of the hight temperature heat flow gets converted to the cold temperature, irreversibly.

The Carnot rule says nothing about where the waste heat must come out. It has to do with thermodynamic efficiency. Friction and such lie in the realm of mechanical efficiency, which Carnot has ignored.

Thermodynamic efficiency revolves around what the gas is doing. It is simplified as the Pressure, Volume, and Temperature (PVT) Work, and heat loss.

Carnot's Rule merely states that the PVT Work for the forward stroke will be reduced by the PVT Work needed to return the engine to the starting point, reverse stroke. It states that the ratio will be proportional to (Th -Tc)/Th. It says nothing of where the energy loss is to come out or whether it is measurable or not.

It does say that the work output divided by the heat obtained, will be less than the perfect engine cycle. Tom has demonstrated that attempting to measure the heat out of the cold plate, by temperature alone, is insufficient to analyze this process.

We know today that the useful work output will be way less than that predicted by the Carnot Rule because of many of the previous mentioned mechanical and thermal losses, plus the non ideal thermodynamic engine cycles.

This, very much, can be determined by measuring the fuel used and useful work output. And, thanks to Tom, not by just measuring a couple of temperatures.

The important thing to get from this is that improvements can be made by reducing those losses by using careful mechanical and thermodynamic designs. But we knew that already.

Example: If the piston is pushed on by the gas on the inside and opposed by the air on the outside, a loss of potential work happens. Unfortunately if run in a vacuum, more work is developed for the forward stroke, but more flywheel power will be used up for the return stroke. No atmospheric push. Not a helpful design change.

Hence the reason for 'careful' design changes.

[Tom Booth]

...

Fools minus one law, All heat going into a heat engine becomes waste heat. ... The Carnot rule says nothing about where the waste heat must come out.

Need I say more?

Meaningless BS of no consequence not worthy of serious consideration.