Anomalous Heat Engine behavior

[Tom Booth]

I made this video because I was very shocked to find that my model Stirling engine, ("running on ice" rather than heat) appeared to repeatedly re-freeze the ice it was running on.

After this happened a couple times, the engine getting stuck/frozen to the ice, I decided to wait and see if it happened again, but this time made a video.

Well the ice did re-freeze a third time (the above video) and about 10 minutes later, as I was uploading the video to YouTube and writing a description, it froze again a fourth time.

I was running the engine, not as an intentional experiment, but because I had made a new piston for the engine and I had applied grinding paste to the piston and cylinder to get a better fit. (The piston was a little too tight for the cylinder).

In other words, the engine was not running under normal unloaded conditions, rather, it was running very slowly doing the work of honing down its own cylinder coated with grinding paste.

According to the "Carnot Efficiency" formula, as it is generally applied, this model engine should have been at best, (being.very generous), running at about 20% efficiency.

As generally interpreted, this would mean that 80% or more of the ambient heat entering the engine, should have been going through the engine melting the ice.

Instead, for at least half an hour, the ice kept re-freezing on the top surface in direct contact with the bottom of the engine.

After that, I left the engine to run and went to bed.

By morning when I woke up the engine had stopped running. The ice was only half melted. The piston had been ground down so much it had become loose in the cylinder and had lost compression.

Normally the engine would have run longer, until the ice was completely melted.

I call this "anomalous" because, every time I lifted up the engine, exposing it to the air, the upper surface of the ice melted very rapidly becoming wet. But with the engine back on top running, the water on the surface of the ice froze to the bottom of the engine again.

If the engine is only, at best, 20% efficient, according to "Carnot efficiency" so that 80% of the "waste heat" from the ambient air above the engine is going through the engine to warm the ice, logically, the wet upper surface of the party melted ice should have continued to melt, not freeze solid to the bottom of the engine, over and over again.

Previously I had seen what appeared to be the same thing happening on someone's YouTube video, but without any insulation surounding the ice.

For a long time I had attributed this to adhesion or suction, because the surface of the ice was wet, but having seen it for myself, I can confirm that it is possible that the engine became "stuck" to the ice because the ice became frozen to the bottom of the engine

In this other YouTube video, it can be seen that at first the surface of the ice is wet and the engine slides around and has to be repeatedly repositioned to keep it from sliding off to the side.

After running for a while, when he picks up the engine, the ice is stuck to the bottom, apparently having frozen solidly to the ice, as I saw for myself.

As seen in the first video, I really had a hard time prying the engine loose from the ice. It was definitely frozen to the bottom of the engine, not just adhering to a wet surface.

There are some additional, very odd, or anomalous results I've seen in experimenting with model Stirling engines that to my mind, just don't make sense, if the commonly accepted interpretation and application of the so-called "Carnot Efficiency" formula is true.

To say the least, there does not seem to be a lot of heat actually passing through these engines.

[Tom Booth]

To correct a little detail, the room temperature, according to my records was 65°F

If the ice was at typical household freezer temperature, say about 10°F that would put the "Carnot efficiency" at somewhere around 10% not 20% (The 20% efficiency would be if the engine were running on a cup of hot water).

Allegedly, that would imply, (according to the generally accepted "Carnot limit" theory) that 90% or more of any heat supplied to the engine would be "rejected" straight through to the sink (the ice) as "waste heat".

So, I find it rather perplexing that rather than rapidly melting, the ice continued to re-freeze onto the bottom of the engine, not once but four times over the course of 45 minutes or so.

Unfortunately, the engine piston and cylinder were completely ruined by running through the night with grinding compound, so I had no working engine to do any further experimenting with at the time.

I had made an epoxy piston, intending to use it in an experiment with the engine, the original intention of which was to see what difference it would make, as the original graphite piston could conduct quite a lot of heat. Epoxy on the other hand is a very good insulator.

An epoxy piston, theoretically, would conduct less heat, allowing the engine to operate more efficiently, but I never got that far.

Epoxy, however, I have found, does not seem to work well in an aluminum cylinder. Too much friction is generated between the aluminum and epoxy, which is why I was running the engine with grinding paste on the piston in the first place, to try and remedy the problem, to give the piston and cylinder more clearance.

Perhaps if I use a normal graphite piston and just coat the bottom end with a layer of epoxy to insulate it.

I've been trying to think of some way to duplicate the conditions without ruining another engine.

It is not so much the cost of the kit to build another model as the time involved in building and modifying another engine. Beyond that, just coming up with a good plan of attack has delayed further testing.

I just thought of coating the end of a graphite piston with epoxy this afternoon, so that gives me something to do.

In addition, I'd need to rig up some form of prony break or other load on the engine to simulate the work involved in the engine running with thick gritty grinding paste all over the piston and cylinder.

My tentative theory is that the combination of the non-heat conducting piston, along with the work involved in overcoming the friction generated by the grinding compound resulted in the ambient heat on which the engine was operating, being converted to mechanical work, rather than passing through to the ice.

Now that I have finally come up with a plan, (to just insulate the end of a graphite piston, rather than use a solid epoxy piston), maybe I will find time to do some experimenting again soon.

In the mean time, another anomaly to ponder.

Why does a Stirling engine running on a cup of hot water run faster when the path to the "sink" (the ambient air on the top cold side of the engine) is blocked by insulation?

Without the insulation, this engine had a top speed of 270 RPM.

With the sink, or cold side heat exchanger insulated, theoretically stuffing up the waste heat "exhaust" path to the sink, so that the engine would not be able to operate at all, rather than rendering the engine inoperative, as might be expected, instead, with the sink insulated, the engine speed increased to 295 RPM.

At around 20% "Carnot efficiency", according to accepted theory, there would be 80% or more of the heat going into the engine from the bottom, passing through the engine and out the top, to the sink.

Without being able to cool itself, by dumping its "waste heat" to the cooler ambient air, the engine should quickly overheat and stall.

Instead it ran faster than ever.

[Tom Booth]

This is perhaps the most perplexing observation I've made regarding Stirling type heat engines.

The question is; according to many sites with explanations of how heat engines work, a flywheel is necessary because no heat engine can be 100 percent efficient. Therefore it is impossible to convert all the heat in the gas to work. After the gas expands, so the theory, or alleged actuality goes, the piston is left at the extremity of the cylinder, there is still heat in the gas inside the engine, and therefore internal pressure, preventing the piston from returning. The pressure is less due to some of the heat being converted to work, but still, some internal pressure because no heat engine can be 100% efficient.

Therefore, to do the work of returning the piston to it's starting position to complete the cycle, some energy is stored in the flywheel.

This stored momentum in the flywheel is what drives the piston back down the cylinder.

This heat engine operating description was all well and good and I had no real reason to question or dispute it, until I came across a YouTube video of a Stirling engine operating without a flywheel.

I was able to find additional videos showing the same thing. Remove the flywheel, and a Stirling engine will run just the same. Usually it will run at a higher RPM without the weight of a flywheel holding it back, but it will run quite well, just the same.

Someone suggested on a forum, that perhaps this was possible due to air, or the expanding gas, escaping past the piston.

To test this, after removing the flywheel from an ordinary model Stirling engine, (the aluminum flywheel can be seen pushed back at an angle in the following video), I completely sealed the piston and cylinder with the finger from a latex glove and rubber bands

If any air were escaping the cylinder past the piston, this should be obvious. The little latex sac or "balloon" would inflate with any escaping hot air.

I think it is obvious that in this experiment, no air is escaping the cylinder to inflate the balloon.

Usually these engines run on a very small candle or alcohol burner. I'm applying quite a lot of excess heat with a propane torch.

Regardless of the amount of heat being applied, this does not prevent the engine from running and completing a cycle with the flywheel removed.

What is happening to the heated air in this completely sealed engine that allows the piston to return each cycle without a flywheel to push it back in opposition to the pressurized, expanded hot air?

It takes a long time, relatively speaking, for these engines to heat up to operating temperature. While running, the piston is traveling so fast, there is scarcely enough time for all the heat to be disipate to a sink to cool the gas in the engine enough for the piston to return, in the split second it takes to complete each cycle.

[Tom Booth]

What I have found rather perplexing, and somewhat obsurd is the reactions I've gotten when posting questions and videos, about these observations to various online science and physics forums.

The accusations, hostility, irrationality, attacks on my character, doxing, locking of threads and bannings have been quite rabid.

[Tom Booth]

An example of something often seen in Stirling engine operation, especially at start up, that I think demonstrates clearly that whatever it is that draws the piston back inward, it is not dependent on the momentum stored in the flywheel.

Especially at around the 3:00 minute mark of this video, (and also can be seen in many others) the piston is drawn back inward in opposition to the rotational force of the flywheel.

I don't think I could count on both hands the number of lectures by academics, teaching a classroom of students about heat engines, Carnot efficiency and the second law of thermodynamics where it was told that it is impossible for the piston in a heat engine to return and complete the cycle without a flywheel because no heat engine is 100% efficient, therefore all the heat cannot be converted to work, without going all the way down to absolute zero, which of course, as we all know, is impossible.

What?

Absolute zero?

The flame from a bunsen burner can be applied to these engines and the piston will still return, without any flywheel, and apparently, without any need for a lot of heat removal to a cold "sink".

[Tom Booth]

Here we have what appears to be a respectable website of a major university:

https://web.phys.virginia.edu/

On this site there is found an article regarding heat engines, at the begining of which is found this blurb:

The Ultimate in Fuel Efficiency for a Heat Engine

All standard heat engines (steam, gasoline, diesel) work by supplying heat to a gas, the gas then expands in a cylinder and pushes a piston to do its work. So it’s easy to see how to turn heat into work, but that’s a one shot deal. We need it to keep repeating to have a useful engine. The heat and/or the gas must therefore be dumped out of the cylinder before the next cycle begins, otherwise all the work the gas delivered on expanding will be used up compressing it back!

https://galileo.phys.virginia.edu/cl...rnotEngine.htm

Not to pick on the University of Virginia particularly. This kind of blanket assertion is, for the most part, universal and accepted without question by all the established educational systems of planet earth, as far as I've been able to assertain.

But heat is essentially FUEL for a heat engine. So, does it really make sense, that, in order to run, a heat engine must continually dump most of it's fuel?

The general idea is that the piston drives a wheel (as in the diagram at the beginning of this lecture), which continues to turn and pushes the gas back to the original volume.

Yes, of course. But then how does the piston return where there is no flywheel, or where the flywheel has been removed?

How to explain this "anomalous" phenomenon?

The answer to that, it seems, is another blanket response.

IGNORE IT!

Don't look into it, don't examine it, don't do any experiments to explore it. Don't allow discussion about it. Exclude anyone who does or attempts to do so

Keep your head burried as deeply in the sand as possible. Ignore the fact that the emporer is naked.

Nothing put forward regarding the operation of heat engines since Carnot makes a lick of sense. The mathematics is a total pipe dream without any rational foundation, completely based on fictional nonsense concocted in Carnot's and some others pure imagination without any basis in fact and zero empirical evidence.

The only individual who made any real effort to dispell all this idiocy and foolishness and to say anything sensible about how heat engines really operate was Nikola Tesla.

The real anomaly is how anyone ever took so-called "Carnot efficiency" seriously.

[Tom Booth]

Tesla wrote an article in 1900, a portion of which amounted to a refutation of what we know today as the Carnot efficiency limit.

Probably many here on the forum are very familiar with it, but to summarize what Tesla had to say about heat engines:

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

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, ...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, ... necessitating continuous pumping out. 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.

https://teslauniverse.com/nikola-tes...g-human-energy

In other words, Tesla's thought on the subject of heat engines amounted to running a heat engine on cold, below the temperature of the ambient surroundings rather than on added heat elevated to a temperature above ambient.

What is the perceived advantage of this?

The cold "sink" only need be created once. Heat from the ambient is supplied for free, supplied continuously as the atmosphere is constantly heated by the sun. No need for burning fuel.

But there is no such thing a free refrigeration!!

Of course not. But a heat engine runs on a temperature difference and converts the fuel/heat entering the engine into other forms of energy.

So, the heat goes in, but before it reaches the cold sink, the heat is transformed into mechanical work and/or electricity, or goes out in some other form and so, the initial cold that provides a temperature differential along with the ambient heat need not be filled up and destroyed by the heat flowing into the heat engine. The heat is used up - converted to some other form before reaching the ice, or other cold "sink".

The "anomalous heat engine behavior" described in this thread, such as a Stirling engine freezing the ice it runs on is just as Tesla described. A Stirling engine running on ice and producing useable work output prevents the ice from melting, because the heat, that would otherwise melt the ice is being converted into a form of energy that can no longer effect the ice. The energy goes out as electricity, or in some other useable form.

But, says the skeptic, only a small fraction of the heat can be converted, the rest will go into the ice and melt it. Also more energy would be needed to run a heat pump to keep the ice cold than could be produced from the ambient heat.

Tesla didn't think so. He thought, some energy could be gained in such a manner.