Is Carnot efficiency valid?

[studiot]

Some might find these quotes on the subject of interest.

@Tom Booth  you might like to reflect on why neither heat nor work can be considered to be properties.

 

[exchemist]

1 hour ago, Tom Booth said:

I did not see that request, as I said I have some backtracking to do.

Anyway it's in the public domain. Copies can be downloaded from any of dozens of sites.

Wikipedia has an online text which is useful for reference and searchable:

https://en.m.wikisource.org/wiki/Reflections_on_the_Motive_Power_of_Heat

What I referenced is in the appendix A. "extracts from unpublished writings of Carnot".

(My apologies to everyone for any other comments I haven't gotten to yet.)

Thanks. It's very interesting. One can see he was very nearly there. He was on the track of heat being due to motion of the molecules and was becoming sceptical of the idea of caloric being any sort of material fluid. 

[Tom Booth]

On 2/4/2023 at 2:29 PM, swansont said:

Who said heat is not passing through to the ice? Certainly not me.

It has been the observed outcome of my several experiments.

Heat applied to the engine on the hot side does not appear in a measurable form in the quantities suggested by the Carnot efficiency formula at the presumed "sink" (cold side).

So, this has lead me to ask the question: if heat is not passing through to the ice, what could be the reason?

My measuring instruments don't seem to be broken.

So is the Carnot efficiency equation really valid?

The first response I inevitably get is that I'm a crank or whatever, but hay, I've recorded it all on video. There is nothing preventing anyone from doing these simple, inexpensive experiments.

I've had engines running on the flame from a propane torch on the hot side with hardly any change whatsoever at the "sink".

If the heat isn't passing through, this leads me to doubt the Carnot efficiency equation, or the interpretation that states such a large percentage of the supplied heat in actual Joules absolutely MUST be "rejected" to the "cold reservoir".

So, can this be tested? Maybe there is some basis for concluding that the equation does not actually apply to Stirling hot air engines.

I mean Carnot et al were talking mainly about steam engines.

In a steam engine some water is brought to a boil in an enclosed vessel where it builds up pressure.

A small amount of steam, under high pressure is admitted to the cylinder with the piston at or near TDC through a valve which is then quickly shut.

The pressurized steam is then allowed to expand performing work pushing the cylinder. The steam is then allowed out to a condenser.

Well, we have the latent heat of evaporation stored up in the steam at boil, then released as heat of condensation.

It is natural and actually accurate to conclude that the steam has in some way "transported" heat from the boiler to the condenser, because it has.

A Stirling Hot Air engine however does not involve any such phase change. There is only the expansion and contraction of a gas.

Should we expect that the same amount of heat be "transported" in a hot air engine as in a steam engine?

 

Edited February 5, 2023 by Tom Booth

[swansont]

24 minutes ago, Tom Booth said:

It has been the observed outcome of my several experiments.

Your experiments are not described particularly well, and I was describing what I observed.

24 minutes ago, Tom Booth said:

Heat applied to the engine on the hot side does not appear in a measurable form in the quantities suggested by the Carnot efficiency formula at the presumed "sink" (cold side).

I will ask yet again: have these quantities been measured? If not, you can’t make this claim.

 

24 minutes ago, Tom Booth said:

So, this has lead me to ask the question: if heat is not passing through to the ice, what could be the reason?

My measuring instruments don't seem to be broken.

So is the Carnot efficiency equation really valid?

The first response I inevitably get is that I'm a crank or whatever, but hay, I've recorded it all on video. There is nothing preventing anyone from doing these simple, inexpensive experiments.

I finally watched the beginning of the video in the OP. You don’t explain what you are doing and there are no measurements, but you show the water (close to) boiling and when there’s no insulation, the engine runs well. When the insulation is in place, it stops. 

You ask in the OP why it doesn’t stop, but it clearly stops! You don’t comment on this at all. 

 

 

 

 

 

[studiot]

On 2/4/2023 at 7:57 PM, Ghideon said:

Source: https://www.nature.com/articles/nphys3518.pdf

(I do not wish to take the discussion off topic, we discuss the case of Carnot limit for macroscopic engines. Just wanted to share in case there is any interest in papers discussing limits of applicability in the context of Studiots comment.)

I'm having a little trouble sorting the sheep from the goats in this paper.

1) Can you explain why their Carnot Cycle is in the wrong order ?

It should be two expansions followed by two compressions but their diagram a shows the expansions and contractions alternating

2) In the text they refer to work extracted, but I can only find details of work done on their particle.

3) I'm interested to learn how resistance free (= frictionless) adiabatic processes can be done on a charged or charge separated particle in water where surely Van Der Waals forces must operate.

4) What exactly is expanding and contracting in a single particle ?

5) From what I can gather they are saying that whilst a single measurement of their single cycle efficiency parameter can exceed Carnot, the statistical average either of infinite measurements on one particle, or one measurement on infinite number of particles, will equal Carnot. This of course implies that if some measurements are greater than Carnot, some will be less.

Edited February 5, 2023 by studiot

[Tom Booth]

1 hour ago, swansont said:

You ask in the OP why it doesn’t stop, but it clearly stops! You don’t comment on this at all. 

My phone has a limited recording capacity, so I had paused the video several times.

With the first engine without insulation the engine sat on the steamer until the water got up to boil so the engine was already well pre-heated over the simmering water for some time. I paused the camera during the warmup period.

The second engine with the Aerogel blanket insulation had a cold start. It is quite typical of Stirling engines to take some time to reach operating temperature and have a few false starts if not yet warm enough.

------------

The reason Stirling engines in general typically need a few pushes to get going is that they have some characteristics of a "Maxwell's demon" and it usually takes some time for the hot and cold working fluids to become segregated.

How this takes place is that during compression the working fluid is displaced to the hot side of the chamber. Then with expansion the working fluid is displaced over to the cold side.

I'm sure you are aware that when a gas is compressed it heats up, expanded it cools down. So while turning the engine over by hand, at one part of the cycle, the gas is compressed and moved to the hot side, then for the other half of the cycle the gas is expanded and moved to the cold side, back and forth., back and forth rapidly until a temperature differential is well established and the engine can run freely.

Of course this segregation or heat pump activity is maintained once the engine is running well.

Edited February 6, 2023 by Tom Booth

[swansont]

27 minutes ago, Tom Booth said:

My phone has a limited recording capacity, so I had paused the video several times.

With the first engine without insulation the engine sat on the steamer until the water got up to boil so the engine was already well pre-heated over the simmering water for some time. I paused the camera during the warmup period.

The second engine with the Aerogel blanket insulation had a cold start. It is quite typical of Stirling engines to take some time to reach operating temperature and have a few false starts if not yet warm enough.

That’s interesting, because the heater is clearly on and there are bubbles, as if it’s just about to boil, just as it was when you stopped the uninsulated engine and removed it and showed the water. The first engine started right up. 

There’s no obvious cut as you transition from one system to the other. It looks like it’s all one take.

 

 

[Tom Booth]

8 minutes ago, swansont said:

That’s interesting, because the heater is clearly on and there are bubbles, as if it’s just about to boil, just as it was when you stopped the uninsulated engine and removed it and showed the water. The first engine started right up. 

There’s no obvious cut as you transition from one system to the other. It looks like it’s all one take.

 

 

If you watch carefully there is a beep and jump in the video of sorts  between the time  water is poured into the steamer and when it boils. That actually took a few minutes for the water to get up to a simmer.

The first engine had all that time to warm up and was ready to run when I restarted the camera.

Edited February 6, 2023 by Tom Booth

[swansont]

 

1 minute ago, Tom Booth said:

If you watch carefully there is a beep and jump in the video of sorts  between the time  water is poured into the steamer and when it boils. That actually took a few minutes for the water to get up to a summer.

The first engine had all that time to warm up and was ready to run when I restarted the camera.

I’m not talking about the first engine. That’s not the one that repeatedly stops, that you claimed didn’t stop.

”There’s no obvious cut as you transition from one system to the other. It looks like it’s all one take.” is clearly not talking about the lead-in to the first engine.

[Tom Booth]

Just now, swansont said:

 

I’m not talking about the first engine. That’s not the one that repeatedly stops, that you claimed didn’t stop.

”There’s no obvious cut as you transition from one system to the other. It looks like it’s all one take.” is clearly not talking about the lead-in to the first engine.

The only reason for having the first engine in the video at all was so people could see the type of engine that is under the insulation. So I didn't bother recording the start up for the first engine which is largely irrelevant IMO, but the first engine went through several false starts as well. That is very typical for this type of engine.

I just got the first engine going off camera and then restarted the film when I had it warmed up and ready to run.

[swansont]

5 minutes ago, Tom Booth said:

The only reason for having the first engine in the video at all was so people could see the type of engine that is under the insulation. So I didn't bother recording the start up for the first engine which is largely irrelevant IMO, but the first engine went through several false starts as well. That is very typical for this type of engine.

I just got the first engine going off camera and then restarted the film when I had it warmed up and ready to run.

There is no cut between you putting the first engine on the boiling water and starting it up. The cut is before that. You take the engine off, show the water, and put it back on. So it’s cooling off for about 10 seconds, but has no problem starting up after. 

Your video documents things that are irrelevant and fails to document things that are. You’re not showing the engines under the same conditions and not explaining these details until someone calls you out on the inconsistencies in your narrative.

[Tom Booth]

31 minutes ago, swansont said:

There is no cut between you putting the first engine on the boiling water and starting it up. The cut is before that. You take the engine off, show the water, and put it back on. So it’s cooling off for about 10 seconds, but has no problem starting up after. 

Your video documents things that are irrelevant and fails to document things that are. You’re not showing the engines under the same conditions and not explaining these details until someone calls you out on the inconsistencies in your narrative.

Valid criticisms to some extent as it was a completely unplanned raw video taken in my kitchen when I happened to have some time.

I recorded what I thought relevant at the time. If I recorded everything the video would have been 3 hours long.

Ten seconds is no time to cool down after sitting over steam for ten minutes.

Another problem was the flywheel on the #2 engine was buried in the insulation which I made as thick as possible. I had tried trimming it away with an exacto knife, but had not done a very good job, so there was some drag on the flywheel of the second engine from the flywheel contacting the insulation. I kept trying to push the insulation down out of the way but it kept puffing back up.

If you watch more of the video it can be seen clearly that at one point the engine wouldn't run, then it almost stops and I push the insulation down and it picks up speed and keeps running.

I think it's pretty clear the problem was the insulation causing drag on the flywheel.

After that first video, the next day I cut away the insulation a little more and with a slightly better set up, made a second video but only posted it too the Stirling engine forum because of the issues with posting video here.

In the second run I was able to work out some of the problems like steam getting through and under the blanket and inside the glass globe as well as the insulation rubbing. And some better temperature readings in preparation for using the probes, which I have yet to do.

 

 

Edited February 6, 2023 by Tom Booth

[Tom Booth]

Something curious happened during the experiment that seemed rather unusual, I don't know what to attribute it to or what if any significance it might have.

Normally these engines are intended to run on a cup of hot Coffee and are rather difficult to get started and to keep going requiring a relatively high ∆T compared to other Low temperature difference engines.

The most notable feature is  perhaps the loud irregular clatter from the displacer.

This particular model has a magnetic displacer. That is a small magnet attached to the piston lifts the displacer as the piston reaches the down, full compression position.

With expansion the piston pulls away, the magnetic pull on the displacer is broken and the displacer drops down.

This is a very noisy operation as the displacer click up against the top of the chamber then drops back and hits the bottom

There is usually no end to this clatter of the displacer as long as the engine is running, but in the experiment, after the engine was kept running for a very long time on the continuously available steam heat, the engine fell almost completely silent.

All I can imagine is that the engine achieved some homeostasis where the displacer was virtually suspended, caught by the magnet each revolution, before hitting the bottom, then dropped before hitting the top, just oscillating in between.

Covered with insulation I can only guess. Perhaps running for so long the heat softened the plastic so it made much less noise. I can't really be sure without running it that way again without insulation or with a window or scope inside.

It's probably insignificant, but I'm curious to find out what was actually going on for the engine to run so smooth and silently when normally it is so annoyingly loud. 

Another thing that struck me as unusual was that while trying to fix the insulation my finger inadvertantly got caught by the flywheel and it actually hurt a little and the engine did not stop.

These engines usually stop at the touch of a feather. It seemed to have more torque than when running under normal circumstances without insulation.

This has been a consistent observation. These engines run with either more speed or more torque or both and also run longer (if the heat source is finite, like a cup of hot water) when the cold side is insulated. 

By "these engines" I mean LTD Stirling engines generally, not just the magnetic type.

Edited February 6, 2023 by Tom Booth

[Tom Booth]

On 2/4/2023 at 2:57 PM, Ghideon said:

On 2/4/2023 at 5:05 AM, studiot said:

the Carnot formula is not hogwash if used for the purpose for which it was intended.

@Tom Booth here is an example where the scientists probe at the limits of applicability:

From my general reading on the subject, it is claimed that this Carnot limit applies to ALL heat engines, broadly defined.

My use of the equation seems to be in harmony with how it is generally applied in courses and lectures on the subject, example problems etc.

Here is a typical example chosen at random out of a search result just now.

https://blog.mide.com/thermodynamic-theory-of-the-ideal-stirling-engine

For the authors qualifications, here is his LinkedIn profile page:

https://www.linkedin.com/in/luke-saindon-43971066

Note the following claim:

 

Quote

To have a Stirling run continuously you need to have a hot section that gets constantly heated by some source, and a cold section that is cooled in some way. Without constantly heating the hot section and cooling the cold section eventually enough heat would be transferred between the two that you would just end up with two warm sections. Once this happens you no longer have this temperature differential between sections, efficiency would drop to 0, and no heat would be transferred through the engine since no temperature differential exists.

 I happen to be doing this exact experiment, testing this claim or assumption. Somehow I cannot equate "cooling the cold section" with my doing the opposite: insulating the cold section with a combination of acrylic, Aerogel and a glass globe. And yet the engine did "run continuously", once it got going.

There is not any misapplication of the Carnot limit on my part. I'm just testing it's general application as given, as others are applying it.

My experiments have consistently produced results contrary to these expectations, (if no [external] cooling is applied to the engine's cold side it should not be able to run).

I'm postulating that in lieu of external cooling, perhaps the engine is effecting internal cooling as a result of expansion work.

This does not seem to be too much of a stretch of the imagination, IMO from general thermodynamic principles. The only real barrier to acceptance of that postulate is the (in my estimation arbitrary) Carnot efficiency limit "Law" or theory or assumption.

Edited February 6, 2023 by Tom Booth

[exchemist]

10 hours ago, studiot said:

I'm having a little trouble sorting the sheep from the goats in this paper.

1) Can you explain why their Carnot Cycle is in the wrong order ?

It should be two expansions followed by two compressions but their diagram a shows the expansions and contractions alternating

2) In the text they refer to work extracted, but I can only find details of work done on their particle.

3) I'm interested to learn how resistance free (= frictionless) adiabatic processes can be done on a charged or charge separated particle in water where surely Van Der Waals forces must operate.

4) What exactly is expanding and contracting in a single particle ?

5) From what I can gather they are saying that whilst a single measurement of their single cycle efficiency parameter can exceed Carnot, the statistical average either of infinite measurements on one particle, or one measurement on infinite number of particles, will equal Carnot. This of course implies that if some measurements are greater than Carnot, some will be less.

Yes, the opening paragraph makes clear they only claim to beat the Carnot limit in a small  number of non-equilibrium cases. The Carnot cycle, like just about all of classical physics and chemistry, is concerned with equilibrium thermodynamics, i.e. regimes in which concepts such as temperature have a meaning.  

[Ghideon]

11 hours ago, studiot said:

I'm having a little trouble sorting the sheep from the goats in this paper.

Thanks for your reply. My intention was to support your comment by adding a scientific example where Carnot terminology was used in what I believed was at the edge of its applicability. Sorry if I misinterpreted and added confusion. I have not (yet) possess the knowledge to comment on the results or methods in the paper.

35 minutes ago, exchemist said:

Yes, the opening paragraph makes clear they only claim to beat the Carnot limit in a small  number of non-equilibrium cases. The Carnot cycle, like just about all of classical physics and chemistry, is concerned with equilibrium thermodynamics, i.e. regimes in which concepts such as temperature have a meaning.  

Thanks; that seems to be the point I tried to make by providing the example. 

Edited February 6, 2023 by Ghideon
language fix

[exchemist]

31 minutes ago, Ghideon said:

Thanks for your reply. My intention was to support your comment by adding a scientific example where Carnot terminology was used in what I believed was at the edge of its applicability. Sorry if I misinterpreted and added confusion. I have not (yet) possess the knowledge to comment on the results or methods in the paper.

Thanks; that seems to be the point I tried to make by providing the example. 

It was only fairly recently that I finally got clear the distinction between statistical thermodynamics, which I studied at university, and statistical mechanics. The two terms often seem to be used interchangeably. However, my understanding is the former is concerned with equilibrium processes, i.e. those in which one has an ensemble with a  Boltzmann distribution among the available energy levels. Statistical mechanics is broader, embracing both equilibrium thermodynamics and non-equilibrium situations.

When one is dealing with individual atoms, or things such as population inversions, it obviously makes little sense to apply concepts designed to describe equilibrium ensembles. (This is what we have in these regular, breathless pop-sci articles blithering on about "negative temperature", for example. Unless you have a Boltzmann distribution, you can't speak sensibly about temperature at all. ) 

Edited February 6, 2023 by exchemist

[studiot]

Thank you both, the paper in Ghideon's link is worth discussing and we can all help each other understand it.

My comments were not adverse criticism.

 

I would just like to comment that the second Law refers to cyclic processes, both equilibrium, reversible and non equilibrium, non reversible.

The key is the cyclicity. The integral in the inequality is a cyclic integral.

It has long been known that it is possible to pick out situations within a cycle that do not conform.

[Tom Booth]

On 2/5/2023 at 3:22 AM, Ghideon said:

Based on personal experience from my garage; the second law of thermodynamics can be compared to the contents of a spilled assortment box. The contents of the box tend to end up in a disorganized mess. The probability of the contents of the box becoming sorted is low.

(Side note: Here is a video describing the statistical aspect of thermodynamics; the description does not rely upon archaic steam engines:  https://www.khanacademy.org/test-prep/mcat/chemical-processes/thermodynamics-mcat/v/second-law-of-thermodynamics)

 

Your point?

A clip from the transcript:

Quote

segment:0:14 heat will never be seen to flow spontaneously.

0:17 from a colder object to a hotter object.

Stirling engines are precision engineered machines. Even most of the toys or models. Many people who attempt to build one fail to get it to work, we have them coming into the SR forum all the time asking for help because their engine will not run and they can't figure out why.

There is nothing spontaneous about these machines. Few people even  understand how they are supposed to work. NOBODY really understands fully how they ACTUALLY work I'd venture to guess. They certainly do not work in the way traditionally supposed.

BTW, I appreciate the concern, but generally speaking people can stop trying to teach me about fundamental thermodynamics.

On 2/5/2023 at 4:24 AM, sethoflagos said:

TLDR. This stuff is beyond you. Flick the switch on your tin foil hat from transmit to receive. You might learn something.

Sorry for pointing out where you were wrong/ignorant. If you can't take the heat get out of the kitchen as they say.

This thread is about how a Real Stirling engine works and if the dreamt up arbitrary Carnot limit actually applies or not.

Your description of how a Stirling engine operates "opposite" to other heat engines or the Carnot cycle is simply wrong, regardless of what you might have gleaned from Googling up a Wikipedia article that is also wrong.

You might try taking your own advice:

Quote

This stuff is beyond you. Flick the switch on your tin foil hat from transmit to receive. You might learn something.

 

On 2/5/2023 at 4:25 AM, exchemist said:

And yes, an engine rejecting less waste heat than the prediction of the Carnot efficiency limit would violate a physical "law" of the universe.

Where is your experimental proof of this?

There are at least two interpretations of the Carnot limit, one is basically valid IMO, the other is apparently (based on experimental results and other observations) hogwash.

Which interpretation do you think the little engine might be violating?

1) That at best, discounting friction, inertia etc. Provided 1000 joules of heat the engine can only utilize the 1000 joules SUPPLIED and no more.

Or

2) That at best the engine can utilize 20% or less of the 1000 joules SUPPLIED to it. At best, only 200 joules are available to be converted.

I've seen both interpretations espoused, sometimes in the same article, the writer apparently unaware of the contradiction.

 

 

Edited February 6, 2023 by Tom Booth

[exchemist]

43 minutes ago, Tom Booth said:

Your point?

A clip from the transcript:

Stirling engines are precision engineered machines. Even most of the toys or models. Many people who attempt to build one fail to get it to work, we have them coming into the SR forum all the time asking for help because their engine will not run and they can't figure out why.

There is nothing spontaneous about these machines. Few people even  understand how they are supposed to work. NOBODY really understands fully how they ACTUALLY work I'd venture to guess. They certainly do not work in the way traditionally supposed.

BTW, I appreciate the concern, but generally speaking people can stop trying to teach me about fundamental thermodynamics.

Sorry for pointing out where you were wrong/ignorant. If you can't take the heat get out of the kitchen as they say.

This thread is about how a Real Stirling engine works and if the dreamt up arbitrary Carnot limit actually applies or not.

Your description of how a Stirling engine operates "opposite" to other heat engines or the Carnot cycle is simply wrong, regardless of what you might have gleaned from Googling up a Wikipedia article that is also wrong.

You might try taking your own advice:

 

Where is your experimental proof of this?

There are at least two interpretations of the Carnot limit, one is basically valid IMO, the other is apparently (based on experimental results and other observations) hogwash.

Which interpretation do you think the little engine might be violating?

1) That at best, discounting friction, inertia etc. Provided 1000 joules of heat the engine can only utilize the 1000 joules SUPPLIED and no more.

Or

2) That at best the engine can utilize 20% or less of the 1000 joules SUPPLIED to it. At best, only 200 joules are available to be converted.

I've seen both interpretations espoused, sometimes in the same article, the writer apparently unaware of the contradiction.

 

 

Do try to get a grip of your mind. You don't need to actually run a red traffic light to tell whether doing so would break the law. All you need do is read the law.

Edited February 6, 2023 by exchemist

[Tom Booth]

On 2/5/2023 at 5:02 AM, studiot said:

 

Yes difficult indeed.

Which is why it is such a shame that you threw your toys out of the pram at a critical moment when I had just posted the diagram showing how Carnot overcame that difficulty.

Again a pity that you did not complete the translation of his works, putting that hugely insightful statement into its proper context.

 

I should point out a typo in the quote from Carnot's unpublished writings: "best" should have been heat:

Quote

But it would be difficult to explain why, in the development of motive power by heat, a cold body is necessary; why, in consuming the heat (not best)of a warm body, motion cannot be produced

Can't say how that cropped in, possibly a. OCR error in whatever online copy I c/p'd. (Some PDF)

As far as your diagrams, I've seen these so-called proofs a thousand times (slight exaggeration, but dozens certainly). As I recently mentioned to Ghideon this thread is not entitled elementary thermodynamics.

You seem to have all your ducks in a row ready to post an entire treatise on the subject from start to finish, that is neither appropriate nor necessary. If you want to play the headmaster of your own thermodynamics course I would suggest you start your own thread on the subject. The focus here is very narrow: Is the so-called Carnot efficiency formula valid or applicable to a Stirling engine, and is it falsifiable: can it be tested experimentally.

If you feel your chart in some way relates to that topic feel free to carry on, if not, carry on anyway if you like, but don't expect a response from me for your off topic derails that threaten to swell to encyclopedic proportions.

Quote

a pity that you did not complete the translation of his works, putting that hugely insightful statement into its proper context.

It's "proper" context is there for all to see. Maybe you could elaborate on whatever it is you might be trying to say there.

How would you interpret Carnot's statement in whatever it is you consider "it's proper context" ?

[joigus]

@Tom Booth's reports and our answers remind me more and more of the lyrics of Space Oddity, by David Bowie,

Quote

Ground Control to Major Tom
Ground Control to Major Tom
Take your protein pills and put your helmet on
Ground Control to Major Tom (ten, nine, eight, seven, six)
Commencing countdown, engines on (five, four, three, two)
Check ignition and may God's love be with you (one, lift off)

This is Ground Control to Major Tom
You've really made the grade
And the papers want to know whose shirts you wear
Now it's time to leave the capsule if you dare
This is Major Tom to Ground Control
I'm stepping through the door
And I'm floating in a most peculiar way
And the stars look very different today

For here
Am I sitting in a tin can
Far above the world
Planet Earth is blue
And there's nothing I can do

Though I'm past one hundred thousand miles
I'm feeling very still
And I think my spaceship knows which way to go
Tell my wife I love her very much she knows
Ground Control to Major Tom
Your circuit's dead, there's something wrong
Can you hear me, Major Tom?
Can you hear me, Major Tom?
Can you hear me, Major Tom? Can you-

Here am I floating 'round my tin can
Far above the moon
Planet Earth is blue
And there's nothing I can do

 

[Tom Booth]

4 hours ago, exchemist said:

Do try to get a grip of your mind. You don't need to actually run a red traffic light to tell whether doing so would break the law. All you need do is read the law.

LOL...

You equate physical LAW with traffic rules and regulations? You really are in sorry shape. In need of a dose of reality, lost in idealizations and abstractions. If the book says, it must be true.

Yes you do need to run the traffic light if someone is alleging it's actually IMPOSSIBLE! if you are going to test the claim. 

[sethoflagos]

4 hours ago, Tom Booth said:

Sorry for pointing out where you were wrong/ignorant. If you can't take the heat get out of the kitchen as they say.

Your not in the kitchen, Tom. The adults won't let you play there any more will they because of what you did.

 

[Tom Booth]

3 minutes ago, sethoflagos said:

Your not in the kitchen, Tom. The adults won't let you play there any more will they because of what you did.

 

If you do not want to read or respond to posts in an intelligent and constructive way, or make some contribution towards the objectives proposed, why not go waste your time elsewhere and bother someone else with your inanities.

You pretty obviously know absolutely nothing about how a real Stirling engine operates, but if you are going to mislead people I do feel it is within my place here to point out the errors and inaccuracies in your statements as compared with reality.

What you posted about the Stirling engine cycle bears no resemblance to either Robert Stirling's original invention or any subsequent models or modifications.

Compression of the working fluid results in heat not cold. It's elementary thermodynamics.

18 hours ago, studiot said:

 

4) What exactly is expanding and contracting in a single particle ?

Good question. While I agree Kinetic theory provides the best explanation and I generally advocate that, I'm not at all certain of it's absolute accuracy.

For example I picture gas particles under high pressure in an engine cylinder something like marbles packed together in a jar. Can some be actually zipping around at near light speed while others float about aimlessly?

I think "partial pressure" may afford some explanation. Larger air molecules may be packed tightly together while smaller molecules move in between. Maybe possible for a Hot Air engine with mixed gas but what about an engine charged with pure helium and hermetically sealed?

More pressure on a compressed gas and there is phase change to liquid with something like an 800X reduction in volume depending on the gas, the transition is not as sudden as generally supposed perhaps, there is a gradual contraction of the gas.

"4) What exactly is expanding and contracting in a single particle ?"

Perhaps nothing. Presumably there would be no intermolecular forces between particles if there is only one.

19 hours ago, exchemist said:

Thanks. It's very interesting. One can see he was very nearly there. He was on the track of heat being due to motion of the molecules and was becoming sceptical of the idea of caloric being any sort of material fluid. 

Not just "becoming sceptical" he  systematically demolishes the theory:

Quote

 

When a hypothesis no longer suffices to explain phenomena, it should be abandoned.

This is the case with the hypothesis which regards caloric as matter, as a subtile fluid.

The experimental facts tending to destroy this theory are as follows:

 

The list of facts cited by Carnot is too long to reproduce here.