Stirling Engine & Heat Pump

[Tom Booth]

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Tom, your rage ....

LOL..

Hardly. I come here when I need a laugh.

It is rather comical and silly for you to be so hopelessly fixated on your stale dusty "classical" explanations for everything.

No imagination or curiosity or life. If you are not AI you sure act and sound like a programmed robot.

Your so concerned that gas molecules cannot attract. In the mean time, is molecular theory even still a thing?

How would you handle thinking about quantum erasure. Entanglement, superposition, observer effect, many worlds hypothesis.

Maybe in the next universe over where you apparently come from, gas molecules don't attract. In this universe they do

[VincentG]

VincentG, Let me please ask the following:

Do you agree that gasses push, and never pull? Is it caused by kinematic collisions of real gas molecules?

I would be a fool to guess, and I certainly don't know for sure. There is enough debate in all of these fields, even among experts, that I find it hard to be certain of anything other than what I can see for myself.

We should all stop using AI responses for answers as it often can be misleading or easy to affect bias.

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[Fool]

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Your so concerned that gas molecules cannot attract. In the mean time, is molecular theory even still a thing?

You're so concerned that molecules attract, you've blinded yourself to when their attraction isn't part of a phenomenon.

Coming here for a laugh is all well and good, but, you use an awful lot of banter, vituperation, ad hominem, cursing, and crying to the administration, to be considered 'jolley'. LOL

How would you handle thinking about quantum erasure. Entanglement, superposition, observer effect, many worlds hypothesis.

Tom you really ott to quit mixing real gas macro state pressure with micro state quantum mechanics and fantasy until you've learned way more classical science. Ignoring the easily testable fact that gasses always push to fill their container because you don't understand quantum mechanics is poor form at best.

I would be a fool to guess, and I certainly don't know for sure. There is enough debate in all of these fields, even among experts, that I find it hard to be certain of anything other than what I can see for myself.

Fair enough. No one knows for sure. Guessing is for children. I get it. At best healthy scientific skepticism. At worst, I suppose, unhealthy ignorance by choice detrimental unawareness. Forget for a moment anyone considered an "expert". Think for yourself. Tom keeps saying gas molecules attract. He hints that they get "pulled" into a vacuum. How is it possible that 'nothing' can be so pulling? How can nothing have any forces? Even gravity and electron proton attraction requires something massive. Nothing can only do nothing.

To proceed into learning thermodynamics without having a stance on this primary characteristic of the materials you work with, will leave you not able to grasp anything else in the science.

Tom has chosen to throw science, mathematics, theory, other people's data, and logic, out and instead rely on his own limited quantity, poorly instrumented, poorly recorded, and poorly measured phenomena.

Please show me an expert that states somewhere that gasses pull, or pull into a vacuum. Do not confuse molecular attraction.with the phenomenon of gas pressure. Molecular interactions are a microstate. Gas pressure is a macrostate.

Show me a PV or phase diagram or data table that has negative absolute pressure. Show me a PV diagram that has negative absolute anything, volume, temperature, pressure, enthalpy, entropy, mass. Measure a negative absolute pressure, record it and present it, you will be the first.

Gas molecules have attractive and repulsive force, from the electrons and protons. Attractive forces have little effect on the pressure, temperature, and volume characteristics for the gasses, pressure, temperatures, and densities, our studies here require. Molecular repulsive forces are responsible for the bouncing that causes pressure from transfer of momentum during impacts. Tom's misdirection here is derailing your thought processes. Look closely. Verify a few of the facts you hear from experts. Figure out what is reliable data, and what is antidotal. Learn what it takes to do reliable scientific laboratory work. The reliable, corroborative, puzzle pieces fit together only one way when you see it.

Molecular attraction as the gas gets colder and starts to liquefy affects the PVT relationship some, but it doesn't stop a gas from pushing. Unfortunately there is so much more to explain to make this more clear.

In other words, if you can't see the characteristics, between a gas, at any temperature and density, and a vacuum, from your own simple experiments, the rest of the thermodynamics will be lost to you. Tom has already lost it.

Think about how the characteristics, known observed phenomena, of solid, liquid, and gas differ for the same substance and amount. Study phase diagrams. Fluid dynamics, liquid and gaseous. Ask for explanations if need be. Gasses always pushing, never pulling, is blatantly obvious if your view is sufficiently wide enough.


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[VincentG]

Please show me an expert that states somewhere that gasses pull, or pull into a vacuum. Do not confuse molecular attraction.with the phenomenon of gas pressure. Molecular interactions are a microstate. Gas pressure is a macrostate.

I'm not making any claims that gasses pull into a vacuum. I've sated before that something like the 55 gallon drum crushing experiment is due to high pressure outside vs low pressure inside. All evidence suggests that gas will continue to expand to fill whatever void they occupy.

How is it possible that 'nothing' can be so pulling? How can nothing have any forces? Even gravity and electron proton attraction requires something massive. Nothing can only do nothing.

All I am saying is that Tom seems to be talking about very small molecules having very small attraction to other very small molecules. For you to definitively rule that out is as ridiculous as Tom stating it has a significant role in these engines. It's just hypothesizing, that's all.

What I have personally observed is that it may be hard to tell the difference between gas rapidly relaxing its push due to a sudden temperature drop, and an actual contraction. The gas when cooled is giving up its own internal energy to then exert less force on the vessel containing it.

From the perspective of the gas inside the fixed vessel, it might seem like there is a contraction at the moment of cooling. If you were to take a snapshot of any one cubic centimeter at both tmax and tmin, there should be the same mass of gas, but would there be the same number of molecules exerting pressure on the cubic square? If not, then is the volume of gas really the same at tmax and tmin?

[Tom Booth]

The attractive forces are represented mathematically in the Van de walls equation as a constant that is different for each gas and determined experimentally.

The attractive force (represented by "a") is always present in the equation for all pressures and volumes. it does not only appear during phase change.

As usual "fool" you completely misrepresent my position with your straw man arguments.

[matt brown]

If you ask do gasses contract, you will often get the colloquial answer, YES. But it really isn't true, and only applies to constant pressure cooling. And that 'contraction' only happens because an outside pressure compresses the gas volume. Not because the gas "pulls".

Gasses always push and the kinetic theory is correct. Contraction implies a spontaneous event vs cause and effect, so it's bad buzz in science.

Fool - your wording obscures that you're referring to an isobaric compression in 1 cylinder driven by ambient pressure where the compression appears magical (spontaneous) when the pressure inside cylinder is/falls below ambient. If the same isobaric compression was between 2 interconnected cylinders then nothing would appear magical since we'd see both pistons move and know that 1 piston is supplying work input.

Tom's suffering from a delusional woke mind virus where his fantasy agenda is his alternate reality (national epidemic). In the past, nature supplied a trail by fire that weeded out such lunacy.

[Fool]

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Matt, thanks. You are correct, contraction and filling a container, are contradictory. It's just fanciful guessing verses known observation. One of these days someone will hand out balloon pets, and they will see that gasses do push. One of these days they will see a demonstration of putting dry ice into a sealed balloon or plastic bag and watch it expand without turning into liquid. They might even use numbers to calculate from dry ice's mass to how big the balloon will swell.

You are correct about WOKE. The Republicans aren't aware how destructive it is to our nation to propose such terrorism. Ronald Reagan said 'its not that the government will fix your problems, it's that the government is the problem.' Definitely an oxymoron. Like shooting yourself in the foot, cause you aren't running fast enough. Oh my.

Yes 'apparent' gas attraction is only seen in isobaric compressions. The only way to understand gasses is to see how they behave in a fixed volume container. In space they will expand forever. In an atmosphere they are subjected to the forces and temperatures of outside pressure. Something that is easy to miss in laboratories and garages on Earth.

Thanks for the input. I was beginning to think I was the only person here rooted in realty. The rest have all succumbed to blind leaders.


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[Fool]

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As usual "fool" you completely misrepresent my position with your straw man arguments.

You probably will reject my sincere intention to not misrepresent you here. I have no need, desire, or benefit to misrepresent you or anyone else anywhere.

That said, please do not confuse my pointing out consequences of your points, with misrepresentation. One consequence of breaking the second law, is the ability to break the first law.

One consequence of the point that molecules always attract, is the thought that it may always have a big effect on our engines. Your point misleads the discussion. Your point is the strawman easily defeated. Waste of time.

Maybe this will help. CO2 sublimes at standard atmospheric pressures. It goes from solid to gas. When cold enough CO2 molecules bond from their attraction. But they don't quite touch because of their repulsion. Both repulsion and attraction become practically zero only a few molecule radiuses out.

So, how far out are gas molecules, on average. We'll use density to compare.

Solid CO2 has a density of 1562 kg/m3

Gaseous CO2 has a density of 1.977 kg/m3

1562/1.997 = about 782.

The cube root of 782 is about 9

So they are, on average, about 9 times further away than their molecular radius. Not very affected by attractions and definitely unbonded/free. It's no wonder that they are freely moving around and bouncing.

You are missing a lot regarding bonds, molecular forces and such. Vanderwall forces only apply to certain molecules. Most have much larger forces. Noble gasses are examples of molecules lacking other forms of attraction and are affected by Vanderwall Forces.

All those forces are affected by distance, radius, 'r'. Attractions get smaller as density gets smaller.

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[Fool]

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I'm not making any claims that gasses pull into a vacuum. I've sated before that something like the 55 gallon drum crushing experiment is due to high pressure outside vs low pressure inside. All evidence suggests that gas will continue to expand to fill whatever void they occupy.

Good. Rooted in reality. Yes.

All I am saying is that Tom seems to be talking about very small molecules having very small attraction to other very small molecules. For you to definitively rule that out is as ridiculous as Tom stating it has a significant role in these engines. It's just hypothesizing, that's all.

Wait a minute. I never ruled out molecular attraction. It applies at very high density, and pressure, and very low temperature. Tom needs to understand when they apply, and when they are insignificant/negligible. Tom was making claims of contraction that he is now slowly backing out of.

Hypothesizing is taking observation, theory, data and coming up with a new theory that can be tested. It is not a wild ass guess. There are times for, and benefits from, wild ass guesses, and they are tamed by scientific facts. But they are not theorizing or hypothesizing. Sorry, I digress.

What I have personally observed is that it may be hard to tell the difference between gas rapidly relaxing its push due to a sudden temperature drop, and an actual contraction. The gas when cooled is giving up its own internal energy to then exert less force on the vessel containing it.

From the perspective of the gas inside the fixed vessel, it might seem like there is a contraction at the moment of cooling. If you were to take a snapshot of any one cubic centimeter at both tmax and tmin, there should be the same mass of gas, but would there be the same number of molecules exerting pressure on the cubic square? If not, then is the volume of gas really the same at tmax and tmin?

In a fixed container the gas doesn't change volume. What gas is in there occupies the entire volume all the way to zero K. At zero K density is zero, and there is no gas in the volume. Each cubic centimeter has the exact same numbers in them until liquid condenses. They are just moving more slowly, bouncing softer.

The density doesn't change until the gas is cold enough to start liquifying. As the gas condenses and falls to the floor, or sticks to the walls, less gas is filling the volume. Both density and pressure decrease, for the molecules that are remaining a gas. When the pressure drops, the boiling point drops. There is always some gas present, however small. It is always pushing, filling the container, and provides a positive pressure.

When engineering around the boiling temperature, it is incorrect to use the ideal gas law. Steam tables, or phase diagrams, must be used instead.

In an engine, not all the gas is heated or cooled. That does affect what happens to those separate areas, despite the fact that the entire volume could be considered fixed/constant. And it often isn't constant volume, especially in a running engine.

The point I'm making is, density, volume, expansion, and compression depend only on the size of the container and number of moles of gas that is contained or moving.

The motion of gas is from pressure differential, and never from contraction. Even when it appears that way to the casual observer. Magicians make used of colloquial and misleading ideas to provide illusions. I'm just correcting that misleading and potential misunderstanding.

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[Fool]

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It might help to use the analogy of a lottery or bingo ball blowing sphere. The balls are blown around, speed equals temperature. They bounce off the walls and each other.

Every time a ball is removed the volume of the container doesn't change it's size. Less balls are bouncing, same speed, pressure different. This is the same as condensing liquid onto the walls. Eventually only one ball would be left. It still bounces through the full volume at the same speed, but lower pressure.

Turn the fan speed up. Same number of balls. Same volume. Higher pressure. Down, same number of balls same volume lower pressure.

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[matt brown]

Yes 'apparent' gas attraction is only seen in isobaric compressions. The only way to understand gasses is to see how they behave in a fixed volume container. In space they will expand forever. In an atmosphere they are subjected to the forces and temperatures of outside pressure. Something that is easy to miss in laboratories and garages on Earth.

The history of thermo is loaded with lacking info and delusion. Consider this classic engine which everyone should know, but few have carefully studied...

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This concept was popular in past and remains so today, solely due to bad science. Note 1807 date, so only a decade prior Stirling, yet decades before Ericsson. The premise is simple: hot air expands. Maybe so, but this obscures the fact that such a scheme will require a pressure differential to effect an engine. This regulated open cycle has single-acting pistons where 1 bar on both sides of each piston 'stalls' engine. If we open the valves between both cylinders and manually move the inter-connected pistons then the 100cc in cold cylinder expands via heating into 200cc in hot cylinder. Then, when we close the valves between both cylinders and open the hot cylinder exhaust valve while we manually move the pistons then the 200cc in hot cylinder exhausts to ambient. If we negate the manual involvement, no work could occur simply because the pressure on both sides of each piston remained 1 bar thruout this cycle. Yet, a closer look at the manual involvement would reveal that a slight Wneg occurs during intake into hot cylinder while a slight Wpos occurs during exhaust from hot cylinder. IOW there was no spontaneous flow from cold to hot cylinder, and the hot cylinder will require a slight pressure differential between it's piston faces.

Meanwhile, if the buffer pressure was a vacuum then the gas flow from cold to hot cylinder would appear spontaneous and show notable Wpos during transfer to hot cylinder and notable Wneg during exhaust from hot cylinder when closed cycle, but a major free lunch when open cycle with endless vacuum (good luck with that). My point is that a heat engine requires a pressure differential and grasping how this plays out is paramount to any scheme. Early engine designers did not have access to modern thermo, so they were easily misled. Their focus on ambient and vacuum engines was largely due to their limited thermo knowledge and limited metallurgy which limited Pmax. The real advantage of the Otto cycle is not ICE, but a compression process that increases Pswing of cycle.

[Tom Booth]

.... The only way to understand gasses is to see how they behave in a fixed volume container. In space they will expand forever.

If gas in space "expands forever" why are we here at all?

Everything started as gas in space, which space gas molecules, drew together by mutual attraction to form stars, planets and everything else in the universe.

Gas in a 55 gallon drum will implode the drum.

[Tom Booth]

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As usual "fool" you completely misrepresent my position with your straw man arguments.

You probably will reject my sincere intention to not misrepresent you here. I have no need, desire, or benefit to misrepresent you or anyone else anywhere.

That said, please do not confuse my pointing out consequences of your points, with misrepresentation. One consequence of breaking the second law, is the ability to break the first law.

One consequence of the point that molecules always attract, is the thought that it may always have a big effect on our engines. Your point misleads the discussion. Your point is the strawman easily defeated. Waste of time.

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Another misrepresentation.

I never said any such thing, that molecules "always attract" or "always" have a big effect.

The attractive and repulsive forces cancel or are in complete equilibrium to start with.

Adding heat results in the repulsive forces dominating resulting in expansion.

Doing work, loosing energy and cooling results in the opposite. The expansive force no longer dominated resulting in "contraction".

I don't care if you view "contraction" as being pushed in by atmospheric pressure, the result is the same, but forces of attraction between gas molecules quite obviously does exist.

If you think not your opinion contradicts dozens of scientific facts and references already cited previously.

[Tom Booth]

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I'm not making any claims that gasses pull into a vacuum. I've sated before that something like the 55 gallon drum crushing experiment is due to high pressure outside vs low pressure inside. All evidence suggests that gas will continue to expand to fill whatever void they occupy.

Good. Rooted in reality. Yes.

All I am saying is that Tom seems to be talking about very small molecules having very small attraction to other very small molecules. For you to definitively rule that out is as ridiculous as Tom stating it has a significant role in these engines. It's just hypothesizing, that's all.

Wait a minute. I never ruled out molecular attraction. It applies at very high density, and pressure, and very low temperature. Tom needs to understand when they apply, and when they are insignificant/negligible. Tom was making claims of contraction that he is now slowly backing out of.

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I'm not "slowly backing out" of anything.

More lies and misrepresentations.

You straw man my position by intentional exaggeration and misrepresentations, then when I try to correct or clarify your BS you claim I'm "backing out".

No, your just lying and straw manning. My position has not changed. I stick with facts, empirically demonstrable science and experimental outcomes.

You just spew all manner of contradictory and nonsensical BS off the top of your head on a regular basis.

[Tom Booth]

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In a fixed container the gas doesn't change volume. What gas is in there occupies the entire volume all the way to zero K. ...
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A "fixed container" like a balloon? A 55 gallon drum? A tanker?

Where? In outer space?

No gas is still a gas at zero K nincompoop.

Not even helium.