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A closed cylinder, say an oxygen or nitrogen tank, at Tc. Gas inside is Tc. Equilibrium. Inside vibrations are the same as tank wall vibrations, are the same as outside atmosphere vibrations. Lots and lots of impacts. Equilibrium stays at Tc.

If a faster moving gas molecule hits the tank wall and they are moving the same speed, they will bounce off each other elastically and maintain equal momentums but opposite directions. The "temperature" will maintain at Tc.

If a fast moving gas molecule hits a slow wall molecule, more momentum will go into the wall molecule increasing the wall molecule temperature, and the slower momentum will go into the gas reducing the gas molecule temperature. Lower than Tc

Direction effects this as a wall molecule moving away from a fast gas molecule will have a negative momentum and slow the gas molecule even more.

The above can be seen in physics demonstrations of elastic collisions. Mass makes a difference to. A small mass will speed up a larger mass less, and retain its own speed more ping-pong ball hitting a bowling ball. Newton's Cradle is a good demonstrator of this too.

When the piston starts moving outward, all the gas molecular hits will have a reduction in speed reducing gas temperature. The wall must be moving away from the gas. Force and distance is work. It caused a transfer of vibration energy to kinetic movement energy through pushing and movement away from the gas. Work output. Gas temperature dropping.

The transfer is a result of the physical mechanics of collisions, and motion away from the gas. IOW, it just happens as a result of the conditions and motions.

I must come back later to say more. Good day to all.

VincentG wrote: ↑Sat Jun 22, 2024 7:12 am ...
If the piston is fixed, it's a Cv/zero work condition, and "possibly" the gas temperature can rise above Tmax.

But let the piston move, and the gas "knows", and loses temperature?

Probably the working fluid temperature could get hotter than the applied heat temperature, if the heating is rapid and uneven, applied to only one end of a cylinder. Then the rapidly expanding gas at one end can act as a piston and compress the gas at the opposite end like a fire piston before temperatures can equalize. That is the basic principle behind a Vuilleumier heat pump.

An engine won't run until "up to operating temperature"

Depending on the heat absorbing, conducting, reflecting properties of the material of the walls, aluminium or epoxy etc. I think that "reaching operating temperature" amounts to the interior of the engine walls getting warm or hot enough that they are no longer absorbing heat and so the hot gas molecules will then just bounce off without loosing heat. No ∆T and no "give". The walls don't move or absorb any heat.

If the piston can move though, then the molecules will bounce around this hot chamber until they hit something that "gives"; physically moves: the piston, which is made to move easily with as little friction as possible. (And should also not be cold or heat absorbent).

That in my opinion is why in my experiments, an insulated engine with a presumably uniformly hot interior and no cold side runs better than an engine with a large cold "sink".

With a cold "sink" side, the molecules don't necessarily keep bouncing off hot walls until they hit the piston that moves and takes away kinetic energy by moving rather than thermal energy. Instead of moving the piston they hit a cold wall and lose thermal energy instead before ever reaching the piston.

For a gas, though, it's kinetic energy is also it's temperature. So giving up energy in the form of heat to a cold wall or kinetic energy to a moveable wall is all the same to the gas, it just hit something and lost or didn't lose kinetic energy a hot immovable wall will not absorb kinetic energy from the gas.

If that "something" the gas hits won't move or take in heat (no ∆T to transfer heat) nothing happens. The gas molecules just bounces off.

If the "wall" (piston) is the same temperature (no ∆T) but moves, then kinetic energy is transfered. The gas looses kinetic energy, but again, for a gas, it's kinetic energy is also it's temperature, so it gets "cold". Moves more slowly.

That's my theory anyway.

So my plan for applying these principles is to make an all ceramic engine that absorbs/conducts little heat, so the interior walls reach "operating temperature" quickly, so as to absorb virtually no heat. or don't need to, no cold metal to absorb heat anywhere, no cold side, (just metal on the heat input area).

In that way the hot gas will have more opportunity to bounce around without loosing any heat until it hits the piston and transfers kinetic energy to the piston.

There is no advantage to wasting heat to a cold surface when that energy can just as well, and just as quickly and effectively be transfered to the piston as kinetic energy.

"Cooling" (loss of kinetic energy or "internal energy" from the gas) will result when it hits the piston so that the temperature and pressure drops and the piston can return.

The goal is work output not "waste heat" output. So why facilitate the removal of energy via "waste heat" when removal through "work" is equally, if not more effective?

P.S. "fool" above, (posted simultaneously) seems to be saying more or less the same thing as far as I can tell with his first two paragraphs:

A closed cylinder, say an oxygen or nitrogen tank, at Tc. Gas inside is Tc. Equilibrium. Inside vibrations are the same as tank wall vibrations, are the same as outside atmosphere vibrations. Lots and lots of impacts. Equilibrium stays at Tc.

If a faster moving gas molecule hits the tank wall and they are moving the same speed, they will bounce off each other elastically and maintain equal momentums but opposite directions. The "temperature" will maintain at Tc.

Th or Tc, point is equal temperature, no heat transfer, energy conserved.

But it is a contradiction IMO to then insist there must be a cold "sink" ala Carnot. He's only seeing part of the picture, unfortunately.

There is, a seeming conundrum which fool touches on but doesn't see the solution to:

not all the added vibrations goes into the motion of the piston. Some must stay in the gas to maintain that larger volume. The only way to reduce that volume is to reduce the internal temperature by cooling and or compression and cooling

To "push the piston" to BDC and get work out of it, the gas has to expand. But if it is expanded then heat needs to be removed to get the gas to contract, so it looks like a catch 22.

But that isn't really the case. If expansion is very rapid leaving TDC then the heat is converted to velocity. The expansion continues adiabatically. The expanding gas continues to strike the piston and lose kinetic energy and cool down.

No need for heat removal to a "sink".

Maybe not the theoretic "ideal" of heat input all the way to BDC then trying to instantly remove all the excess, (a virtual impossibility), but it's possible and practical and it works, and experimentally there is no residual heat preventing the easy return of the piston.

If somebody thinks that "violates the Carnot limit", I could care less. What works works. To say it doesn't is to deny observable reality. Clear experimental outcomes.

The assumption that: "The only way to reduce that volume is to reduce the internal temperature by cooling and or compression and cooling" is simply not true and that can be fairly easily demonstrated experimentally.

I've done just that to my own satisfaction many many times.

If nobody else wants to bother that's not really my concern. I've got engines to build. I'm not in the business of trying to convince anyone of anything or "overturn 200 years of science". I'm mostly just trying to mind my own business, but these "fools" will just not leave me alone with this unproven obsolete "Carnot" crap trying to ram it down my throat all the time.

It's obviously complete garbage.

VincentG wrote: ↑Fri Jun 21, 2024 4:37 am Tom, I hope this didn't go unnoticed.

VincentG wrote: ↑Thu Jun 20, 2024 4:33 am The following is from this paper on entropy.
https://www.sfu.ca/~mbahrami/ENSC%20388 ... ntropy.pdf

Entropy Change 
The entropy balance is easier to apply that energy balance, since unlike energy (which has  many forms such as heat and work) entropy has only one form. The entropy change for a  system during a process is: 
 Entropy change = Entropy at final state ‐ Entropy at initial state  system  S final
S  S initial
  
Therefore, the entropy change of a system is zero if the state of the system does not  change during the process. For example entropy change of steady flow devices such as  nozzles,  compressors,  turbines,  pumps,  and  heat  exchangers  is  zero  during  steady  operation. 
Mechanisms of Entropy Transfer 
Entropy can be transferred to or from a system in two forms: heat transfer and mass flow.  Thus, the entropy transfer for an adiabatic closed system is zero. 
Heat Transfer: heat is a form of disorganized energy and some disorganization (entropy)  will flow with heat. Heat rejection is the only way that the entropy of a fixed mass can be  decreased. The ratio of the heat transfer Q/ T (absolute temperature) at a location is  called entropy flow or entropy transfer 
Sheat  Q Entropy tr  
T
ansfer with heat (T  const.)
Since T (in Kelvin) is always positive, the direction of entropy transfer is the same of the  direction of heat transfer. 
When two systems are in contact, the entropy transfer from warmer system is equal to  the  entropy  transfer to the colder system  since the  boundary has no  thickness  and  occupies no volume. 
Note that work is entropy‐free, and no entropy is transferred with work.  
Mass Flow: mass contains entropy as well as energy, both entropy and energy contents of  a system are proportional to the mass. When a mass in the amount of m enters or leaves  a system, entropy in the amount of ms (s is the specific entropy) accompanies it. 
Entropy Balance for a Closed System 
A closed system includes no mass flow across its boundaries, and the entropy change is  simply the difference between the initial and final entropies of the system.  
The entropy change of a closed system is due to the entropy transfer accompanying heat  transfer and the entropy generation within the system boundaries: 

I have no more interest in "entropy" than I have in the "Carnot limit". Both are complete fiction.

Anyway, what's your point? I don't see the relevance.

It draws an important distinction between closed cycle and open cycle mass flow type systems.

Tom Booth wrote:To "push the piston" to BDC and get work out of it, the gas has to expand. But if it is expanded then heat needs to be removed to get the gas to contract, so it looks like a catch 22.

We know that you have that off science theory, I and the reliable tools of science disagree with you on how much temperature drop the expansion will produce at the maximum work it can perform. In the "Let's beat up Carnot" thread, I provided calculations that reliability demonstrate my point. Where are your calculations? Failure to give adequate mathematical support for your theory, is failure to have a theory.

Tom Booth wrote:I have no more interest in "entropy" than I have in the "Carnot limit". Both are complete fiction.

Anyway, what's your point? I don't see the relevance.

We know you are a stubborn, ignorant, science denier. You prove again and again over and over. You have posted this in many many threads here, mostly in threads you've started. In the polite style of this forum, either post something scientific and on topic, and helpful, or stay out of others threads. VincentG is probably not going to tell you himself.

Entropy is a common useful thermodynamic mathematical tool. It might be hypothetical, like the square root of minus one, or even negative numbers, but it is very useful for those that learn how to use it. Ignoring it because you deny it is just narcissistic cognitive dissonance.

My thoughts are that you are that way as a result of lack of instruction, information starved. Still it makes it rude to be so ignorant and so belligerent about you position. The reason the second law is "rammed down your throat", as you have put it, is purely because it's obvious you don't understand it.

VincentG, I am sorry for the off topic straightening of offensive posters. He doesn't understand that what he does to other posters threads is way worse than what others do in his threads. He is the one that appears to have shunned science. I just respond in kind out of reflex.

I will get back to the discussion of how vibrations transfer energy before we were interrupted by Toms repetitive disruptive opinions.

Tom's good to have around my threads, helps to practice patients and he has some good moments.

When the piston starts moving outward, all the gas molecular hits will have a reduction in speed reducing gas temperature. The wall must be moving away from the gas. Force and distance is work. It caused a transfer of vibration energy to kinetic movement energy through pushing and movement away from the gas. Work output. Gas temperature dropping.

The transfer is a result of the physical mechanics of collisions, and motion away from the gas. IOW, it just happens as a result of the conditions and motions.

Can we assume the minimum speed of a gas molecule is the speed of sound? In that case, as a percentage, the speed of a slow piston(even an F1 piston is under 90mph), seems relatively insignificant.

On top of that, I'd bet that most gas molecules are probably not hitting the piston at all.

VincentG wrote:Tom's good to have around my threads, helps to practice patients and he has some good moments.

True. I just would like him to be a little more open minded, kind, and tolerant, and less stubborn and belligerent. We all have the need to speak and be corrected.

VincentG wrote: ↑Sun Jun 23, 2024 6:41 am
Can we assume the minimum speed of a gas molecule is the speed of sound? In that case, as a percentage, the speed of a slow piston(even an F1 piston is under 90mph), seems relatively insignificant.

On top of that, I'd bet that most gas molecules are probably not hitting the piston at all.

This is why I'm moving away from piston engines completely with my theories and tests.
Temperature in a fluid is internal kinetic energy. Why don't we use that in stead of wanting to turn that into pressure first? If you can point all that internal kinetic energy into the same direction towards a turbine, why bother with pistons and pressures?
As you touch on, I think a lot of energy is lost because the molecules are bouncing off an immovable wall.

Does that make sense?

This is why I'm moving away from piston engines completely with my theories and tests.
Temperature in a fluid is internal kinetic energy. Why don't we use that in stead of wanting to turn that into pressure first? If you can point all that internal kinetic energy into the same direction towards a turbine, why bother with pistons and pressures?
As you touch on, I think a lot of energy is lost because the molecules are bouncing off an immovable wall.

Short answer, we don't have much energy to start with in the standard 300k-600k cycle. Turbines are great but they need a minimum mass flow rate to be effective. With water this happens pretty easily, but with gas it's not so easy without internal combustion.

If you can make a closed cycle design with increased charge pressure(more mass), and effectively high temperature delta, than I do think that has potential, like in my ambient energy thread. Starting the flow without a big tax from a compression cycle is one challenge I can see.

I really do look to microbursts for inspiration here. They are among the only events in nature where cold really does flow aggressively to hot, albeit due to mass differences and not "internal energy". Perhaps that is why it's so hard to find a good coherent explanation of their mechanism.

Fool wrote: ↑Sat Jun 22, 2024 5:59 am I find it interesting that vibrations transferring into a gas makes the gas vibrate more manifesting into the macro world as higher, temperature and pressure. That pressure can push on a piston making it move and the gas vibration reduces without making the piston hotter. Thermal to kinetic energy conversion.

I find it also interesting that not all the added vibrations goes into the motion of the piston. Some must stay in the gas to maintain that larger volume. The only way to reduce that volume is to reduce the internal temperature by cooling and or compression and cooling.

We're told that all the kinetic energy of a gas comes from just the translational energy and I have a full plate gaming this without worrying about vibrations.

Per Vincent's comment "But let the piston move, and the gas "knows", and loses temperature?" Jeez, that gas is smart...

VincentG wrote: ↑Sun Jun 23, 2024 9:06 am
If you can make a closed cycle design with increased charge pressure(more mass), and effectively high temperature delta, than I do think that has potential, like in my ambient energy thread. Starting the flow without a big tax from a compression cycle is one challenge I can see.

I really do look to microbursts for inspiration here. They are among the only events in nature where cold really does flow aggressively to hot, albeit due to mass differences and not "internal energy". Perhaps that is why it's so hard to find a good coherent explanation of their mechanism.

There's a lot we can learn from nature that most have chosen to ignore. The trick here is simply to take our modern thermo shopping for some low hanging fruit, but we've become so brainwashed by high tech everything that most guys can't grasp many 3rd world issues without some "re-education". It's like trying to unsee the seen where 1st world guys have chosen to think their way is the only/best way regardless of any shortcomings.

The heat engine stems from the hot air balloon, but the whole heat thing is over rated. I think gaming mass vs pressure differential might bring home more bacon.

VincentG wrote: ↑Sun Jun 23, 2024 9:06 am

This is why I'm moving away from piston engines completely with my theories and tests.
Temperature in a fluid is internal kinetic energy. Why don't we use that in stead of wanting to turn that into pressure first? If you can point all that internal kinetic energy into the same direction towards a turbine, why bother with pistons and pressures?
As you touch on, I think a lot of energy is lost because the molecules are bouncing off an immovable wall.

Short answer, we don't have much energy to start with in the standard 300k-600k cycle. Turbines are great but they need a minimum mass flow rate to be effective. With water this happens pretty easily, but with gas it's not so easy without internal combustion.

If you can make a closed cycle design with increased charge pressure(more mass), and effectively high temperature delta, than I do think that has potential, like in my ambient energy thread. Starting the flow without a big tax from a compression cycle is one challenge I can see.

I really do look to microbursts for inspiration here. They are among the only events in nature where cold really does flow aggressively to hot, albeit due to mass differences and not "internal energy". Perhaps that is why it's so hard to find a good coherent explanation of their mechanism.

Yeah that's why I'm not going to try with a pure gas engine. It'll have to be water and water vapor.
It's moving away from the Stirling engine, but I think we're past the pure Stirling discussions here anyway haha.

Look up the cryophorus, that's the basis of it. There are a few people working on this already with good results, but they're wasting tons of heat. I'm hoping to make it way more efficient.

https://youtu.be/kQx8JacCWMU?si=vjoU1QIcmWYIgnoE

The latest video from Jeremiah. He basically has a big thermal battery, a turbine and a condensor. Under vacuum so there's only water in the system.