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For heat to be removed from the cold end, by the working fluid, it must have an _average_ temperature throughout the cycle, that is below that of the cold end.
It's easy to postulate that the working fluid temp might drop below that temp briefly, but I'm really struggling to see how it could be below Tc on average while the engine still runs.

MikeB wrote: ↑Tue Apr 30, 2024 4:28 am For heat to be removed from the cold end, by the working fluid, it must have an _average_ temperature throughout the cycle, that is below that of the cold end.
It's easy to postulate that the working fluid temp might drop below that temp briefly, but I'm really struggling to see how it could be below Tc on average while the engine still runs.

Why "on average"?

What is the temperature of the working fluid in a conventional household refrigeration system "on average"?

What is the temperature of the working fluid in a conventional household refrigeration system "on average"

This is a good point Tom. I've recently been thinking of this scenario. A perfectly insulated 70 degree Fahrenheit room has a certain internal energy. If you could divide the room, one half 400k, the other half 200k, internal energy would be the same(I think). But potential energy goes through the roof.

If instead one third stays at 300k, could that energy be used up to bring the other two thirds to 200k and 400k, respectively?

And if heat can be destroyed, will the room eventually reach 0k as all the rocks are lifted?

VincentG wrote: ↑Tue Apr 30, 2024 4:58 am ...
If instead one third stays at 300k, could that energy be used up to bring the other two thirds to 200k and 400k, respectively?

And if heat can be destroyed, will the room eventually reach 0k as all the rocks are lifted?

I don't know what you mean there (,highlighted in bold)

"used" how?

Do you mean each part of the room is 300?

300:300:300?

Then one of those is "used"

Or divided 300:200:400?

That makes no sense though

In any event, the 0°K Carnot theory is caloric theory silliness. If all this is supposed to involve a hot air engine of some sort.

Air liquefies at about 77° K

So the "working fluid" would condense before you could reach 0°K

Anyway your description of this scenario seems lacking in important details.

If this has anything to do with the Tesla's or Carnot's or Kelvin's "self-acting machine" (The term originally came from Carnot I think, then Kelvin in 1851 in his version of the 2nd Law: “It is impossible for a self-acting machine, unaided by any external agency, to convey heat from one body to another at a higher temperature")

Tesla's proposal in essence depends on to quote:

"...expending initially a certain amount of work to create a sink".

Also energy derived from the ambient environment is not a finite quantity of heat like that in "a perfectly insulated room".

Why does the Vuilleumier cryocooler need three temperatures? You'd think if it were running on Tom's theory it would only use two. Three, indicates a reliance on Carnot theory. Hmmm. It also requires two displacers.

It's a combination of a, heat engine, running on hot to middle temperature. Cryo cooler, running on cold to middle temperature. Not ever cold to hot. I wonder if, by your theory, a new machine, one that's never been built, running on your "new" theory, could be built? Get right on that please. When, if, you get one running, it will bolster your theory.

I know why you don't. It will prove you wrong and it's more fun yanking us around with your emotional opinion posts, rather than science. If we could only build this, we'd have free energy, warp drive, food replicators, and matter transporters.

Yes your theory opposes both the first and second laws of thermodynamics. Sorry, but that is what this thread is claiming with zero conclusive evidence. I guess my scientific skepticism shows. Good luck.

I know why you don't. It will prove you wrong and it's more fun yanking us around with your emotional opinion posts, rather than science. If we could only build this, we'd have free energy, warp drive, food replicators, and matter transporters.

Yes your theory opposes both the first and second laws of thermodynamics. Sorry, but that is what this thread is claiming with zero conclusive evidence. I guess my scientific skepticism shows. Good luck.

Are you referring to me here?

Fool wrote: ↑Tue Apr 30, 2024 10:13 am Why does the Vuilleumier cryocooler need three temperatures? ...

It doesn't

That's like saying why does your refrigerator need three temperatures?

Hot at the compressor, cold in the ice box and ambient surroundings.

Compression generates heat, expansion results in cold. Then you have the ambient surroundings.

Tom Booth wrote: ↑Tue Apr 30, 2024 2:56 am Have you measured this heat you think gets transfered to the "cold hole" in a running Stirling engine?

No. Have you?

Stroller wrote: ↑Tue Apr 30, 2024 2:00 pm

Tom Booth wrote: ↑Tue Apr 30, 2024 2:56 am Have you measured this heat you think gets transfered to the "cold hole" in a running Stirling engine?

No. Have you?

Of course. only like 20 times. Or at least I've tried. But you can't measure what isn't there.

Of course fool and company just say I'm not getting an increase in temperature because my little toy Stirling engines use such an infinitesimal amount of heat and are so so inefficient and produce such little power the heat leaving the engine is not enough to be measurable.

Even though it is for sure 90% of the heat going into the engine and straight out the other side, in perfect accord with Carnot.

Carnot always wins. You can't beat Carnot.

VincentG wrote:Are you referring to me here?

No Sir. I do worry, LOL, that Tom's falsehoods will confuse people. Hope that, it appears, you see through.

Tom Booth wrote:That's like saying why does your refrigerator need three temperatures?

Actually your refrigerator works on a different process than Carnot or Vuilleumier cryocooler. The Vuilleumier cryocooler requires hot cold and ambient.

The heat absorbed by the engine at high temperatures and at low temperatures is rejected at ambient temperatures.

https://link.springer.com/chapter/10.10 ... 9-5286-8_4

Your refrigerator takes in electricity and converts it to work that then is converted to cold temperature. Heat is rejected to ambient.

Vuilleumier cryocooler, takes in heat, converts it internal energy, that is then converted to work, and that gets converted to cold. Heat is rejected to ambient. From both displacers.



Stroller, many of Tom's experiments are inconclusive. They lack sufficient and proper instrumentation, theory, and practice. They are interesting.

Fool wrote: ↑Tue Apr 30, 2024 6:10 pm ...
Actually your refrigerator works on a different process than Carnot or Vuilleumier cryocooler. The Vuilleumier cryocooler requires hot cold and ambient.

The heat absorbed by the engine at high temperatures and at low temperatures is rejected at ambient temperatures.

https://link.springer.com/chapter/10.10 ... 9-5286-8_4

Your refrigerator takes in electricity and converts it to work that then is converted to cold temperature. Heat is rejected to ambient.

Vuilleumier cryocooler, takes in heat, converts it internal energy, that is then converted to work, and that gets converted to cold. Heat is rejected to ambient. From both displacers.
...

1)The refrigerator uses electricity to run a compressor. The compressor compresses the working fluid with a piston.

1)The Vuilleumier cycle uses heat to expand one volume of air (through a regenerative displacer) which first volume acts like an "air piston" to compress a second volume of air.

2) Refrigerator: heat of compression is rejected to ambient

2) Vuilleumier: heat of compression is rejected to ambient

3) Your refrigerator expands the compressed working fluid through an expansion valve.

3) The Vuilleumier cycle uses a regenerative displacer to absorb heat out of (cool) the first volume of air to expand the second, previously compressed volume of air

Other than using a high heat source as a power source to effect compression (similar to how a gas refrigerator uses heat)
The basic refrigeration cycle is identical.

The "hot" in the Vuilleumier is the power source that drives the cycle. Like a refrigerator the Vuilleumier produces cold, it does not "require" cold, any more than a refrigerator "requires" cold they both produce cold.

Both "reject" or dump/transfer heat of compression to ambient.

The only real difference is the method used to effect compression

Your refrigerator uses an actual piston.

The Vuilleumier uses a heat driven "air piston".

Now if you don't mind, try to recognize your own ignorance and lack of comprehension and lack of understanding and quit accusing me of spreading "falsehoods".

Tom Booth wrote: ↑Tue Apr 30, 2024 2:21 pm at least I tried to.... you can't measure what isn't there.

Of course fool and company just say I'm not getting an increase in temperature because my little toy Stirling engines use such an infinitesimal amount of heat and are so so inefficient and produce such little power the heat leaving the engine is not enough to be measurable.

I agree with you that heat-energy entering the hot side and being converted to kinetic-energy in the form of flywheel acceleration and electricity generation etc will mean a lower temperature on the cold side than you'd get if you simply powered a displacer from a different energy source external to the system.

And it is difficult to measure such small systems. I'll have a go at building some sensors into my much larger LTD stirling and bring some data to the discussion.

The Vuilleumier cycle requires hot and ambient to run the machine. It requires a insolated space to cool. As you point out, three temperatures. And the heat absorbed from that cold space is rejected to ambient. It won't work trying to cool the ambient temperature and reject to the hot space. It needs all three.

A motor driven refrigerator absorbs heat from an insulated cold space, and rejects it to ambient. It doesn't have a "hot space" just the two temperatures.

Thanks for corroborating that with your last post. It obeys Carnot Theory, not yours. Yours fails to describe the reason for three temperatures. Show us a PV diagram for your Theory. Please.

Fool wrote: ↑Wed May 01, 2024 12:38 am The Vuilleumier cycle requires hot and ambient to run the machine. It requires a insolated space to cool. As you point out, three temperatures. And the heat absorbed from that cold space is rejected to ambient. It won't work trying to cool the ambient temperature and reject to the hot space. It needs all three.

A motor driven refrigerator absorbs heat from an insulated cold space, and rejects it to ambient. It doesn't have a "hot space" just the two temperatures.

Really? I didn't know that. Thanks! Learn something new every day. I thought refrigerators had something called a condenser where the working fluid gets quite hot. I guess a long hollow tube filled with refrigerant doesn't count as a "space".

No worries though, in a few minutes "fool" will return and claim that paragraph he just wrote doesn't exist at all.

Pointing out his complete lack of comprehension of any kind of refrigeration or cooling system is just me "twisting" things.

Thanks for corroborating that with your last post. It obeys Carnot Theory, not yours. Yours fails to describe the reason for three temperatures. Show us a PV diagram for your Theory. Please.

I suppose a refrigerator "rejects heat" through a quasistatic isothermal process, just like a Carnot engine.

The condenser is the ambient temperature heat rejection exchanger. Yes it is isothermal. It gets hotter than ambient so heat will come out. A delta T is needed for heat transfer.

If it were quasi static it would be more efficient. It isn't, so it can, and does, have a higher wattage. It cools faster at the expense of a little efficiency.