Carnot reveal for Tom

Discussion on Stirling or "hot air" engines (all types)
stephenz

Re: Carnot reveal for Tom

Post by stephenz »

Tom Booth wrote: Mon Jul 10, 2023 7:49 pm
I think you missed my previous post:

viewtopic.php?f=1&t=5547&p=19690#p19686

The T1 thermocouple was actually plugged in backwards so there was no drop in temperature below ambient. As far as previously running on just hot water poured into a cup, I'm not so sure one way or the other. The engine has been modified at this point but I'll keep tinkering and testing and make sure my thermocouples are plugged in the right way next time!
Yeah I totally missed that.
I would encourage you to redo the measurements though.
Tom Booth
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Re: Carnot reveal for Tom

Post by Tom Booth »

stephenz wrote: Mon Jul 10, 2023 7:31 pm
As for the top plate not being aluminum, I can update the calculation if you'd like using stainless steel density and specific heat. Can you confirm the dimensions? diameter, thickness?
Giving the plates a more thorough close examination under a good bright light, they do now appear to me to be aluminium-like . Perhaps some aluminium alloy or "pot metal", but almost certainly MOSTLY alumunum, I think, maybe. I get the impression it is heavier than "normal" aluminum I'm more familiar with.

I could try doing some kind of analysis if it makes a difference.
Nobody

Re: Carnot reveal for Tom

Post by Nobody »

"Researchers in the field do not agree on a theory for cold fusion."
From Wikipedia:

https://en.m.wikipedia.org/wiki/Cold_fusion

Tom, I have concerns for your well being. Fleischmann and Pons, their biggest mistake was publishing egregious claims before having peer reviews. Somewhere I read that one of their errors was in, concluding erroneously, what their observed temperature swings ment. They had trouble understanding what appeared as excessive heat. They also, and still, lack any theory as to how cold fusion would work. The difference between a magic demonstration and science is the science/MATHEMATICS. The MATHEMATICAL theory IS the science. Without it we have almost nothing.

Fleischmann and Pons still think cold fusion is possible and that their research is valid. They have been paid a lot, millions, with nothing to show.

Presenting your demonstrations here, in this public forum, is publishing. Be wary. Its a small forum. We tend to treat things here as opinion so our comments tend to be gentle. The world can be way more harsh.

A case in point, From Wikipedia:
https://en.m.wikipedia.org/wiki/Andrew_Wakefield

Andrew Wakefield's biggest mistake was in trying to proffit from his fraudulent theory. That's when it became criminal. He still thinks he is correct, something I call cognitive denial.

My concern lies with the thought of not informing you. It's one thing to have an opinion, it's another to try to proffit from it. Please be careful.

It takes a very strong and honest man to admit a mistake. I admire that. Your anti Carnot comments here have risen from the depths of libel to just an honest misunderstanding of the second law. I get it. That law is very hard to fathom. What did it for me was calculating the C.O.P. (Coefficient Of Production) for a reversible heat engine running backwards. It was then that I realized that the Carnot engine is not just a maximum it is 100% perfectly efficient, as is the ideal Stirling Engine. Not that we could actually build a perfect machine. What is hard to accept and understand is the mechanisms of thermodynamics. Those perfect cycles are nothing more than a direction to shoot towards. All attempts to shoot higher are an erroneous waste of time. It's a good thing that the perfect cycles set the goal so high, "perfect".

Carnot law is a mathematical construct and provable only by mathematics. Reality can only be used for it's disproof. It is similar to any attempt of disproving the value of Pi. You won't find a "disproof" of Pi or Carnot. I've tried.

Why? Is it so difficult to accept, if an engine absorbs some heat and produces some work it then requires some work/heat-rejection to cycle back to the beginning. The difference between absorbed and rejected heat, becomes the heat that is converted to work. Not during the two equal and opposite adiabatics. A pair of adiabatic processes will never create a "cold hole" because their work cancels each other and they transfer zero heat.

However? people accept that a heat pump absorbs heat from a cold sink by way of work input, it then must also reject heat to a hot source also requiring work input. The difference between absorbed and rejected heat, is the work that is added. Not during the two equal and opposite adiabatics. A pair of adiabatics will never pump heat, because their work cancels each other and they transfer zero heat.

Why do people not believe that one can adiabatically compress a gas, raising the temperature, to create a "hot hole" for free? The reverse of creating a "cold hole"? A pair of adiabatic processes will never create a "hot hole" because their work cancels each other and they transfer zero heat.

The second law basically states that you can't have one without the other. Engine heat-pump duality. Without the engine's heat rejection to a cold sink, a heat pump's C.O.P. would be 1.0, the same as for a resistance heater.

Hook the two together, a 25% engine to a 4 C.O.P. heat pump, and 100% of the heat will be returned to the hot source and zero will be rejected to the cold sink. Of course zero power will be available. Conservation of energy.

Carnot law is pure optimism. Please get used to it.
Nobody

Re: Carnot reveal for Tom

Post by Nobody »

I guess I should have added the following too:

Carnot engine efficiency:

n= (Th - Tc)/Th

Carnot heat pump C.O.P. (Coefficient Of Production):

C.O.P.=Th/(Th - Tc)

C.O.P. is just the inverse of n.
VincentG
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Re: Carnot reveal for Tom

Post by VincentG »

Carnot does not explain molecular anomalies. For instance, the immense force exerted by the phase change of water to ice. In the same way it does not game the kinetic energy gain of heated air, or inversely the energy potential from the molecular stillness of the cold.

Why is it encouraged to continue the development of nearly every other science, but this is written in stone as the end of the road?

I'm admittedly uneducated, but I agree with Mark Twain.
Tom Booth
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Re: Carnot reveal for Tom

Post by Tom Booth »

Nobody wrote: Tue Jul 11, 2023 7:22 am ....
Carnot law is a mathematical construct and provable only by mathematics. ...
LOL.... "Tom, I have concerns for your well being. ..." That's funny.

Your above statement regarding the Carnot "Law" I do not agree with.

The so-called law has a very definite (theoretical) basis in physical reality. It is the temperature difference, nothing more or less than that. It has both a physical (empirical) and a mathematical basis. As such it is subject to experimental testing.

If heat were actually a fluid, like water, in "reservoirs". One high and one low, I could see how in draining one reservoir into the other it might be "impossible" to utilize all the potential of the upper reservoir.

As the upper reservoir empties into the lower reservoir, the lower reservoir fills up higher, so the upper reservoir can "never" be drained completely.

So why should it not be possible to demonstrate such a physical reality by direct experiment?

Using actual water it is very easy to demonstrate at my kitchen sink with a couple glasses of water and some flexible tubing.

The atmosphere however, is a virtually infinite source or sink. If I have a finite heat source I should be able to "drain" that to the atmospheric sink 100% more or less, depending on the weather.

As interpreted and applied in academic courses on thermodynamics it is alleged that that is not possible and my finite heat resource can only be drained 20%

I can see how the conclusion is reached quite clearly because if you heat a mug of water in the microwave from ambient to boiling you have raised the temperature 20% (on the kelvin scale) so it can only be drained back down 20% Carnot efficiency is therefore 20% you cannot do any better than that.

That is a mathematical as well as an empirical reality.

Why do these academics make the assertion that you cannot have a "perfect" heat engine because it is impossible to reach absolute zero.???

If I run my heat engine on the glass of boiling hot water until "ALL" the heat is gone and the water is back at ambient, have I used ALL of that 20%???? it would seem so. Has the temperature of the water fallen to absolute zero? No.

IMO the Carnot limit REALLY meant, at some time in history that a heat engine could, at the absolute best, only utilize the heat available between the source and sink temperatures.

That is, if you heat the source up 10% on the kelvin scale, the engine cannot use more heat than what has been made available. Once that 10% has been used up the engine will stop, and because of friction, it will stop before that.

Perfectly reasonable.

But at some point some academic who did not really comprehend all this started teaching students this crazy idea that if you heat water up 10% on the absolute scale then only 10% of that 10% is available to run the engine and the other 90% of the heat used to boil the water has to be "rejected".


WHAT????

That's insane.

It's like saying if I give the bank $2 for change, the bank will only be able to give me back four cents in return, because two dollars is 2% of $100 so the exchange is limited to 2% and 2% of two dollars is 4 cents.

The Kelvin scale is like that 100% or $100 from which this exchange ratio is derived.

Now the "bank" is trying to tell me that the reason I can only get back four cents for my two dollars is, well, it's complicated and "can only be proven mathematically".
Nobody

Re: Carnot reveal for Tom

Post by Nobody »

Tom,

I'm going to ignore your bank and water analogies. Easily disproven. If you continue please equate temperature with the strength of gravity g. Acceleration strength. It is more appropriate. E=mgh.

You seem to think it is possible to get the same efficiency out of a 273K cup, 8oz, of water heated to 373K, as a, much larger volume of 273K heated to 274K with the same input energy.

Please show me a machine that can run off that same heat quantity after being put into the hull of the QE2 sitting in the north Pacific Ocean where it delta T is negligible.

Please show me a machine that can do so. Carnot law just says otherwise. Until you can build a machine, and show us the measured efficiency, and that it is better, plus, the mathematics that supports that claim, the Carnot claim will be supreme. Mathematics proves Carnot. If the engine runs from a delta T, it seems that larger would be better.

You can't build a "cold hole" without using up more work than you get back. Inequality of Clausius. Entropy increase. Would you like a list of irreversible processes?

You must think everyone is stupid, ignorant, and unmotivated. People are, and have been, trying to break the laws of thermodynamics and Carnot since before Carnot. They have been trying everything you talk about here. If you want to take away the cooling side of engines, go ahead. My guess is you will grow old, or will learn why it is impossible, as I have. I have not stopped trying. I've observed that other areas of engine design promise better returns. Not that they will pay either. Just an inkling and that they are more fun.

VincentG,
Carnot may not apply to phase change conditions, however entropy and the first and second laws do.
VincentG
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Re: Carnot reveal for Tom

Post by VincentG »

Nobody and everybody,

I'll offer an answer for the cold hole theory later but for now, keep in mind that those laws also apply to nuclear energy. Now, I am not equating a hot air engine to nuclear power, but is it that much of a stretch to imagine a process that lies between a horribly inefficient ICE/typical ECE and nuclear power?
stephenz

Re: Carnot reveal for Tom

Post by stephenz »

Tom Booth wrote: Tue Jul 11, 2023 9:42 am ../.. 20% ../..
Tom, where is the 20% coming from?
Tom Booth
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Re: Carnot reveal for Tom

Post by Tom Booth »

Nobody wrote: Tue Jul 11, 2023 12:31 pm Tom,

I'm going to ignore your bank and water analogies. Easily disproven.
..
Seems like an evasion. If it is so easily disproven why not do so now? I'm listening.
Tom Booth
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Re: Carnot reveal for Tom

Post by Tom Booth »

stephenz wrote: Tue Jul 11, 2023 1:35 pm
Tom Booth wrote: Tue Jul 11, 2023 9:42 am ../.. 20% ../..
Tom, where is the 20% coming from?
Which 20%?
stephenz

Re: Carnot reveal for Tom

Post by stephenz »

those 20%:
The atmosphere however, is a virtually infinite source or sink. If I have a finite heat source I should be able to "drain" that to the atmospheric sink 100% more or less, depending on the weather.

As interpreted and applied in academic courses on thermodynamics it is alleged that that is not possible and my finite heat resource can only be drained 20%
Tom Booth
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Re: Carnot reveal for Tom

Post by Tom Booth »

Nobody wrote: Tue Jul 11, 2023 12:31 pm Tom,

... If you continue please equate temperature with the strength of gravity g. Acceleration strength. It is more appropriate. E=mgh.

I don't believe that.

Gravity is appropriate in Carnot's water wheel because it is gravity that "pulls" water down from the high reservoir.

The molecular motion of gases is not influenced by gravity. A Stirling engine can operate upside down.

Show me that some force of this "thermal gravity" exists and you might have a point.
stephenz

Re: Carnot reveal for Tom

Post by stephenz »

natural convection?
Tom Booth
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Re: Carnot reveal for Tom

Post by Tom Booth »

stephenz wrote: Tue Jul 11, 2023 1:48 pm those 20%:
The atmosphere however, is a virtually infinite source or sink. If I have a finite heat source I should be able to "drain" that to the atmospheric sink 100% more or less, depending on the weather.

As interpreted and applied in academic courses on thermodynamics it is alleged that that is not possible and my finite heat resource can only be drained 20%
I'm basically driving 20% from the Carnot limit formula as applicable to most of my experiments involving running a Stirling engine on a "reservoir" of boiling hot water.

Water boils at 100°C

A typical ambient temperature for the cold reservoir is about 25°C

Plug that into the Carnot formula and you get roughly 20% "efficiency".

Why?

Because on the Kelvin scale 373.15°K (100°C) is 20% higher on the kelvin scale than 298° K (25°C) and no other reason.
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