Stirlingengineforum.com

Don't know what's "cold" about 100°C

Anyway, your making up numbers or "rocks" out of thin air imagination proves not anything at all.

The fact is the "Carnot engine" and/or cycle, as published in Carnot's book in 1824 "transported" ALL the "Caloric" trough to the "cold reservoir".

This was still true according to Kelvin's commentary in the 1987 edition.

at the end of a cycle of operations, when a body is left in precisely its primitive physical condition, if it has absorbed any heat during one part of the operations, it must have given out again exactly the same amount during the remainder of the cycle. The truth of this principle is considered as axiomatic...
the fundamental axiom adopted by Carnot may be considered as still the most probable basis for an investigation of the motive power of heat; although this, and with it every other branch of the theory of heat, may ultimately require to be reconstructed upon another foundation, when our experimental data are more complete. On this understanding, and to avoid a​repetition of doubts, I shall refer to Carnot's fundamental principle, in all that follows, as if its truth were thoroughly established.

https://en.m.wikisource.org/wiki/Reflec ... /Chapter_4

In other words Qc = Qh. According to the Carnot theory/engine/cycle, for at least 63 years. According to the Carnot/Kelvin theory, All the heat going into the engine continued on straight through to the "cold reservoir".

By 1900, Tesla, who had a photographic memory and read all the published scientific literature in 8 languages related in his article that this was still the case at that time.

Today, Wikipedia relates:

Sadi Carnot, who reasoned purely on the basis of the caloric theory, developed his principle of the Carnot cycle, which still forms the basis of heat engine theory

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

The same identical cycle is still taught in university courses and textbooks, unaltered. With a token acknowledgement that, well,... some infinitesimal, severely limited quantity of the heat gets transformed into work, along with an equation, which is pure "anti-perpetual motion guesswork".

Efficiency = Heat absorbed/work done by the engine.

η = W/Q1 = (Q1-Q2)/Q1

= 1- (Q2/Q1)

The quantity of Heat absorbed is Q1.

The quantity of Heat was rejected in Q2.

W represents how much work the system has completed.

https://unacademy.com/content/question- ... y-formula/


In the Carnot engine Q2 = Q1

Work = 0

By that, according to modern thermodynamics, heat engines are all impossible. The Carnot engine with zero work and zero efficiency, which converts zero heat into useful work output is the epitome of all heat engines.

Zero useful work output is the best anyone should ever hope to achieve.

Credit for use of the phrase "anti-perpetual motion guesswork" in reference to the Carnot efficiency equation, used in several of his papers:

https://www.researchgate.net/profile/Bo-Miao-4

Tom Booth wrote: ↑Wed Apr 17, 2024 6:18 am

Fool wrote: ↑Tue Apr 16, 2024 10:59 am Tom, by "removing rocks" you are reducing the inside pressure. ....

...That is why it will generate zero CYCLIC work. ...

Even your description conveys zero work. Rocks are removed, forward stroke. All the same rocks are put back on, return stroke. Equal and opposite "rock" work out and in. Zero cyclic total.

You can't beat Carnot. Lots of proof. Even your own thought example proves it.
...

Perhaps you make a valid argument. The same could be said, however, of Kahn's Carnot engine.


https://youtu.be/aAfBSJObd6Y


If not, why not?


He removes rocks to expand the gas then replaced all the rocks to compress the gas. If my "ideal" engine is bogus then the Carnot engine also does zero work and is just as bogus.

The Kahn Academy video leaves out the fact that because heat is added during expansion and removed during compression the rocks end up higher that at the beginning of the cycle. New Rockies are added from a lower reservoir. For the example I keep returning to, when the cycle is complete, they are 20% higher. 20% of the maximum height they reached during the cycle.

Your example, the rocks end up all back where they started. Zero change in height for zero change in heat.

matt brown wrote: ↑Wed Apr 17, 2024 10:31 pm Gadz Tom, for a guy who fancies himself as a world authority on engines, you must have missed that our common vertical piston configuration was called "inverted" in early ICE days, so "BDC" here in Vmin and "TDC" is Vmax.

If you (and anyone else) can't grasp source/sink issue (Carnot limit) from Khan's video, then you're wasting your time chasing the Holy Grail.

And as for any cold boiling nonsense, just clickbait. The video link that Fool supplied has the real story...very little water will flash to steam with pressure drop, surely nothing near vigorous boil. The latent heat of vaporization for water STP is 540 cal/g, and few molecules will have enough 'heat' to vaporize despite ANY pressure drop.

Tom's demonstration shows him pulling on the diaphragm, and pushing, to change the boiling, and he seems to think that isn't manipulating the internal system with work. Boiling in a vacuum is a work and internal energy process. Removing work causes a reduction in pressure, so the water is above the boiling point temperature briefly until temperature drops. It is adiabatic with work out.

If you want a heat transfer demonstration of cold boiling, remove the pump and put ice on top. Or, put your hand on the bottom in a cool room.

Matt, you can tell we are getting to him as his rebuttals are filling with more and worse ad hominems towards you, me , our education Carnot, Kelvin, Caloric and Kinetic Theories. All of which are useful if used properly, and even sometimes improperly. Education is the key to knowing how to use them. Carnot and the rest were brilliant for using what they had to work with. Our current theory is very robust if fully learned. He is twisting what we say in ever increasing misrepresentations.

This was still true according to Kelvin's commentary in the 1987 edition.

Actually the date was 1897. By 1987 the Caloric Theory had been abandoned in favor of the Kinetic Theory. Perhaps the fact that the old mathematics was reverified was missed by you? Thus, rendering all your comments about Conserved and flowing calorics, moot.

Taken as written, Kevin's comment violates the first law, conservation of energy. If all the energy goes straight through, like mass through a waterwheel, no energy can come out as work.

The point you keep missing is that all the mass of water goes through a waterwheel, yet not all the energy, of mass times height times gravity, comes out the bottom. Some of it comes out as work in the form a spinning wheel.

Caloric theory works just fine if the exact same thought is entertained. Same number of "heats", lower temperature, less energy. It leads to the definition of entropy. All of which was reverified as we discarded caloric heat carriers and replaced it with kinetic heat carriers, wiggling/vibration. More wiggling, higher temperature, higher energy, more heat-flow-potental. Higher adiabatic line, harder to recompress. Higher Tc, higher Qcz, higher adiabatic line.

If a waterwheel can put out work with all the mass going through, losing some of its energy by altitude drop, a heat engine can output work if all the caloric goes straight through losing some of its energy by temperature drop.

Tom Booth wrote: ↑Wed Apr 17, 2024 9:37 pm

matt brown wrote: ↑Wed Apr 17, 2024 8:56 pm

Tom Booth wrote: ↑Wed Apr 17, 2024 6:18 am
Perhaps you make a valid argument. The same could be said, however, of Kahn's Carnot engine.

https://youtu.be/aAfBSJObd6Y

If not, why not?

He removes rocks to expand the gas then replaced all the rocks to compress the gas. If my "ideal" engine is bogus then the Carnot engine also does zero work and is just as bogus.

Many of Khan's thermo videos are lacking. To simplify stuff, let's consider Khan's video as a crude Stirling cycle with 600k source, 300k sink, 12 equal rocks, an inverted piston, and a cylinder where temperature can be regulated.

(1) starting at BDC with 12 rocks and 600k cylinder, remove 6 rocks to get piston to TDC
(2) remove all rocks, and regulate cylinder to 300k
(3) put rocks back on, one at a time
(4) piston will move from TDC after 3 rocks
(5) piston will reach BDC with 6 rocks
(7) compare rock count and piston motion vs temperature
(8) news flash...rock count during 300k compression was 1/2 rock count during 600k expansion
(9) whereby Wpos/Wneg = .5 but any Wnet is in the 6 rocks we removed/discarded

Carnot wins again, this time with rocks...

LOL

Of course, with a mythical engine you can make up any nonsense you like. Including an engine that has full compression at BDC.

The guy putting on and removing rocks is still doing all the work.

Mythical negative output Carnot engine looses to any engine that actually exists.

Since in reality a Carnot engine passes ALL the heat through to the "cold reservoir' Q2 = Q1

Work output = big fat zero

Which is why it won't run at all without outside assistance.

Tom, it is logically consistent to supply example numbers to help explain the concept.

You say a Carnot is mythical, and then say "Since in reality a Carnot engine passes ALL the heat through to the "cold reservoir' Q2 = Q1". At best very entertaining.

By Kinematic Theory: all the energy, heat or otherwise can't go straight through a Carnot Engine. You are confusing Calorics with heat energy. Calorics are just carriers. They carry different quantities of heat as specified by the temperature. They go in the top at Th and come out the bottom at Tc. In the example I keep going back to. 400K and 300K, they have only 80% of the energy left. Same as water going through a waterwheel, height in 100' height out 80'. For 80% of potential left to run down hill. 20% comes out as work.

Tom Booth wrote:Zero useful work output is the best anyone should ever hope to achieve.

Using heat-addition only cycle, or adiabatic only cycle? Yes I totally agree.

Maybe it would be helpful to draw a distinction between passing "heat" though an engine and passing "energy" through an engine. And yes I know there's no such thing as heat. What I mean is a distinction between passing total temperature through v. passing total energy through?

Fool wrote: ↑Thu Apr 18, 2024 8:48 am

This was still true according to Kelvin's commentary in the 1987 edition.

Actually the date was 1897. ...

Obviously a typo, since the accompanying link I posted was to the 1897 edition. Sorry about that.

Fool wrote: ↑Thu Apr 18, 2024 9:08 am ...

Tom,...

You say a Carnot is mythical, and then say "Since in reality a Carnot engine passes ALL the heat through to the "cold reservoir' Q2 = Q1". At best very entertaining.
...

LOL

Geez, you got me. LOL

In reality, Carnot's theoretical, mythical, non existent engine, according to Carnot's and Kelvin's theories would pass through ALL the heat.

It's an expression. As if that really requires explaining.

Fool wrote: ↑Thu Apr 18, 2024 8:48 am .....
Perhaps the fact that the old mathematics was reverified was missed by you? Thus, rendering all your comments about Conserved and flowing calorics, moot.
...

I guess so...

"Reverified" how? When? By whom? Where? Using what methodologies? What experiments?

Throughout this thread you've been struggling unsuccessfully to do that by your own made up, convoluted, impossible "slight of hand" mathematics.

Why not just direct me to the relevant historic data when this "Carnot Limit" mathematics was "reverified".

Sorry, never happened.

If it had, this thread would have no purpose and we wouldn't be having this conversation.

Provide a citation/reference please to support your assertion: "the old mathematics was reverified", Specifically the Carnot efficiency limit formula, which by all appearances is nothing more than a measure of or restatement of the temperature difference in the form of a ratio. Hardly a "mathematics" at all.

High temperature is a, low temp is b, the difference is some percentage of the temperature scale.

The alleged controlling influence the temperature difference is supposed to have, according to the Carnot limit formula has never been verified.

If you think it has been, please provide the specific information requested. When, where, by whom, by what method etc.

Anything?

I'd love to see it.

So far, in ten years I've seen nothing.

Please! Please! Please...

Show me the "reverification".

Though there was never any verification in the first place. Just a hair brained theory based on an obsolete concept of "heat".

Fool wrote: ↑Thu Apr 18, 2024 8:48 am ...
If a waterwheel can put out work with all the mass going through, losing some of its energy by altitude drop, a heat engine can output work if all the caloric goes straight through losing some of its energy by temperature drop.

By Kinematic Theory: all the energy, heat or otherwise can't go straight through a Carnot Engine. You are confusing Calorics with heat energy. Calorics are just carriers. They carry different quantities of heat as specified by the temperature. They go in the top at Th and come out the bottom at Tc. In the example I keep going back to. 400K and 300K, they have only 80% of the energy left. Same as water going through a waterwheel, height in 100' height out 80'. For 80% of potential left to run down hill. 20% comes out as work.

Well, that's the THEORY. Still kicking around since 1824.

Now where is the evidence?

Any kind of actual verification (or "reverification").

A theory is only as good as it's success at predicting an experimental outcome.

All I've seen so far is failures.

Prediction: blocking the "flow of heat" with an insulation heat barrier between engine anf "sink" will cause a bottleneck, overheating the engine. The engine will stall.

Outcome; fail. The engine keeps running. (Sometimes running even better!)

Prediction,: with other avenues of heat conduction eliminated, the cold side temperature of the engine should still increase to throw off the "waste heat" carried through the engine via the working fluid.

Outcome: fail, the cold plate stays at ambient. In some cases, grows colder rather than warmer, even after many hours of operation.

Etc. etc.

"Prediction: blocking the "flow of heat" with an insulation heat barrier between engine anf "sink" will cause a bottleneck, overheating the engine. The engine will stall.

Outcome; fail. The engine keeps running. (Sometimes running even better!)

Prediction,: with other avenues of heat conduction eliminated, the cold side temperature of the engine should still increase to throw off the "waste heat" carried through the engine via the working fluid.

Outcome: fail, the cold plate stays at ambient. In some cases, grows colder rather than warmer, even after many hours of operation."

"Better"??? Where is your evidence? Power output? Zero. A magnetically levitated flywheel in a vacuum will spin a long time too. A device running in a cold room with zero power output, has plenty of cooling. I think you have heat loss in unexpected places. You refuse to try the experiment in a heated room or box, thus reducing any likelihood that it will be cooled accidentally. You insulated the piston side instead of turning it over and heating the piston side while insulting the flat side. Insulating the flat side would eliminate cooling by air breeze from motion of flywheel or piston.

Dynamometer: Rubber band/spring, ruler, hinge, string and weight, and an rpm reader.

Please do a well instrumented science experiment on a large power producing engine, rather than a hap hasard one. You are getting poorly gathered data that goes against modern theory, most likely the data is wrong. In other words, it is not proof. Just a curiosity.

This is not the thread to bring this up.

Tom Booth wrote:Anything?

I'd love to see it.

So far, in ten years I've seen nothing.

Please! Please! Please...

Show me the "reverification".

You've seen plenty. You just unfoundedly deny it all. This thread has mentioned several modern verifications. You just are closed off to them, and use misinformation to satisfy yourself.

Then Kahn Academy lectures are another series of Verification.

Over 200 years of building engines and not one has had an efficiency greater than the Carnot limit predicts, most not even half (Senft). No heat pump has had a COP greater than Carnot predicts. I do get tired of your demands for things that are so obvious. To me it's like someone demanding to prove the sky is blue.

What you should be looking for is why your data is wrong. I could help.

VincentG wrote: ↑Thu Apr 18, 2024 9:59 am Maybe it would be helpful to draw a distinction between passing "heat" though an engine and passing "energy" through an engine. And yes I know there's no such thing as heat. What I mean is a distinction between passing total temperature through v. passing total energy through?

All the energy entering the engine, leaves the engine. Zero is stored. Most of it leaves as heat to the colder surroundings. Some of the energy comes out as work to help us.

When an engine is at rest and started up, some initial energy is stored in the motion of the parts. When running steady state energy stored is cyclic increasing and decreasing but overall is zero. When the engine stops all stored energy is released. Especially after it has cooled off.