According to mainstream physics: Is heat "destroyed" in a heat engine?

[Tom Booth]

15 minutes ago, studiot said:

I'm suprised Tom didn't go back to the realy father of thermodynamics, that ancient Greek who thought the Earth was flat and that there were four elements earth, water, air and heat (fire).

So can I quote them to promote my flat earth leanings ?

Anyway going back to retrieve quotes from Carnot an his contemporaries it is not suprising the they talekd of 'destroying' heat.
After all they thought it to be a substance.

And their word for it was caloric, which  unfortunately survives to this day in French as Chauler, Portugese and Spanish as calor, etc.

Atom was another ancient Greek concept that we now understand quite differently from the original.

So what, our knowlesdge and understanding of physics has improved over the millenia so keeping older ideas is only useful if for engineers if it provides an easy route to calculation or to historians.

What you seem to be failing to understand is that the "destruction" of heat was a NEW concept based on the realization that heat is energy that changes form and not an indestructible fluid.

[studiot]

17 minutes ago, Tom Booth said:

concept based on the realization that heat is energy that changes form and not an indestructible fluid.

And who, exactly, realised that and when did this Eureka moment arrive ?

You have been noted as castigating Carnot many times for his 'belief in caloric'

 

[Boltzmannbrain]

7 hours ago, exchemist said:

Agreed. However the trouble with cranks, as some of us know to our cost from previous encounters, is that getting us to accept strange and potentially misleading terminology is quite often a rhetorical ruse to promote their crank ideas. In this case it is likely to be, in some way yet to be disclosed, his notion that the Second Law of Thermodynamics is false or can be broken. (This individual has spent over a decade, off and on, on various forums, obsessing about this.) This is why we are wary of agreeing with his peculiar statement without qualifying it. We would not be nearly so cautious if the poster had a track record of posting in good faith.

 

Yeah, I had a feeling this was a motivation.  Thanks for the backstory. 

[exchemist]

1 hour ago, studiot said:

I'm suprised Tom didn't go back to the realy father of thermodynamics, that ancient Greek who thought the Earth was flat and that there were four elements earth, water, air and heat (fire).

So can I quote them to promote my flat earth leanings ?

Anyway going back to retrieve quotes from Carnot an his contemporaries it is not suprising the they talekd of 'destroying' heat.
After all they thought it to be a substance.

And their word for it was caloric, which  unfortunately survives to this day in French as Chauler, Portugese and Spanish as calor, etc.

Atom was another ancient Greek concept that we now understand quite differently from the original.

So what, our knowlesdge and understanding of physics has improved over the millenia so keeping older ideas is only useful if for engineers if it provides an easy route to calculation or to historians.

Chaleur shurely? 😄

Chauler is a verb, meaning to lime or whitewash.

Here is a link to Carnot's original: http://www.numdam.org/item/10.24033/asens.88.pdf

Chaleur just means heat and, so far as I can see, will have long predated Lavoisier''s  scientific concept of caloric. Lavoiser seems to have introduced caloric because he realised the idea of phlogiston didn't work. 

 

 

[Tom Booth]

27 minutes ago, exchemist said:

Chaleur shurely? 😄

Chauler is a verb, meaning to lime or whitewash.

Here is a link to Carnot's original: http://www.numdam.org/item/10.24033/asens.88.pdf

Chaleur just means heat and, so far as I can see, will have long predated Lavoisier''s  scientific concept of caloric. Lavoiser seems to have introduced caloric because he realised the idea of phlogiston didn't work. 

 

 

Not to negate your point necessarily. But just to be clear, the excerpts cited that use the word translated "destroyed" are from Carnot's unpublished writings which remained unknown for some time.

In the meanwhile, Carnot's successors followed his published work promoting theories Carnot himself had already abandoned as reflected in the unpublished writings.

Edited February 15, 2023 by Tom Booth

[studiot]

30 minutes ago, exchemist said:

Chaleur shurely? 😄

I stand corrected. Thanks. +1

[Tom Booth]

1 hour ago, studiot said:

And who, exactly, realised that and when did this Eureka moment arrive ?

You have been noted as castigating Carnot many times for his 'belief in caloric'

 

I don't believe I can be legitimately accused of "castigating Carnot" the man. Only the primitive theory of heat as an indestructible fluid that flows from one "reservoir" to seek out another "lower reservoir".

I admire Carnot the man, for being, perhaps the first to discard his own theory. Unfortunately the world did not have access to his later insights for many years to come.

[studiot]

4 minutes ago, Tom Booth said:

I don't believe I can be legitimately accused of "castigating Carnot" the man. Only the primitive theory of heat as an indestructible fluid that flows from one "reservoir" to seek out another "lower reservoir".

I admire Carnot the man, for being, perhaps the first to discard his own theory. Unfortunately the world did not have access to his later insights for many years to come.

Note again you have avoided a direct question.  (That's the line with a question mark that you quoted).

 

As I understand Carnot's crowning glory it was the realisation that

"If you have a source of heat you can obtain work from it "

or words to that effect.

 

So please provide a proper reference with all important dates, as I requested.

 

[Tom Booth]

1 hour ago, Boltzmannbrain said:

Yeah, I had a feeling this was a motivation.  Thanks for the backstory. 

More slanderous lies.

My only motivation originally was to exhibit the recorded results of some experiments.

I proposed the idea that perhaps those results could be explained on the basis of conservation of energy. Heat being transformed into work, producing a cooling effect.

These were simple observations and speculations based on basic known  principles.

Your characterization is completely  unwarranted, unfair and untrue. I'm simply trying to get at the truth, and hopefully let the experimental results tell their story and let the chips fall where they may. I have no stake in the outcome one way or the other. Except that by understanding better how these engines actually work, perhaps some improvements could be made.

28 minutes ago, studiot said:

Note again you have avoided a direct question.  (That's the line with a question mark that you quoted).

 

As I understand Carnot's crowning glory it was the realisation that

"If you have a source of heat you can obtain work from it "

or words to that effect.

 

So please provide a proper reference with all important dates, as I requested.

 

I only know of the history as described by Carnot himself in his unpublished writings.

Many many experiments were cited by Carnot as being responsible for his change of mind on the subject of the nature of heat.

Quote

 

When a hypothesis no longer suffices to explain phenomena, it should be abandoned.

This is the case with the hypothesis which regards caloric as matter, as a subtile fluid.

The experimental facts tending to destroy this theory are as follows:

(1) .... (2).... (3)... etc. etc.

 

Read it for yourself.

The term translated "caloric" seems to be in question. I'm open to the possibility this may be a mistranslation.

Edited February 15, 2023 by Tom Booth

[studiot]

13 minutes ago, Tom Booth said:

I only know of the history as described by Carnot himself in his unpublished writings.

Many many experiments were cited by Carnot as being responsible for his change of mind on the subject of the nature of heat.

Then you shouldn't make claims you have no knowlege of and can't or won't back up.

You most definitely made claims about others than Carnot, naming several prominent workers from the past.

 

29 minutes ago, Tom Booth said:

Carnot's successors

 

 

 

14 hours ago, Tom Booth said:

  Quote

When work is transformed into heat or heat into work,
the 'quantity of work is dynamically equivalent to the
quantity of heat.

It has also been expressed in this way :

"When equal quantities of mechanical effect are produced by any means whatever from purely thermal sources,... equal quantities of heat are put out of existence... " (Kelvin).

This law has been confirmed in a variety of ways :

1. The experiments of Joule, Rowland, and others in generating heat by the expenditure of work.

2. The experiments of Him and others, showing that when work is done by a heat-engine heat disappears.

Henry Smith Physics for university students (Volume 2)

 

Need I go on to find more or even mention that dreaded word Stirling ?

 

2 hours ago, Tom Booth said:

What you seem to be failing to understand is that the "destruction" of heat was a NEW concept based on the realization that heat is energy that changes form and not an indestructible fluid.

You made these claims and I am asking for the third time for your references.

As a reference point and example Thompson is recorded as being the first to ues the term internal energy in 1852.

Quote

https://www.tau.ac.il/~tsirel/dump/Static/knowino.org/wiki/Internal_energy.html

The internal energy of a system is simply its energy. The term was introduced into thermodynamics in 1852 by W. Thomson (the later Lord Kelvin).

 

[Tom Booth]

2 hours ago, studiot said:

2 hours ago, Tom Booth said:

concept based on the realization that heat is energy that changes form and not an indestructible fluid.

And who, exactly, realised that and when did this Eureka moment arrive ?

I believe that (underlined) was your question you are demanding I answer. Correct?

Who was the first to realize heat is a form of energy that can be transformed?

As far as I know the realization came to many, gradually, over time, with continued experimentation.

In those unpublished writings Carnot proposed numerous additional experiments that could be or should be performed, in order to further progress, to gain more empirical data on the subject.

24 minutes ago, studiot said:

Then you shouldn't make claims you have no knowlege of and can't or won't back up.

You most definitely made claims about others than Carnot, naming several prominent workers from the past.

I've already cited the relevant quotations from Carnot, Kelvin and Maxwell previously in this thread. Other than that I'm not entirely sure what you are going on about as far as "claims".

[studiot]

13 minutes ago, Tom Booth said:

Other than that I'm not entirely sure what you are going on about as far as "claims".

Yes, you are correct. There were several versions of the caloric theory over time,

Which is why I said "dates are all important".

What someone may have though at one time could well have been quite different from what they thought 2o or 30 years lalter.

Here is a short history of Caloric and what went before and to some extent after with dates

 

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

[exchemist]

1 hour ago, Tom Booth said:

I don't believe I can be legitimately accused of "castigating Carnot" the man. Only the primitive theory of heat as an indestructible fluid that flows from one "reservoir" to seek out another "lower reservoir".

I admire Carnot the man, for being, perhaps the first to discard his own theory. Unfortunately the world did not have access to his later insights for many years to come.

It wasn't his theory, though.

It was Lavoisier's, which Carnot inherited as the then prevailing model and which he suspected was faulty, as some of your earlier extracts from his Appendix A showed.  

[Tom Booth]

6 minutes ago, exchemist said:

It wasn't his theory, though.

It was Lavoisier's, which Carnot inherited as the then prevailing model and which he suspected was faulty, as some of your earlier extracts from his Appendix A showed.  

The Caloric theory predated Carnot, but I'm mainly referring to Carnot's likening heat powering a heat engine to water going over a mill wheel. As far as I'm aware that was Carnot's original conception.

[exchemist]

36 minutes ago, Tom Booth said:

The Caloric theory predated Carnot, but I'm mainly referring to Carnot's likening heat powering a heat engine to water going over a mill wheel. As far as I'm aware that was Carnot's original conception.

Yes, Carnot applied the concept of caloric in that way in his analysis of heat engines. And got it essentially right. 

Edited February 15, 2023 by exchemist

[Ghideon]

1 hour ago, Tom Booth said:

The Caloric theory predated Carnot, but I'm mainly referring to Carnot's likening heat powering a heat engine to water going over a mill wheel. As far as I'm aware that was Carnot's original conception.

The opening question was "According to mainstream physics: Is heat "destroyed" in a heat engine?". Do you want the answer as stated by current mainstream physics of today? Or do you want the answer as it was in mainstream physics at some specific time in the past? (Or other alternative?). Since many historical references are brought up, can you clarify?

 

Edited February 15, 2023 by Ghideon

[swansont]

18 hours ago, Tom Booth said:

Fantastic.

Since for the most part an isothermal expansion is an unrealizable ideal not possible in a real engine we are pretty much in full agreement.

It’s perfectly fine to use idealized processes in one’s analysis.

And the point is that even if a process is not perfectly isothermal, it is possible to have work done by a change in pressure and volume, meaning such work is not derived from a change in temperature. 

Are we still in agreement?

[Tom Booth]

1 hour ago, swansont said:

It’s perfectly fine to use idealized processes in one’s analysis.

And the point is that even if a process is not perfectly isothermal, it is possible to have work done by a change in pressure and volume, meaning such work is not derived from a change in temperature. 

Are we still in agreement?

I guess not.

Isothermal or not, "heat" as such is being consumed, or used up.

If you walked past a fireplace and saw logs all afame in the hearth, then came back three days later and saw what appeared to be the same logs still burning, would you conclude that wood is not consumed by fire?

It is the same with Isothermal expansion, without heat being continually added there would certainly be cooling.

There would certainly be a temperature change if heat were not added to compensate for that being converted. Right? Do you disagree?

Do you think that because there is no temperature change there is no consumption of heat? Like the apparent eternally burning log?

2 hours ago, Ghideon said:

The opening question was "According to mainstream physics: Is heat "destroyed" in a heat engine?". Do you want the answer as stated by current mainstream physics of today? Or do you want the answer as it was in mainstream physics at some specific time in the past? (Or other alternative?). Since many historical references are brought up, can you clarify?

 

That heading was due to Swansont informing me that I am only allowed to ask questions about mainstream science.

Frankly I'm not particularly interested in past/present theories per se.

This thread originated in the Lounge on the assumption we would be free to discuss "anything" freely, there at least.

But there too, the thread was locked and sent to "Trash". Though it appears that Swansont has modified his admonition to ask questions "only about mainstream science". So mainstream science it is.

However, any thoughts on the subject are OK by me.

It appeared that the Maxwell's demon thread was closed because of what I wrote in this thread:

Quote

The cold produced by a heat engine is the result of destroying the heat, so that it no longer exists.

Apparently that comment was too much for Swansont.

Edited February 15, 2023 by Tom Booth

[Tom Booth]

I was mistaken, Swansont made that comment on a different closed thread: 

Quote

You can ask questions and get answers about mainstream physics. That’s all.

 

[Phi for All]

3 minutes ago, Tom Booth said:

I was mistaken, Swansont made that comment on a different closed thread: 

 

!

Moderator Note

We have rules about wild-ass guesswork when it comes to science. People like you waste a LOT of time with your obtuseness. This has been explained before, but you have a really shitty, shitty style of discussion. You push your ideas while ignoring replies that run counter to what you're claiming. That's just preaching, and we are a DISCUSSION forum with rules against preaching. You act like you're posing legitimate questions, but you're repeating the same mistakes, which get pointed out, and then you ask people to point out your mistakes, which again shows you aren't listening. 

I'm going to recommend we ban you, since you can't discuss in good faith and just seem interested in wasting everyone else's time.