Is Carnot efficiency valid?

[swansont]

18 hours ago, Tom Booth said:

As far as I understand the forum rules, it is apparently forbidden to bring up a "closed" topic. I believe I was previously banned from the forum as a result of just mentioning a YouTube video of one of my experiments that I had previously posted (in a topic that was closed), so I'm kind of in a bind and I'm probably already walking on thin ice with this topic as well, I imagine.

!

Moderator Note

Yes. If you keep insisting a claim is correct without evidence or considering the mainstream physics that’s offered up in rebuttal, we eventually get tired of it. There’s no point in discussion if all that happens is we go over the same ground.

Claims contrary to accepted physics must be supported by evidence. Repeating a claim is not evidence. Misunderstanding physics is not evidence of the physics being wrong, either

 

[Ghideon]

11 hours ago, Tom Booth said:

Oh well. Some food for thought anyway in connection with all this:

This could be a suitable label for the video as it is posted in the mainstream section on a scientific forum:

Quote

"NOTE: The video you are about to watch contains false and misleading information. The claims made in this video have not been scientifically proven and are not supported by evidence. We strongly advise viewers to approach this content with skepticism and to seek out credible sources for information."

 

1 hour ago, exchemist said:

Yes, Tom is a perpetual motion machine of the second kind devotee. He thinks all heat can be converted to work, with no waste heat rejected.  

Thanks for confirming my suspicions regarding the presented ideas.

[Tom Booth]

4 hours ago, swansont said:

!

Moderator NoteYes. If you keep insisting a claim is correct without evidence...

 

My efforts to present evidence have been continually and systematically thwarted.

The evidence is primarily in the form of video recorded experiments.

I'm not making any "claim" other than I've made such and such observation. Here is a video recording of my observation/experiment.

I am here, because I would like to get the views of others on the matter.

I'm going to run an additional experiment, or series of experiments using temperature probes as recommended by another forum member here.

Should I refrain from recording these subsequent experiments? Refrain from posting additional video?

It seems that is the case. When I post an experiment, a visual record of my procedure, and I'm here to elaborate on, answer questions, implement improvements in methodology and so forth, cooperating, considering any and all alternative explanation and points of view etc I get slapped with a moderator note, warning, demerit, locked threads, three day ban or just general insult and ridicule directed at my character and motives 

Why Tom is an "Over Unity" crank. A "perpetual motion" nut. An incompetent ignoramus who doesn't understand the terminology etc. etc.

Video of a seeming anomaly is forbidden but personal insults against the presenter of the evidence get a pass.

 

Andrew Hall is, or was a respected member of the Stirling Engine Society. Secretary I believe.

Anyway, he recently posted an interesting demonstration/experiment.

I would like to cite HIS video recording, including actual pressure and volume recordings, but am, under the circumstances reluctant.

If interested, I have devoted a thread on the SE forum to Hall's experiment, comparing the results of his with mine.

The thread there parallels this thread, but the SE forum has no restrictions or aversion to posting video.

I arranged a different setup for the next experiment using the temperature probes and did a kind of trial run, which gave some interesting readings (using the temperature readout on the thermal camera, I haven't drilled holes in the engine for the probes yet)

It looks as though the new arrangement should work better, I placed a section of truck radiator hose on the steamer pot to confine the steam to the bottom of the engine better and avoid having steam rising up through and possibly get under the Aerogel blanket on top of the engine.

https://stirlingengineforum.com/viewtopic.php?f=1&t=5497&sid=250a18d1aa52cce976579e3231fbb182#p18487

Edit: Sorry, I forgot I already posted here earlier about the radiator hose modification.

If I may, here is the Hall demonstration video:

 

 

Edited January 28, 2023 by Tom Booth

[swansont]

2 minutes ago, Tom Booth said:

My efforts to present evidence have been continually and systematically thwarted.

The evidence is primarily in the form of video recorded experiments.

You don’t need video to present the evidence that’s needed. You can just write down numbers. You can upload schematics if necessary. This has been pointed out to you several times over the rears

 

Quote

I'm not making any "claim" other than I've made such and such observation. Here is a video recording of my observation/experiment.

You appear to be claiming that thermodynamics is flawed in various ways. You can present results of experiments and it will take a lot less time to read than the 24 minutes of the video in your OP. (and not everyone can watch videos)

 

2 minutes ago, Tom Booth said:

I am here, because I would like to get the views of others on the matter.

I'm going to run an additional experiment, or series of experiments using temperature probes as recommended by another forum member here.

You should run an experiment showing how fast the cold reservoir heats up (it should start out colder than ambient; perhaps 0 degrees C, but with no ice) Do that with the engine running and without; the latter will give a baseline for losses to the surroundings) That will show heat flow into the cold reservoir. Reservoir volume should be known and the same in both trials. You should understand why this is a requirement.

 

2 minutes ago, Tom Booth said:

Should I refrain from recording these subsequent experiments? Refrain from posting additional video?

Refrain from posting videos: yes.

Take notes like any reasonable student or scientist would do, and report the results.

2 minutes ago, Tom Booth said:

It seems that is the case. When I post an experiment, a visual record of my procedure, and I'm here to elaborate on, answer questions, implement improvements in methodology and so forth, cooperating, considering any and all alternative explanation and points of view etc I get slapped with a moderator note, warning, demerit, locked threads, three day ban or just general insult and ridicule directed at my character and motives 

You were admonished after continuing to do it after being told not to.

2 minutes ago, Tom Booth said:

Why Tom is an "Over Unity" crank. A "perpetual motion" nut. An incompetent ignoramus who doesn't understand the terminology etc. etc.

Video of a seeming anomaly is forbidden but personal insults against the presenter of the evidence get a pass.

 

These are based on observations of what you’ve posted. They indicate you don’t understand the theory you’re critiquing. You’re focused on efficiency and seemingly befuddled by heat, are fixated on the caloric model (which was abandoned long ago) and don’t seem to get what an analogy is. Not much of this has changed over the years.

[Tom Booth]

14 minutes ago, swansont said:

...not everyone can watch videos)

 

You should run an experiment showing how fast the cold reservoir heats up (it should start out colder than ambient; perhaps 0 degrees C, but with no ice) Do that with the engine running and without; the latter will give a baseline for losses to the surroundings) That will show heat flow into the cold reservoir. Reservoir volume should be known and the same in both trials. You should understand why this is a requirement.

 

Refrain from posting videos: yes.

Take notes like any reasonable student or scientist would do, and report the results.

I can understand accessibility is a legitimate consideration that I should be more mindful of.

Thanks for the recommendations. 

It may take more time as I only have the one small piece of Aerogel so can't make a side by side comparison running vs. not running.

Starting out "colder than ambient" is interesting, but not sure how that could be implemented. Put the engines in a freezer?

Wouldn't that just make the freezer compartment the effective "ambient".

Also, a cold engine, if taken out of a freezer just before the experiment would not be equalized in temperature with the surroundings and would take in heat from all sides and all directions making it, I should think, virtually impossible to monitor or determine with accuracy where the heat might actually be coming from or how much from what source or through what medium.

Getting a baseline for the time it takes for a frozen engine to warm up is interesting though. I'll give it some serious thought.

[swansont]

3 minutes ago, Tom Booth said:

Starting out "colder than ambient" is interesting, but not sure how that could be implemented. Put the engines in a freezer?

Put a container of cold water on the cold reservoir surface. A small plastic bag, perhaps. Enough to cover the plate. You want a known (and fixed) thermal capacity, but not so big that the temperature change is hard to measure.

(I just put ice chips directly on it when I was showing off my stirling engine on a hot day to get it to run, but I wasn’t doing a controlled experiment)

[Tom Booth]

4 minutes ago, swansont said:

Put a container of cold water on the cold reservoir surface. A small plastic bag, perhaps. Enough to cover the plate. You want a known (and fixed) thermal capacity, but not so big that the temperature change is hard to measure.

(I just put ice chips directly on it when I was showing off my stirling engine on a hot day to get it to run, but I wasn’t doing a controlled experiment)

Again, a container of cold water, colder than the surrounding ambient, would absorb heat from all sides and all directions. If covered with insulation we are back to the same issue of the adequacy, conductivity, thermal capacity, etc. of the insulation.

Might just as well put a container of ambient temperature water on top of the engine and stick the whole setup in the oven. Relatively speaking it would be the same situation.

[swansont]

11 minutes ago, Tom Booth said:

Again, a container of cold water, colder than the surrounding ambient, would absorb heat from all sides and all directions.

Which is why you do a control run, with the engine not running.

11 minutes ago, Tom Booth said:

Might just as well put a container of ambient temperature water on top of the engine and stick the whole setup in the oven. Relatively speaking it would be the same situation.

No, that wouldn’t be the same. It might make the experiment harder, since the engine doesn’t actually do much work. But as long as you document all the pertinent detail, go ahead

[Tom Booth]

1 minute ago, swansont said:

Which is why you do a control run, with the engine is not running.

So we need to record the time it takes for a certain specific quantity of cold water sitting in a container on the engine (not running) to heat up under the influence of ambient heat.

Then, repeat the experiment with the engine running to see if there is a difference.

I can see a problem with that.

Is the steamer sauna running in both circumstances? If not then the conditions are not the same. The sauna machine emits heat to the general surroundings.

Another consideration is the insulating factor regarding the displacer inside the engine that the water is sitting on working up and down (or not), agitating the air helping to bring up the heat or if idle, blocking the heat due to it's insulating properties, or even acting as a conductor.

I'm thinking perhaps some very small heating element attached directly to the bottom of the engine would at least reduce the potential problem of the sauna heating up the entire surroundings and billowing steam.

We really want all the heat supplied to go into the engine and ONLY into the engine.

 

[Ghideon]

1 hour ago, Tom Booth said:

Why Tom is an "Over Unity" crank. A "perpetual motion" nut. An incompetent ignoramus who doesn't understand the terminology etc. etc.

I would rather say Tom creates some cool experiments and uses a variety of methods and equipment to observe the behaviour of sterling engines under different conditions. But when trying to explain the observed behaviour one can choose to relay on mainstream science or unscientific fringe stuff like Over Unity / Perpetual Motion. If seeking support for the second option on a forum devoted to the first option it should not be too surprising to meet some resistance.

I think I grasp where the basic misunderstanding of physics is; I might try to explain if there is some interest. 

[Tom Booth]

2 minutes ago, Ghideon said:

...

I think I grasp where the basic misunderstanding of physics is; I might try to explain if there is some interest. 

Sure, I'm all ears.

[Ghideon]

1 hour ago, Tom Booth said:

Sure

Let's try*. An ideally isolated and closed cylinder contains a piston. Insulation is ideal / perfect; no heat can flow in or out of the cylinder or through the piston and no gas can escape the cylinder or pass by the cylinder:

 

Heat is added (for instance through a temporary opening in the perfect insulation:

 

Since the gas in the lower compartment, below the piston, is heated the piston is pushed up. The heat source is removed and perfect isolation is (re)applied. The system is now at rest and will remain so indefinitely since no heat can be transferred in or out or through the cylinder:

Ok so far? If so we may move on to the next part.

 

*) I see this as an opportunity to learn; I'm sure expert members will highlight any errors in my attempt.

 

 

Edited January 28, 2023 by Ghideon
Duplicated image

[Tom Booth]

1 hour ago, Ghideon said:

Let's try*. An ideally isolated and closed cylinder contains a piston. Insulation is ideal / perfect; no heat can flow in or out of the cylinder or through the piston and no gas can escape the cylinder or pass by the cylinder:

 

Heat is added (for instance through a temporary opening in the perfect insulation:

 

Since the gas in the lower compartment, below the piston, is heated the piston is pushed up. The heat source is removed and perfect isolation is (re)applied. The system is now at rest and will remain so indefinitely since no heat can be transferred in or out or through the cylinder:

Ok so far? If so we may move on to the next part.

 

*) I see this as an opportunity to learn; I'm sure expert members will highlight any errors in my attempt.

 

 

You seem to be forgetting Newtons first law of motion.

[Ghideon]

6 minutes ago, Tom Booth said:

You seem to be forgetting Newtons first law of motion.

Thanks; we assume the device mass to be negligible and friction is neglected.  (It is an ideal setup intended to illustrate basic physical principles, not engineering) 

 

[Tom Booth]

3 minutes ago, Ghideon said:

Thanks; we assume the device mass to be negligible and friction is neglected.  (It is an ideal setup intended to illustrate basic physical principles, not engineering) 

 

Newtons first law of motion is a basic physical principle. To assume mass, friction etc. can be neglected would, I dare say constitute pseudoscience, or at least a departure from reality.

BTW I noticed the thread has been moved to the "pseudoscience and speculations" department.

The rules include:

 

"Some kind of scientific model, comparison with evidence, specific predictions or other ways of falsifying your idea are a MUST. Consider the first question you must address as "How could this be tested to ensure that it's true?" That's what a model does it allows one to predict outcomes under specific conditions so that they can be compared with experiment."

What I am asking is when and where have these common sense rules been applied to the Carnot efficiency limit equation?

I can find no actual historic record of any such thing. This led me to ask the above question: "How could this be tested to ensure that it's true?"

 

[studiot]

All the basics necessary to compare the stirling (Ghideon please note correct spellung  -  sterling refers to money, gold and silver) cycle with the carnot cycle are in this excellent extract. It also provides conventional labelling to aid common discussion.

 

 

Edited January 28, 2023 by studiot

[Ghideon]

3 minutes ago, Tom Booth said:

Newtons first law of motion is a basic physical principle. To assume mass, friction etc. can be neglected would, I dare say constitute pseudoscience, or at least a departure from reality.

 

You can for instance neglect friction if the friction is very low compared to other forces. It does not mean friction is exactly zero. It means that the friction is low enough to allow for other forces, more important to the discussion, to dominate. 

But if you wish to complicate things, feel free to modify my example. It will not change the end result or principles, but likely make the discussion more complicated than necessary. 

12 minutes ago, studiot said:

sterling refers to money, gold and silver

Thanks; I need to update the spelchek on my computer. 

[Tom Booth]

6 minutes ago, Ghideon said:

You can for instance neglect friction if the friction is very low compared to other forces. It does not mean friction is exactly zero. It means that the friction is low enough to allow for other forces, more important to the discussion, to dominate. 

But if you wish to complicate things, feel free to modify my example. It will not change the end result or principles, but likely make the discussion more complicated than necessary. 

Well, Studiot has posted the PV diagrams for the Stirling and Carnot cycles (idealized).

It should, I think be noted that BOTH include adiabatic expansion AFTER the removal of the heat source and isolation of the cylinder.

BTW your images are not displaying.

 

Edited January 28, 2023 by Tom Booth

[studiot]

12 minutes ago, Ghideon said:

Thanks; I need to update the spelchek on my computer. 

Make that check out to studiot in sterling please.

6 minutes ago, Tom Booth said:

It should, I think be noted that BOTH include adiabatic expansion AFTER the removal of the heat source and isolation of the cylinder.

Did you not read the associated text.

Only the Carnot includes adiabats

Edited January 28, 2023 by studiot

[Ghideon]

29 minutes ago, Tom Booth said:

BTW your images are not displaying.

I'll try to fix that.

[Tom Booth]

1 hour ago, studiot said:

Make that check out to studiot in sterling please.

Did you not read the associated text.

Only the Carnot includes adiabats

My apologies. You are correct.

Feel free to continue. I'm interested in seeing where you might be going with this.

BTW, thanks!

I've seen various PV diagrams probably a thousand times and kind of just assumed the Stirling cycle was more or less the same as the Carnot and I guess took the "constant volume" processes as adiabatic, since, how could there actually be any "constant volume" with a piston attached to a crank?

Your comment has prompted me to look at Stirling's old patent drawings:

 

A rather complicated linkage system there!

Constant volume heat addition would make a heat engine, possibly, have more torque, more like an IC engine, if the heat and pressure had more time at TDC to build up pressure.

It might be interesting to try and replicate this linkage system.

[Tom Booth]

5 hours ago, swansont said:

Which is why you do a control run, with the engine not running.

No, that wouldn’t be the same. It might make the experiment harder, since the engine doesn’t actually do much work. But as long as you document all the pertinent detail, go ahead

What I mean is, by introducing cold water into a warmer environment, the water will heat up because of the higher temperature surroundings, AS IF placed in an oven, regardless of what the engine does or doesn't do.

Still, some sort of small water bath or perhaps conductive gell on top of the engine under the insulation could add some thermal stability making the thermometric readings easier, but having the water colder than the ambient just introduces a new pretty wild variable and instability to the system.

How to ensure a constant degree of coldness would be an issue. The source of heat that caused the water to heat up, which it certainly would do when introduced to a warmer environment, becomes less certain. etc. etc. etc.

I've been thinking about how to deal with the displacer agitating the working fluid issue and may have come up with a solution.

My tentative hypothesis is that I'm not seeing much heat at the presumed "sink" due to the engine converting the heat to mechanical "work" output as well as the specific sequence of expansion and contraction of the working fluid by the piston. Principally, the gas in the engine is being cooled down by the work performed during rapid (adiabatic) expansion.

A comparison could be made by replacing the piston with a immovable plug in the cylinder and working the displacer with a servo mechanism.

I've done something similar previously using the Arduino programmed to actuate a servo motor to move the displacer.

This should replicate all the conditions excepting the compression and expansion of the working fluid by the piston.

 

 

[Ghideon]

On 1/26/2023 at 11:05 AM, Tom Booth said:

The "heat" of the particle does not need to be subsequently removed to a sink after this "fall" in temperature. The heat (motion/kinetic energy) has already been transfered to the piston and transformed into mechanical motion.

The whole Carnot water mill idea is juvenile and should be completely discarded once and for all. There is no "benefit" in it whatsoever.

 

On 1/27/2023 at 9:54 PM, Tom Booth said:

In this thread I'm just trying to find out basically, If I supply 500,000 joules of heat to a Stirling engine and  the Carnot efficiency limit calculations reveal that at best, only 100,000 joules of that heat can be converted to work, why can't I seem to find the other 400,000 joules?

Why is my engines "sink" not heating up more than it appears to be, especially when smothered by  insulation?

Maybe it is heating up under the insulation. So why doesn't it stop running?

 

On 1/26/2023 at 1:09 PM, Tom Booth said:

If the Carnot efficiency be 20% then supposedly, only 20% of the heat supplied (above the ambient baseline) will be available to convert into "work" output. The other 80% of the heat supplied MUST be eliminated, "rejected" to the sink or "cold reservoir". (According to generally accepted theory ala Carnot limit)

So where is the misunderstanding?

If your hypothesis is correct* one consequence is that it allows for less complicated devices to act as heat engines and it also allows for over unity devices**. Since over unity devices / perpetual motion does not exist according to established theories there is a misunderstanding somewhere. Looking at a simpler devices (compared to a complete Stirling engine) may be helpful. 

 

(I'll try to fix the missing images later)

 

*) As far as I can understand your hypothesis by reading your comments, reading between the lines and the fact that link to over unity device support is posted.

**) @sethoflagos raised a related point already; it might have been lost in all the details about the experiments

On 1/27/2023 at 3:20 PM, sethoflagos said:

If the Carnot limit was only a little bit of an underestimate, we'd have over unity-machines and all that nonsense. 

 

Edited January 29, 2023 by Ghideon
Reference to @sethoflagos 

[Tom Booth]

1 hour ago, Ghideon said:

 

 

If your hypothesis is correct* one consequence is that it allows for less complicated devices to act as heat engines and it also allows for over unity devices. Since over unity devices / perpetual motion does not exist according to established theories there is a misunderstanding somewhere. Looking at a simpler devices (compared to a complete Stirling engine) may be helpful. 

 

(I'll try to fix the missing images later)

 

*) As far as I can understand your hypothesis by reading your comments, reading between the lines and the fact that link to over unity device support is posted.

Maybe someone can explain to me how and/or why if I SUPPLY by heating, with some actual fuel or other ACTUAL, REAL, FACTUAL heat source, such as an electrical heating element 500,000 Joules of very palpable heat 400,000 joules of heat must GO MISSING or we are threatened with the dread "OVER unity" ???????

As I vaguely understand the so-called "Over Unity" concept, which I by the way DO NOT espouse in any way personally that would constitute a ratio of 500,000 Joules in and > 500,000 Joules out. 500,000 joules SUPPLIED by ME or my heating element or whatever and some additional amount supplied by the "Orgone energy" or some such preposterous nonsense.

I'm in no way talking about getting something for nothing. I'm not talking about drawing energy from some Cosmic Either Force, background "Zero Point Energy" or any such similar nonsense.

500,000 Joules SUPPLiED.

ACTUALLY supplied.

What actual mechanism, force or power determines that only the completely arbitrary amount of (at least) 400,000 of those VERY REAL supplied quantities of measurable heat must end up at some specific place designated "Cold Reservoir".

We are not talking about losses to friction or other known causes of inefficiency such as stale fuel, water in the grass tank, lack of lubrication, poor ignition, clogged catalytic convertor etc etc

I'm not a physicist. Just a simple engine mechanic/repairman (person) Engine problems have causes that can usually be identified and repaired.

This "Carnot Limit" has just, allegedly swept away 400,000 Joules of perfectly good heat for no apparent reason whatsoever.

What rational basis is there for this mathematical derivation?

I'm not talking about utilizing heat from one "reservoir" either. I'm talking actual ADDED heat above the surrounding ambient.

If I lift up 500,000 gallons of water and let it run through a turbine can only 100,000 gallons be utilized to turn the turbine?

But if I "lift up" 500,000 Joules of heat 400,000 Joules DISAPPEARS or allegedly MUST be unusable.

BECAUSE??????

People THINK some guy 200 years ago declared it so (though he actually didn't, but if he did, at any rate, made a retraction).

Well somebody later took what he said and tried to represent it as a formula?

We are talking about a very real, measurable, palpable quantity of energy being forcibly abducted, conveyed across a distance "rejected" to the "Cold Reservoir".

This is a singularly remarkable phenomenon without precedent in the annuls of science, is it not? When a very real quantity of energy is transported from one place to another without any apparent cause.

"ENTROPY" ?

I can see some losses as a result of "entropy", friction and so forth, maybe. Like resistance in electrical wires. Some small percentage of loss is inevitable. Unavoidable.

Some heat will be conducted away from our heat engine, get through the insulation etc. Understandable.

We are however talking 80% here. With NO Explanation other than a simplistic formula concocted two centuries ago originally based on a now discarded theory of heat and apparently reinterpreted several times as there was no absolute temperature scale when Carnot made his postulates.

Nobody's talking about getting MORE out than what was put in or "overunity".

We are talking maybe A Joule or two LESS UNDERUNITY.

Maybe 500,000 joules in and 150,000 joules out, by maybe reducing parasitic heat loses or reducing friction or whatever.

No "overunity" in that, as far as I can see.

Where is the "overunity" in 500,000 Joules input and just 100,000 + 1 Joules output ?

That is nowhere even close to "overunity" we are miles away from "overunity".

 

What is the justification for this alleged MASSIVE deficit?

If someone deposited $500,000 in the bank and then came back the next day and found that $400,000 had been mysteriously withdrawn, wouldn't that person be asking some questions?

What does the teller have to say?

Sorry sir, that's just ENTROPY. You may withdraw up to $100,000 minus some early withdrawal penalties and fees but your other $400,000 has disappeared as a result of entropy.

Have a nice day!

 

Edited January 29, 2023 by Tom Booth

[sethoflagos]

1 hour ago, Tom Booth said:

Maybe someone can explain to me how and/or why if I SUPPLY by heating, with some actual fuel or other ACTUAL, REAL, FACTUAL heat source, such as an electrical heating element 500,000 Joules of very palpable heat 400,000 joules of heat must GO MISSING or we are threatened with the dread "OVER unity" ???????

Because it didn't "GO MISSING"! 

500 kJ of heat @ 500 K has been transformed to 100 kJ of Shaftwork plus 400 kJ of heat @ 400 K 

It's still there but at a lower temperature.

Add a second machine operating between 400 K and 300 K and that 400 kJ of heat @ 400 K can be further transformed into another 100 kJ of Shaftwork plus 300 kJ of heat @ 300 K

On some space base for example with ready access to a cryogenic heat sink, you can potentially recover almost all of the original 500 kJ of thermal energy.

Just recognise that extracting the kinetic energy from slow moving particles requires contact with particles that are almost stationary.

14 hours ago, Ghideon said:

I think I grasp where the basic misunderstanding of physics is. 

I think one of the main issues is a very confusing terminology.

In the above example we have one (ideal) machine with a 'thermal efficiency' of 0.20 coupled to another with a 'thermal efficiency' of 0.25. Normally when we combine various efficiencies in series we multiply them together and would expect an overall efficiency of 0.05. And yet here we get an overall 'thermal efficiency' of 0.40. It sends a very odd message.

To a practical layman, a low efficiency figure implies some failings in the design that can be incrementally improved with a little attention to detail. This is an entirely understandable viewpoint to take.

But the above examples are idealised, 'perfect' machines with no avoidable losses. By any reasonable definition they should be classed as 100% efficient.

As they would be if instead of W/Q_H we accepted the Carnot limit for what it is and used

Machine Efficiency = W/Q_H x T_H/(T_H - T_C) 

Edited January 29, 2023 by sethoflagos