Is Carnot efficiency valid?

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44 minutes ago, exchemist said:

Yes you are quite right. Your diagram represents the Carnot cycle efficiency formula in the the form η=(TH - TL) / TH .  The length of the line from absolute zero to TH is 100% and, using the temperatures you have chosen, the length of it to TL is 80%.  That's all it is.

However what I think some other posters have been trying to do is explain how that very simple formula for the maximum possible efficiency is derived.

That too is fairly simple, but it does require you to understand the gas laws and what an isothermal and an adiabatic process are. The Carnot cycle simply applies these to a fixed amount of gas doing work by expanding against a piston and then being cooled so that it can repeat the cycle and do more work.

So if the gas laws are true, the Carnot efficiency formula is true.

More detail here:

Let me ask what I believe is a pertinent question as when it comes to mathematics, I got as far as trigonometry. Differential calculus and such is a bit over my head, so perhaps there is a gas law expert or two or more here that could figure this out.

You stated above:

Quote

The Carnot cycle simply applies these to a fixed amount of gas doing work by expanding against a piston and then being cooled so that it can repeat the cycle and do more work.

There is this PV diagrams that was generated in real time taking real measurements using an LTD Stirling engine very much like the one I used I'm my experiment.

The horizontal line at 0 (left hand side of the graph) cutting through the center of the ovals represents atmospheric pressure.

The narrower oval in the center area was generated with the engine running no-load.

The larger oval was generated with the engine under load.

These are actual readings taken in real time.

The diagram indicates that both under no-load and load conditions the internal pressure of the engine falls below the outside atmospheric pressure.

I have confirmed this with the researcher who did the experiment. The center 0 line cutting through the middle is atmospheric pressure and the internal pressure, especially under load, (with addition shaft work, aside from simply rotating the flywheel) drops below that line.

My question is, I would think that such a drop in pressure would corelate with a corresponding drop in temperature as well.

The problem with taking temperature readings is that with rapid compression and expansion the working fluid temperature fluctuates rapidly and there are apparently no probes responsive enough to record these fluctuations in real time.

However, using the gas law, could the temperature at any point on this graph be mathematically calculated?

My assumption is that cooling from expansion work causes a drop in temperature which subsequently results in the recorded pressure drop.

Of particular interest is the increase in the pressure drop which to me implies an increase in the temperature drop with the increase in work output.

Also, would the pressure falling below atmospheric pressure not also indicate that the temperature must have also fallen below the atmospheric (ambient) temperature?

Edited by Tom Booth

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21 hours ago, Tom Booth said:

Perhaps. Certainly worth experimenting with, IMO.

Thanks for the reply. some further reasoning about the experiment: Let's again assume one engine, per your initial setup. Insulation is good and we have means to measure the temperature at the cold side and the hot side. At the start the cold side temperature is same as ambient (room) temperature.

What should we look for when the engine is started? Is it correct that you predict that the temperature will drop below ambient when engine is running*?

Assume the heat added on the hot side is not the maximum what the engine can handle. So therefore we can increase the temperature on hot side . What result do you predict on the cold side? Will the temperature drop further on the cold, isolated side? I ask since this could be easier to measure; we may check the temperature differences and trends and maybe easier get rid of errors.

(* I am aware of the implications of this ...)

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20 minutes ago, Ghideon said:

Thanks for the reply. some further reasoning about the experiment: Let's again assume one engine, per your initial setup. Insulation is good and we have means to measure the temperature at the cold side and the hot side. At the start the cold side temperature is same as ambient (room) temperature.

What should we look for when the engine is started? Is it correct that you predict that the temperature will drop below ambient when engine is running*?

Assume the heat added on the hot side is not the maximum what the engine can handle. So therefore we can increase the temperature on hot side . What result do you predict on the cold side? Will the temperature drop further on the cold, isolated side? I ask since this could be easier to measure; we may check the temperature differences and trends and maybe easier get rid of errors.

(* I am aware of the implications of this ...)

That there might actually be a refrigerating effect at the cold heat exchanger, I would prefer to consider unproven, untested wild speculation that goes way beyond the simple demonstration of the deposition of waste heat predicted by the Carnot (so-called) efficiency (so-called) equation.

A point brought up is that we don't actually know the exact amount of heat going into the engine. We don't know the actual work being done, so it is not possible to make assumptions about any temperature readings at the sink.

To my mind 80% of the heat supplied from actively hot boiling water, (not just a warm cup of coffee on its way to cooling down) is way over the limit of what this little engine is rated to handle by the manufacturer. (I think the specifications state no more than 80°C if I recall correctly, I can check on that)

But, to be fair, the working fluid is air, which is an extremely poor conductor.

What differentiates things though is inside the engine the displacer is being worked up and down continually accelerating convective heat transfer into the engine (presumably). The sink has been insulated with progressively higher and higher grades of insulation. (presumably)

It is not inconceivable that acting as an absorber/conductor Aerogel, or other insulating material might actually serve to somewhat INCREASE heat conduction away from the engine infact also increasing surface area for heat dissipation to the actual or final ambient "sink".

I don't contest the validity of such arguments (much).

All I know is that the result MANY Stirling engine enthusiasts and model engine builders on the forum expected, (including myself to a great degree) did not take place as predicted.

Instead, in earlier experiments, the engine actually ran faster, as my previous outlandish theory about expansion work cooling predicted.

I'm honestly not trying to "prove" any one theory over another, I would just like to know, is this Carnot efficiency something that can be demonstrated experimentally.

I thought my insulation idea was a surefire test, but apparently not so much.

I suppose proving an alternative hypothesis would tend to negate the former view, but to me that seems like a long shot, and proving me wrong does not exactly validate the Carnot efficiency formula.

After 200 years, demonstrating the correctness of the formula experimentally should not be difficult. It should perhaps be a routine high school science class experiment.

Perhaps it is, but if so, why withhold that information?

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1 hour ago, Tom Booth said:

I'm honestly not trying to "prove" any one theory over another, I would just like to know, is this Carnot efficiency something that can be demonstrated experimentally.

I did not ask for a complete explanation or theory, just if you had an idea what to look for in the experiment or what to expect; it may trigger new ideas about how and where to measure.

1 hour ago, Tom Booth said:

After 200 years, demonstrating the correctness of the formula experimentally should not be difficult. It should perhaps be a routine high school science class experiment.

I did a quick check* Stirling engines are common among the suppliers of school material so there is at least a market for Stirling engines in education. I do not know the percentage ofd students that perform experiments but it was mandatory when I studied in a tech oriented school (a long time ago).

1 hour ago, Tom Booth said:

Perhaps it is, but if so, why withhold that information?

What do you suggest the answer to be?

Anyway, it is not withheld, examples from schools are easy to find on google or other search engine of your choice.
Possible reasons for the numbers of hits to be limited:
-information about minors and their school work may not be freely published online due to local laws.
-The topic is not very interesting; I don't for instance see many releases of kids confirming Pythagoras or that their physics task found F=ma to be correct.

*) Locally, may not apply globally

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Carnot efficiency properly applies to the Carnot engine, I suppose, but allegedly the Carnot engine has an efficiency that NO OTHER engine can exceed.

Stirling engines are at least, theoretically supposed to be able to approach the carnot limit, but at any rate a Stirling engine being probably less efficient, but certainly no more efficient, should if anything "reject" MORE heat at the sink not less than predicted by the equation, so therefore should be suitable as a stand in for a Carnot engine.

Would it be possible for a Stirling engine to be LESS efficient than a Carnot engine and yet also "reject" less heat, percentage wise?

I'll concede, we don't have enough information to draw a conclusion at this point. So how to proceed?

I think the idea of putting two (or more) engines with the sink sides adjoined would largely solve the problem of ambient heat infiltration from the environment. No heat would be able to reach the 'sink" except through either one or the other engine. This simplifies  measurements by eliminating the ambient "wildcard" contributing unknown quantities of heat into the "cold reservoir".

Other suggestions for comparative analysis, measuring heat transfers with the engine running vs. not running might yield additional data.

I attempted such a comparative experiment previously which I ran several times using different quantities of ice.

I placed a non-operating Stirling engine on a cup of ice (surrounded by insulation) and recorded the time it took for the ice to melt. Then repeated the experiment with the engine running.

In every instance, running/not-running the engines on cups of ice, as well as single ice cubes added to cups of ice water, the ice or ice cube invariably took longer to melt when under a running engine vs. the "dummy" inoperative engine.

Most people on the forum predicted the opposite result, due to the running engine actively churning the working fluid, presumably transporting heat to the sink in an active way, while the "dummy" engine was just sitting there.

A review of all the tests indicated that the ice took 15% more time to melt under the running engine than under the inoperative engine.

43 minutes ago, Ghideon said:

I did not ask for a complete explanation or theory, just if you had an idea what to look for in the experiment or what to expect; it may trigger new ideas about how and where to measure. (...)

I've developed a more or less complete theory of an alternative "Stirling" engine cycle, to be sure. But I'm not here to promote that.

I was previously banned from the forum for "soapboxing" for, I assume, that very reason.

Since 100% of my "evidence" is digital video recordings and other data I've made widely available on the internet, I'm not allowed to post or link to here it puts something of a cramp in my style.

However in attempting to obey the forum fules, I'm then accused of being "reluctant" to present my theories and evidence or "running scared"

At any rate MY theories are NOT the Carnot limit equation, were developed entirely independently from my own observations, research and experiments, some of which includes making various modifications to "stock" model engines.

I'm not at all "reluctant", rather I feel severely hampered by the restrictions. No video, no links? Presenting experimental video recorded evidence is soapboxing?

My explanations must conform to previously known "ideal" processes (isothermal or adiabatic) well sorry but if those are the rules, discussion of any novel findings is rendered impossible. That is not due to me running away. But it's not really appropriate to a thread devoted to demonstrating the factuality of the Carnot equation either.

Best I feel I could do is start another thread and C/P the data I've already posted or uploaded from other forums, and maybe post written descriptions of the experiments, but I already had other threads here that were abruptly closed, then reprimanded and banned for simply "bringing up" the same.

I guess I'm doing it again, just mentioning I have a YouTube  channel, apparently.

So damned if I do and damned if I don't (present my own evidence or theories anywhere in this forum).

Edited by Tom Booth
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Maybe it would be OK to post these two images:

The first image is an actual real-time PV diagram generated by sensors placed on or in a running Stirling engine (again LTD type as in my experiment presented here) the isotherms however are from a different chart superimposed over the actual PV diagrams so should not be considered in any way real or accurate but just my attempt to get some idea what might be going on temperature wise I side the engine.

The second diagram is my attempt at portraying my "alternative" Stirling engine cycle.

That was done a fairly long time ago however and I should probably add a few details and explanatory notes, but more or less still representative of what I THINK probably goes on inside (and to some degree outside) a running Stirling engine.

The numbers appended to both 1,2,3,4,5 relate one chart to the other.

#5 is duplicated on the PV diagram because it represents that entire section.

In other words that entire section 5,5 in the PV diagram is what is described and pictured in the other chart at #5 where the cycle cuts across the isotherms and a rather steep cooling occurs due to expansion work.

I called this adiabatic but that is only because that was the best description I had at the time but there naturally would be some heat transfer by both work on the outside atmosphere by the piston as well as simultaneously into the engine due to the colder than ambient temperature reached by the working fluid. Some relatively minor details are not specifically represented.

The words "Temperature Increasing" are from the superimposed isotherm chart and is not part of my evaluation but refers to the diagonal red arrow showing the direction of temperature increase for the isotherms.

The red horizontal line, my estimate of where atmospheric pressure might be, should probably be a bit lower. The actual weather conditions, atmospheric pressure at the time readings were taken are unknown (to me at this time).

If a clear day with a high pressure system in the area, perhaps it is close to being accurate, at any rate the diagram and the atmospheric pressure is typical of other similar real-time PV recordings of Stirling engines (one posted earlier for example where atmospheric pressure was represented by the horizontal line at 0.

Edited by Tom Booth
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As far as "atmospheric pressure", it has crossed my mind that a perfectly horizontal line is probably slightly inaccurate, by how much I couldn't say.

In other words the piston moves out against atmospheric pressure. How much of the atmosphere is actually displaced and to what extent?

Presumably this would cause a localized pressure increase in the cylinder immediately above (on the outside/atmosphere side of) the piston.

During contraction of the working fluid the returning atmosphere rushing into the cylinder wod likely be trailing behind somewhat, so effectively, "atmospheric pressure" acting on the piston would not actually be entirely stable but would increase slightly with expansion of the working fluid and decrease slightly with contraction.

Significance? Probably none. Possibly a slight heating and cooling of the air above the piston in reverse of the heating and cooling of the internal gas.

Well, my infrared camera showed a localized "hot spot" in the power piston area. Friction? Localized compression? Maybe  the Hot interior of the engine showing where insulation was lacking at the piston?

The isotherms superimposed are only meant to be vaguely suggestive.

Likely the temperature is not uniform. Remember the working fluid is divided roughly into two compartments one hot and the other cold

In my chart, the snowflake/crystals are meant to represent that the cold side working fluid has dropped in temperature below the temperature of the heat exchanger. At that point however the working fluid has been displaced almost entirely to the cold side.

Logically the engine takes in or absorbs some heat into the cold working fluid at that point. But the heat source is covered.

Conclusion?

The cold side "sink" is being chilled during expansion similarly to how an expanding refrigerant chills a refrigerator.

Likewise we see the reverse during compression. Some heat is being returned to the hot side back to the heat source.

The engine is acting as a heat pump.

Google, in a real word attempted application, wanted to use Stirling engines on their data centers to cool the building and generate electricity.

It didn't work out.

The Stirling engines acted like insulators, keeping the data center hot.

So what does this do to "...a fixed amount of gas doing work by expanding against a piston and then being cooled so that it can repeat the cycle and do more work."

"Being cooled" ?

Is the gas "being cooled" by the sink?

How is that possible if the working fluid is actually refrigerating the sink, acting like a heat pump?

I'm not trying to prove a theory, just drawing tentative conclusions based on the available data.

Edited by Tom Booth
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Speaking in broad terms, in designing a Stirling engine, It would seemingly be important to know how the engine actually functions.

Apparently, not like a water wheel so much as a dam that rather than facilitating heat flow, causes it to back up. Resists the natural direction of heat migration, with the exception of one outlet. The piston.

The difference though, between a Stirling engine and a turbine in a penstock is that there is not actually any material fluid flow through the piston Only transfer of kinetic energy.

My little engine in this experiment came with a graphite piston. Graphite is an excellent conductor of heat, better than steel, comparable to aluminium. Probably not the best choice if the idea is to contain heat but convey  kinetic energy to a crankshaft.

If a design goal is to resist heat flow through the engine, the last thing anyone should want to intentionally incorporate would be a heat sink or cooling jacket, That would be like blowing a big hole in a hydroelectric dam providing an alternative path around the turbine.

I tried making a piston out of a non-conductive material once. Epoxy. Awful heat conductivity.

I ran the engine on ice with the epoxy piston, insulated, as usual.

The ice block had already started to melt and was slick on the surface.

After setting the engine on the ice and letting it run for about 15 minutes or so, I decided to pick up the engine to see what was happening and it was stuck.

The melted surface of the ice in contact with the engine had frozen. I had to forcibly break the engine loose.

Puzzled, I set it back and let it run another 15 minutes. It stuck to the ice again.

15 minutes later I went and got my phone and took a video, just in case it froze like that again.

It did, and I got my effort to break it loose on camera.

It happened again after the video. Every time after breaking the engine loose, the ice became slick from the heat in the room, but then with the engine back running on top, the surface of the ice in contact with the engine re-froze.

I had previously run the same  engines on ice numerous times, but never had anything like that happen before.

At the time that epoxy piston was formed by pouring liquid epoxy into the cylinder and letting it cure, so the piston was extremely tight.

I had also been running the engine, not as an experiment, but just to break in the piston.

I had smeared the piston and cylinder with grinding compound. (A thick paste with carbide grit) so that the piston and cylinder would have a better fit.

After taking the video and having the ice refreeze one more time I let the engine run the rest of the night and went to bed.

By morning the engine had stopped and the ice was melted but the piston and cylinder were ruined.

Edited by Tom Booth
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10 hours ago, Tom Booth said:

Carnot efficiency properly applies to the Carnot engine, I suppose, but allegedly the Carnot engine has an efficiency that NO OTHER engine can exceed.

Stirling engines are at least, theoretically supposed to be able to approach the carnot limit, but at any rate a Stirling engine being probably less efficient, but certainly no more efficient, should if anything "reject" MORE heat at the sink not less than predicted by the equation, so therefore should be suitable as a stand in for a Carnot engine.

Would it be possible for a Stirling engine to be LESS efficient than a Carnot engine and yet also "reject" less heat, percentage wise?

I'll concede, we don't have enough information to draw a conclusion at this point. So how to proceed?

I think the idea of putting two (or more) engines with the sink sides adjoined would largely solve the problem of ambient heat infiltration from the environment. No heat would be able to reach the 'sink" except through either one or the other engine. This simplifies  measurements by eliminating the ambient "wildcard" contributing unknown quantities of heat into the "cold reservoir".

Other suggestions for comparative analysis, measuring heat transfers with the engine running vs. not running might yield additional data.

I attempted such a comparative experiment previously which I ran several times using different quantities of ice.

I placed a non-operating Stirling engine on a cup of ice (surrounded by insulation) and recorded the time it took for the ice to melt. Then repeated the experiment with the engine running.

In every instance, running/not-running the engines on cups of ice, as well as single ice cubes added to cups of ice water, the ice or ice cube invariably took longer to melt when under a running engine vs. the "dummy" inoperative engine.

Most people on the forum predicted the opposite result, due to the running engine actively churning the working fluid, presumably transporting heat to the sink in an active way, while the "dummy" engine was just sitting there.

A review of all the tests indicated that the ice took 15% more time to melt under the running engine than under the inoperative engine.

I've developed a more or less complete theory of an alternative "Stirling" engine cycle, to be sure. But I'm not here to promote that.

I was previously banned from the forum for "soapboxing" for, I assume, that very reason.

Since 100% of my "evidence" is digital video recordings and other data I've made widely available on the internet, I'm not allowed to post or link to here it puts something of a cramp in my style.

However in attempting to obey the forum fules, I'm then accused of being "reluctant" to present my theories and evidence or "running scared"

At any rate MY theories are NOT the Carnot limit equation, were developed entirely independently from my own observations, research and experiments, some of which includes making various modifications to "stock" model engines.

I'm not at all "reluctant", rather I feel severely hampered by the restrictions. No video, no links? Presenting experimental video recorded evidence is soapboxing?

My explanations must conform to previously known "ideal" processes (isothermal or adiabatic) well sorry but if those are the rules, discussion of any novel findings is rendered impossible. That is not due to me running away. But it's not really appropriate to a thread devoted to demonstrating the factuality of the Carnot equation either.

Best I feel I could do is start another thread and C/P the data I've already posted or uploaded from other forums, and maybe post written descriptions of the experiments, but I already had other threads here that were abruptly closed, then reprimanded and banned for simply "bringing up" the same.

I guess I'm doing it again, just mentioning I have a YouTube  channel, apparently.

So damned if I do and damned if I don't (present my own evidence or theories anywhere in this forum).

Hmm. One of the more annoying features of your posting style is the way your evident paranoia occasionally breaks through. I'd cut that out if I were you. And I'm afraid you are rather like a cracked record, going over and over the same ground in different ways, without apparently showing the slightest intention of listening to what you are told and learning. So the threads don't really advance much and it is hardly surprising if at some point they get closed down. You become a bore, in essence.

What I do find interesting in your threads though, is the incidental detail, as is often the way with crank threads. I loved your ice engine, especially the insight I eventually got that it was really just like the early "atmospheric" steam engines (work done on the stroke in which latent heat is removed). In the present case, the little excursion into the history of caloric and the realisation that thinking of heat as a fluid, flowing from high to low temperature and thereby doing work, was behind Carnot's ideas, was a new insight for me.

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I made an effort at running an engine using this arrangement:

The engine is operating with a small pocket on top to hold an ice cube.

Below, is an opening to admit ambient heat.

I thought the advantage of this arrangement is that the engine could run in the same direction it was designed to run in, with the heat source on the bottom plate.

Other than the opening on bottom for heat input the engine was otherwise encased in insulation.

The ice cube would act to initiate a ∆T but once in operation, would the ice melt?

If the top of the engine was being refrigerated by the engine itself, the ice should take some extra time to melt at least.

Well the engine started and ran under it's dome of insulation and seemed to be churning away to beat the band, running quite well.

I carried the engine through the house and up the stairs to show my wife the successful new arrangement, rather jubilant I might add.

Then as I was animatedly explaining what was going on in the middle of the conversation the engine abruptly seized.

I was like "what the heck..." Perhaps in not such mild language

My wife interjected with the comment:

"Maybe it froze up again"

I can't actually confirm that, but I was not able to get the engine restarted.

I took it back down stairs to examine. (The "lid" was secured down with tape)

By the time I got the lid off the ice appeared to be rapidly melting, but still some ice in there.

I cleaned up the engine and it was able to run normally again.

I was not able to draw any conclusion from these results.

The experimental arrangement however was tentatively a success if the apparent "freezing up" of the power cylinder could somehow be avoided. A materials issue, probably.

Did it literally freeze up, due to excessive cooling? That was hard to believe, even for me.

Convinced however, that there is a "resistance" to heat flow or "pushing back" of heat by the engine and that the engine is certainly converting rather than transmitting heat primarily, I have set about designing a new flavor of heat engine NOT based on the Carnot concept of heat flowing through the engine like water.

A hot side only arrangement with no cold side.

Here is one arrangement I'm currently in the process of building.

The project is a fairly simple conversion of an air compressor into this new "sink"-less external combustion engine.

Rather than a COLD side, the cold sink for "waste heat" has been replaced by a rather simple air spring. lacking any functional outlet for "waste heat' as no waste heat is anticipated.

Secondary heat of compression in the air spring should simply be returned to the engine.

Time will tell if this idea actually works or not.

I'm also working simultaneously on a twin compressor conversion.

The valved cylinder heads will be replaced using simple steel plates

Enough about my theories and conversion projects.

How can we demonstrate the percentage of waste heat predicted by the Carnot efficiency equation is accurate?

Edited by Tom Booth
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As I saw it, what was needed is some form of metering device.

If ice were used as the "sink" or cold reservoir, the flow of heat into the "reservoir" could be determined on the basis of the rate of ice melt.

The running vs. not running engine type test could at least demonstrate some difference.

A very low budget solution.

The result of this experiment has already been described above. The ice took longer to melt with a running engine on top vs. an idle one.

In the first trial of this type, the ice took, if I recall, 27 hours to completely melt under the inoperative engine and 33 hours to melt under the running engine.

This only confirms known principles however and is unremarkable IMO.

*

With a running engine converting SOME of the heat to work output, less heat is "rejected" to the sink. (The ice melts more slowly).

I surmised however that perhaps, since heat is NOT a fluid and zero heat is literally "flowing" into the sink, there is a good chance that the majority of the ice melt in either instance is primarily due to imperfect insulation.

That is, perhaps the ice under the running engine is .melting more due to heat infiltration through the insulation rather than heat "flow" through the engine.

I've been puzzling on how to overcome this imperfect insulation issue.

The adjoined engine idea suggested previously affords a real solution to this problem.

Another engine might act as a "perfect" insulator. The heat to melt the ice would have to pass through one engine or the other.

A minimum of four identical engines would be required to be able to run (and not run) them concurrently.

We could get away with two if the experiments were run sequentially.

Engines of special design might however be necessary.

Setting up such an experiment could take some time.

*The above heat flow image BTE was originally from this site: http://labman.phys.utk.edu/phys221core/modules/m10/engines.html

The link is simply provided for credits, though probably a stock image anyway. There are no copyright notices displayed on the page, but I do like to cite my sources.

2 hours ago, exchemist said:

Hmm. One of the more annoying features of your posting style is the way your evident paranoia occasionally breaks through.

Paranoia ?

And exactly what in my post do you consider "evident" of paranoia ?

Edited by Tom Booth
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I said the moderation policies around here "cramp my style". I like video. I have dozens of recorded video experiments. It answers toward credibility so others can see what I'm talking about and judge for themselves.

For example, I say my engine got "stuck", apparently frozen.

People can watch the video and judge for themselves, they don't have to take my word for it.

I've been banned from the forum previously for simply mentioning or "bringing up" a video. That is not paranoia that's FACT.

Edited by Tom Booth
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1 hour ago, Tom Booth said:

As I saw it, what was needed is some form of metering device.

If ice were used as the "sink" or cold reservoir, the flow of heat into the "reservoir" could be determined on the basis of the rate of ice melt.

The running vs. not running engine type test could at least demonstrate some difference.

A very low budget solution.

The result of this experiment has already been described above. The ice took longer to melt with a running engine on top vs. an idle one.

In the first trial of this type, the ice took, if I recall, 27 hours to completely melt under the inoperative engine and 33 hours to melt under the running engine.

This only confirms known principles however and is unremarkable IMO.

*

With a running engine converting SOME of the heat to work output, less heat is "rejected" to the sink. (The ice melts more slowly).

I surmised however that perhaps, since heat is NOT a fluid and zero heat is literally "flowing" into the sink, there is a good chance that the majority of the ice melt in either instance is primarily due to imperfect insulation.

That is, perhaps the ice under the running engine is .melting more due to heat infiltration through the insulation rather than heat "flow" through the engine.

I've been puzzling on how to overcome this imperfect insulation issue.

The adjoined engine idea suggested previously affords a real solution to this problem.

Another engine might act as a "perfect" insulator. The heat to melt the ice would have to pass through one engine or the other.

A minimum of four identical engines would be required to be able to run (and not run) them concurrently.

We could get away with two if the experiments were run sequentially.

Engines of special design might however be necessary.

Setting up such an experiment could take some time.

*The above heat flow image BTE was originally from this site: http://labman.phys.utk.edu/phys221core/modules/m10/engines.html

The link is simply provided for credits, though probably a stock image anyway. There are no copyright notices displayed on the page, but I do like to cite my sources.

Paranoia ?

And exactly what in my post do you consider "evident" of paranoia ?

References to being shut down or banned, men in black (in your previous thread) and so forth. In the latest post it is this passage:

" I already had other threads here that were abruptly closed, then reprimanded and banned for simply "bringing up" the same.

I guess I'm doing it again, just mentioning I have a YouTube  channel, apparently.

So damned if I do and damned if I don't (present my own evidence or theories anywhere in this forum)."

Unlike normal people, who just get on with discussing the science, you whine about moderation policy, casting yourself in the role of victim. Give us all a break from that. I'm far more interested in your wrong-headed arguments, especially when they get me to explore bits of the history of science that are unfamiliar to me. 😀

Edited by exchemist
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1 hour ago, exchemist said:

References to being shut down or banned, men in black (in your previous thread) and so forth. In the latest post it is this passage:

" I already had other threads here that were abruptly closed, then reprimanded and banned for simply "bringing up" the same.

I guess I'm doing it again, just mentioning I have a YouTube  channel, apparently.

So damned if I do and damned if I don't (present my own evidence or theories anywhere in this forum)."

Unlike normal people, who just get on with discussing the science, you whine about moderation policy, casting yourself in the role of victim. Give us all a break from that. I'm far more interested in your wrong-headed arguments, especially when they get me to explore bits of the history of science that are unfamiliar to me. 😀

Having a beef with draconian moderation policies applied arbitrarily and making mention of the fact is not "paranoia".

Uhhh.. "men in black" in a previous thread?

What was the context?

No doubt another joke or something you took too seriously.

You only NOW come to the realization that Carnot viewed heat as a fluid and a heat engine as some kind of water mill heat flowed through?

This was after I simply made casual MENTION of one of my YouTube videos that happened to be in an old closed thread.

Banned for simply making casual MENTION of one of my videos of an experiment.

What exactly is the purpose of someone starting a thread on a forum anywhere other than to make a presentation of some ideas.

I was continually bludgeoned with "moderator notes" and warnings for simply doing what people generally do on forums.  Have a discussion or try to.

Edited by Tom Booth
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1 hour ago, Tom Booth said:

Having a beef with draconian moderation policies applied arbitrarily and making mention of the fact is not "paranoia".

Uhhh.. "men in black" in a previous thread?

What was the context?

No doubt another joke or something you took too seriously.

You only NOW come to the realization that Carnot viewed heat as a fluid and a heat engine as some kind of water mill heat flowed through?

This was after I simply made casual MENTION of one of my YouTube videos that happened to be in an old closed thread.

Banned for simply making casual MENTION of one of my videos of an experiment.

What exactly is the purpose of someone starting a thread on a forum anywhere other than to make a presentation of some ideas.

I was continually bludgeoned with "moderator notes" and warnings for simply doing what people generally do on forums.  Have a discussion or try to.

Yes, I knew vaguely that caloric was supposed to be a sort of nebulous fluid, but I never studied the history of science formally so never had any reason to think much about it. I grouped it mentally with phlogiston and the aether as one of those many dead ends in the development of science. But now I can see what a good (though still wrong) idea it was, and how illuminating it was to people at that time.

Anyway, that's the chief thing I get from these threads started by cranks. There was an excellent one last year about IR and climate change, which alerted me to a c.19th Irish experimenter by the name of John Tyndall, who basically built the first IR spectrometer without realising it!

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1 hour ago, Tom Booth said:

What exactly is the purpose of someone starting a thread on a forum anywhere other than to make a presentation of some ideas.

Could it also be to ask questions of those who know more than they do ?

Is that possible ?

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1 hour ago, studiot said:

Could it also be to ask questions of those who know more than they do ?

Is that possible ?

Naturally.

That is the main reason I like posting on Science forums. For the feedback from trained scientists and mathematicians etc. who hopefully are curious, understand scientific methodology and can be unbiased and objective.

I don't have a formal adult scientific training but my father did. I practically grew up in his home chemistry lab as he was training for a position as a science instructor.

Kind of like growing up with Bill Nigh the science guy as your dad, along with my older brothers always doing experiments.

My mother on the other hand was deeply spiritual/religious.

Unfortunately forums are not as popular as they once were. Not sure why.

On one forum, after posting on it for years, the guy running the forum finally confessed he was actually the only real person on the forum. The rest were all made up characters. His "sock puppets". Not an unusual tactic to make the forum appear more active and interesting than it really is to anyone that might happen to wander in.

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46 minutes ago, Tom Booth said:

That is the main reason I like posting on Science forums. For the feedback from trained scientists and mathematicians etc. who hopefully are curious, understand scientific methodology and can be unbiased and objective.

And yet you seem to mostly ignore the input you receive.

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49 minutes ago, Tom Booth said:

On one forum, after posting on it for years, the guy running the forum finally confessed he was actually the only real person on the forum. The rest were all made up characters. His "sock puppets". Not an unusual tactic to make the forum appear more active and interesting than it really is to anyone that might happen to wander in.

That would make you one of his sockpuppets.

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On 1/30/2023 at 1:03 PM, Ghideon said:

I get the impression that your idea* allows for two Stirling engines to be mounted cold plate to cold plate to increase the efficiency of both the engines?

*) If correct that is...

These engines can operate inverted.

So a Stirling engine ice sandwich with bought engines right out of the box is not out of the question.

I might just go ahead and send for one of these upside down engines.

I like this source/manufacturer as the displacer timing/advance on these particular style of engines is easily adjustable.

They are also put together with ordinary nuts and bolts making modifications easier, if necessary.

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7 hours ago, Tom Booth said:

I said the moderation policies around here "cramp my style". I like video. I have dozens of recorded video experiments. It answers toward credibility so others can see what I'm talking about and judge for themselves.

For example, I say my engine got "stuck", apparently frozen.

People can watch the video and judge for themselves, they don't have to take my word for it.

What thermodynamic principle does an engine getting stuck demonstrate?

7 hours ago, Tom Booth said:

I've been banned from the forum previously for simply mentioning or "bringing up" a video. That is not paranoia that's FACT.

No, it was for re-introducing material from a locked thread.

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1 hour ago, Bufofrog said:

And yet you seem to mostly ignore the input you receive.

Only posts that are generally counter productive, merely insulting, ad-hominem, derogatory etc.

Sometimes I don't have time to respond immediately but the posts keep accumulating rapid fire and I have to pick and choose.

I'm taking the time to answer this one now, though basically devoid of any useful or constructive content

If you can cite an important post I overlooked or "ignored" I'd appreciate it.

I try to answer everybody when possible.

What I find distasteful is moderators who use the power of their moderator status to punish and censor people that merely happen to have a different POV on a subject. Who cannot tolerate or even entertain the idea they could ever be mistaken.

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I think your (rather long) answers essentially answers my question with "yes, the cold side of the Stirling engine will cool below ambient temperature if sufficiently insulated."

Using a thermometer under the isolation on the cold side should be able to show this. Note that if the temperature probe is too large and is made of a material that transfers heat it may disturb the experiment.

21 hours ago, Tom Booth said:

I attempted such a comparative experiment previously which I ran several times using different quantities of ice.

Recommendation: don't focus too much on ice based experiments unless you have some way to properly control the temperature of the ice. There seem to be many sources of errors which allows for different interpretations and varying outcomes.

4 minutes ago, Tom Booth said:

Who cannot tolerate or even entertain the idea they could ever be mistaken.

But you seem to claim that every single engineer* in the whole world  the last 200 years are mistaken?

*) and scientist, teachers and others...

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53 minutes ago, swansont said:

What thermodynamic principle does an engine getting stuck demonstrate?

Probably none. That's the point. It's an anomaly that appears to run contrary to "known science".

The engine is supposed to be, according to accepted scientific principles, dumping heat into the ice.

The engine was at room temperature. About 80°F at the time it was first placed on the ice. The ice was already begining to melt. Instead of melting the ice more with the heat, presumably being transfered, the ice re-froze, not just once but four times in the course of about 45 minutes observation.

Possibly it demonstrated cooling by expansion work would be my hypothesis.

24 minutes ago, Ghideon said:

I think your (rather long) answers essentially answers my question with "yes, the cold side of the Stirling engine will cool below ambient temperature if sufficiently insulated."

Using a thermometer under the isolation on the cold side should be able to show this. Note that if the temperature probe is too large and is made of a material that transfers heat it may disturb the experiment.

Recommendation: don't focus too much on ice based experiments unless you have some way to properly control the temperature of the ice. There seem to be many sources of errors which allows for different interpretations and varying outcomes.

But you seem to claim that every single engineer* in the whole world  the last 200 years are mistaken?

*) and scientist, teachers and others...

There are a lot of additional Ifs to consider. If the engine timing is adjusted properly, if there is proper load balancing (not a lot of excess heat) If the engine is performing sufficient work output, off the top of my head.

A Stirling engine will begin acting as a heat pump and begin creating a temperature differential just by turning it over with your finger to get it started to some degree with no external ∆T applied.

A Stirling engine IS a Stirling heat pump, as far as the mechanics and structure of the machine itself

Quote

But you seem to claim that every single engineer* in the whole world  the last 200 years are mistaken?

Apparently. With a few notable exceptions.

Mistakes can be perpetuated indefinitely if no one ever questions it. Especially if they "seem right" or correct or are simply the best working  theory or tool available.

Most science in fact is just an approximation to eventually be proven wrong.

Edited by Tom Booth
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15 minutes ago, Tom Booth said:

There are a lot of additional Ifs to consider. If the engine timing is adjusted properly, if there is proper load balancing (not a lot of excess heat) If the engine is performing sufficient work output, off the top of my head.

That seems reasonable. But under the insulation the temperature will be rather stable once the Stirling engine has run for a while? Temperature will likely vary depending on the load and added heat (and more) but if the effect you propose is there the temperature should read below ambient if the insulation is good enough. Initially it is good enough tho show experimentally, beyond doubt and in a repeatable fashion, that effect you predict exits; exact numbers can be found in later experiments?