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Nikola Tesla Vs. The Second Law Of Thermodynamics


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A Stirling "hot air engine" converts heat into work by adiabatic expansion.

 

That is, heat is introduced to air, in a sealed chamber, through a heat exchanger.

 

As a result, the air expands.

 

This is adiabatic expansion, as in an engine running at a high RPM, there is not enough time for heat exchange by conduction to a "cold reservoir".

 

Rather, energetic air molecules striking the piston and causing it to move, transfer their kinetic energy to the piston.

 

At some point, as the piston is driven outward, a state of equilibrium is reached and the inner gas pressure inside the engine becomes equivalent to the outside atmospheric pressure.

 

However, energy has been transfered to the piston, and possibly also the flywheel if one is present. This momentum carries the piston beyond the point of equilibrium, expanding the gas, further lowering it's temperature. The internal energy level of the engine has now fallen below the outside energy level and atmospheric pressure now begins to drive the piston back inward.

 

There is a point at the extremity of the pistons outward travel when the temperature of the gas inside the heat engine drops below the ambient "sink".

 

I theorized about 10 years ago, that insulating the cold side heat exchanger of a completely standard "off the shelf" Stirling hot air engine, so as to PREVENT THE REVERSE FLOW OF HEAT FROM THE SINK, back into the engine, would allow the engine to use it's stored momentum to in effect, refrigerate the ambient "sink" side of the engine, and increase the efficiency of the engine beyond the Carnot efficiency limitation

 

My recent experiments seem to have confirmed this hypothesis.

 

Insulating the cold "sink" of a Stirling engine to prevent reverse flow from the sink back into the engine demonstrates a considerable improvement, and increases engine RPM.

Edited by TomBooth
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Carnot efficiency is the maximum theoretical efficiency of a heat engine operating between ANY two temperatures.  That would be for a "perfect" engine without any loses to friction, heat leakage,bad s

I ordered this digital thermometer a few days ago. It comes with four probes for taking simultaneous readings. It doesn't record data to the cloud or have software to build charts and plug into the co

I said "If", hypothetically.   Just supposing that the engine could utilize that additional 7 joules otherwise rejected to the sink. That would only bring the temperature back down to equilibrium with

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A Stirling "hot air engine" converts heat into work by adiabatic expansion.

 

That is, heat is introduced to air, in a sealed chamber, through a heat exchanger.

 

As a result, the air expands.

 

This is adiabatic expansion, as in an engine running at a high RPM, there is not enough time for heat exchange by conduction to a "cold reservoir".

 

Rather, energetic air molecules striking the piston and causing it to move, transfer their kinetic energy to the piston.

 

At some point, as the piston is driven outward, a state of equilibrium is reached and the inner gas pressure inside the engine becomes equivalent to the outside atmospheric pressure.

 

However, energy has been transfered to the piston, and possibly also the flywheel if one is present. This momentum carries the piston beyond the point of equilibrium, expanding the gas, further lowering it's temperature. The internal energy level of the engine has now fallen below the outside energy level and atmospheric pressure now begins to drive the piston back inward.

 

There is a point at the extremity of the pistons outward travel when the temperature of the gas inside the heat engine drops below the ambient "sink".

 

I theorized about 10 years ago, that insulating the cold side heat exchanger of a completely standard "off the shelf" Stirling hot air engine, so as to PREVENT THE REVERSE FLOW OF HEAT FROM THE SINK, back into the engine, would allow the engine to use it's stored momentum to in effect, refrigerate the ambient "sink" side if the engine, and increase the efficiency of the engine beyond the Carnot efficiency limitation

 

My recent experiments seem to have confirmed this hypothesis.

 

Insulating the cold "sink" of a Stirling engine to prevent reverse flow from the sink back into the engine demonstrates a considerable improvement, and increases engine RPM.

 

 

"increase the efficiency of the engine beyond the Carnot efficiency limitation"
 

Uhoh. Can you please clarify that remark?

 

The Carnot efficiency limitation is 100% and is purely theoretical since Tcold would be at 0 K., an impossibility

 

Are you calculating the efficiency differently?

Edited by OceanBreeze
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"increase the efficiency of the engine beyond the Carnot efficiency limitation"

 

Uhoh. Can you please clarify that remark?

 

The Carnot efficiency limitation is 100% and is purely theoretical since Tcold would be at 0 K., an impossibility

 

Are you calculating the efficiency differently?

 

 

 

 

Carnot efficiency is the maximum theoretical efficiency of a heat engine operating between ANY two temperatures.

 

That would be for a "perfect" engine without any loses to friction, heat leakage,bad seals, etc.

 

Given my previous example, a model Stirling operating between ambient at 300k and boiling water, at whatever that was, 375 or something. The Carnot efficiency limitation at those temperatures is 9% if I remember right

 

Edit: sorry, boiling water is 373 K (about).

 

https://www.omnicalculator.com/physics/carnot-efficiency

 

So, I'm talking, boosting efficiency from 9% to perhaps 9.5% or maybe 10%.

 

The main point being that at anything above the Carnot limit, in this case 9%, heat will no longer be rejected to the sink. Above 9% at those two temperatures, heat is no longer passing through the engine to the sink All of the heat, above the equilibrium baseline, or ambient, is being utilized by the engine for "work". Discounting losses to friction etc.

 

Unless someone has a better explanation.

Edited by TomBooth
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I sent away for FOUR of these Stirling engine kits, to run some experiments with:

 

https://www.stirlinghobbyshop.com/english/stirling-engine-solar-ltd-low-temperature-stirling-engine-ltd-stirling/ltd-stirling-engine-ja-828/#cc-m-product-9759217783

 

I spent quite a lot of time deciding which engines to get. I settled on these because they looked like they would be relatively easy to assemble and disassemble, to make various modifications when necessary for different experiments.

 

I made a couple of videos to show what is in the kits, and how these engines go together.

 

https://www.youtube.com/embed/p5XoocPoyac

 

The first modification I made was to replace the steel bolts that came with the kit with nylon bolts from a local hardware store. The steel bolts were an obvious source of conductive heat loss between the hot and cold heat exchangers.

 

For the experiments, I also used double walled vacuum insulated mugs or flasks.

 

https://www.youtube.com/embed/HQT5JviF-qk

 

Sorry but I could not find a way to embed the videos on this forum.

Edited by TomBooth
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It was ten years ago that I first proposed insulating the Stirling engines cold plate or cold heat exchanger, which is it's connection with the ambient "sink" or cold reservoir, to prevent backward flow of heat into the engine from the "sink".

 

I wrote: "If more heat is extracted as work than what actually reaches the heat sink, then theoretically, insulating the cold end of the displacer chamber against the external ambient temperatures would improve engine efficiency."

 

https://stirlingengineforum.com/viewtopic.php?f=1&t=478&sid=78f4f2a8e6a855c734b01e19c06f2f78

 

This is a representative response:

 

"Hi Tom,
"1. Insulating the cold end will not help (or we would all have been doing so).

"As you say, model hot air engines sometimes slow down because the cold end gradually warms up, thereby reducing the temperature differential. If the cooling is by ambient air, the warmth of the “cold” end can be felt. Since it is above the temperature of the cooling medium, that medium cannot be heating it!

"To insulate it would cause the cold end to heat more rapidly and slow the engine even sooner."

 

 

So I put the idea on a shelf. But it kept nagging at me.

 

Finally, my time for model building and my finances in retirement have allowed me to catch up on these ideas and actually run the experiments.

 

This was my first run, or first attempt at insulating the sink on one of these engines.

 

https://youtu.be/fFByKkGr5bE

 

I actually decided to try this experiment on the spur of the moment, because, although the engine had been running for some time on scalding hot water fresh from the tea kettle, the top of the engine did not feel warm at all. It felt room temperature. It seemed feasible to me at that point that heat from the ambient could be preventing the plate from getting colder. I had actually cut out the disk of insulation for a different experiment.

 

Initially the engine slowed due to the flywheel rubbing on the insulation as I was trying to tape it on, but the engine recovered quickly and began running SLIGHTLY FASTER.

 

I did several more experiments with different engines, with the same result. The engines with the sink or cold side insulate ran at a higher RPM.

 

https://youtu.be/zEqg1TgLqXI

 

The amount of freshly boiled water used was carefully measured for both the uninsulated and insulated engines. In each case the engine with the cold plate insulated ran at a higher RPM and appeared to run stronger.

 

https://youtu.be/Iq6snxiXbGg

Edited by TomBooth
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Of course, another consequence of heat converted to work NOT flowing through the engine to the sink would be, If we turned things around and ran the engine on ICE, then heat entering the engine from the ambient surroundings is what would really be running the engine, and if that heat was being converted to work as it passed into the engine, then, in theory, perhaps the ice would receive less heat than it would receive otherwise, under the same conditions, except with an inoperative engine standing in as a "control".

 

Actually running this experiment, it was found that the ice lasted five hours longer when covered by a running engine than when it was covered by an inoperative engine. The ice being used to run the engine actually took 33 hours to completely melt, and the engine to finally came to a stop.

 

The engine ran quite slow on ice, but very steady. It was in a kind of well of insulation, so there was likely very little heat getting to it. In a future experiment I may add some fan blades to the flywheel to keep more warm air circulating to heat the engine.

 

I made this video after 12 hours of the engine running on ice:

 

https://youtu.be/-7zntz8kwIk

 

As can be seen, the "Hot" or heat input plate, exposed to ambient heat is cold enough that water was condensing on the surface like a glass of ice water would do on a hot summer day.

 

After 32 hours, the engine was beginning to slow down so I took another video, checking to see if the ice had melted. By this time I was becoming rather impatient for the experiment to be over with so I added the aluminum electrical box from an old appliance outlet to draw down more heat.

 

https://youtu.be/lFhUkzHRbWo

 

I had posted this experiment to a physics forum I had been a member of for many years. At first it was fairly well received, but in time, after mentioning Tesla, and my motivation for doing the experiments I was banned. Some of the issues brought up there might be interesting for anyone following this here.

 

https://www.physicsforums.com/threads/should-ice-take-longer-to-melt-when-used-to-run-a-heat-engine.991714/

 

At least the thread was not deleted.

 

I did lodge a complaint in the feedback forum:

 

https://www.physicsforums.com/threads/discussions-locked-without-just-cause.991853/

 

This sort of response is something I've been dealing with for years, so I'm not really that surprised, but I really just wanted to know if these results were to be expected. Certainly I never made any claim that my toy size model hobby shop engine was any kind of "perpetual motion machine".

 

https://www.physicsforums.com/threads/discussions-locked-without-just-cause.991853/

 

An effort to renew the discussion on another science forum I had been on for many years, met with a similar fate:

 

https://www.scienceforums.net/topic/122721-heat-engine-experiments-and-2nd-law-of-thermodynamics/#comments

 

So I wound up hear. Greener pastures, I hope.

 

I have several additional experiments in mind, and most of the experiments I've already done once or twice or sometimes more, I need to repeat with tighter controls and more detailed recording and measuring devices, such as, perhaps infrared imaging camera, temperature probes etc.

 

Of course, if I had not obtained any "positive" results I would not be bothering with such an investment of time and resources.

 

Since running all these experiments so far on unmodified engines, (except for the nylon bolts and insulation) I've also been doing some additional modifications to the engines to try and improve efficiency. I think I still have some way to go.

 

One modification that proved successful so far was adding a regenerator to the engine:

 

The regenerator is an invention of Robert Stirling and is what is really supposed to make these engines very efficient. These toy Stirling engines did not come with any sort of regenerator so I tried adding some. The star shaped ports cut into the displacer and filled with steel wool. This is supposed to capture much of the heat so that even LESS heat reaches the sink. Less than none? Not sure about that, but so far the regenerator, (the engine on the right) is running much faster than the engine without a regenerator on the left.

 

post-96374-0-12753700-1597115527_thumb.jpg

 

 

https://youtu.be/QqN80ZqJLoQ

 

 

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Carnot efficiency is the maximum theoretical efficiency of a heat engine operating between ANY two temperatures.

 

That would be for a "perfect" engine without any loses to friction, heat leakage,bad seals, etc.

 

Given my previous example, a model Stirling operating between ambient at 300k and boiling water, at whatever that was, 375 or something. The Carnot efficiency limitation at those temperatures is 9% if I remember right

 

Edit: sorry, boiling water is 373 K (about).

 

https://www.omnicalculator.com/physics/carnot-efficiency

 

So, I'm talking, boosting efficiency from 9% to perhaps 9.5% or maybe 10%.

 

The main point being that at anything above the Carnot limit, in this case 9%, heat will no longer be rejected to the sink. Above 9% at those two temperatures, heat is no longer passing through the engine to the sink All of the heat, above the equilibrium baseline, or ambient, is being utilized by the engine for "work". Discounting losses to friction etc.

 

Unless someone has a better explanation.

 

 

OK, thanks for clarifying.

 

Carnot efficiency is just the best theoretical efficiency:

 

[math]Efficiency\quad =\quad 1\quad -\quad \frac { { T }_{ C } }{ { T }_{ H } } \quad x\quad 100 %[/math]%

 

In your example Tcold is 300K and Thot is 373K so the efficiency is 19.6 %

 

But, I don’t consider that to be a hard limit. I consider the limit to be at Tcold = 0K

 

At that point the efficiency is hard-limited to 100 % as it should be in any sane system.

 

In your example, there is still a lot of heat energy at the ambient (cold) T of 300 K. The trick would be to devise some way of collecting that energy without the need to input any additional heat energy beyond the 373 K already being used.

 

I don’t know if it is possible, but I would argue that it is not necessarily impossible. There may be some way to bootstrap the engine so that the Tcold dips below ambient, even if only intermittently, allowing for a very slight increase in the T delta and a tiny increase in efficiency.

 

Having said all that, the amount of increase, if indeed any at all is possible, is probably so slight it would be difficult to distinguish from experimental error, or “noise” as we call it.

 

Incidentally, welcome to our asylum and thanks for posting something interesting.

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I was questioned by flummoxed whether my work during lockdown had anything to do with thermodynamics, my reply in my own thread seems just as relevant here

 

'Suppose a black hole is the most ideal black body heat engine," and then go on to say,"then it will convert heat into mechanical energy into a cooler environment. If the black hole was capable of becoming the same temperature as the background space then it would be in a state of equilibrium. The maximum fraction of heat supply that can be used is

 

(T(1) - T(2)/T(1))

 

and from algebra we learn that it is the same thing as saying

 

1 - T(2)/T(1)

 

Where T(1) is the "absolute temperature" of the cavity and T(2) is the temperature of the environment."

 

These were the first heat principles I drew on before deriving the discrete transition equation for the black hole. More or less I ended up with

 

1/3 N*mc^2/KT = (1 - T(2)/T(1))

 

There was an additional factor of index of refractions or some quantized principle numbers of n^2(2)/n^2(1) attached to the transformation from the Rydberg formula, which was the universal starting point for any transition for discrete quantum systems. I later interpreted it from Snell's law and the indices of refraction.

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"In your example Tcold is 300K and Thot is 373K so the efficiency is 19.6 %"

 

Thanks, I made the mistake of using an online calculator, forgetting to reset the temperature scale to Kelvin. I mistakenly assumed the default would be K, but the fields were set to fahrenheit.

 

"But, I don’t consider that to be a hard limit. I consider the limit to be at Tcold = 0K

 

 

 

At that point the efficiency is hard-limited to 100 % as it should be in any sane system."

 

I'll assume you've already read my rant about logical as opposed to fixed or absolute efficiency, so maybe I don't need to reiterate, other than, perhaps, to point out that Tesla's claim was only that due to energy conversion in the engine, heat would not necessarily flow through to the sink.

 

That would only require the engine to reach a degree of cold in equalibrium with the ambient, or a return to whatever baseline temperature before heat was applied to the engine. Tesla considered that would be an absolutely perfect engine.

 

" don’t know if it is possible, but I would argue that it is not necessarily impossible. There may be some way to bootstrap the engine so that the Tcold dips below ambient, even if only intermittently, allowing for a very slight increase in the T delta and a tiny increase in efficiency"

 

That would actually exceed Tesla's modest goal of most of the heat not passing through the engine to the sink and warming the sink and degrading efficiency, so that only a small amount of heat would need to be removed.

 

In a cold running engine running on ice, the ambient heat, then, would not only not reach the sink, but it is being used to refrigerate the sink, thereby increasing the Temperature difference, resulting in an increase in efficiency.

 

I may be mistaken, but I think that would not be in accord with the second law, though that is not my personal concern.

 

It does seem to be what the experiments suggest or indicate may be happening.

 

It is what the experiments were meant to test anyway

 

"Incidentally, welcome to our asylum and thanks for posting something interesting."

 

Well thanks, that is certainly good to hear! Maybe I should quit while I'm ahead.

 

At any rate, I've posted about as much as there is to report. So I may take a break for a while.

 

It may be some time before I have a better set up for conducting more accurate runs, a couple more model engines to put together, supplies to aquire etc.

 

Thanks for the feedback.

 

I'm not ending the show, any additional comments, questions or suggestions are welcome and appreciated, I just have nothing further to report at this time, until I get set up to run more tests.

 

Tom

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I was questioned by flummoxed whether my work during lockdown had anything to do with thermodynamics, my reply in my own thread seems just as relevant here

'Suppose a black hole is the most ideal black body heat engine," and then go on to say,"then it will convert heat into mechanical energy into a cooler environment. If the black hole was capable of becoming the same temperature as the background space then it would be in a state of equilibrium. The maximum fraction of heat supply that can be used is

(T(1) - T(2)/T(1))

and from algebra we learn that it is the same thing as saying

1 - T(2)/T(1)

Where T(1) is the "absolute temperature" of the cavity and T(2) is the temperature of the environment."

These were the first heat principles I drew on before deriving the discrete transition equation for the black hole. More or less I ended up with

1/3 N*mc^2/KT = (1 - T(2)/T(1))

There was an additional factor of index of refractions or some quantized principle numbers of n^2(2)/n^2(1) attached to the transformation from the Rydberg formula, which was the universal starting point for any transition for discrete quantum systems. I later interpreted it from Snell's law and the indices of refraction.

To elaborate further,

 

Basically what it means is that any radiation leaving the cavity (black hole) does so vertically and even cuts down the glare like sunglasses do for the black hole by polarizing the radiation by a reflection from a horizontal surface (which is fine for any localised spot on a supermassive black hole). The black hole gives off an additional glow by a reflection of light.

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The idea behind using Snell's law was really based on the Brewster angle θ which is the angle of incidence. Snell's law will obey

 

tan θ = n(2)/n(1)

 

The transition formula was once again

 

S(ΔT) = k(ΔT)

 

= N⋅mc²/(1 - T (2)/T (1) (tan θ)²)

 

Whenever you see N⋅mc² it is proportional to the pressure and from relativity, an additive correction of density associated to the system. Basically

 

PV = N⋅mc²

 

Under normal convention and from variation using calculus we have also

 

PdV + dPV = dN⋅(m(2) - m(1))c²

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Look up the part, ”the smallest possible refrigerator,” and the conclusions at the end, to be more specific.

Thanks.

 

I think I see above in your post, some use of the heat engine efficiency equation.

 

I'm not sure, well, maybe I should rephrase that, I am sure I don't really follow or understand much of anything you've presented about black holes.

 

But I do have a word or two to say about the heat engine efficiency equation itself.

 

Carnot's original conception of heat and mathematical computations were based on the "heat is a fluid" model, which we now know was all completely wrong, but in that model, the material the engine is made of has no bearing on efficiency.

 

For example, Carnot would likely have argued that my replacing steel bolts with less heat conductive nylon bolts was a waste of time and would have no effect or make no difference in engine efficiency, the logic behind that being, the efficiency depends only on the fall of caloric. It makes no difference whatsoever if the paddle wheel is made out of metal or wood or plastic, and indeed, the efficiency formula takes absolutely nothing into account that any competent mechanic would immediately recognize as impacting engine efficiency. Compression ratio, ignition timing, piston and cylinder geometry, airodynamic flow, dead air space, etc.

 

In other words, the efficiency formula is simplistic nonsense that has no relationship to any real engine or engine efficiency.

 

Any of my model engines, that I've been modifying to increase efficiency should, common sense would seem to tell me, have a certain capability for transforming heat into work that is fairly stable and related in some way to the engine itself, not the state of the fuel (heat).

 

For example, changing out the steel bolts for plastic should reflect, or be reflected in efficiency calculations, but with or without high heat transmitting bolts either engine is efficient or not, based only on the temperature difference and if the temperature difference changes drastically, the efficiency of my model engine changes drastically, the same engine with the same parts put together in the same way is either efficient or not based on a single factor over which an actual engineer has no control, as if how an engine is built makes no difference.

 

IMO temperature difference relates to the quality and availability of fuel (heat) not efficiency, or how well that fuel is actually utilized.

 

How much heat is available is one thing, how well it is utilized is a completely different issue and Carnot's efficiency is really a measure of availability not efficiency. IMO, this is because the whole thing was formulated on the basis of a misconception regarding what heat actually is in the first place.

 

If heat was actually caloric, or a fluid, like water, then all that really would matter is the "height" it fell from. But heat is not caloric and that is not the case at all. There are innumerable factors that influence actual engine efficiency.

 

Of course, it helps to have fuel too, but that really has nothing to do with the efficiency of the engine itself given the availability of fuel.

 

The so-called "efficiency" equation, based on temperature difference, is only a measure of how much heat is actually available in potential. But it doesn't really even measure that, because it does not take into account quantity or volume.

 

Like, how much heat is in a teaspoon of water compared with the heat that could be derived from the Atlantic ocean. At what speed and in what volume can the heat source be circulated through the engines heat exchangers?

 

Now we are going to take this simplistic nonsense equation and apply it to black holes?

Edited by TomBooth
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