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Author Topic: Tesla's Ambient Heat Engine Theory - Right or Wrong ?  (Read 55142 times)

Offline Tom Booth

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #15 on: December 14, 2012, 08:53:15 PM »

Have a look at what he says at 2 :08 in the first video. He explains that the cold side does need a heat sink or the engine stops once it heats up.

He attributes this to friction, which makes sense, considering the relatively enormous amount of surface to surface contact between the inner glass tube (piston) and the outer (cylinder), but this is a secondary effect and has nothing directly to do with what is going on with the gas inside the cylinder.

Also, no doubt, despite glass being a poor conductor of heat, some heat is migrating through the glass. Again, this has no direct bearing on what is happening with the "working fluid", the air inside the cylinder which is the important thing to consider.

The heat of friction is a result of the gas expanding, pushing the piston and the piston dragging against the cylinder wall. There is energy conversion going on:

Flame > Gas Expands > Expanding gas pushes piston > Piston meets resistance dragging on cylinder wall creating friction > friction generates heat.

In other words, the transfer of energy is not a direct transfer of heat from the gas to the cylinder wall (effective heat sink). Even after the gas has given up its heat, which has been transferred or converted into the kinetic motion of the piston and the gas grows cold and contracts, pulling the piston with it, or perhaps more accurately; creates a vacuum which allows atmospheric pressure to push it back there is this heat generated due to friction on the cylinder walls on the return stroke.

At any rate, the question could be settled through experiment.

Free piston Stirlings have been built to such close tolerances that the piston forms an effective air tight seal without actually touching the cylinder walls virtually eliminating this source of friction. Materials even less heat conductive than glass could be used to prevent heat migration through the cylinder walls.

Quote
No heat is 'disappearing'. Its operating principle is no different to any heat engine other than it uses a resonance effect instead of energy in a flywheel to achieve the compression stroke.

The so-called "resonant effect" in this type of engine is pure speculation (and pure fiction IMO). This is not a thermoacoustic engine, though there are some superficial resemblances.

As far as the heat "disappearing"; When a gas expands and does work simultaneously it gives up its energy (heat) to do the work it then tries to get back that heat from its surroundings. i.e. it gets cold. The kinetic energy (heat) of the gas molecules is translated into kinetic energy of the piston or whatever the gas is working against or upon. As a result the temperature of the gas drops. There is no mystery about this  (well, maybe a little) and yes the same thing happens in any heat engine to one degree or another. The more efficient the engine; the greater the temperature drop. The more energy the gas transfers directly into mechanical motion; the greater the temperature drop.

This usually goes unnoticed because the gas, having expanded and done some work generally has plenty of heat around to replace the heat it lost. It seems, or might be said that the gas absorbs heat so it can expand and do work, but this is not really the case and is not really logical.

In a heat engine the gas absorbs heat, expands and does work - loosing heat and is then ready to absorb heat again and the cycle repeats all within a fraction of a second. It is difficult to follow exactly what is going on and in what order, but here IMO is what I think happens:

Heat is applied to the engine. The heat is transferred to the gas, the gas expands and does work against the piston, the energy is transferred to the piston. At this point the gas is expanded to its limit, has given up its energy and finds itself, in effect, "hungry". It can do one of two things, either absorb heat from its surroundings or contract. If there is not enough heat available in the immediate surroundings it will contract.

This is exploited in numerous ways in all kinds of applications.

Under such circumstances as just described, having expanded and done work simultaneously and not being able to find "replacement" heat immediately, the gas may contract to the extent of condensing into a liquid (liquefaction of gasses). The same principle or phenomenon is exploited in some refrigeration systems. etc.

I believe that what is happening in the engine in that youtube video is that in spite of all the heat from friction and conduction the expanded air still cannot find enough heat to replace what it lost and so contracts.

The heat has been transferred to the piston, converted into the mechanical energy or kinetic energy of the piston. The glass cylinder even if relatively hot from friction etc. does not give up its heat to the air readily. Momentarily, as far as the gas is concerned there is no heat readily available to replace what it lost so it contracts.

I think that if heat from friction were eliminated and heat from conduction were eliminated (as well as heat from ambient) one might actually be able to observe a real cooling or refrigeration effect in the cylinder.

That heat could produce a cooling reaction is not so ludicrous as it might sound.

This is, to some degree, speculative, but it is based on sound reasoning and observation, IMO and is backed up by an enormous history of scientific research and experimentation as well as real world applications. It would have to be confirmed by experiment in this specific instance.

On the other hand, I find no support whatsoever, in my research on the question, for the idea that the piston returns due to some "resonant effect". This is IMO a "red herring". Many, however, seem to have latched on to this explanation and you will find many YouTube videos of "Thermoacoustic" Stirling Engines which are IMO, nothing of the sort.
 
A couple random references:

"when a gas expands and does work on its surroundings, its temperature decreases" - http://www.howeverythingworks.org/page1.php?QNum=1257 (second paragraph)

"Isothermal and Adiabatic Expansion.

When a gas expands and does work, as by pushing a piston in a cylinder, we see from the first law of thermodynamics that the equivalent in the form of heat must be supplied from somewhere. If the temperature of the gas is to be kept constant, heat must be supplied to it from the outside, in exact equivalent to the work done. In such cases the expansion is said to be isothermal, ... But if no heat be allowed to enter the gas, as would be the case if the cylinder and piston were perfect non-conductors of heat, the work done in expansion will be at the expense of the heat energy in the gas itself, and its temperature will therefore fall during the expansion. We have seen that the pressure is less as the temperature falls, other things being equal; hence under the conditions the pressure p will fall faster than if the temperature were kept up by the addition of heat from outside.
...
Both isothermal and adiabatic curves are of great importance in thermodynamic studies, but they represent conditions that are only imperfectly realized in practice. "

Cyclopedia of engineering; a manual of steam boilers, steam pumps, steam engines, gas and oil engines, marine and locomotive work"  - http://books.google.com/books?id=JWNGAAAAMAAJ&lpg=PA34&ots=TqYj87FgAI&dq=%22a%20gas%20expands%20and%20does%20work%20as%20by%20pushing%20a%20piston%22&pg=PA34#v=onepage&q=%22a%20gas%20expands%20and%20does%20work%20as%20by%20pushing%20a%20piston%22&f=false


http://youtu.be/OXIZhqypNUI (about 4:00 - 5:30)

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Offline Tom Booth

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #16 on: December 14, 2012, 09:52:34 PM »
Consider the following scenario, might clear it up.
If you had a flow of heat, you can extract a certain portion as work.
Just curious; from an engineering standpoint, how exactly would you do that ?

What exactly is a "flow of heat" to begin with. Heat is not like a river you could just stick a paddle wheel into.

Quote
If that heat is at 'ambient' temperature then for you to be able to extract any work some portion of it must end up at a lower temperature.

"end up" at a lower temperature or already BE at a lower temperature ?

If that heat is Ambient, the temperature is more or less uniform. So there is no "flow" to extract energy from. Right ?

Quote
Also, heat only flows from a higher to lower temperature. (Zero'th law of thermodynamics and is in fact the definition of temperature).

So where is the "lower temperature" in the ambient ? It doesn't exist initially. First, as Tesla stated, you have to dig your "cold hole".

Quote
Combine those two facts  together and then try to devise a device that would extract all the energy from a flow of heat as work before reaching the cold sink (presumably the 4 Kelvin ambient temperature of the universe at heat death ) and you'll realise it is logically impossible.

Nobody is talking about extracting "all the energy" in the absolute sense.

Just all the heat energy supplied to the engine at any given interval or cycle.

If any engine ever was capable of extracting "all the energy" - literally, in the absolute sense, the engine itself would likely implode shrinking into a virtual nothingness beyond detection.

It is more than a "logical impossibility" it is also another straw man argument and a red herring.


Offline Tom Booth

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #17 on: December 15, 2012, 06:54:39 AM »

No confusion here. I was merely making the comment that the you-tube  video showed a device that is entirely consistent with the laws of thermodynamics and not doing anything remarkable from an energy standpoint.

Tom Booth made the comment that more heat than expected is 'disappearing' (or as you point out is being converted to work). I  am simply pointing out that it is not.

Your diagram is entirely correct. Along with the knowledge that the PROPORTION of energy as work that can be extracted from a flow of heat from one reservoir to another is dependent on the temperature difference between them explains why the device as envisaged by Tesla is at best, simply a heat engine that obeys the 2nd Law. Nothing new in that.

Ummm... now I'm confused. I was under the impression that your stance was that the device as envisioned by Tesla was "impossible".

Is the engine in the video violating the second law ?

If the engine runs but no heat is transferred from the heat source to the heat sink then I think yes. That would be a violation of the second law of thermodynamics.

Obviously, as you pointed out, heat IS being transferred.

The question is, how?

If we eliminate friction in the cylinder and eliminate conduction through the cylinder walls, that is, if we assume that this is possible, we are left with heat transfer by the "working fluid", the air or gas in the cylinder.

We will assume that there are no leaks. No transfer of matter is taking place.

Here is the scenario I described earlier which is what I already stated is what I THINK is going on in this engine.

I said first of all that GLASS is a poor heat conductor.

I know this from experience. You could put your hand on one side of a pane of glass and a blowtorch on the other and you would not feel the heat from the blowtorch immediately. It would take some time for the heat to penetrate the glass. The thermal conductivity of glass is about 1. Just a little better than air (.024) but not as good as many substances considered Heat Insulators like Asbestos-cement - 2, Firebrick - 1.4, Porcelain - 1.5 etc. Just for comparison, copper, a good heat conductor is around 400

Reference: http://www.engineeringtoolbox.com/thermal-conductivity-d_429.html

So logically, IMO, heat transfer from the air inside the test tube (engine cylinder) to the air outside the test tube can be all but discounted, at least in consideration of the apparent rapidity of the heat transfer taking place, judging by the speed of the engine.

This is a "free piston" engine, so there is nothing attached to it to restrict its motion (discounting friction), therefore the only thing controlling its motion is pressure changes.

In a Gas, Pressure is related to Temperature and Volume. These three might be thought of as a triangle. When one rises, the other two tend to rise with it, when one falls the other two tend to fall with it unless something is constrained.

If volume is constrained and temperature rises then pressure will rise. If temperature rises and pressure remains the same then volume will increase, etc.

So heat is added to the engine. The piston is free to move so pressure remains relatively steady. Volume increases freely. Temperature may begin to increase but as the volume increases rapidly temperature may remain relatively constant.

As the gas continues to expand rapidly kinetic energy is stored up in the free moving piston. Once the gas has expanded enough to compensate for the temperature increase it stops expanding. Equilibrium has been restored, except that the piston still carries MOMENTUM. As the piston continues down the cylinder the volume continues to increase. As a result, the gas is further expanded, but has now gone beyond the point of equilibrium. The pressure begins to drop and finally falls below the atmospheric pressure outside the cylinder. As the pressure drops but the volume continues to increase the temperature also drops sharply. The net result is an "implosion" as sharp and violent as the heat "explosion" that originally propelled the piston outward, so it is now propelled inward.

In all of this it seems to me that there is no time for heat transfer to the "Heat Sink", nor does there seem to be any necessity that such a heat transfer take place so as to fully explain the motion of the piston.

As a matter of fact, it seems to me that at the extent of the pistons travel down the cylinder its momentum and the expansion of the gas that results from it would of necessity, result not only in a pressure drop below atmosphere but also a corresponding temperature drop below ambient.

The engine, or rather the "working gas" within it, not only does not transfer heat to the sink, it probably absorbs heat from the sink.

When the internal pressure drops, outside atmospheric pressure works upon the piston to push it back inward and in turn the piston works upon the air in the chamber. This results in a transfer of energy from the outside ambient air to the air in the chamber. When dealing with a gas, Energy translates into heat. Kinetic energy transfers from the outside air, to the piston, to the inside air. The temperature of the air being worked upon rises. The air now being compressed meets with the heat being added to the engine and another "explosion" takes place driving the piston outward and the cycle repeats.

This engine is apparently not only not transferring heat to the sink but logically it is in fact taking energy from the sink. It is in effect using the heat added on the "power stroke" to put kinetic energy (and momentum) into the piston which energy is then used to effect refrigeration at the end of the power stroke. The refrigerating effect causes a drop in pressure and temperature which allows heat to be transferred out of the heat sink in the manner of a "heat pump". It is this transfer of energy FROM THE SINK (ambient) that drives the piston in its return stroke.

This, IMO, if true, would constitute a clear contradiction of the second law of thermodynamics. At least according to Wikipedia which states: 

Quote
Heat engine

In classical thermodynamics, a commonly considered model is the heat engine. It consists of four bodies: the working body, the hot reservoir, the cold reservoir, and the work reservoir. A cyclic process leaves the working body in an unchanged state, and is envisaged as being repeated indefinitely often. Work transfers between the working body and the work reservoir are envisaged as reversible, and thus only one work reservoir is needed. But two thermal reservoirs are needed, because transfer of energy as heat is irreversible. A single cycle sees energy taken by the working body from the hot reservoir and sent to the two other reservoirs, the work reservoir and the cold reservoir. The hot reservoir always and only supplies energy and the cold reservoir always and only receives energy. The second law of thermodynamics requires that no cycle can occur in which no energy is received by the cold reservoir.

http://en.wikipedia.org/wiki/Heat

This engine presents something of a mystery. Even the guy who built it, (as a result of an accidental discovery), doesn't quite know how to classify it and asks the question at the end of his video. What kind of engine is this?

Most certainly, attributing its behavior to "resonant effect" explains nothing.

A real thermoacoustic engine has no moving parts except perhaps a loudspeaker.

Offline Tom Booth

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #18 on: December 16, 2012, 03:35:36 AM »
This type of heat engine, whatever it might be called, traditionally it would be a "lamina flow Stirling" I think, with the exception that there is no flywheel - seems to be the simplest possible mechanical heat engine, and might be a good place to start as far as experimenting with or testing Tesla's concept.

Just a piston and cylinder,... and linear generator.

I was thinking something along these lines.

 


Offline Tom Booth

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #19 on: December 16, 2012, 04:49:26 AM »
This is basically the same engine as in the YouTube video except that it is partly enclosed inside of an insulated cold box.

Unlike how I drew it (rather thick) the diaphragm at top should probably be of some very thin flexible material like cellophane. It need not be taught but rather very loose. Its only purpose is to act as a barrier between the cold air in the box and Ambient air outside the box while still allowing the atmospheric pressure in. Necessary as it is atmospheric pressure that, in part, drives the engine (on the return stroke).

The air in the box should be DRY air, as the air temperature would likely need to be well below freezing. Simply placing a desiccant pack in the box might do.

The yellow is of course insulating material. The higher the R value the better. The white inside the yellow is possibly air space (like a thermos) The idea being to keep as much ambient heat as possible OUT of the box. The heat, therefore, in order to get in must do so THROUGH THE ENGINE and as far as possible, nowhere else.

The gray heat fins that perhaps might be mistaken as being intended for a heat sink or for heat dissipation are actually just the opposite. Air is not very good at transmitting heat so there should be as much surface area as possible. These fins are meant to DELIVER heat TO the engine. The check valve is intended for long term pressure equalization when there are pressure changes due to changing atmospheric conditions (this might not be necessary but well, why not?)

It would, of course, be necessary to pre-cool the box by some means to have any hope of getting the engine started, and, maybe even apply a little heat to the fins just for good measure, but if the theory of operation is correct then the engine should act something like a Stirling cryo-cooler on the one end (inside the box) and a regular heat engine at the other end (outside the box).

Although it appeared in the video that it would probably take quite a lot of heat to run such an engine, I'm not so sure.

Remember that Glass is a poor heat conductor. So probably 99% of the heat applied (by a flame) would be simply lost to the air, going around, rather than through the glass tube.

The HOT end, or Ambient end of this engine in a cold box, should probably be made of something other than glass. The whole heating unit might be cast out of aluminum including fins and regenerator or copper tubing or some such heat conducting material. The inner cylinder however should be as non-heat conducting as possible so as to prevent heat migration into the cold box.

Something like this should not be particularly difficult or expensive to put together.

Of course the piston should be frictionless as far as possible. Friction OUTSIDE the cold box, at the generator or at bearings or sleeves holding up the connecting rod should not pose a problem although the connecting rod itself, since it passes through and into the box should be non-heat conducting.

The diaphragm at top might also be double layered with a dead air space between to help reduce heat infiltration.

If something like this can be started by pre-chilling the interior of the box to establish a temperature differential, then theoretically it should continue to run as the engine itself would be drawing energy out of the box, while the piston is at the extremity driven by momentum and on its return driven by atmospheric pressure.

My over all theory on this is that heat is really Kinetic energy.

Therefore, what we want is not so much a FLOW OF HEAT but a flow of kinetic energy.

For there to be a flow, the energy has to have somewhere to go.

Somewhere other than into the cold box.

Ambient heat is the source, but it needs somewhere to go, therefore, the linear generator is probably a necessity. And it should have some kind of load. Lighting lights or charging batteries or perhaps powering a fan to blow air through the heating fins.

In other words the flow of energy needs to continue somewhere, it cannot dead end in the box, it needs to go out the wires to power some electrical load.

In actuality it would be the load on the generator that is drawing the energy. The heat, from the interior of the box is kinetic energy that can be transferred to the load.

In other words, there is not really any such thing as "heat". Heat is just a sensation. It is simply kinetic energy. So the idea is not to establish a flow of heat from heat source to heat sink but rather a flow of energy from source to destination. The destination being the load on the generator.

Perhaps this is nonsense, I don't know. But I don't think it would hurt to do some experimenting and see what happens.

Free Energy | searching for free energy and discussing free energy

Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #19 on: December 16, 2012, 04:49:26 AM »
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Offline Tom Booth

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #20 on: December 16, 2012, 05:06:25 AM »
If you studied electronics, then you know that electricity is also, in fact a kind of Kinetic energy as well and carries a kind of momentum of its own. An oscillating circuit for example utilizes this electrical "momentum" of electricity. The electrons bouncing back and forth through the circuit like a rubber ball into a capacitor or some such and out again from one end of the circuit to the other.

So, theoretically then, the load on the generator attached to the engine might, once established, act something like a siphon drawing off energy or in other words, continuing the flow or train of energy transformation.

Just maybe.

Offline Tom Booth

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #21 on: December 16, 2012, 04:15:15 PM »
Of course, there is the possibility that this type of engine is in some way "thermoacoustic". In that case, the regenerator or "stack" as it is called in a thermoacoustic engine may require a temperature gradient to function.

Personally I don't think so. For one, I read a report on a Stirling Engine Forum. A poster there, experimenting with a large lamina flow Stirling stated:

Quote
The heat tube volume to piston stoke volume ratio has to be very close to get it to show signs of life. You guys that build the test tube models and can't get them to run, just remember that a couple of mm of heat tube length means everything. The tube diameter does not seem to be as important. Although mine is running this ratio still needs to be fine tuned so that the power of the expansion stroke is matched to the power of the contraction stroke. I think that when this balance of power is achieved the engine will accelerate more and the fly wheel weight will not be as important. I have found that the closer I get to this balance of power the fly wheel weight can be lowered to achieve more rpm's. As far as steel wool goes, I stopped using it. The volume of the steel wool is almost impossible to calculate and does not seem to be of any benefit other than a volume fine tuning tool.

http://stirlingengineforum.com/viewtopic.php?f=1&t=1052

The fact that the volume ratio has to be "fine tuned" seems to indicate that there may be some "acoustic" or "standing wave" type phenomenon involved (like a pipe organ) but apparently this does not involve the regenerator if it can actually be eliminated.

But if there is a requirement for some temperature gradient in the heat delivery end of the tube perhaps some modification as illustrated could provide this.

Basically the entire engine might be enclosed in a "cold box" with just a portion of the tube exposed to ambient by way of an air duct or passage.

This however would probably let too much heat into the refrigerated space. At any rate, it is something to play around with.

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #21 on: December 16, 2012, 04:15:15 PM »
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Offline Tom Booth

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #22 on: December 16, 2012, 04:50:20 PM »
Personally, I think that the way heat is delivered to this kind of engine (Lamina Flow Stirling) involves the sudden release of heat (from the regenerator or stack or from the heat cylinder walls) due to the way the piston "bounces" back when the expanding air gives up its kinetic energy to the piston and contracts "pulling" the piston with it. As the piston returns, near the end of the return stroke, I imagine that there is a rather sudden increase in pressure, the gas having become compacted. The effect being like the piston suddenly hitting a "wall" of dense air. This would then cause a concussion wave in the heating chamber which would tend to cause a sudden release of heat from the regenerator or "stack" or from the heat cylinder walls as the air in the heating chamber moves or "vibrates" and so a very rapid expansion of the air results delivering another blow of kinetic energy to the piston.

More than likely though IMO this "concussion wave"  would be a singular phenomenon, (once per cycle) not necessarily a continuous "tone" or "sound wave" as in an acoustic engine.

"Timing" may be important. That is, it may be that these concussion waves need to be delivered with a certain rhythm to be maximally effective.

Is this "acoustic" ? Well sort of. A concussion wave in the air is a sound wave I suppose, technically, maybe.

Any engine of any kind has a certain "rhythm", frequency, or simply RPM. Call it what you will.

Offline Tom Booth

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #23 on: December 16, 2012, 09:55:46 PM »
Here is another idea, probably not applicable to this type of Stirling Engine but it might be useful for helping to maximize the efficiency of any Stirling Engine where a regenerator is used. I recently posted this to the Stirling Engine Forum so I wont repeat it all here.

Elastic (Nitinol?) Regenerator:

http://stirlingengineforum.com/viewtopic.php?f=1&t=1450

If a Stirling Type engine can be made to act in the way Tesla envisioned perhaps this would help. The idea is to take advantage of the efficiency improvement possible with a regenerator while compensating for the losses that are introduced by its use.

Offline Tom Booth

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #24 on: December 17, 2012, 06:07:24 PM »
Another way to keep the hot (ambient) air out while allowing pressure equalization might be to use a trap, like under a sink.

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #24 on: December 17, 2012, 06:07:24 PM »
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Offline Tom Booth

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #25 on: December 18, 2012, 12:55:13 AM »
Thanks for your comments Gianna, I get board when I don't have someone who consistently misconstrues everything I post. It's no fun when everybody agrees with me. Where are all the skeptics and hecklers? I was hoping to hear from TinselKoala. And of course thanks to everyone else who has contributed useful information, input, links etc. Please don't feel ignored. I do appreciate any and all input.

I can't see this working on an ongoing basis.  Assuming the ambient heat is at a higher temperature than than the cold box initially then it will run. Now, if you COULD convert all the heat to work then it would continue indefinitely as the cold sink would always be cooler than ambient.

However we know from Carnot that this is not possible. Some of the heat from the ambient source will be delivered to the cold sink and the temperature will start to rise. Eventually the cold sink temperature will reach ambient temperature and the engine will stop, unless there is some way to cool the cold sink again.

What you say here is, of course, a given. That is, it is the conventional wisdom, the unquestioned truth. Nobody in their right mind would think otherwise or waste precious time and money on a hopeless endeavor that is doomed to failure from the start.

Who was it that said something or other...?

Oh yeah,:

Quote
The law that entropy always increases, holds, I think, the supreme position among the laws of Nature. If someone points out to you that your pet theory of the universe is in disagreement with Maxwell's equations — then so much the worse for Maxwell's equations. If it is found to be contradicted by observation — well, these experimentalists do bungle things sometimes. But if your theory is found to be against the second law of thermodynamics I can give you no hope; there is nothing for it but to collapse in deepest humiliation.    ”

         --Sir Arthur Stanley Eddington, The Nature of the Physical World (1927)


But does entropy increase, decrease or stay the same if this idea were to work ?

I think an argument could be made that entropy would increase.

The earths atmosphere and the heat in it is rather orderly and stable. It you could take that heat and let it find a way to escape and disperse through the electrical grid to destinations unknown or perhaps to be emitted by some light source or as some other electromagnetic impulses to finally radiate out into space to the far reaches of the universe, which condition is more orderly ?

If such an engine were found to work, I have little doubt that the proponents of the second law would figure out some way to explain it. What is a condition of order or disorder but a subjective opinion ?

I believe Tesla's theory anyway. At least I won't dismiss his idea until I, or someone else at least makes some feeble attempt at applying it. Or conducts some experiment to test it. It doesn't appear to me to be all that formidable a task.

Quote
Trying to cool the exhaust  is not possible using a one way trap as you propose. If the exhaust temperature is lower than ambient (as it must be for the engine to run) then the exhaust heat wont flow naturally back to the ambient source. To do so would require us to do work. Exactly the same amount of work or more than could be extracted by the engine in the first place. Net energy result of the cycle is zero or negative.

Thankfully, you have entirely misconstrued and misunderstood the purpose and function of the "one way trap", and apparently also the entire manner of operation of the whole engine and that of Stirling Engines at large or in general.

First of all, there is no "exhaust". This engine is basically a Stirling Engine. Stirling Engines do not have an exhaust. The air does not leave the cylinder.

Because there is no exhaust, of course, the purpose of the trap cannot possibly be to "cool the exhaust".

Again, the exhaust temperature is not lower than ambient because there is no exhaust.

The exhaust heat will not flow back to ambient. If there is no exhaust then of course, there can be no exhaust heat. Right ?

Therefore; Returning the exhaust heat will not require any work because there is no exhaust and therefore no exhaust heat.

The heat passes into the box via the engine and only the engine. It goes in but does not come out. Remember ? It disappears! It is converted into work. Some of that work is used to effect cooling, the rest goes out as electricity so as to increase the entropy of the universe. The kinetic energy of the hot air molecules impacts a small portion of the engine. Heat is taken in by the outer hull of the engine and transferred to the air inside the engines cylinder. That air expands and drives the engine. Part of the power supplied is utilized for generating electricity, the rest is used for cooling. By the time this is accomplished the heat has been used up. If there was an exhaust there would be no heat (above ambient) to be exhausted, but in fact there is no exhaust.

The purpose of the trap is the same as the diaphragm in the earlier illustration. It simply provides an easily movable barrier that prevents hot ambient air from mixing with the cold air surrounding the engine while allowing the pressure of the atmosphere through. Air does not pass through the trap in either direction, except possibly a very small quantity may bubble through in the case of extreme changes in atmospheric pressure.

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Your one way trap idea epitomizes what is required to make this or Tesla's idea work.

Indeed.

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It needs to be able to transfer heat energy from a low temperature to a higher one while consuming less work than is able to be generated by a heat engine operating in the opposite direction.

Classical thermodynamics says this is impossible. Quantum physics is less sure, but statistically the classical result holds true.

This engine is much like an oscillating electrical circuit maintained by intermittent pulses of electricity.

The problem with electricity however is that we do not have a ready and inexhaustible supply on hand to maintain such oscillations indefinitely. Heat, on the other hand is in the air, continually supplied by the sun and renewed on a daily basis. The engine takes in intermittent pulses of HEAT to maintain the oscillations at one end and pulses of atmospheric pressure acting in the reverse at the other end.

Possibly it won't work. Nevertheless, it doesn't seem like a very difficult experiment to carry out. Ay least if we can get past the notion that a trap to keep out hot air is actually an exhaust pipe to let out hot air.


Offline Tom Booth

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #26 on: December 18, 2012, 02:55:05 AM »
Perhaps this will make things more clear.

(It may take a while for the animation to load.)

Never mind, for unknown reasons I'm not able to post an animated Gif here. sorry.

By way of explanation, the dark blue stuff in the trap is a fluid. Probably antifreeze given the temperature. When the engine runs it just moves in the tube back and forth from the pressure changes but no air enters or escapes.

BTW the light blue in the box surrounding the engine is just cold air. Blue to indicate the cold temperature, while outside the box is regular ambient air.

Hope that helps.

edit: I uploaded the gif here: http://calypso53.com/stirling/amb_eng_anim.gif
« Last Edit: December 18, 2012, 05:24:25 AM by Tom Booth »


Offline Tom Booth

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #27 on: December 18, 2012, 07:04:49 AM »
Ok, there is no exhaust as such as in an exchange of gasses, but heat MUST be transferred to the cold sink. I'm calling that 'exhaust' in this instance. If there was no heat transfer to the cold sink the the engine would not run.

I don't suppose you actually took the time to read Tesla's paper. But the theory of his is; And this part is not even controversial, A quantity of heat enters the engine. Some portion of that heat is "converted" into "Work". Perhaps some portion of that heat which is not converted into work reaches the sink.

Tesla surmised or believed or theorized that the energy derived from the heat could be used to remove whatever energy reached the sink.

In his own words:

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As regards heat, we are at a high level, which may be represented by the surface of a mountain lake considerably above the sea, the level of which may mark the absolute zero of temperature existing in the interstellar space.  Heat, like water, flows from high to low level, and, consequently, just as we can let the water of the lake run down to the sea, so we are able to let heat from the earth's surface travel up into the cold region above.  Heat, like water, can perform work in flowing down, and if we had any doubt as to whether we could derive energy from the medium by means of a thermopile, as before described, it would be dispelled by this analogue.  But can we produce cold in a given portion of the space and cause the heat to flow in continually?  To create such a "sink," or "cold hole," as we might say, in the medium, would be equivalent to producing in the lake a space either empty or filled with something much lighter than water.  This we could do by placing in the lake a tank, and pumping all the water out of the latter.  We know, then, that the water, if allowed to flow back into the tank, would, theoretically, be able to perform exactly the same amount of work which was used in pumping it out, but not a bit more.  Consequently nothing could be gained in this double operation of first raising the water and then letting it fall down.  This would mean that it is impossible to create such a sink in the medium.  But let us reflect a moment.  Heat, though following certain general laws of mechanics, like a fluid, is not such; it is energy which may be converted into other forms of energy as it passes from a high to a low level.  To make our mechanical analogy complete and true, we must, therefore, assume that the water, in its passage into the tank, is converted into something else, which may be taken out of it without using any, or by using very little, power.  For example, if heat be represented in this analogue by the water of the lake, the oxygen and hydrogen composing the water may illustrate other forms of energy into which the heat is transformed in passing from hot to cold.  If the process of heat transformation were absolutely perfect, no heat at all would arrive at the low level, since all of it would be converted into other forms of energy.  Corresponding to this ideal case, all the water flowing into the tank would be decomposed into oxygen and hydrogen before reaching the bottom, and the result would be that water would continually flow in, and yet the tank would remain entirely empty, the gases formed escaping.  We would thus produce, by expending initially a certain amount of work to create a sink for the heat or, respectively, the water to flow in, a condition enabling us to get any amount of energy without further effort.  This would be an ideal way of obtaining motive power.  We do not know of any such absolutely perfect process of heat-conversion, and consequently some heat will generally reach the low level, which means to say, in our mechanical analogue, that some water will arrive at the bottom of the tank, and a gradual and slow filling of the latter will take place, necessitating continuous pumping out.  But evidently there will be less to pump out than flows in, or, in other words, less energy will be needed to maintain the initial condition than is developed by the fall, and this is to say that some energy will be gained from the medium.  What is not converted in flowing down can just be raised up with its own energy, and what is converted is clear gain. Thus the virtue of the principle I have discovered resides wholly in the conversion of the energy on the downward flow.

Now perhaps Tesla was over optimistic. It is not necessarily so easy to get a little heat out of a cold heat sink. Generally the colder it gets the more difficult it becomes to remove what little heat remains. So I see no guarantee that Tesla was absolutely right. Nevertheless, I see no guarantee that Carnot or the other fathers of the second law of thermodynamics were entirely infallible either. One or the other may have been overlooking something. But from my own research and studies, I think there is a great deal of evidence in support of Tesla and I have found no evidence that anyone has ever actually tried to apply or test his theory in an objective scientific manner. Carnot was a man who formulated an opinion. An opinion based on the idea that Heat is a fluid. That it runs through a heat engine like water over a water wheel and so must come out the other side. Tesla had the insight to realize that just wasn't the case. Heat is a form of energy. It doesn't necessarily have to come out the other side but can be converted into another form of energy. Something other than sensible heat.

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The end result is the cold sink heats up until it reaches ambient at which point the cycle stops.

Then you have to move that heat through your one way trap back to ambient. There is no way to achieve that without either supplying work or ambient temperature is less than the cold sink.

Your opinion might carry more weight if you could explain in detail exactly how a "resonant effect" causes a piston to reverse its course in a cylinder and hurtle inward against its own momentum as well as against the expanding hot air headed towards the sink. I doubt if you can, yet Tesla's theory throws light on the subject and explains it quite satisfactorily IMO.

Can you explain the behavior of the engine in this video?

http://www.youtube.com/watch?v=cAyw_dOioMU

There is an additional video I came across:

http://www.youtube.com/watch?v=PflY-AFp15c

It shows infrared imagery of a similar type of Glass Test tube Stirling.

One thing that I think is noteworthy is how long it seems to take before enough heat penetrates the glass tube before this engine can get started. The lack of any apparent "resonant" effect is also conspicuous.

My point being that if it takes the heat that long to get into the engine through the glass, it seems reasonable to assume it would take just as long to get back out through the glass to the sink, in the previous engine which is all glass.

I would appreciate it, if you really believe it, if you would tell me more about this so-called "resonant effect" and how it is able to stop a piston in its tracks and cause it to reverse its course in an instant of time, or tell me by what mechanism exactly it is you believe this is taking place.

I personally can see no other rational explanation than that the heat is converted, as Tesla surmised, into another form of energy.

With the linear generator, this conversion takes place on both the forward and backward stroke of the piston. That a conversion of energy is taking away the heat in the expanding gas, converting that heat into work, seems to me the only satisfying explanation.

If you really believe in your "resonant effect" theory than I do wish you would explain in detail just exactly how that works.

You wrote above: "The end result is the cold sink heats up until it reaches ambient at which point the cycle stops."

You seem to realize that once a balance is achieved things come to a halt. When temperatures equalize, then there is noting to drive the engine.

So again, please explain to me how the piston reverses its course once the gas that drives it has given up its heat to the heat sink and temperatures have equalized? Without the momentum of a flywheel to push it back, what causes it to stop and reverse its course and return from whence it came, not only against its own stored up momentum and against the expanding hot gas that pushed it out in the first place but also against the electromagnetic force of the linear generator.

Resonant effect ?

Offline Tom Booth

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #28 on: December 18, 2012, 03:55:52 PM »
It's no more complex than his observation at the beginning of the video that the device tended to oscillate at its natural frequency for a while even without heat applied.
 

I assume you mean this video:
http://www.youtube.com/watch?v=DyPxNNJQo9M

In the beginning he simply states: "What I noticed by accident was that if I took the con rod from the flywheel and applied a small impulse to the piston that it would oscillate for a few seconds backward and forward within the bore."

He does not specify whether he had been running or applying heat to the engine or not, but later in the video he demonstrates how the engine will run for a few seconds after the heat source is removed. In the comments someone stated : "the extra movements of piston after the heat source is taken away is just the heat that is left behind in the tube being used up." - which he did not dispute.

At no time does he suggest that any oscillation takes place without heat having been recently applied to the engine and at no time does he demonstrate anything of the sort.

I suppose if you really think a heat engine of any kind can run at all without heat then we could ask him that specific question if he is still around.

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The mass of the piston is alternately compressing and expanding the gases. Running the motor at that frequency would not require a flywheel.

Oh, now it is the "mass of the piston" that is running the engine compressing and expanding the gas and not the other way around.

Your explanation is sorely lacking in details.

If you can possibly do so, please take us through the cycle of just how a resonant effect engine operates from start to finish.

IMO, you may as well say that this resonant effect can stop a bullet and drive it back down the barrel of a gun.

Mass in motion tends to stay in motion unless it comes up against or is diverted by some outside force. It does not just stop, reverse course and start compressing gas in the opposite direction of its travel.

BTW here is another video from the same gentleman. He first runs the engine with a flywheel, then removes the flywheel and runs it with a linear generator and shows it generating electricity. He then short circuits the generator coils and the engine stops and refuses to run at all. then he runs it with no load.

http://www.youtube.com/watch?v=J9ILlx3XPZ4

I would say that a flywheel may prevent such an engine from running at its "natural frequency" but it still runs just the same. Without the flywheel to slow it down it will run at a constant speed but it is not the frequency or "resonance" that makes it go. That would take some stretch of the imagination IMO.

I think it would be very interesting to run such an engine with a variable load. Then I think it would be obvious that the engine is capable of running at different speeds and not just at some fixed frequency dictated by its dimensions or mass.


Offline Tom Booth

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #29 on: December 18, 2012, 07:01:34 PM »
Another thing I find quite interesting about this type of Stirling Engine and the one in this last video in particular running with the flywheel...

In the earlier videos the guy mentioned about how he installed a rubber bumper in the first and a spring in the second engine to keep the piston from banging into the bottom of the cylinder chamber as it travels back TOWARDS the source of heat.

This seemed to indicate to me that the contraction phase was stronger than the expansion phase, due to some degree MORE heat being "disappeared" than what was supplied.

I explained how this is possible based on Tesla's theory.

The piston is driven out by the expanding gas until a point of equilibrium is reached. The kinetic energy of the expanding gas has largely been converted or transferred to the piston or elsewhere. Once reaching a point of balance, Temperature and pressure equalized, the piston should stop. In most engines at this point the momentum of the flywheel would be needed to push the piston back.

The piston continues beyond the point of equilibrium due to its momentum. At this point it is expanding the gas causing a drop in pressure and temperature. But on the return stroke, the engine is still doing "work" if only to overcome friction, therefore more heat is being converted or transferred from the gas on the return stroke.

The net effect of all this is that the engine converts more heat in the gas into other forms of energy or the heat appears elsewhere as friction etc. but the gas itself is dropping in temperature below that of the sink. In effect, it has, towards the end of its outward stroke, become a refrigerator.

So the piston actually returns towards the heat source with more force than it had on its way out.

What I find interesting in this last video, in light of the above, is the way the engine is hopping across the table TOWARDS the heat source.

Remember the piston bumping into the orifice ?

With the flywheel attached the piston cannot travel as far inward as it would like, but the MOMENTUM is still there, resulting in the engine being bumped toward the heat source with every revolution.

I don't think this can be explained simply due to the flywheel being out of balance. If that were the case the motion would be more or less random in any which way not consistently in one direction, toward the heat source, the same as when the piston was bumping into the end of the chamber, again TOWARD the heat source.

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Re: Tesla's Ambient Heat Engine Theory - Right or Wrong ?
« Reply #29 on: December 18, 2012, 07:01:34 PM »

 

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