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Topic: Tesla's heat engine (split from DDWFTTW) (Read 4244 times) previous topic - next topic - Topic derived from Direct Down Wind Fast...

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Re: Tesla's heat engine (split from DDWFTTW)
Reply #450
The question is simply; can we run a heat engine on ambient heat by utilizing an artificially manufactured "cold hole" or refrigerated space, without that cold space filling up with heat as the heat passes THROUGH the heat engine.
Yes - I understand that.  But that question is abstract.  I have not seen a mechanism described to attempt to do that.    I'm tempted to ask you again to describe what you propose, but I'm pretty sure we're just going in circles at this point.

What I would propose to start with is to just take an off-the-shelf LTD Stirling engine. Get a small block of ice and put it in a dewar flask with an open top. Set the engine on top of the flask and get it running. We might just be surprised to find that the engine runs indefinately and that the ice never melts.

As far as I'm aware, no such experiment has ever been tried.

Re: Tesla's heat engine (split from DDWFTTW)
Reply #451
What I would propose to start with is to just take an off-the-shelf LTD Stirling engine. Get a small block of ice and put it in a dewar flask with an open top. Set the engine on top of the flask and get it running. We might just be surprised to find that the engine runs indefinately and that the ice never melts.

As far as I'm aware, no such experiment has ever been tried.
That doesn't really tell me the mechanism your proposing - but it's closer.  I could presumably study the Stirling engine and figure out for myself what mechanism you're proposing.

But what seems more to the point is that that sounds like a trivial experiment to run.  Why haven't you tried it?

Re: Tesla's heat engine (split from DDWFTTW)
Reply #452
A good Dewar flask is about $200, a half way decent quality off the shelf LTD Stirling engine is about $375.

To be meaningful, such an experiment should probably have at least one control setup. Also, these off-the-shelf engines don't have regenerators and may require additional modifications, such as lengthening the connecting rod slightly, adjusting the timing to optimize the engine for running on ice, I'd also want to try adding a small compressor pump. All in all, if It meant spending upward of $1000 I figured I may as well get a $500 mini metal lathe and some other machining tools and build my own engines. I did spend some money on some cheap engines but they were clearly inadequate and impossible to modify.

Certainly if I had $1,000 or whatever it might take to spare to do the experiment earlier I would have by now. But an engine that does nothing more than keep itself going is not much more impressive than the drinking bird, which we can already see working.

I've already proposed the experiment to model engine builders who presumably already have model engines to work with, hoping for some feedback. For example:

http://stirlingengineforum.com/viewtopic.php?f=1&t=1029

That was about 5 years and 4638 views ago.
Mostly all I've ever gotten is guesses regarding the outcome. Apparently nobody considers it worth bothering with.

But this is why I've gone and purchased a metal lathe and other equipment and recently acquired a place to set up a workshop.

Generally I'm struggling to pay bills and barely have the time and resources for what I've managed to put towards this so far.

  • MikeB
Re: Tesla's heat engine (split from DDWFTTW)
Reply #453
The question is simply; can we run a heat engine on ambient heat by utilizing an artificially manufactured "cold hole" or refrigerated space, without that cold space filling up with heat as the heat passes THROUGH the heat engine.
Yes - I understand that.  But that question is abstract.  I have not seen a mechanism described to attempt to do that.    I'm tempted to ask you again to describe what you propose, but I'm pretty sure we're just going in circles at this point.

What I would propose to start with is to just take an off-the-shelf LTD Stirling engine. Get a small block of ice and put it in a dewar flask with an open top. Set the engine on top of the flask and get it running. We might just be surprised to find that the engine runs indefinately and that the ice never melts.

As far as I'm aware, no such experiment has ever been tried.
This would be truly astounding if able to be realized.

Re: Tesla's heat engine (split from DDWFTTW)
Reply #454
What I would propose to start with is to just take an off-the-shelf LTD Stirling engine. Get a small block of ice and put it in a dewar flask with an open top. Set the engine on top of the flask and get it running. We might just be surprised to find that the engine runs indefinately and that the ice never melts.

As far as I'm aware, no such experiment has ever been tried.
That doesn't really tell me the mechanism your proposing - but it's closer.  I could presumably study the Stirling engine and figure out for myself what mechanism you're proposing.
...

It is true Tesla spoke about heat engines in very broad abstractions.

His basic premise was that because a heat engine in effect turns heat into cold in the course of it's operation, a heat engine should, to put it simply, be able to run "on ice", or more accurately, on ambient heat, without the ice melting, because in the process of heat conversion, the byproduct is a refrigerating effect.

Now there are many many types of "heat engine" to which this principle could, in theory, be applied.

I've narrowed it down to the Stirling type heat engine, but there are many, many types of Stirling engine.

I've further narrowed it down to the LTD type Stirling, as probably the easiest to build in a home workshop, if for no other reason, but there are many possible configurations.

Everything that has been discussed in this topic or thread so far is applicable to the question at hand. It has been discussed from every possible angle. I'm not sure what more I could add to make the proposal more understandable. But certainly, understanding the basics of how a Stirling engine works would be a prerequisite to a discussion on possible ways to modify a Stirling engine to run on ambient heat.

There are dozens of YouTube videos about how a Stirling engine works and also several forums devoted to the topic.

Basically you have a can of air. Completely sealed. Heat the can from the outside and the air inside gets hot and tries to expand. Attach a cylinder with a piston and the expanding air can do some work.

Re: Tesla's heat engine (split from DDWFTTW)
Reply #455
It is true Tesla spoke about heat engines in very broad abstractions.

But this is the key to my problem.  You keep referring to Tesla and Stirling engines.  I'm talking to *you* and wanting a description of the process you proposed.  I gave an example earlier.  I'd like to see a description like...

- Heat the air in an enclosed space.
- Let that air act on a piston.
- When the piston moves it opens a valve that allows the hot air to escape...

I'm no expert on Stirling engines.  I have studied up on them as a result of this discussion so I'm pretty sure I understand the basics.  But what I'm inclined to look at is whether the proposed cycle is theoretically possible - not whether it has been achieved or could be relatively easily.

Quote
Basically you have a can of air. Completely sealed. Heat the can from the outside and the air inside gets hot and tries to expand. Attach a cylinder with a piston and the expanding air can do some work.

Great!  That's exactly the sort of description I'm looking for.  And I have good news... that will definitely work.


Re: Tesla's heat engine (split from DDWFTTW)
Reply #456
It is true Tesla spoke about heat engines in very broad abstractions.

But this is the key to my problem.  You keep referring to Tesla and Stirling engines.  I'm talking to *you* and wanting a description of the process you proposed.  I gave an example earlier.  I'd like to see a description like...

- Heat the air in an enclosed space.
- Let that air act on a piston.
- When the piston moves it opens a valve that allows the hot air to escape...

I'm no expert on Stirling engines.  I have studied up on them as a result of this discussion so I'm pretty sure I understand the basics.  But what I'm inclined to look at is whether the proposed cycle is theoretically possible - not whether it has been achieved or could be relatively easily.

Quote
Basically you have a can of air. Completely sealed. Heat the can from the outside and the air inside gets hot and tries to expand. Attach a cylinder with a piston and the expanding air can do some work.

Great!  That's exactly the sort of description I'm looking for.  And I have good news... that will definitely work.



OK, the question is, what happens after?

What happens when the air in the can expands and does work on the piston? We have this thing called the first law of thermodynamics that says that the heat is converted to work, therefore the air that did the work loses heat as it does the work on the piston and so gets cold which reduces the pressure in the can allowing the piston to return to its starting place.

The Second law however states that the above scenario is IMPOSSIBLE. The piston cannot return to its starting position without first cooling the can and cooling the air in the can by "ejecting" at least some of the heat to some external cold "reservoir". According to the second law, not ALL the heat can be converted into work. There will always be some "waste heat" to be removed.

Why? Well, it all becomes rather vague IMO. Something to do with entropy. The "universe" must move towards greater disorder. Whatever.

According to Tesla's theory, which is the topic of the thread, a very efficient heat engine should be able to run on ice indefinitely without the ice melting. But certainly, if some heat does reach the ice, the engine should be able to keep the ice frozen by operating some form of heat pump to remove the heat as required and still have a surplus of energy to drive a dynamo and produce electricity.

We can do all we can to make the engine as efficient as possible, but we are not really talking about anything new. We already know that a Stirling engine can run "on ice". Anyone can watch a dozen videos on YouTube of Stirling Engines doing just that.

What I haven't seen on YouTube is anyone bothering to keep the ice insulated from the surrounding ambient heat so that heat can only reach the ice by passing THROUGH the engine.

If Tesla was right, the ice should, at the very least melt MUCH MORE SLOWLY with an engine on top of it CONVERTING THE HEAT INTO SOMETHING ELSE which should have a refrigerating effect. The engine should, to one degree or another PREVENT HEAT FROM REACHING THE ICE, by converting the heat into another form of energy.

If that doesn't happen with any off-the-shelf Stirling engine then there isn't much sense in taking the question any further IMO.

I'm not really inclined to go into agonizing detail regarding how Stirling engines work. Information on the subject is abundant on the internet, I see no real point in my repeating it here.

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

https://www.youtube.com/watch?v=taDHMw38aE0

What would happen if instead of Bill Nye in the above video, putting ice in a glass beaker exposed on all sides to heat infiltration from the surrounding air, put the ice in a Dewar flask, completely insulated from the surrounding ambient heat? How much longer would the engine run? Could it run indefinitely? Could the engine actually have a refrigerating effect and prevent the ice from melting?

There really isn't any more to it than that, other than perhaps, what kind of heat pump do we want to try having the engine operate to help keep the ice cold, or perhaps produce temperatures even colder than ice.

There is no question as to whether or not a Stirling cycle is feasible. Obviously Stirling engines do work. The only question is, could one work if "powered by" ice. We already know it can. Can a Stirling engine running on ice convert enough of the incoming ambient heat into work, so that no heat reaches the ice? So that the ice does not melt and the engine can therefore operate indefinitely?

We are still talking about a Stirling cycle. We are simply using ambient as the heat source rather than the heat sink to run a Stirling engine. There is nothing more to explain.

Re: Tesla's heat engine (split from DDWFTTW)
Reply #457
I'm not really inclined to go into agonizing detail regarding how Stirling engines work. Information on the subject is abundant on the internet, I see no real point in my repeating it here.

And I'm not asking you to describe how a Stirling engine works - unless that happens to be exactly the mechanism you're proposing.  And even then I'm not asking you to describe it unless you want me to weigh in on the topic.

If you're getting exactly what you came here for I guess you're good to go.  Of course it doesn't seem to me that you are getting what you came here for (but I could be wrong).  As a result of your being here I've studied up on the gas laws.  I learned I was wrong about some stuff I was pretty sure I knew.  I studied up a bit on the Stirling engine.  Others have weighed in as well.

From what I understand, you don't have the funds to do the desired experiment yourself and you can't get others to do it for you.  I was under the impression that you were hoping to convince people that your proposal was workable.  But I don't see you trying to do that, so I'm no longer sure what your objective is.

My objective here is to have fun.  It's a diversion.  I enjoy discussing physics, particularly physics that seems counter-intuitive.  If that's your objective as well, then we're all having fun.


Re: Tesla's heat engine (split from DDWFTTW)
Reply #458
OK, the question is, what happens after?

What happens when the air in the can expands and does work on the piston? We have this thing called the first law of thermodynamics that says that the heat is converted to work, therefore the air that did the work loses heat as it does the work on the piston and so gets cold which reduces the pressure in the can allowing the piston to return to its starting place.

The Second law however states that the above scenario is IMPOSSIBLE. The piston cannot return to its starting position without first cooling the can and cooling the air in the can by "ejecting" at least some of the heat to some external cold "reservoir". According to the second law, not ALL the heat can be converted into work. There will always be some "waste heat" to be removed.

Why? Well, it all becomes rather vague IMO. Something to do with entropy. The "universe" must move towards greater disorder. Whatever.

There's nothing remotely "vague" about it.  Entropy has a clear, mathematical definition - it's just as precisely defined (and closely related to) the other thermodynamics quantities like heat, work, etc.  If you know how, you can do calculations with it.

Moreover it's perfectly clear intuitively why the second law holds.  You cannot convert the kinetic energy of gazillions of molecules of air into (say) compressing a single spring (and make no other compensating change to the system) because it would require a miracle to do so.  All the air molecules would have to conspire to strike the spring in the right way at the right time.  Because there are so many air molecules, the odds of that happening are absurdly small.  It doesn't violate conservation of energy, but (for all intents and purposes) it never happens.

A good analogy is is this.  Make a movie of just about any interesting process - breaking an egg, throwing a rock into a pond, landing or crashing a kite or glider, etc.  Now run the movie in reverse.  Nothing about the reverse process violates any law of physics except the second law.  So the second law is what tells you that ridiculous things like water currents conspiring to push a rock up out of a lake and sending it flying into the air don't happen.

Re: Tesla's heat engine (split from DDWFTTW)
Reply #459
I'm not really inclined to go into agonizing detail regarding how Stirling engines work. Information on the subject is abundant on the internet, I see no real point in my repeating it here.


And I'm not asking you to describe how a Stirling engine works - unless that happens to be exactly the mechanism you're proposing.  And even then I'm not asking you to describe it unless you want me to weigh in on the topic.

If you're getting exactly what you came here for I guess you're good to go.  Of course it doesn't seem to me that you are getting what you came here for (but I could be wrong).  As a result of your being here I've studied up on the gas laws.  I learned I was wrong about some stuff I was pretty sure I knew.  I studied up a bit on the Stirling engine.  Others have weighed in as well.

From what I understand, you don't have the funds to do the desired experiment yourself and you can't get others to do it for you.  I was under the impression that you were hoping to convince people that your proposal was workable.  But I don't see you trying to do that, so I'm no longer sure what your objective is.

My objective here is to have fun.  It's a diversion.  I enjoy discussing physics, particularly physics that seems counter-intuitive.  If that's your objective as well, then we're all having fun.



Fun is always good.

I will definately keep working at building engines and experimenting, if someone else doesn't beat me to it.

Beyond that, I do wish to maintain some kind of audience in case there is some kind of revolutionary breakthrough. I want it on record. Even if it doesn't work or lead to anything, someone else can learn from the mistakes and not waste time.

The one thing that keeps me going is it seems nobody has ever tried these various relatively simple experiments.

Re: Tesla's heat engine (split from DDWFTTW)
Reply #460
OK, the question is, what happens after?

What happens when the air in the can expands and does work on the piston? We have this thing called the first law of thermodynamics that says that the heat is converted to work, therefore the air that did the work loses heat as it does the work on the piston and so gets cold which reduces the pressure in the can allowing the piston to return to its starting place.

The Second law however states that the above scenario is IMPOSSIBLE. The piston cannot return to its starting position without first cooling the can and cooling the air in the can by "ejecting" at least some of the heat to some external cold "reservoir". According to the second law, not ALL the heat can be converted into work. There will always be some "waste heat" to be removed.

Why? Well, it all becomes rather vague IMO. Something to do with entropy. The "universe" must move towards greater disorder. Whatever.

There's nothing remotely "vague" about it.  Entropy has a clear, mathematical definition - it's just as precisely defined (and closely related to) the other thermodynamics quantities like heat, work, etc.  If you know how, you can do calculations with it.

Moreover it's perfectly clear intuitively why the second law holds.  You cannot convert the kinetic energy of gazillions of molecules of air into (say) compressing a single spring (and make no other compensating change to the system) because it would require a miracle to do so.  All the air molecules would have to conspire to strike the spring in the right way at the right time.  Because there are so many air molecules, the odds of that happening are absurdly small.  It doesn't violate conservation of energy, but (for all intents and purposes) it never happens.

A good analogy is is this.  Make a movie of just about any interesting process - breaking an egg, throwing a rock into a pond, landing or crashing a kite or glider, etc.  Now run the movie in reverse.  Nothing about the reverse process violates any law of physics except the second law.  So the second law is what tells you that ridiculous things like water currents conspiring to push a rock up out of a lake and sending it flying into the air don't happen.

Entropy as some kind of measure of "disorder" seems just a tad subjective to me. My sense of order and arangement could be different from yours and yours could be different from my friends and whatever we can think of may be different from nature.

Living things grow and increase in complexity. Are we all to believe there is no such thing as creativity. No building up of anything. Only a gradual and inevitable breaking down towards that final heat death of the universe?

As far as mathematics goes. I suppose I could develop a mathematics based on the number of hairs on angels heads determined by their nearness to God. That doesn't necessarily make it a real thing or a real quantity.

Re: Tesla's heat engine (split from DDWFTTW)
Reply #461
Entropy as some kind of measure of "disorder" seems just a tad subjective to me. My sense of order and arangement could be different from yours and yours could be different from my friends and whatever we can think of may be different from nature.

Yes, but entropy is not defined as "some kind of measure of disorder".  That is just a very rough description of what it tells us.  As Cold One says, it's rigorously defined.

Quote
Living things grow and increase in complexity. Are we all to believe there is no such thing as creativity. No building up of anything. Only a gradual and inevitable breaking down towards that final heat death of the universe?

Nope - that's not what the 2nd law says.  If you add energy to a system it can definitely move toward lower entropy.

Quote
As far as mathematics goes. I suppose I could develop a mathematics based on the number of hairs on angels heads determined by their nearness to God. That doesn't necessarily make it a real thing or a real quantity.

What?

Re: Tesla's heat engine (split from DDWFTTW)
Reply #462
Spork perhaps you would like to revisit the engine I posted a drawing of earlier.



Could it work? Would the engine get progresively colder? Would the cold water bath eventually freez or boil?

Could we make the flywheel a fan and replace the evaporative cooler with a radiator?
  • Last Edit: November 27, 2017, 08:01:37 AM by Tom Booth

Re: Tesla's heat engine (split from DDWFTTW)
Reply #463
Spork perhaps you would like to revisit the engine I posted a drawing of earlier.



Could it work? Would the engine get progressively colder? Would the cold water bath eventually freeze or boil?

Could we make the flywheel a fan and replace the evaporative cooler with a radiator?

Can an inanimate machine. An engine, lower or reduce its own "entropy"?

What happens in a Stirling engine with a regenerative displacer? (As pictured above)

Lets start with the displacer in the lower position. At the bottom of the air chamber. In the top of the chamber there are randomly moving hot air molecules. Now the displacer/regenerator moves up and the air in the chamber moves down through the displacer/regenerator The Hottest air molecules transfer heat to the regenerator while the colder air molecules are relatively unaffected and sink to the bottom of the chamber. The regenerator goes back down and the heat is transferred back to the air. Is this or is it not a kind of mechanical Maxwell's demon? Seems like it kind-of is to me.

At the first stage of the cycle with the regenerator at the bottom of the chamber we have only random molecular motion incapable of doing any work. With some slight up and down motion of the regenerator we now have heat being added back to the air so that now it can expand and do work. Is that not a kind of almost spontaneous reduction in "entropy"?

It takes very little energy to move the lightweight displacer up and down but in the process a greater amount of energy becomes available for doing work, and this machine carries on quite happily on its own ORGANIZING random molecular HEAT energy putting it into a state where it can perform work and using the energy derived to ORGANIZE additional random molecular motion in a cyclical manner.
  • Last Edit: November 27, 2017, 12:20:46 PM by Tom Booth

Re: Tesla's heat engine (split from DDWFTTW)
Reply #464
OK suppose the previously illustrated engine gets going, started with a hot block of steel or whatever.

It is compressing air which increases the temperature of the air in the tube. We are removing that heat with the cold water bath, then expanding the air for additional cooling before it comes in contact with the cold side of the engine. The engine is effectively running on Ambient heat, but, we are raising the temperature of the air ABOVE ambient in the process of compressing it, so why not use that heat to increase the temperature difference. Instead of the "Starter" block of hot iron or whatever we can now generate our own heat from compressed air. The engine is able to utilize that heat, converting the heat into work and so also helping to pre-cool the air before it gets to the cooling water/ice bath.



  • Last Edit: November 27, 2017, 01:09:33 PM by Tom Booth

Re: Tesla's heat engine (split from DDWFTTW)
Reply #465
Well hold on a minute. We were using a break on the expansion turbine just to put a load on the turbine so it could do work, which is a way to reduce the temperature of the air expanding through the turbine.

Why let that work go to waste just generating heat?

Suppose instead we add a pulley or some gears or something and use the energy from the decompressing air driving the turbine to bootstrap the engine to make compressing the air easier?

Something like this:



In case it is not recognizable from the above drawing. This is basically a modified LTD type Stirling Engine similar to this one:

https://www.youtube.com/watch?v=yeKXfF6gR-s

The idea is to simply add a very small air compressor or vacuum pump to generate a temperature differential.

  • Last Edit: November 27, 2017, 02:27:38 PM by Tom Booth

Re: Tesla's heat engine (split from DDWFTTW)
Reply #466
It might be noted that Stirling Engines of this type have been built that can operate on as little as 2 or 3 degrees C temperature difference.

The cooling system surrounding the engine is patterned after a Linde Air Liquefaction machine. This relatively simple method of cooling can produce extremely cold temperatures.

Air liquefies at -320 F

Of course, I would hardly expect that such a little Stirling Engine could ever get THAT cold but there is no reason it should have to.

This would be very similar to what Tesla was striving for I believe. To run a heat engine on ambient heat and using a Linde Type Air Liquefaction cooling system. The only real difference I think is that Tesla would have HAD TO liquefy the air as his heat engine was probably a Steam Engine and his idea seems to have been to run some kind of engine on liquid air that would be boiled with atmospheric heat.

Just for reference here is an illustration of the Linde Air-Liquifaction machine. As can be seen it consists mainly of a throttling device, a compressor and a water cooling jacket.




Re: Tesla's heat engine (split from DDWFTTW)
Reply #467
We can relate this to the previous discussion. Compress air into a tank and ALL of the energy is LOST?

As heat?

Here we are using at least some of this "lost" heat to run the heat engine that compressed the air that produced the heat that powered the engine.

But after using the heat from the compressed air which is theoretically giving back in heat ALL the energy that we put into compressing the air in the first place...

Well, we still have compressed air in the pipe.

The compressed cooled air can be expanded through the turbine and some additional energy reclaimed.

And in the process of reclaiming all this energy from the compressed air--- the air is getting colder and colder. This serves to increase our temperature difference which translates into. More power and greater efficiency.

Or am I crazy?

Of course such a scheme could never work.

Or could it?

  • MikeB
Re: Tesla's heat engine (split from DDWFTTW)
Reply #468
OK, the question is, what happens after?

What happens when the air in the can expands and does work on the piston? We have this thing called the first law of thermodynamics that says that the heat is converted to work, therefore the air that did the work loses heat as it does the work on the piston and so gets cold which reduces the pressure in the can allowing the piston to return to its starting place.
Something is unclear here.  Are you thinking of a totally insulated can, cylinder and piston where you can by some means add heat to the air, but it is not able to absorb or reject heat from/to the surroundings?  In this case I think you don't have the correct action.

To do work on a piston, there must be an opposing force on the piston such as a weight against the piston movement or simply ambient air pressure against the piston.  Let's assume the external side of the piston is exposed to ambient air pressure.  So we have a system at equilibrium, same pressure inside the can and cylinder as outside, neglecting the weight of the piston if it does not move horizontally.

Now you add heat to the internal air, which raises its temperature and pressure enough to start moving the piston.  Piston moves, heat in the internal air is used to do this work and piston motion stops once the internal air has cooled to the point where internal pressure equals the external pressure.  The internal air is still at a higher temperature than the external air because it's less dense.  System is at equilibrium and just sits there if it is perfectly insulated.

You have to let heat escape the system for the piston to return to its initial position with internal pressure equal to external.

Re: Tesla's heat engine (split from DDWFTTW)
Reply #469

So I was on a plane all day today and you guys put out a lot of words.  I get back late Weds night and will try to start catching up then.

Re: Tesla's heat engine (split from DDWFTTW)
Reply #470

Of course such a scheme could never work.

Or could it?

No.  Any system without a source of external energy is never going to create more energy and the working of your system does that.

So no, it won't work continuously.  It will run down and exhaust itself and come to a constant temperature with the environment.  Just as the drinking bird stops working when it runs out of water to evaporate.

And no, I don't feel the need to explain the laws of thermodynamics to you.  They have lots of information on that in college and in textbooks.  Take a course.  Learn why not.  Or waste your time in attempting to violate the laws and become famous  (Just be sure to explain how you did it for consideration for a Nobel Prize with the Prize money).  Either way, no skin off my back.

Windgrins :grin:
Lunatic Fringe, I know you're out there.  You've got to blame someone for your own confusion.

Re: Tesla's heat engine (split from DDWFTTW)
Reply #471

Of course such a scheme could never work.

Or could it?

No.  Any system without a source of external energy is never going to create more energy and the working of your system does that.

So no, it won't work continuously.  It will run down and exhaust itself and come to a constant temperature with the environment.  Just as the drinking bird stops working when it runs out of water to evaporate.

And no, I don't feel the need to explain the laws of thermodynamics to you.  They have lots of information on that in college and in textbooks.  Take a course.  Learn why not.  Or waste your time in attempting to violate the laws and become famous  (Just be sure to explain how you did it for consideration for a Nobel Prize with the Prize money).  Either way, no skin off my back.

Windgrins :grin:


In theory, as well as in fact I suppose, the drinking bird could be set next to an inexhaustible water source; river, lake, ocean, toilet bowl tank with a float valve whatever, so it doesn't run out of water. True or no?

What would the above depicted engine run on? What do you suppose it would eventually run out of? Cooling water? Add a water line and a float valve. Problem solved. Or what is it that is in short supply?

You say "Any system without a source of external energy is never going to create more energy..." but the engine has a source of external energy, the same as the bird has. Doesn't it?

Or what is the "system"?

Ambient heat comes from the sun shining on the atmosphere. That seems pretty external to me.


Re: Tesla's heat engine (split from DDWFTTW)
Reply #472
Here's an interesting article about using ambient heat to make useful energy.

It's basically a "molecular thermal diode" which converts ambient heat to electricity.

Overall, no energy is created, but energy is converted from thermal noise to useful work if this actually works.  It isn't working by heat engine principles.  Is it a "Maxwell's Demon"?  Could these shifting voltages do actual work?  The reason it isn't perpetual motion is that it converts ambient energy to useful energy supposedly, thus cooling the environment.  But it would be startling nonetheless.

One can think of it (if it works, a little like solar panels which convert ambient sunlight to electricity).  They aren't PM but produce a relatively endless supply of high grade energy (until the sun dies).

>>>So long as the graphene's temperature allowed the atoms to shift around uncomfortably, it would continue to ripple and bend.
Place electrodes to either side of sections of this buckling graphene, and you'd have a tiny shifting voltage.
By Thibado's calculations, a single ten micron by ten micron piece of graphene could produce ten microwatts of power.
It mightn't sound impressive, but given you could fit more than 20,000 of these squares on the head of a pin, a small amount of graphene at room temperature could feasibly power something small like a wrist watch indefinitely<<<

https://futurism.com/physicists-found-loophole-graphene-unlock-clean-limitless-energy/

Windgrins :grin:
Lunatic Fringe, I know you're out there.  You've got to blame someone for your own confusion.

Re: Tesla's heat engine (split from DDWFTTW)
Reply #473
OK, the question is, what happens after?

What happens when the air in the can expands and does work on the piston? We have this thing called the first law of thermodynamics that says that the heat is converted to work, therefore the air that did the work loses heat as it does the work on the piston and so gets cold which reduces the pressure in the can allowing the piston to return to its starting place.
Something is unclear here.  Are you thinking of a totally insulated can, cylinder and piston where you can by some means add heat to the air, but it is not able to absorb or reject heat from/to the surroundings?  In this case I think you don't have the correct action.

To do work on a piston, there must be an opposing force on the piston such as a weight against the piston movement or simply ambient air pressure against the piston.  Let's assume the external side of the piston is exposed to ambient air pressure.  So we have a system at equilibrium, same pressure inside the can and cylinder as outside, neglecting the weight of the piston if it does not move horizontally.

Now you add heat to the internal air, which raises its temperature and pressure enough to start moving the piston.  Piston moves, heat in the internal air is used to do this work and piston motion stops once the internal air has cooled to the point where internal pressure equals the external pressure.  The internal air is still at a higher temperature than the external air because it's less dense.  System is at equilibrium and just sits there if it is perfectly insulated.

You have to let heat escape the system for the piston to return to its initial position with internal pressure equal to external.

In any real engine, the weight of the piston, connecting rod, crankshaft, flywheel, things like momentum and inertia, friction etc. can't be neglected.

Real engines do not move "infinitely slowly", like the mythical Carnot engine.

In any real engine the heated gas builds up pressure, it has quite a bit of inertia and friction to overcome. It actually pushes the piston and does work. It seems, or appears, that in a real (heat) engine, the gas does work and looses energy simultaneously so that at the end of the stroke the gas is already cold. The heat does not have to escape to any external heat sink. At least, IMO this appears to be the case.

It may be that the excess heat is temporarily absorbed by the regenerator in a Stirling heat engine rather than being ejected to a sink.
  • Last Edit: November 28, 2017, 07:45:36 AM by Tom Booth

Re: Tesla's heat engine (split from DDWFTTW)
Reply #474

Of course such a scheme could never work.

Or could it?

No.  Any system without a source of external energy is never going to create more energy and the working of your system does that.

So no, it won't work continuously.  It will run down and exhaust itself and come to a constant temperature with the environment.  Just as the drinking bird stops working when it runs out of water to evaporate.

And no, I don't feel the need to explain the laws of thermodynamics to you.  They have lots of information on that in college and in textbooks.  Take a course.  Learn why not.  Or waste your time in attempting to violate the laws and become famous  (Just be sure to explain how you did it for consideration for a Nobel Prize with the Prize money).  Either way, no skin off my back.

Windgrins :grin:


In theory, as well as in fact I suppose, the drinking bird could be set next to an inexhaustible water source; river, lake, ocean, toilet bowl tank with a float valve whatever, so it doesn't run out of water. True or no?

What would the above depicted engine run on? What do you suppose it would eventually run out of? Cooling water? Add a water line and a float valve. Problem solved. Or what is it that is in short supply?

You say "Any system without a source of external energy is never going to create more energy..." but the engine has a source of external energy, the same as the bird has. Doesn't it?

Or what is the "system"?

Ambient heat comes from the sun shining on the atmosphere. That seems pretty external to me.

All good questions.  Allow me to help you state it more clearly and to state what won't occur:

1)  What will never occur is to take ambient energy and create more ambient energy than you started with. (COE).
2)  Can one take ambient thermal energy via some process of conversion and make it into useful energy by lowering the temperature of the environment which gets replenished from an outside source?  (Supposedly one cannot with a heat engine).

But like a flapping flag, one can capture energy from wind by taking the energy of random motion and shaking an attached magnet next to a coil of wire.   This produces a current which can be rectified and used to do useful work.  The energy comes from the wind being slowed by the flag (no energy creation).   The books all balance because the energy of the closed system never increases.  But a type of randomness is used to do useful work.

Can one do it on a thermal molecular level by capturing the energy of vibrating molecules and using it to do useful work?  I don't know the answer to that.

Windgrins :grin:
  • Last Edit: November 28, 2017, 07:31:25 AM by windgrins
Lunatic Fringe, I know you're out there.  You've got to blame someone for your own confusion.