Well, as many suspect, it may be that I did something to foul up the experiment and skew the results. Unconsciously putting my thumb on the scale in some way.
I'm well aware of experimenter bias. The engine running or not, could make a difference or make no difference.
Possibly I opened the refrigerator door or put a TV dinner in the oven changing the ambient environment or something else influenced the results nobody could ever guess. Which is why I originally reached out to the Science and Physics forums to see if they might be familiar with this kind of experiment and possibly could tell me what I might be doing wrong, if the results were different from "the usual".
But as it turned out, there were no "usual" to compare with, I guess.
One suggestion was, that the running engine might be, in effect, holding back the heat, which is why less heat is getting through, only because less is going in.
That would compare with the water analogy.
A turbine at the outlet of a reservoir would hold back the water to some degree, so less water would flow. Less than if no turbine were present and the water were free flowing.
However, if there were an inoperative turbine blocking the outlet, possibly that would block more water than a turbine that was running and letting water through.
So it is really a toss up.
First the experiment needs to be repeated by others that don't have a bias towards trying to prove Tesla right.
Though I don't think that is actually true, others seem to think so.
I'd really be just as content to prove Tesla or whomever wrong, I don't really care, I just want to build a better engine, and can't really do that without understanding how it actually works.
Though, in actuality, if the "Carnot limit" were shown to be invalid, that in itself would tend to suggest working towards making Stirling engines more efficient could have it's rewards, but if the efficiency limit is real, the prospect is pretty hopeless. May as well find something else productive to do with my time.
At this point I'm only continuing because my experiments have failed to prove Tesla wrong, and incidentally myself, as even before reading Tesla's article, I had accidently stumbled into the same thorny bramble by devising a heat engine that theoretically could operate on the heat in the air, by combining a heat engine with an air-cycle refrigeration system.
A government contractor familiar with those test solar dish Stirlings in Arizona told me that those engines ran 24 hours a day, even at night by in some way continuing to run. He said they had built in air conditioners.
So, he wanted me to help him design a similar system, but smaller, that he could market to homeowners.
I didn't know where it would lead, but I started trying to combine Stirling engines and various refrigeration and air conditioning systems. It kind of made sense. A Stirling engine could run on ice. So the refrigeration would keep the engine cold enough to run through the night.
The resulting engine I finally came up with, as it turned out, seems to operate on the same principle, and basically the same hardware as Tesla's heat engine. But I knew nothing about that at the time. I had inadvertently either duplicated Tesla's engine, in principle at least, or I made the same error by ignoring, or not being cognizant of the "second law".
I was designing the engine on the basis of what I knew as an experienced engine mechanic, not a student of thermodynamics.
When the contractor ran my proposed engine by some DOE or some such associates the determination was my engine was impossible. That it violated the second law of thermodynamics.
That was the first I heard of it. (T2nd L of T)
I could visualize the engine running quite happily in my imagination. I could not see any mechanical reason why the engine wouldn't work. For all intents and purposes it already was working but just hadn't been built yet.
It was while researching why some SOB thought my design wouldn't work, over the next few months, that I stumbled across Tesla's article explaining precisely why it would!
So, I'd like to settle the matter one way or the other and just get on with my life.
"Carnot efficiency" though, seems entirely arbitrary, now that I've studied it, and as far as that bisects the second law, as far as it's applicability to heat engines, that seems baseless and arbitrary to me as well.
Toss in "entropy" as well. That is just a kind of outgrowth of the original errors. It seems to me.
There is no experimental proof that there is any reality to "entropy" either IMO. It's on the level of a philosophy of life, like Murphy's Law. Nothing more. Not a very useful or inspiring philosophy at that.
Ted Warbrooke's Stirling 1: Question
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Alphax
Re: Ted Warbrooke's Stirling 1: Question
Tom,
Yes. It does. And it will be. It is an elegant and simple experiment in its own right.First the experiment needs to be repeated by others
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Nobody
Re: Ted Warbrooke's Stirling 1: Question
I still don't see what the Carnot Limit has do with it?
Carnot said a running engine will convert 20% of the heat coming in to work out. Think:
Percentages-
For a running engine, 100 in, 80 out to melt the ice, 20 out on shaft.
Carnot says nothing of a non-running engines, nor about the rates of influx of energy, just the efficiency.
One can infer from others and using simple logic that:
For a stalled engine, 100 in, zero out on the shaft, so by default- 100 out to melt the ice.
The question as to which will melt ice faster Isn't answered by Carnot. In fact Carnot's Limit seems to be supported by your experimental findings.
The thought that a stopped or stalled engine will suddenly have zero energy flowing in is just wrong.
All heat engines to date have experimental data that have efficiencies far below the Theoretical Carnot Limit calculated for their situation. None have broken that prediction. Not even close. And when all the mechanical and peripheral losses are added in, far worse.
Carnot said a running engine will convert 20% of the heat coming in to work out. Think:
Percentages-
For a running engine, 100 in, 80 out to melt the ice, 20 out on shaft.
Carnot says nothing of a non-running engines, nor about the rates of influx of energy, just the efficiency.
One can infer from others and using simple logic that:
For a stalled engine, 100 in, zero out on the shaft, so by default- 100 out to melt the ice.
The question as to which will melt ice faster Isn't answered by Carnot. In fact Carnot's Limit seems to be supported by your experimental findings.
The thought that a stopped or stalled engine will suddenly have zero energy flowing in is just wrong.
All heat engines to date have experimental data that have efficiencies far below the Theoretical Carnot Limit calculated for their situation. None have broken that prediction. Not even close. And when all the mechanical and peripheral losses are added in, far worse.
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Nobody
Re: Ted Warbrooke's Stirling 1: Question
There are two types of pulse jet engines. Valved and valveless. There is even one valveless pulse jet that was wood fired.
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Alphax
Re: Ted Warbrooke's Stirling 1: Question
@ nobody
I have tried to encourage Tom to forget all about Carnot, but he struggles to do that.
As far as I can tell, Tom doesn't "like" Carnot's limit and thinks it is "wrong" yet cannot satisfactorily articulate his dislike or his objection in a single sentence.
As far as I am able to understand Tom's objection to Carnot, it seems (to me) to rest on the use of Absolute zero implicit in Carnot's equation. But he has yet to articulate his objection in a single sentence. I think I can put his argument for him, and will start by restating Carnot's limit/theorem in a single sentence. Then I'll attempt to express Tom's objection to it in a single sentence and allow Tom to correct or adjust my interpretation of Tom's objection so that we may all better understand what Tom is trying to say.
Here goes:
Carnot's efficiency says that the efficiency of a heat engine is given by: one minus (the temperature of the cold working fluid divided by the temperature of the hot working fluid).
And that is basically it - one simple sentence. Mathematically it is usually expressed as E = 1-(Tcold/Thot).
Tom objects to it, and I think he doesn't actually object to that sentence (I could be wrong - Tom will say if I am).
What I think he objects to in Carnot's theorem/Limit/efficiency is the use of Absolute zero implicit in degrees Kelvin (or Rankine if you are American and prefer your delta Ts to be Fahrenheit compatible rather than Centigrade compatible).
I still don't see what the Carnot Limit has do with it?
I have tried to encourage Tom to forget all about Carnot, but he struggles to do that.
As far as I can tell, Tom doesn't "like" Carnot's limit and thinks it is "wrong" yet cannot satisfactorily articulate his dislike or his objection in a single sentence.
As far as I am able to understand Tom's objection to Carnot, it seems (to me) to rest on the use of Absolute zero implicit in Carnot's equation. But he has yet to articulate his objection in a single sentence. I think I can put his argument for him, and will start by restating Carnot's limit/theorem in a single sentence. Then I'll attempt to express Tom's objection to it in a single sentence and allow Tom to correct or adjust my interpretation of Tom's objection so that we may all better understand what Tom is trying to say.
Here goes:
Carnot's efficiency says that the efficiency of a heat engine is given by: one minus (the temperature of the cold working fluid divided by the temperature of the hot working fluid).
And that is basically it - one simple sentence. Mathematically it is usually expressed as E = 1-(Tcold/Thot).
Tom objects to it, and I think he doesn't actually object to that sentence (I could be wrong - Tom will say if I am).
What I think he objects to in Carnot's theorem/Limit/efficiency is the use of Absolute zero implicit in degrees Kelvin (or Rankine if you are American and prefer your delta Ts to be Fahrenheit compatible rather than Centigrade compatible).
Re: Ted Warbrooke's Stirling 1: Question
I think if we are going to discuss the Carnot limit, whoever desires to do that should probably start a thread on the subject, unless Alphax has no objection, though the Stirling 1 discussion has already been derailed by "Tom's experiments", now, turning into the "what does Tom think about Carnot efficiency" thread.
For the sake of the continuity of the forum these topics should probably be split off, or even moved to another more appropriate venue entirely, as from past experience a Carnot efficiency debate could go on and on interminably, and the forum owner has already made it clear this forum is not the appropriate place for that sort of thing.
For the sake of the continuity of the forum these topics should probably be split off, or even moved to another more appropriate venue entirely, as from past experience a Carnot efficiency debate could go on and on interminably, and the forum owner has already made it clear this forum is not the appropriate place for that sort of thing.
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Alphax
Re: Ted Warbrooke's Stirling 1: Question
Agreed.
I don't feel the need to start a Carnot thread myself.
As you say, "Tom's Experiment" has taken us away from the Stirling-1 discussion, but I have found the diversion very interesting.
I will start a new thread to discuss "Tom's experiment".
I don't feel the need to start a Carnot thread myself.
As you say, "Tom's Experiment" has taken us away from the Stirling-1 discussion, but I have found the diversion very interesting.
I will start a new thread to discuss "Tom's experiment".
Re: Ted Warbrooke's Stirling 1: Question
If you don't mind, something neutral like "efficiency experiments" as a title that is, might be more appropriate, as you will be doing your own.
There are already enough threads of mine on these issues.
There are already enough threads of mine on these issues.
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Alphax
Re: Ted Warbrooke's Stirling 1: Question
Now, back to Ted Warbrooke's Stirling -1 engine and Thermal Lag engines in general (they seem to me to be much the same thing).
TO RECAP:
This thread, so far, has thrown up the following main points:-
1. Ted Warbrooke's Stirling-1 is probably within the same class of Stirling engine as Peter Tailer's Thermal Lag engine which predates Warbrooke's device but lacked it's widespread popularity and familiarity until relatively recently since when all manner of interpretations of "Thermal Lag Engines" may be found on Youtube. Which, speaking personally, I am happy to see!
2. It is clear that Thermal Lag engines are radically different to other types of Stirling engine (i.e. they do not fall into alpha, beta or gamma types) because they lack a mechanically phase-coupled displacer. They have only one moving part (the power piston) and do not need a flywheel.
3. Instead, the phase coupling (the "Lag") is self-regulating and able to exploit the finite time taken for heat transfer within the working fluid to give the engine its resonant cycle. The advantage of self-timed resonance is that it eliminates "parasitic" losses attributable to forcing the displacer to maintain timing of the heat transfer and should therefore be more efficient. Tailer expressed it as the thermal lag (the finite time for heat transfer) as being the driving force of the engine.
4. Academic opinions on how the Thermal Lag engine work are not in consensus. Notably, two groups of world experts have a fundamental disagreement on the basic physics of their working principle (Tailer et al Versus Organ, if I can put it that way).
5. One feature of the Thermal Lag engine that is essential in Organ's interpretation of the physics is that Tailer's Thermal Lag engine is fundamentally a pulse engine and as such it requires a pulse tube between power piston (i.e. cold end) and hot-end. Tailer appears to have a contrary review. It is clear from the many Thermal Lag examples built by amateurs that most actually do appear to have some sort of "pulse tube' though these are generally rudimentary and look more like restrictions between hot and cold end diameters than long pulse tubes. I have also read accounts of home-builders stating that a thermal break at the same location is essential, and Youtube is awash with working examples that have restrictions (acting as short pulse tubes), thermal breaks or both restrictions and thermal breaks between hot end and piston. A few consistent accounts give the finding that it is highly beneficial to allow the piston to almost touch the cold-end face of the restriction/thermal break component. Frequently the restriction/thermal break component is also a means to physically join the heating (hot end) tube with its regenerator onto the (cold end) cylinder in which the piston oscillates.
6. The question I began with is still not answered: will the Thermal Lag engine scale up readily, or not?
The question arises because, unlike conventional alpha, beta and gamma engines, a single piston Thermal Lag engine relies on its own capacity to resonate and resonant frequency is commonly length dependant. Moreover, the implication of the "thermal lag" (according to Tailer) is that it represents the equivalence of the usual 90 degree phase lag in conventional engines and since no displacer is present, there may be some dependance on the surface area-to-volume ratio, gas permeability and porosity (or packing density) of the regenerator material where most of the heat transfer (source of the vital time delay that regulates resonant frequency) occurs.
SO.... as before..... opinions are sought ....... can the Thermal Lag Engine be scaled up successfully? If yes, then why? If not, then why?
Also - if you believe I have unfairly or wrongly summarised points 1 to 6 above then feel free to correct me.
TO RECAP:
This thread, so far, has thrown up the following main points:-
1. Ted Warbrooke's Stirling-1 is probably within the same class of Stirling engine as Peter Tailer's Thermal Lag engine which predates Warbrooke's device but lacked it's widespread popularity and familiarity until relatively recently since when all manner of interpretations of "Thermal Lag Engines" may be found on Youtube. Which, speaking personally, I am happy to see!
2. It is clear that Thermal Lag engines are radically different to other types of Stirling engine (i.e. they do not fall into alpha, beta or gamma types) because they lack a mechanically phase-coupled displacer. They have only one moving part (the power piston) and do not need a flywheel.
3. Instead, the phase coupling (the "Lag") is self-regulating and able to exploit the finite time taken for heat transfer within the working fluid to give the engine its resonant cycle. The advantage of self-timed resonance is that it eliminates "parasitic" losses attributable to forcing the displacer to maintain timing of the heat transfer and should therefore be more efficient. Tailer expressed it as the thermal lag (the finite time for heat transfer) as being the driving force of the engine.
4. Academic opinions on how the Thermal Lag engine work are not in consensus. Notably, two groups of world experts have a fundamental disagreement on the basic physics of their working principle (Tailer et al Versus Organ, if I can put it that way).
5. One feature of the Thermal Lag engine that is essential in Organ's interpretation of the physics is that Tailer's Thermal Lag engine is fundamentally a pulse engine and as such it requires a pulse tube between power piston (i.e. cold end) and hot-end. Tailer appears to have a contrary review. It is clear from the many Thermal Lag examples built by amateurs that most actually do appear to have some sort of "pulse tube' though these are generally rudimentary and look more like restrictions between hot and cold end diameters than long pulse tubes. I have also read accounts of home-builders stating that a thermal break at the same location is essential, and Youtube is awash with working examples that have restrictions (acting as short pulse tubes), thermal breaks or both restrictions and thermal breaks between hot end and piston. A few consistent accounts give the finding that it is highly beneficial to allow the piston to almost touch the cold-end face of the restriction/thermal break component. Frequently the restriction/thermal break component is also a means to physically join the heating (hot end) tube with its regenerator onto the (cold end) cylinder in which the piston oscillates.
6. The question I began with is still not answered: will the Thermal Lag engine scale up readily, or not?
The question arises because, unlike conventional alpha, beta and gamma engines, a single piston Thermal Lag engine relies on its own capacity to resonate and resonant frequency is commonly length dependant. Moreover, the implication of the "thermal lag" (according to Tailer) is that it represents the equivalence of the usual 90 degree phase lag in conventional engines and since no displacer is present, there may be some dependance on the surface area-to-volume ratio, gas permeability and porosity (or packing density) of the regenerator material where most of the heat transfer (source of the vital time delay that regulates resonant frequency) occurs.
SO.... as before..... opinions are sought ....... can the Thermal Lag Engine be scaled up successfully? If yes, then why? If not, then why?
Also - if you believe I have unfairly or wrongly summarised points 1 to 6 above then feel free to correct me.
Last edited by Alphax on Wed Feb 16, 2022 2:05 pm, edited 8 times in total.
Re: Ted Warbrooke's Stirling 1: Question
H.C. Andersen :
"See here! Must we have this brood too, just as if there weren't enough of us already? And-fie! what an ugly-looking fellow that duckling is! We won't stand for him." One duck charged up and bit his neck.
"Let him alone," his mother said. "He isn't doing any harm."
"Possibly not," said the duck who bit him, "but he's too big and strange, and therefore he needs a good whacking."
Best wishes from Denmark, Tom . . .
"See here! Must we have this brood too, just as if there weren't enough of us already? And-fie! what an ugly-looking fellow that duckling is! We won't stand for him." One duck charged up and bit his neck.
"Let him alone," his mother said. "He isn't doing any harm."
"Possibly not," said the duck who bit him, "but he's too big and strange, and therefore he needs a good whacking."
Best wishes from Denmark, Tom . . .
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Alphax
Re: Ted Warbrooke's Stirling 1: Question
Tom,
Of course! Happy to oblige..... in due course, and when I have obtained some results.
If you don't mind, something neutral like "efficiency experiments" as a title that is, might be more appropriate, as you will be doing your own.
There are already enough threads of mine on these issues.
Of course! Happy to oblige..... in due course, and when I have obtained some results.
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matt brown
- Posts: 752
- Joined: Thu Feb 10, 2022 11:25 pm
Re: Ted Warbrooke's Stirling 1: Question
Guys, I doubt any thermal lag is going anywhere, check out:
http://scielo.sld.cu/pdf/im/v16n1/im04113.pdf
Colin West wrote a short paper for ORNL back in 1982, then another with Chen in 1987. The 1987 paper is notable for having a single intake/exhaust port near BDC of pis/cyl design similar 2 stroke ICE. Basic thermal lag is an adiabatic gas spring (W=0) where expansion is_slightly_ modified with some isothermal input, whereby cycle achieves 3 point PV plot with slight W>0.
Alphax - thermal lag will not scale up since the input & output nearly balance at small scale, and cooling area per gas vol will decrease with size. This is the schmooze with many such models where they barely 'work' as models...
http://scielo.sld.cu/pdf/im/v16n1/im04113.pdf
Colin West wrote a short paper for ORNL back in 1982, then another with Chen in 1987. The 1987 paper is notable for having a single intake/exhaust port near BDC of pis/cyl design similar 2 stroke ICE. Basic thermal lag is an adiabatic gas spring (W=0) where expansion is_slightly_ modified with some isothermal input, whereby cycle achieves 3 point PV plot with slight W>0.
Alphax - thermal lag will not scale up since the input & output nearly balance at small scale, and cooling area per gas vol will decrease with size. This is the schmooze with many such models where they barely 'work' as models...
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Alphax
Re: Ted Warbrooke's Stirling 1: Question
Hi Matt
We had some discussion on Calcoen & Vandermeersch's engine a while back (see my post Thu Feb 10, 2022 3:31 am). They are the two guys that built the engine reported in the paper you refer to, which actually comes down more in favour of Tailer's explanation of how the engine works and is somewhat against Allan Organ's pulse tube interpretation.
But I can't see anything in their work (which is still the best documented account of the workings of a Thermal Lag engine to date) to suggest anything informative about scaling up......
Your opinion (that Thermal Lag will not scale up) is very interesting. You express your view very well - are you able to give any examples or further illustrations of why you think it might not scale up?
The only opinions collected on this thread so far are three: mine, yours and Tom Booth's.
Your opinion is Thermal Lag won't scale up, Tom Booth's opinion is Thermal Lag will scale up and mine (so far) is it might scale up but I see potential problems with the regenerator matrix SA/V and packing fraction.
This is why I started the thread..... to learn what other people think about scaling it up, so thank you for that - if you have any more to say I'd be happy to hear it.
We had some discussion on Calcoen & Vandermeersch's engine a while back (see my post Thu Feb 10, 2022 3:31 am). They are the two guys that built the engine reported in the paper you refer to, which actually comes down more in favour of Tailer's explanation of how the engine works and is somewhat against Allan Organ's pulse tube interpretation.
But I can't see anything in their work (which is still the best documented account of the workings of a Thermal Lag engine to date) to suggest anything informative about scaling up......
Your opinion (that Thermal Lag will not scale up) is very interesting. You express your view very well - are you able to give any examples or further illustrations of why you think it might not scale up?
The only opinions collected on this thread so far are three: mine, yours and Tom Booth's.
Your opinion is Thermal Lag won't scale up, Tom Booth's opinion is Thermal Lag will scale up and mine (so far) is it might scale up but I see potential problems with the regenerator matrix SA/V and packing fraction.
This is why I started the thread..... to learn what other people think about scaling it up, so thank you for that - if you have any more to say I'd be happy to hear it.
Re: Ted Warbrooke's Stirling 1: Question
There are at least two things I've come across, so far, in reading through that PDF that I think would tend to negate the conclusion: "thermal lag will not scale up since the input & output nearly balance at small scale, and cooling area per gas vol will decrease with size."matt brown wrote: ↑Thu Feb 17, 2022 12:16 am Guys, I doubt any thermal lag is going anywhere, check out:
http://scielo.sld.cu/pdf/im/v16n1/im04113.pdf
Colin West wrote a short paper for ORNL back in 1982, then another with Chen in 1987. The 1987 paper is notable for having a single intake/exhaust port near BDC of pis/cyl design similar 2 stroke ICE. Basic thermal lag is an adiabatic gas spring (W=0) where expansion is_slightly_ modified with some isothermal input, whereby cycle achieves 3 point PV plot with slight W>0.
Alphax - thermal lag will not scale up since the input & output nearly balance at small scale, and cooling area per gas vol will decrease with size. This is the schmooze with many such models where they barely 'work' as models...
Right at the start of the paper, in the abstract it states
This is repeated again soon after:the relationship between the heat transfer capacity of the engine and its working frequency becomes apparent from the measurements, indicating that larger heater areas and limited cold heat transfer characteristics allow more work production per cycle at higher operating frequencies.
Maybe I interpret that differently than someone else might, but to me it sounds like less heat rejection -> increase power output. Which comports with my own experimental results with other types of Stirling engines as well. If making the engine bigger reduces the surface area of the cold sink, that appears to prove, from the experimental results discussed in the PDF, to be a good thing. With less heat wasted to the sink, power output increases. (Reminder to self: Don't start ranting about Carnot)The results are discussed in the paper and yield that engine performance at different frequencies is determined by the heat transfer capacity of the hot and cold heat exchangers, and that the heat rejection should be limited and well bounded in time in order increase power output.
Another concern is that the test engine was constructed:
These choices of material are frankly; abysmal.The piston chamber, machined from a brass piece, is cooled with a water jacket and the heater, also made from brass tubes, is designed to vary its dimension in order to extend the interface between the heater and the cooler. A stainless steel mesh is inserted into the heater in order to provide heat transfer area and...
Brass is a much better thermal conductor than stainless.
Just like electricity, heat follows the path of least resistance, so where is the heat going to go? The whole engine is brass, with a water jacket!!
The heat IMO will tend to bypass the regenerator, bypass the working fluid, tend towards destroying the ∆T. The whole engine made of brass, will tend to divert heat AWAY from power production, out of the working fluid and into the water jacket or the external air.
Still, the conclusion that limiting this abysmal waste of heat will "increase power output" Duh! seems valid.
This material choice is perhaps not the worst possible. An all copper engine would be worse, but an all brass engine is a close second.
Anyway, I will press on and see what other gems this paper might have to offer.
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Nobody
Re: Ted Warbrooke's Stirling 1: Question
The name/classification of these engines needs to be looked at. Thermal lag is already a well defined word.
https://en.m.wikipedia.org/wiki/Thermal ... rmal%20lag.
Basically it is the time it takes for something to equalize with a temperature change. A brick to heat up in the sun, or cool off at night.
I'm not sure heat lag is the root driving force. Air spring engine might be a better term, but I kind of like pulse engines better. They seem to require timed tuned pulses. Since valveless pulse jet engines can be scaled, it seems logical that Stirling pulse engines should be as well. The basic difference is internal verses external heating.
From what I've heard, smaller valveless pulse jet engines are harder to get working than larger. The same would seem true of Stirling pulse engines.
Smaller would have a shorter narrower pulse tube. Hence more air friction/damping. They would run at higher frequencies, requiring more precise tuning. Maybe a lighter gas.
The old volume of air verses internal surface area ratio all over, except inside out.
The compromise, of course, would be that heat is transfered faster in the smaller engine, more surface area per volume. Larger pulse engines might benefit from multi tube heat exchangers to compensate for that loss.
The toroidal vortex (smoke ring) seen in the jam jar example might be enough to alleviate that last mentioned compromise. The spinning toroidal vortex might be part of the lag process as the air mass would spin against the hot cap picking up heat as different parts of the air spin to the outer side. They might benefit from a head designed to intensify that effect.
The compression stroke is powered by the momentum of the air over-rushing in and out of the hot and cold sides. Acting kind of like an air spring pendulum.
I think the subject of regeneration needs to be looked into. The wire wool needs to be between the heater and cooler. In a pulse engine the pulse tube or orifice is in that position, a regenerator located there would interfere with the flows momentum, and it would heat the fluid/air too soon in the cycle causing it to lose the lag or pulse timing. The fluid needs to wait until at the ends of the hot-cold tube to begin heating and cooling.
There should always be a insulated thermal break between hot and cold. Conducting from hot directly to cold is always a efficiency killer.
That may mean, with no regenerator, it will always have very poor efficiency Bummer. Their simplicity makes it worth the investigation.
Wow! That got long! LOL!
https://en.m.wikipedia.org/wiki/Thermal ... rmal%20lag.
Basically it is the time it takes for something to equalize with a temperature change. A brick to heat up in the sun, or cool off at night.
I'm not sure heat lag is the root driving force. Air spring engine might be a better term, but I kind of like pulse engines better. They seem to require timed tuned pulses. Since valveless pulse jet engines can be scaled, it seems logical that Stirling pulse engines should be as well. The basic difference is internal verses external heating.
From what I've heard, smaller valveless pulse jet engines are harder to get working than larger. The same would seem true of Stirling pulse engines.
Smaller would have a shorter narrower pulse tube. Hence more air friction/damping. They would run at higher frequencies, requiring more precise tuning. Maybe a lighter gas.
The old volume of air verses internal surface area ratio all over, except inside out.
The compromise, of course, would be that heat is transfered faster in the smaller engine, more surface area per volume. Larger pulse engines might benefit from multi tube heat exchangers to compensate for that loss.
The toroidal vortex (smoke ring) seen in the jam jar example might be enough to alleviate that last mentioned compromise. The spinning toroidal vortex might be part of the lag process as the air mass would spin against the hot cap picking up heat as different parts of the air spin to the outer side. They might benefit from a head designed to intensify that effect.
The compression stroke is powered by the momentum of the air over-rushing in and out of the hot and cold sides. Acting kind of like an air spring pendulum.
I think the subject of regeneration needs to be looked into. The wire wool needs to be between the heater and cooler. In a pulse engine the pulse tube or orifice is in that position, a regenerator located there would interfere with the flows momentum, and it would heat the fluid/air too soon in the cycle causing it to lose the lag or pulse timing. The fluid needs to wait until at the ends of the hot-cold tube to begin heating and cooling.
There should always be a insulated thermal break between hot and cold. Conducting from hot directly to cold is always a efficiency killer.
That may mean, with no regenerator, it will always have very poor efficiency Bummer. Their simplicity makes it worth the investigation.
Wow! That got long! LOL!