Stirlingengineforum.com

stephenz wrote: ↑Sun Jul 09, 2023 10:07 am No the drinking bird example certainly does not qualify to justify your own observations. edit: unless of course, you covered the top plate with a wet fabric. haha

The Stirling engine rejects waste heat through a cooler (heat sink) which has a temperature greater than that of the environment.
The drinking bird rejects heat to the environment through evaporation, to what the temperature drop of of the head is a buy product of its energy behind removed by the phase change process.

As far as the Carnot Limit, and by the way, Carnot has been dubbed "the father of thermodynamics" as well as I believe, originator of the second law, in my experience, the general scientific community considers the Carnot limit and the second law as synonymous, you seen to want to create a distinction.

My argument is that the Carnot limit is invalid.

The drinking bird IS an example of a heat engine and therefore the Carnot Limit should apply to it as well.

I don't consider phase change a "cold reservoir", do you? So the bird, in actuality operates within a single reservoir without a "sink".

The temperature difference is, well, there isn't any. Infact the bird will operate on a glass of water that is above ambient. As far as I know there is no corollary to any of the numerous iterations of the second law that would exclude the bird from being subject to the Carnot limit. Or for that matter, a Stirling engine running on ambient heat driving a swamp cooler or other evaporative cooling system. The bird itself drives or powers its own evaporative cooling, as it's mechanical swinging motion powered by ambient heat greatly assists the evaporation process. It is not entirely a passive recipient of the benefits of evaporative cooling but uses it's own energy resource, ambient heat, to drive the cooling cycle, dipping and swinging.

IMO, a Self cooling Stirling engine using ambient heat to power some alternative, cooling process, possibly more effective than mere evaporative cooling, is no more or less a violation of the Carnot Limit than the bird.

Now let me ask you this:
How is your engine altered compared to a standard LTD engine? Wouldn't a standard LTD engine be capable of exhibiting the same behavior as the engine depicted in your video?

Not necessary. Thermally, Most off the shelf model Stirling engines are pretty "leaky", transferring heat from the hot to the cold side by conduction, convection or radiation without producing any power, even if sitting idle.

I have always made some common sense modifications to the engines I've been experimenting with. Primarily swapping out heat conductive parts for non-heat conductive ones.

An off the shelf LTD engine also does not have a regenerator. Many would say, that a regenerator is an essential element to qualify as a Stirling engine.

It would be very difficult for an LTD to cool itself while surrounded by and having direct exposure to the ambient heat. Just like any refrigerator or freezer, the engine requires effective insulation as appropriate to prevent the ambient heat from nullifying any below ambient self-cooling effect, like trying to keep food cold in a refrigerator with no insulation.

I chose model engines that are capable of having their timing advance adjusted. Often a modification, such as the addition of a regenerator will also require a timing adjustment.

The engine in the above photo with the new glass piston and cylinder has had the throw extended to increase the compression/expansion ratio.

Very precise timing adjustments are necessary as timing influences both heat utilization and power output.

What we have been calling "dwell" can have an influence. The amount of play in the displacer connecting rod can have an influence on dwell.

Lubrication, varying the load, more or less friction, adjusting the displacer thickness and travel distance

Of course, if the engine is above a heat source, such as a cup of hot water, convection will carry heat from the sides of the cup up to and around the top of the engine and this sort of incidental heat transfer needs to be avoided for there to be any hope of detecting some very slight refrigerating effect.

Not sure if there is anything else I've neglected to mention.

Guys, I tried.
I don't have the patience to just repeat the same thing over and over again.

Oh and by the way, put a glass of water in the fridge and run the drinking bird again. Call me if it doesn't drink.

Tom Booth wrote: ↑Fri Jul 07, 2023 2:22 am
Heat is a form of energy that can be converted into other forms of energy, not a permanent substance or fluid.

This line is typical buzz that leads to faulty conclusions. Exactly what is "heat" in this sentence ???

(1) if heat means energy, then statement is lame
(2) if heat means temperature, then statement is wrong since temperature is a measurement

What I take it to mean here (and likely the common usage by many) is that heat is a quantity of energy between two temperatures. Note the indefinite "a" vs otherwise definite 'the', since this quantity of energy is variable. This leads us to another usage where heat is some type of energy function like BTUs, calories, specific heat, heat of vaporization, etc.

I suspect the common usage of heat is due to its monosyllabic buzz, but this simple buzz obscures often complex issues.

Tom's cold plate insulation experiments are interesting. All values are small at this level, but this doesn't require a NASA review to grasp.

(1) Anyone suggesting Tom needs more accurate instruments to field his claim should at least ask Tom to check his digital thermometer against boiling water. Anyone running coffee experiments has noticed just how lame these digital gizmos are, and why brewers use old world thermometers.

(2) Tom's discovery is on gamma LTD where any PV is an approximation of a cycle, but cycle could be between (for example) Stirling and Otto. Simply claiming it an out-of-phase Stirling cycle leads to faulty conclusions, especially since gamma PV is really a composite of TWO cycles (where this seems to always pass by unnoticed). I've always suspected that these LTD models approximate a 3 process cycle, not a 4 process.

(3) And most obvious, but clearly ignored...if Tom's experiments indicate that eliminating cold sink is possible AND others have similar results (youtube), why is this apparently only possible with LTD vs other heat engine formats ???

Thermal imagers and other infrared thermometers are not meant for accuracy, nor are they made to measure the temperature of fluids. Relying of solids as proxy for fluid temperature is not correct.

You picked up on a point I made earlier, the temperature deltas are too low to rely on a inaccurate devices for this.
The link I provided shows you with a lab grade equipment the order of magnitude of the temperaure delta across the displacer cylinder of an LTD when ran as heat pump. +/- 0.2 C. This is incredibly low. Trying to measure this kind of temperatures with a FLIR is just a waste of time, amplified by the wrong conclusions drawn from those measurements.



The lack of willingness from Tom to go ahead and build additional apparatus to prove the claims laid out, is only showing little confidence in what's going on; but more importantly it questions the credibility. You just can't make those claims and hope the video will be enough to back it up.It's just plain silly. Tom complained that he got banned from forums, accused of pseudoscience, and so on. I can't stand (internet) bashing in general, but at the very least change the attitude and realize you are the one has to prove everything, and if you aren't willing then don't complain if you bashed around.


Lastly, if no one is capable of reproducing this behavior consistently and impossible to reproduce on a larger scale engine, then perhaps this is a good tip of what's going on. There have been laboratory grade engines built, capable of holding seals really well, how come those labs aren't reporting cooler temperatures sub-ambient?

matt brown wrote: ↑Sun Jul 09, 2023 12:57 pm ...
(2) Tom's discovery is on gamma LTD

Not sure what "discovery" your talking about but assuming you mean the possibility of a "self-cooling" heat engine, the observation that mainly sent me down this road was "Lawnmower of doom"'s discovery that he could run his DIY thermoacoustic Stirling without a flywheel. That was supposed to be "impossible" which related to the whole second law... I'll demote that to THEORY, that it's impossible to convert all the heat into work so the piston needs some stored energy in a flywheel to push it back.

Not seeing the logic in the whole thermoacoustic narrative, I extrapolated from there to see if this phenomena was true of other types of Stirling engine.

LTD's are just cheap and plentiful and not requiring a lot of fuel are easy and inexpensive to work with and modify.

..if Tom's experiments indicate that eliminating cold sink is possible AND others have similar results (youtube), why is this apparently only possible with LTD vs other heat engine formats ???

It's more apparent because these engines are already largely optimized so as not to waste a lot of heat through conduction.

High temperature engines are often made of metal and little thought is given to how much heat is being conducted through the metal engine body, "short circuiting" the engine.

LTD's have acrylic bodies, I think, almost exclusively, which is a natural heat insulator.

If the same principles were applied to other Stirling engines, LTD's are nothing special.

stephenz wrote: ↑Sun Jul 09, 2023 1:27 pm Thermal imagers and other infrared thermometers are not meant for accuracy, nor are they made to measure the temperature of fluids. Relying of solids as proxy for fluid temperature is not correct.

You picked up on a point I made earlier, the temperature deltas are too low to rely on a inaccurate devices for this.
The link I provided shows you with a lab grade equipment the order of magnitude of the temperaure delta across the displacer cylinder of an LTD when ran as heat pump. +/- 0.2 C. This is incredibly low. Trying to measure this kind of temperatures with a FLIR is just a waste of time, amplified by the wrong conclusions drawn from those measurements.



The lack of willingness from Tom to go ahead and build additional apparatus to prove the claims laid out, is only showing little confidence in what's going on; but more importantly it questions the credibility. You just can't make those claims and hope the video will be enough to back it up.It's just plain silly. Tom complained that he got banned from forums, accused of pseudoscience, and so on. I can't stand (internet) bashing in general, but at the very least change the attitude and realize you are the one has to prove everything, and if you aren't willing then don't complain if you bashed around.


Lastly, if no one is capable of reproducing this behavior consistently and impossible to reproduce on a larger scale engine, then perhaps this is a good tip of what's going on. There have been laboratory grade engines built, capable of holding seals really well, how come those labs aren't reporting cooler temperatures sub-ambient?

Your characterizations are not true.

I have several thermocouple type digital thermometers I've been using and am certainly not unwilling to experiment.

You make these false accusations even after I just posted pictures of the engine I'm in the process of rebuilding to do exactly that, as I said, run additional tests.

stephenz wrote: ↑Sun Jul 09, 2023 1:27 pm
Lastly, if...impossible to reproduce on a larger scale engine, then perhaps this is a good tip of what's going on. There have been laboratory grade engines built, capable of holding seals really well, how come those labs aren't reporting cooler temperatures sub-ambient?

Excellent logic that is hard to counter. Fun fact: Einstein carefully studied various experiments, tho never conducted any of his own.

Tom Booth wrote: ↑Sun Jul 09, 2023 1:38 pm
If the same principles were applied to other Stirling engines, LTD's are nothing special.

Are you suggesting that an original 2 cylinder Rider engine will continue to run after cooling is cut to compression cylinder ?

Tom Booth wrote: ↑Sun Jul 09, 2023 1:44 pm

stephenz wrote: ↑Sun Jul 09, 2023 1:27 pm Thermal imagers and other infrared thermometers are not meant for accuracy, nor are they made to measure the temperature of fluids. Relying of solids as proxy for fluid temperature is not correct.

You picked up on a point I made earlier, the temperature deltas are too low to rely on a inaccurate devices for this.
The link I provided shows you with a lab grade equipment the order of magnitude of the temperaure delta across the displacer cylinder of an LTD when ran as heat pump. +/- 0.2 C. This is incredibly low. Trying to measure this kind of temperatures with a FLIR is just a waste of time, amplified by the wrong conclusions drawn from those measurements.



The lack of willingness from Tom to go ahead and build additional apparatus to prove the claims laid out, is only showing little confidence in what's going on; but more importantly it questions the credibility. You just can't make those claims and hope the video will be enough to back it up.It's just plain silly. Tom complained that he got banned from forums, accused of pseudoscience, and so on. I can't stand (internet) bashing in general, but at the very least change the attitude and realize you are the one has to prove everything, and if you aren't willing then don't complain if you bashed around.


Lastly, if no one is capable of reproducing this behavior consistently and impossible to reproduce on a larger scale engine, then perhaps this is a good tip of what's going on. There have been laboratory grade engines built, capable of holding seals really well, how come those labs aren't reporting cooler temperatures sub-ambient?

Your characterizations are not true.

I have several thermocouple type digital thermometers I've been using and am certainly not unwilling to experiment.

You make these false accusations even after I just posted pictures of the engine I'm in the process of rebuilding to do exactly that, as I said, run additional tests.

Good. Looking forward to it.

What I'm claiming is that this 'anomaly' is only related to LTD models due small scale values. Any deviation from small scale engine with gamma type cycle will nix this anomaly and bring back Carnot with a vengeance.

Mankind existed for eons watching the sun go around the earth until someone proved otherwise. As a long time sailor who can navigate via sextant, I find it amusing when modern guys with GPS complain about their poor navigation skills (GPS is only a navigation tool).

matt brown wrote: ↑Sun Jul 09, 2023 2:06 pm

stephenz wrote: ↑Sun Jul 09, 2023 1:27 pm
Lastly, if...impossible to reproduce on a larger scale engine, then perhaps this is a good tip of what's going on. There have been laboratory grade engines built, capable of holding seals really well, how come those labs aren't reporting cooler temperatures sub-ambient?

Excellent logic that is hard to counter. Fun fact: Einstein carefully studied various experiments, tho never conducted any of his own.

You (both?) Seem to have misunderstood something or other.

A good, low friction piston seal is necessary for a Stirling engine to run at all. It was an off hand remark that has no bearing on any potential sub-ambient cooling

matt brown wrote: ↑Sun Jul 09, 2023 2:48 pm What I'm claiming is that this 'anomaly' is only related to LTD models due small scale values. Any deviation from small scale engine with gamma type cycle will nix this anomaly and bring back Carnot with a vengeance.

...

It's interesting that you think that, but I don't. A physical principle, if it works on a small scale works on any scale.

You have very tiny IC engines and monster size IC engines. Same with refrigeration systems. You are, of course entitled to your opinions.

stephenz wrote: ↑Sun Jul 09, 2023 2:24 pm

Tom Booth wrote: ↑Sun Jul 09, 2023 1:44 pm

stephenz wrote: ↑Sun Jul 09, 2023 1:27 pm Thermal imagers and other infrared thermometers are not meant for accuracy, nor are they made to measure the temperature of fluids. Relying of solids as proxy for fluid temperature is not correct.

You picked up on a point I made earlier, the temperature deltas are too low to rely on a inaccurate devices for this.
The link I provided shows you with a lab grade equipment the order of magnitude of the temperaure delta across the displacer cylinder of an LTD when ran as heat pump. +/- 0.2 C. This is incredibly low. Trying to measure this kind of temperatures with a FLIR is just a waste of time, amplified by the wrong conclusions drawn from those measurements.



The lack of willingness from Tom to go ahead and build additional apparatus to prove the claims laid out, is only showing little confidence in what's going on; but more importantly it questions the credibility. You just can't make those claims and hope the video will be enough to back it up.It's just plain silly. Tom complained that he got banned from forums, accused of pseudoscience, and so on. I can't stand (internet) bashing in general, but at the very least change the attitude and realize you are the one has to prove everything, and if you aren't willing then don't complain if you bashed around.


Lastly, if no one is capable of reproducing this behavior consistently and impossible to reproduce on a larger scale engine, then perhaps this is a good tip of what's going on. There have been laboratory grade engines built, capable of holding seals really well, how come those labs aren't reporting cooler temperatures sub-ambient?

Your characterizations are not true.

I have several thermocouple type digital thermometers I've been using and am certainly not unwilling to experiment.

You make these false accusations even after I just posted pictures of the engine I'm in the process of rebuilding to do exactly that, as I said, run additional tests.

Good. Looking forward to it.

Great.

The problem on those Science forums BTW was the same. They seemed to expect me to instantaneously comply with their demands that I redo an experiment according to their criteria.

If I said, sure, though it will take me a while to get around to that I'm very busy lately, they would characterize it as "refusal" which is ridiculous.

Tom, I often find myself confused as to the end goal of your claims. It is well established that a Stirling engine is a reversible cycle, and can therefore act as a heat pump. So as Matt has concluded, yes it can operate without external cooling, and given less than ideal phasing it should be able to trade crank power for sub ambient cooling of the cold side.

So then lets assume your tests are completely valid, though I agree that the test conditions are anything but "scientific". What is the result? What is the practical application of what you have found? Maybe you are suggesting a wood fired or solar air conditioner with air as the working gas? That sounds great to me, but that should be the goal then no?

Otherwise I thought we were focused on electric power production, in which case what is the application of your findings? Is there a benefit to net power production?

VincentG wrote: ↑Sun Jul 09, 2023 3:26 pm Tom, I often find myself confused as to the end goal of your claims.

First of all, I have to object to the characterization that I'm making any "claims".

Way back when I was persuaded to design a solar dish Stirling engine by an acquaintance who I believe was a military contractor. Long story short, the design I came up with was rejected because some government analyst said it "violates the second law of thermodynamics" which I knew nothing about at the time.

This engine design I had come up with used an air cycle refrigeration system for cooling. The design specification was to make the solar "dish" as small as possible. Well I had eliminated it altogether. What I designed was basically an ambient heat powered Stirling engine. I was quite pleased with having exceeded the specifications and my contractor friend had suggested he would fly me out to his factory in California to be involved in the manufacture, so to say the least I was disappointed and puzzled when the whole plan was suddenly dropped.

So I looked into this second law thing to figure out what was supposed to be wrong with my design. Eventually I came across Tesla's article about his ambient heat powered heat Engine, which was, for him a life long project.

In principle, Tesla's "Self Acting Engine" paralleled my own design, so I felt somewhat vindicated, Tesla was a pretty smart guy, but I still had no real proof. Maybe we were both wrong. Maybe Carnot and Kelvin were right.

Studying the history, I was not satisfied that the question had ever been conclusively settled. It seemed Cannot had been wrong about nearly everything, in particular the nature of heat itself. This "second law" seemed rather vague, self contradictory In some ways.

The whole idea of a Stirling engine that could operate on atmospheric heat seemed important enough to investigate further.

So, this is just research. Trying to find out the truth one way or the other who was right.

At this point I'm pretty convinced nearly everything and everybody is wrong and a Stirling engine operates on principles nobody ever suspected. It seems to be a kind of oscillation between expansion and contraction, bouncing back and forth between two heat sources, first one dominating, then the other.

So where does that leave us? I don't know. But I think the idea that a Stirling heat engine works by means of a "flow" from hot to cold is wrong. Seems more like the piston is getting batted back and forth between two heat sources like a ping pong ball between two players. One player is the dominant heat source and the other player is the lesser heat source. I'm not entirely sure the two heat sources cannot be equally matched, I'm still thinking about it and still researching and experimenting. That's about all.

Application?

I'm still thinking about that as well. Could be anything between no practical application to the sky is the limit. The Jury is still in session I think.

First things first. I think we still need to find out if it even works at all.