Stirlingengineforum.com

The desire not to poo poo an idea, squelch enthusiasm, is in opposition to the desire to point out an obvious fraud. That conundrum makes us open to compassion and deception.

Don't let yourself be deluded into believing in, something impossible, just because a promotion is appealing and not fully explained. If it doesn't make sense, it isn't worth the time or money. If they avoid explanation the reason becomes obvious. If they claim other explanations are wrong, the reason there is obvious too. Lack of explanation is lack of integrity.

It is the job of the promotor to fully explain what you are getting. If they answer with, "I don't know either", walk away. Run away if you need to.

If the promotion appears too good to be true, it probably isn't "too good", and always likely to be "too bad" sucker.

I have no doubt that a GEET (out of here) apparatus will make an engine run. It puts 20% gasoline in a jar and bubbles air through it picking up vapours, just as for a carburator. It heats those vapours drying out any water droplets. Burns the gasoline mixed with fresh air. It then cools the exhaust by warming the vapors.

Tell me Tom, after a lawnmower runs out of fuel, how long will it run on a quarter cup of gasoline? 8 minutes? More?

What I see is a fancy carburetor that can separate gasoline and water, burning the gasoline. No plasma, vacuum, cavitation, syngas, reformation, magnetics, etc needed. It would even run on straight fuel. A very long, large, and cumbersome carburetor.

If you pump a lot of moisture through an engine you will be effectively steam cleaning the inside of the engine. Gee I wonder why the inside is "clean", (sarcasm)!

You may very well be right.

I recently watched a sales pitch for something purporting to be some secret "GEET" plans, never previously revealed by Paul Pantone, but after watching the promotional video it became clear that the plans were for a conventional HHO generator that used electrolysis.

It is certainly prudent not to throw money away on what may be a scam.

However:

The GEET plans were posted on Pantone's website on a donation basis and from what he said in his book he only ever received one donation for about $100.

The GEET "carburator" can be built out of common plumbing supplies and other parts that can be picked up at the local hardware store.

Not exactly what I would call a high risk investment.

Deleted I was logged out and my post was lost.

Will have to repost later.

Goofy wrote: ↑Wed Aug 02, 2023 1:20 pm I have build several expansion engines (not exactly Stirling engines), when running on compressed air at perhaps 6 bar, they
easily go down to -50 Celsius on the exhaust, in one stage. At least that's what my (cheap) digital thermometer can go down to.
They also seems to suddenly "get stocked" or freeze up, but I think that because of moisture in the compressed air, as I don´t
do anything special to remove it after compressing.
Btw, this will only happens with load on, because PRESSURE is converted to work during expansion.

We have learnt over and over again that it is HEAT that is converted to work, but there shouldn't be any thing wrong with at gas at 200 bar being at 10 kelvin, and still do "work" on a piston ?
We are also told, that all the energy in a compression process, turns into heat. So when put it in at storage tank to go down to ambient temperature, what energy are you left with ? Still a lot in my opinion.
OK, we then tell our self, that the stored energy comes from the ambient heat energy, and then the equation comes to an equal.

If we imagine an engine/turbine expand a gas at 200 bar/10 kelvin out in freezing/vacuum space will it run at all ? ? ?
If yes, then by what heat ?
Carnot tells us there is still "a lot" energy down to 0 kelvin, so . . .

This is a remarkable confirmation (from a no doubt, highly trained and professional Marine engineer who knows what he's talking about), of at least some of the phenomenon I've been talking about in here for years, starting around the time I started this thread on "Stirling engine thermodynamics".

https://www.stirlingengineforum.com/vie ... ?f=1&t=478

What Goofy is describing is a 90° F below freezing drop in temperature (-50 °C) in one compression-cooling-expansion cycle.

In my observations and analysis of Stirling engines in general, it appeared to me, back before starting that thread in 2010 that a Stirling engine goes through a similar compression/expansion/work/cooling cycle as an expansion engines used to liquify air.

Btw, this will only happens with load on, because PRESSURE is converted to work during expansion.

I was writing back in 2010 on that thread in the very first post:

That is rather speculative, but I was also thinking that if what I have described above is true - i.e. that the heat is converted into work, then a Stirling Engine should operate cooler and be more efficient when under a heavy load doing some kind of actual work rather than just running without a load - not doing any work.

I would like to hear in more detail about Goofy's expansion engines.

BTW, the term "expansion engine" relates more to the use to which ehe engine is put rather than to anything particularly special about the engine. Though I'm sure dedicated "expansion engines" are optimized for the purpose, any old lawnmower engine could be used as, (with minor modifications) or converted for use as an "expansion engine".

I've also run into a lot of people who mistakenly believe that an "expansion engine" is a machine that is driven by a motor to expand air or gas, which is not the case.

An expansion engine is driven by, powered by the expanding gas. Basically it is just a compressed air motor, or a pneumatic engine running on compressed air, similar to a steam engine. The expanding gas does the "work" of driving the engine.

This is apparently confusing even to people familiar with expansion engines or air-cycle refrigeration systems, because such systems often have a motor/generator, fan, compressor and expansion engine (or turbine) all on the same shaft, so it might not be apparent what is driving what in these "bootstrap" systems.

It would be nice if Goofy dropped in more often. It's nice to have someone with his qualifications and training and familiarity with the complex mathematics on my side for a change, though I say that with some reservation. I don't think he's on anybody's "side", but he certainly seems to share my POV to some degree on these matters.

So, my basic "hypothesis", which I've been putting forward in here for years, literally, since 2010 (how anyone can say I don't have any "hypothesis" I don't know, though it seems to have mostly fallen on deaf ears) is simply this:

After the compression stroke, a Stirling engine, during the subsequent expansion stroke, acts like an "expansion engine" (such as used for liquefaction of gases or in air-cycle refrigeration.)

The compressed gas, expanding, and doing work to drive the engine, cools dramatically.

A Stirling engine though, does not overtly pre-cool the hot compressed gas in any obvious way, so the temperature drop is not so extreme as in an expansion engine or ACM (Air Cycle Machine), but obviously, there MUST be a substantial temperature drop during expansion with work output.

This type of expansion cooling is not new. Air-cycle refrigeration was, I believe, the earliest form of refrigeration.

http://www.douglas-self.com/MUSEUM/POWE ... irfrig.htm

In 2010, my musing on the subject in relation to Stirling engines was mere speculation, and a decade passed by before I ever got around to bothering with any experiments. After all, nearly everyone seemed to think that my theory was ridiculous. Everybody knows a Stirling engine works by "rejecting" heat to the sink. The cold side of the engine could never be colder than ambient.

Well, after a few years of experimenting and making observations, it is more clear to me now than ever.

The hot compressed air IS pre-cooled in a Stirling engine, but in a way that I never would have expected.

Just like a heat pump, the air is compressed to a temperature hotter than the "heat input" side of the engine.

As heat naturally flows from a hotter to a colder material or substance, some portion of the heat in the compressed hot working fluid in the engine is transfered OUT to the hot plate before expansion takes place.

During expansion, work is extracted.

As can be read at the above link:

COLD-AIR REFRIGERATION

It is not possible to make a vapour-compression refrigerator using air because air cannot be liquefied at any reasonable temperature and pressure. (The conditions are quite different in machines specifically designed to liquify air) Therefore little or no reduction in temperature occurs on passing compressed air through a throttling valve. Instead work must be removed from the compressed air by making it drive a reciprocating engine or turbine. The use of an expanding engine is not merely a cunning way to reduce the power required to drive the process; it is essential for it to work at all. The work from the engine is used to help drive the compressor, improving the efficiency,

The reason Air-Cycle refrigeration has always been considered "inefficient" is because enormous heat is generated in compressing air, which heat is all thrown away, then the cold produced is so extreme, heat must be added back to the cold exhaust for any practical refrigeration.

A Stirling engine utilized much more of the heat, but can still be viewed as a kind of air cycle refrigeration system converting heat into work in a process that results in cooling.

One thing I should mention, the quote taken from the above link is actually not entirely true:

COLD-AIR REFRIGERATION

It is not possible to make a vapour-compression refrigerator using air because air cannot be liquefied at any reasonable temperature and pressure. (The conditions are quite different in machines specifically designed to liquify air) Therefore little or no reduction in temperature occurs on passing compressed air through a throttling valve.

The Linde and other methods for achieving cryogenic temperatures low enough to liquify air use the same basic method as conventional refrigeration with nothing more than a throttling valve. True, the reduction in temperature is "little" per cycle, when compared with the extraction of "work" by an expansion turbine or engine, but as seen in the Linde method, the comparatively "little" cooling provided by an expansion valve can be accumulated as the cycle is repeated until the air liquifies.

The important point in the above quote is how much more effective an expansion engine can be per cycle compared to an expansion valve, because of the work output that removes a lot more energy from the gas all in one swoop.

Instead of a fall in temperature of a degree or two, or even a fraction of a degree per cycle, an air cycle system using an expansion ENGINE, by extracting work may see a precipitous drop in temperature of easily 50° or more per cycle even with relatively modest compression.

You are actually effecting a refrigeration cycle when simply blowing on some hot soup to cool it down.

In pursing the lips a kind of "expansion valve" is formed and the "compressed air" from the lungs is thereby cooled.

Tom Booth wrote: ↑Fri Aug 18, 2023 4:08 am

Goofy wrote: ↑Wed Aug 02, 2023 1:20 pm
We have learnt over and over again that it is HEAT that is converted to work...

That's a casual comment fit for housewives.

It's "pressure" that's converted to work and even that's a loose term since it's only a crude measure of kinetic energy. Fool said it exactly right how force x distance = work before he detailed system vs surroundings via moveable wall (piston). I liked his batter bunting to slow the baseball, and this is a good analogy for expansion process.

Tom, next time you're in the unicorn forest, ask the unicorns how the pressure follows absolute temperature when constant volume. We all know that pressure is a collective measure of force, but if the same mass of gas was traveling twice as fast, then there would be twice as many gas molecules hitting the same area per same time with each molecule having four times the force (the velocity squared thingy) as in 2(2^2)=8. So, how does 2x T = 2x P ??? (when Cv)

matt brown wrote: ↑Fri Aug 18, 2023 7:29 pm

Tom Booth wrote: ↑Fri Aug 18, 2023 4:08 am

Goofy wrote: ↑Wed Aug 02, 2023 1:20 pm
We have learnt over and over again that it is HEAT that is converted to work...

That's a casual comment fit for housewives.

It's "pressure" that's converted to work ...

If you read the rest of Goofy's post he says the same thing. That it is pressure that is converted to work, though this is not what "We have learnt over and over again".

matt brown wrote: ↑Fri Aug 18, 2023 7:29 pm ...

Tom, next time you're in the unicorn forest, ask the unicorns how the pressure follows absolute temperature when constant volume. We all know that pressure is a collective measure of force, but if the same mass of gas was traveling twice as fast, then there would be twice as many gas molecules hitting the same area per same time with each molecule having four times the force (the velocity squared thingy) as in 2(2^2)=8. So, how does 2x T = 2x P ??? (when Cv)

What your driving at here is hard to say exactly, but you talk about work from heat or T temperature or pressure or whatever and you said "Fool said it exactly right how force x distance = work" so, what are you asking exactly?

I think, though this may be wrong, but I'll take a shot and say, what you are asking is how can you have heat converted to pressure do work pushing the piston through a distance and end up with CV (constant volume).

Either a force, heat, pressure or whatever does work moving the piston through a distance or not. You can't have work output and end up with the same volume. Is that about right?

Goofy,

How much work are you going to get out of liquid helium at 200 bars and 10 K?

Speaking adiabatically, of course.

At the bottom of this issue, or the reason why it has become an issue has mainly to do with my experiments running LTD Stirling engines on ice.

The reason for these experiments in the first place were twofold.

First, gas is cooled and liquified by having it perform adiabatic expansion in a cylinder in an engine while under a load. The engine driving a generator for example.

We know liquifying some gases is extremely difficult. Helium for example can hardly be liquified by any extreme of external cooling and pressure, yet it can be liquified by this method of having it do work expanding in a cylinder to drive an engine to do external "work".

I first mentioned this in here all the way back in 2010:

https://www.stirlingengineforum.com/vie ... ?f=1&t=478

This method of gas liquefaction is used on an industrial scale all around the world every day. So, if "heat"/energy can be taken from the gas as "work" so effectively, why should there be any need to "reject" most of the heat as is supposed to be absolutely necessary by "LAW" as calculated by the Carnot efficiency limit?

That was before I knew anything about Tesla's work in this area.

Secondly, Tesla, who I can't say was the dumbest person who ever lived, disagreed with this "Carnot limit" advocated by Kelvin, which Tesla actually studied and wrote about in his 1900 article in Century magazine. Tesla envisioned that a heat engine running "on cold" rather than heat would actually be running on the heat of the ambient atmosphere and that if the engine were very efficient at converting heat into work, then little or no heat at all would be "rejected" to the source of this cold. (Tesla had been working on this until five years earlier in 1895 when his workshop burned to the ground and he lost everything.)

A Stirling engine running on ice for example.

If kept perfectly insulated, then ice used to run a Stirling engine on ambient heat would melt more slowly, or not at all.

This seemed like a very easy experiment, so, to see if Tesla was right, I did this experiment and...

When ice was used to run my little LTD model Stirling engines it melted very measurably more slowly. I reported these results on various Science and Physics forums for feedback.

I did not post these experiments in any hostile way at all. I honestly did not know if my results were unusual. The experiment was so simple and straightforward I thought perhaps it had already been done many times and the people on the Science forums could provide some insight.

Well, this caused quite an uproar. I was accused of all sorts of things and literally banned from every Science forum I posted on. Here for example:

https://www.physicsforums.com/threads/s ... ne.991714/

The line through my name on that forum indicates my banned status.

Seems rather odd to me, to be banned from a Science forum for reporting on the results of a simple experiment.

Anyway, many additional experiments followed.

So far, as far as I know, only "Goofy" has reported having done some such experiments, apparently with the same or similar results, earlier in the thread:

https://www.stirlingengineforum.com/vie ... 120#p19900

I hope more people in this forum will do some practical experiments with their small Stirling engines. I should not be so difficult to
isolate the cold side of the engine and see if there is something to Tom´s experience.

- And you don´t need high precession thermocouple's to do this. Look for the tendencies, not the "correct" temperature.

But have anyone in here done that ?

Yes, I have my self ;-) (...) - Goofy

I don't think that this "Carnot efficiency problem" will ever be settled by any amount of intellectual sparing or debate. No charts and graphs or calculations etc. depicting "Ideal" gas behavior.

Tom Booth wrote: ↑Wed Aug 30, 2023 12:21 pm
Helium for example can hardly be liquified by any extreme of external cooling and pressure, yet it can be liquified by this method of having it do work expanding in a cylinder to drive an engine to do external "work".

Was that a typo? If the expansion of the gas cools it down far enough to liquify it, where is the pressure coming from to push the piston?

MikeB wrote: ↑Thu Aug 31, 2023 4:40 am

Tom Booth wrote: ↑Wed Aug 30, 2023 12:21 pm
Helium for example can hardly be liquified by any extreme of external cooling and pressure, yet it can be liquified by this method of having it do work expanding in a cylinder to drive an engine to do external "work".

Was that a typo? If the expansion of the gas cools it down far enough to liquify it, where is the pressure coming from to push the piston?

Well, that's the trick.

Initially the gas is released into the cylinder (or turbine) at high pressure.

The gas expands and does work driving the piston which causes the gas to lose "internal energy".

Some of the gas loses so much energy in the process of doing work to drive the engine that it condenses into a liquid. Whatever fails to condense into a liquid the first time through is again compressed to a high pressure, cooled and again used to drive the engine.

The expansion engine itself is often coupled to the compressor, so the work that the gas does driving the engine is used to compress more gas, so the process can be made more efficient.

Of course, the expanding gas cannot do all the work of compressing more gas, so a motor may also be coupled to the engine to make up for loses.

Apparently some of the gas enters the cylinder at high velocity and does enough work setting the piston in motion to liquify while some of the gas expands and continues driving the piston (or turbine) but does not get cold enough or lose enough energy to liquify and so is taken and recompressed.

But the cold, unliquefied gas is used to pre-cool the new batch of compressed gas before it is expanded.

There is also a "vacuum" created by the partial condensation of the gas as well as the vacuum created by the compressor so the engine "exhaust" is at a low pressure.

To put it simply, the gas released from high pressure, expands and sets the piston in motion transferring energy to the piston.

The gas, when highly compressed, repels itself by molecular repulsion so when released, expands very forcefully losing internal energy. But then after losing energy it can't get back, molecular attraction becomes dominant and some of the gas molecules are attracted enough to condense into a liquid.

A difficulty in discussing this topic:

The theory of small turboexpanders and their design method are not fully standardised. Although several companies around the world manufacture and sell turboexpanders, the technology is not available in open literature.

https://www.semanticscholar.org/paper/M ... f19e975ecc

That was way back in 2008 but, I think it may be even more difficult to find clear information on the subject now.

Note "industry insiders" and "private" in this turbo-expander/compressor video:

https://youtu.be/5c9Tm578SLo?si=2CvhuqA79ghKJVwe

There were a few very good explanatory videos and websites online maybe 10 years ago but it seems to be getting even more difficult, though the basic technology goes back to the late 1800's

Here is an abstract that gives some historical information:

Abstract

The idea that an expansion turbine might be used in a cycle for the liquification of gases was first suggested by Lord Rayleigh about 85 years ago. (That's 125 years ago now, Old book - T.B.) In a letter to “Nature” dated June 28, 1898, he suggested the use of a turbine instead of a piston expander for the liquification of air. At that time refrigeration machines operating on an air cycle had become commercially successful and attempts were being made to go to lower and lower temperatures so that eventually the air itself would be liquified. Because all lubricating oils become solid at cryogenic temperatures, there were difficulties in lubricating the piston and cylinder in a reciprocating expansion engine. The adoption of a turbine expander would avoid these difficulties. Rayleigh emphasized that the most important function of the turbine would be the refrigeration produced rather than the power recovered. This was a year before air was first liquified in a reciprocating expander by Claude in 1899.

https://link.springer.com/chapter/10.10 ... -9865-3_59

Tesla, if we can take his word for it, was already using a turbine to liquify air in 1895 when his workshop burned down.

Another interesting snip:

Computational Fluid Flow Analysis of High Speed Cryogenic Turbine Using CFX
S. Upadhyay, S. Srivastava, S. Sagar, Surabhi Singh, Hitesh Dimri
Physics, Engineering
Asian Journal of Engineering and Applied…
2015

A turbo expander also referred as an expansion turbine, is a centrifugal or axial flow turbine through which a high pressure gas is expanded to produce work that is often used to drive a compressor. The low pressure exhaust gas from the turbine is at a very low temperature that is 120K or less depending upon the operating conditions. It is widely used as sources of refrigeration in industrial processes and liquefaction of gases such as oxygen, nitrogen, helium, argon and krypton.

https://www.semanticscholar.org/paper/E ... 8baf6e143b