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Heat Engines (Stirling & Nitinol) - Tom Booth - 07-20-2024
Hello, I just joined the forum.
I was never exactly into "overunity". I was mostly just interested in how heat engines work. Stirling "Hot Air" engines in particular.
I was living off-grid and mostly just wanted to generate some electricity from my wood stove.
Living off grid and researching "alternative energy" I came across something about Stirling engines that can run on heat from any source, such as a wood stove or solar. That seemed like the way to go, but looking into it further, no Stirling engines were available.
Well, it still seemed to me like a good idea, and people were building Stirling engines out of tin cans and scrap metal and whatnot. Probably I could build one myself, but I really didn't understand how they work, so I started doing research.
I joined a Stirling engine forum. The idea was pretty basic. Heat up a can full of air, it expands, pushes out a piston, then cool it down, take the heat away and the air "contracts" so the piston can be pushed back. Pretty simple.
I had problems getting this working though, and kept on researching, reading OLD thermodynamics books (I didn't have money for new ones) which I found fascinating. Some of the references I found said that heat "disappears" or is "consumed" in a heat engine. In other words, "heat" is a form of energy. A heat engine converts heat into mechanical work, which leaves behind cold. This was even used to get gases cold enough to turn them into a liquid.
So maybe you really didn't need to REMOVE heat from a heat engine. You just supply heat and it "disappears", as it is converted into mechanical "work".
This was getting pretty wild. So a Stirling engine was also kind of like a refrigerator? When a heat engine converts heat into work the heat "disappears" and when the heat is gone, (converted), the result is refrigeration?
So I also started studying methods of refrigeration and the methods used for liquifying gases.
At some point in all this research and study I came across a portion of an old article written by Nikola Tesla.
Tesla suggested that it would be possible to run a heat engine on cold. Actually it would be running on the heat in the environment. But because heat is energy, and because the heat is converted into "other forms of energy" which effectively removes the heat, a heat engine could run on cold, (or actually, heat in the environment) perpetually. In other words, since the heat would be converted by the heat engine into forms of energy that are not heat, leaving behind cold, the heat engine running on cold could run forever.
In other words, let's say you ran a Stirling engine on ice. According to Tesla, in theory, you could run a Stirling engine on ice and the ice would never melt.
Well, that seemed like a pretty interesting possibility. Tesla also mentioned in his article that this contradicted what he had read from Carnot and Kelvin (the "Carnot Limit" or the 2nd Law of Thermodynamics).
Well, me, being basically, completely ignorant about all this and not being able to find any historical records of any experiment that settled or resolved the disagreement, I decided to do some experiments to see who was right; Carnot and Kelvin or Nikola Tesla. To me, Tesla's idea seemed plausible.
The results of my experiments, running some model Stirling engines on ice turned out rather interesting.
The ice lasted quite a bit longer, took several hours longer to melt, when being used to run a Stirling engine. Of course, I had to keep the ice insulated where it was not in contact with the engine.
I also used a "control". A Stirling engine just sitting on ice but not running.
The ice always lasted considerably longer when the engine was running than when it was not running.
This was so interesting to me, I posted these experiments on a Science/Physics forum for some feedback.
Well, I did not get the reception I had expected. I was met with a lot of rather harsh criticism and ridicule and soon found myself banned.
If anyone is interested, that thread on the physics forum is here:
Physics Forum
It doesn't seem to be well known that Tesla had so much interest in, and spent so much time working on this idea of a "Self-Acting Engine" that could run on the heat in the environment.
Anyway, I've been banned from I think, all the major Science and Physics forums. I've also pretty much been run off the Stirling engine forum by a few critics who will just not leave me alone.
I don't mind constructive criticism at all, but some of these people advocating for the "Carnot Limit" IMO are really rabbid.
So, after doing some looking around for a forum where I might be able to just talk about the progress of my various experiments in peace I found this forum.
Now, like I say, I don't mind criticism, but enough is enough. These people don't just criticize, they seem to want me banned from the internet altogether.
Anyway, my most recent experiments have been testing the strength of some 3mm Nitinol wire I obtained just recently.
It's not really possible to see what's happening in that video, but if you slow it down to 0.25 speed you might be able to see the wire fly to the left in a blur. But it happens so fast, so I made another similar video in Slow motion:
You can, of course, slow it down even more using the YouTube playback speed controls.
That type of bottle is pretty hard plastic BTW. Thicker than most ordinary water or soda bottles.
I used it because, due to the round shape of the bottle, the Nitinol gets trapped and cannot straighten out when heated, without breaking through the side of the bottle.
Apparently the force that develops is even strong enough to split a rock in half.
RE: Heat Engines (Stirling & Nitinol) - Tom Booth - 07-20-2024
To provide a little more background, and give some idea about where I am and what direction I'm heading in:
A lot of my time, unfortunately, for the past 10 years or more, has been spent engaging in a lot of debate and argument on various forums. Especially science and physics forums but also the Stirling engine and Hot Air engine forums and groups. A lot of which have come and gone.
In some ways I wish I had just spent more time doing experiments and hands on research and less time seaking advice and validation, but in the long run I learned a lot. Still, a lot of the debate seems like a big waste of time to me now.
But, I thought all the while that certainly these questions had already been worked out. Surely any experiment I might come up with had already been done before.
So I went basically begging on the Science and Physics forums asking: "Is this right?" Or "are these the results I should be getting?".
I went humbly, seeking advice and guidance, asking questions in all sincerity, like "Should ice take longer to melt when used to run a heat engine?"
What do I know? Maybe that experiment was already well known and the results had been determined a hundred times before already.
When the question first came up in my mind, about who was right, Kelvin or Tesla, and what was heat really? Is it a substance that does not change as Sadi Carnot and Kelvin had believed, or just ENERGY that can be transformed, as Tesla believed, I though certainly experiments had already been done to make that determination.
But try as I might, reading and researching the entire history of heat and heat engines, I couldn't find any historical records of any actual experiments to determine if heat passed or flowed THROUGH a heat engine, going in one side and out the other, or if the HEAT only went INTO a heat engine to be "consumed" as a kind of FUEL, in which case it would, essentially "disappear".
The idea that heat could "disappear" while being transformed from one form of energy into another seemed very strange and incomprehensible to me. But actually my father had been a chemist and I had grown up around science and had learned to try and look at things objectively and try not to make assumptions that were not verified by actual experiment, so when I saw that some scientists seemed to have one point of view and others had another point of view, but the conflict had never actually been resolved EXPERIMENTALLY as far as I could see,
Well...
I guess I'd just have to do some experiments myself.
On the Stirling engine forums I had learned as a matter of "fact" that heat engines or Stirling engines do not run on HEAT, but that they run on a temperature differential. You need BOTH hot and cold. HEAT on one side of the engine and COLD on the other side.
I was informed that the heat had to be added to expand the air in the engine to drive the piston, but then the heat also had to be taken away to complete the cycle, reduce the pressure so the piston could return to start the process over again. This was an absolute. There was no question about it.
That's what everybody said and apparently KNEW, for sure, without any question. But... Where were the actual experiments? Who actually proved this?What actual experiments were performed?
I thought for sure I must just be overlooking some chapter in all the books or some period in history when such experiments were conducted, so I asked, and asked often, on the Science and Physics forums. "Who conducted the experiments that proved all this?" How do we know for certain that Nikola Tesla was wrong? I mean, he was a pretty smart guy right? And we do now know that heat really IS just a form of energy and that a heat engine transforms that energy into WORK. Right?
Anyway, not finding any answers I felt completely satisfied with, I finally did a little experiment and I decided to record the experiment on video.
I thought, if heat has to "FLOW THROUGH" a Stirling heat engine and come out the other side to be removed at the "heat sink" or cold side; if the heat had to go IN and then come OUT again, what would happen if this "flow" of heat were blocked by insulation?
I proposed this experiment on the Stirling engine forum a long long time ago and basically got laughed at.
I was told with great assurance that a Stirling engine could not operate with insulation blocking heat from leaving the cold side. Of course the engine would overheat and stop running, no question about it.
Well, it wasn't until years later that I was finally able to afford to just purchase several identical model Stirling engines to experiment with.
Actually, by the time I could afford to buy the engines I had almost forgotten about that debate. But once I had an actual Stirling engine to test, I thought why not?
I would do that experiment and post it to the Stirling engine forum to show how a Stirling engine will overheat and stall when covered by insulation. I was sure that everyone had been right. The engine would overheat and stall.
So I decided to record the experiment on video just for fun.
And this was that experiment:
I didn't know with 100% certainty what would happen. I had never done any such experiment before, but I suspected that everybody in the Stirling engine forum was right and that the engine would quickly overheat and stop running as soon as it was completely covered by insulation.
But that didn't happen.
The engine kept going.
I kept filming, waiting for the engine to overheat and stop running, but it never did. It kept running until the hot water finally cooled down, but my phone ran out of memory long before that happened.
Infact, after rewatching the video several times and counting the revolutions, it turned out that the RPM actually increased slightly after the cold side of the engine was covered with insulation.
I went ahead and posted the video to the Stirling engine forum anyway.
This created a rather heated and still ongoing controversy, and there were many additional experiments conducted (by me) with other forum members making suggestions about what I might be doing wrong.
More experiments using "better" insulation, thicker insulation, more thorough insulation of all different types and using all kinds of different methods and taking all kinds of measurements using thermal imaging and so forth.
The results, seem to me, pretty consistently the same.
Trying to stop a Stirling engine by trying to block the heat from leaving the cold side doesn't work. The engine just keeps running.
Reference: https://www.physicsforums.com/threads/should-ice-take-longer-to-melt-when-used-to-run-a-heat-engine.991714/#google_vignette
RE: Heat Engines (Stirling & Nitinol) - Tom Booth - 07-21-2024
I sketched out this idea for a simple Nitinol engine last night:
It is designed to use just small pieces of Nitinol wire as "knees" or "elbows".
I could build a working(?) model rather easily, I think, only using probably less than six inches of Nitinol wire total. At about $0.50 per inch (more or less depending on thickness) that's under $5 for the nitinol per engine (with three "arms" each).
I think it could be scalable by just adding additional "arms" on a longer crankshaft.
In case it isn't clear how it is supposed to work, the bowl or trough (blue) contains hot water, which could come from a solar water heater, "waste" process water, water heated on a wood stove or whatever.
The Nitinol has a transition temperature of say 80°C (variable according to composition) so it is soft and flexible at room temperature but when it hits the hot water it will begin to straighten driving the flywheel and at the same time lifting itself out of the hot water, quickly becoming soft again.
Basically it would work like peddling a bicycle. But, in theory at least, you could have a virtually unlimited number of "legs" peddling on the same crankshaft.
The "muscle wire" would only be required in short sections for the "knee" or "elbow".joints.
Nitinol also responds to a current of electricity passing through it.
So I would think that in theory, by the addition of a commutator of some sort, or individual switches built into the "arms", the engine could run as an electric motor directly on the DC current from a PV panel or batteries.
RE: Heat Engines (Stirling & Nitinol) - Tom Booth - 07-22-2024
In my opening post, I mentioned an article I had read by Nikola Tesla.
I did a couple searches here to see if there was any previous discussion of that article but did not find any, so I thought it would be worth posting a bit more about it before going on.
Here is a brief clip:
The relevant text is under the heading:
"A Departure from known methods - Possibility of a 'Self-Acting' Engine"
There are several online versions of the article.
https://teslauniverse.com/nikola-tesla/articles/problem-increasing-human-energy
A downloadable PDF:
https://teslasciencecenter.org/wp-content/uploads/2022/04/THE-PROBLEM-OF-INCREASING-HUMAN-ENERGY_Century_Magazine.pdf
What I got out of Tesla's article is he thought he found a kind of loophole in the second law of thermodynamics.
Very simply, a heat engine, running on COLD (below the temperature of the ambient surroundings, and actually running on atmospheric heat) could run indefinitely.
Or put another way, a heat engine combined with a heat pump (or refrigerator) could run on environmental heat. But since heat is a form of energy, not a fluid (Caloric theory adhered to by Carnot and Kelvin in the formulation of the Second Law of Thermodynamics) a heat engine CONVERTS heat/energy into mechanical motion or "work". Therefore the heat being used to run the engine is USED UP by the engine and so does not pass through into what Tesla called a "Cold Hole".
Therefore, the heat pump or refrigerator that created the COLD would only need to run intermittently, if at all.
In Tesla's words:
But let us reflect a moment. Heat, though following certain general laws of mechanics, like a fluid, is not such; it is energy which may be converted into other forms of energy as it passes from a high to a low level. ... heat is transformed in passing from hot to cold. If the process of heat transformation were absolutely perfect, no heat at all would arrive at the low level, since all of it would be converted into other forms of energy.
...We would thus produce, by expending initially a certain amount of work to create a sink for the heat ... to flow in, a condition enabling us to get any amount of energy without further effort. This would be an ideal way of obtaining motive power. We do not know of any such absolutely perfect process of heat-conversion, and consequently some heat will generally reach the low level,... and a gradual and slow filling of the latter will take place, necessitating continuous pumping out. But evidently there will be less to pump out than flows in, or, in other words, less energy will be needed to maintain the initial condition than is developed by the fall, and this is to say that some energy will be gained from the medium. What is not converted in flowing down can just be raised up with its own energy, and what is converted is clear gain. Thus the virtue of the principle I have discovered resides wholly in the conversion of the energy on the downward flow."
The next section reveals just how diligently Tesla worked on this and how quite a number of his inventions were actually spin -offs from this central effort to develop a kind of perpetual, self running combination heat engine / refrigerator.
"FIRST EFFORTS TO PRODUCE THE SELF-ACTING ENGINE — THE MECHANICAL OSCILLATOR — WORK OF DEWAR AND LINDE — LIQUID AIR.
Having recognized this truth, I began to devise means for carrying out my idea, and, after long thought, I finally conceived a combination of apparatus which should make possible the obtaining of power from the medium by a process of continuous cooling of atmospheric air. This apparatus, by continually transforming heat into mechanical work, tended to become colder and colder, and if it only were practicable to reach a very low temperature in this manner, then a sink for the heat could be produced, and energy could be derived from the medium. This seemed to be contrary to the statements of Carnot and Lord Kelvin before referred to, but I concluded from the theory of the process that such a result could be attained. This conclusion I reached, I think, in the latter part of 1883, when I was in Paris...
...1889, when I again took up the idea of the self-acting machine. A closer investigation of the principles involved, and calculation, now showed that the result I aimed at could not be reached in a practical manner by ordinary machinery, as I had in the beginning expected. This led me, as a next step, to the study of a type of engine generally designated as “turbine,” which at first seemed to offer better chances for a realization of the idea. Soon I found, however, that the turbine, too, was unsuitable. But my conclusions showed that if an engine of a peculiar kind could be brought to a high degree of perfection, the plan I had conceived was realizable, and I resolved to proceed with the development of such an engine, the primary object of which was to secure the greatest economy of transformation of heat into mechanical energy. A characteristic feature of the engine was that the work-performing piston was not connected with anything else, but was perfectly free to vibrate at an enormous rate. The mechanical difficulties encountered in the construction of this engine were greater than I had anticipated, and I made slow progress. This work was continued until early in 1892, when I went to London, where I saw Professor Dewar’s admirable experiments with liquefied gases. Others had liquefied gases before, and notably Ozlewski and Pictet had performed creditable early experiments in this line, but there was such a vigor about the work of Dewar that even the old appeared new. His experiments showed, though in a way different from that I had imagined, that it was possible to reach a very low temperature by transforming heat into mechanical work, and I returned, deeply impressed with what I had seen, and more than ever convinced that my plan was practicable. The work temporarily interrupted was taken up anew, and soon I had in a fair state of perfection the engine which I have named “the mechanical oscillator.” In this machine I succeeded in doing away with all packings, valves, and lubrication, and in producing so rapid a vibration of the piston that shafts of tough steel, fastened to the same and vibrated longitudinally, were torn asunder. By combining this engine with a dynamo of special design I produced a highly efficient electrical generator, invaluable in measurements and determinations of physical quantities on account of the unvarying rate of oscillation obtainable by its means. I exhibited several types of this machine, named “mechanical and electrical oscillator,” before the Electrical Congress at the World’s Fair in Chicago during the summer of 1893, in a lecture which, on account of other pressing work, I was unable to prepare for publication. On that occasion I exposed the principles of the mechanical oscillator, but the original purpose of this machine is explained here for the first time.
In the process, as I had primarily conceived it, for the utilization of the energy of the ambient medium, there were five essential elements in combination, and each of these had to be newly designed and perfected, as no such machines existed. The mechanical oscillator was the first element of this combination, and having perfected this, I turned to the next, which was an air-compressor of a design in certain respects resembling that of the mechanical oscillator. Similar difficulties in the construction were again encountered, but the work was pushed vigorously, and at the close of 1894 I had completed these two elements of the combination, and thus produced an apparatus for compressing air, virtually to any desired pressure, incomparably simpler, smaller, and more efficient than the ordinary. I was just beginning work on the third element, which together with the first two would give a refrigerating machine of exceptional efficiency and simplicity, when a misfortune befell me in the burning of my laboratory, which crippled my labors and delayed me. Shortly afterward Dr. Carl Linde announced the liquefaction of air by a self-cooling process, demonstrating that it was practicable to proceed with the cooling until liquefaction of the air took place. This was the only experimental proof which I was still wanting that energy was obtainable from the medium in the manner contemplated by me.
The liquefaction of air by a self-cooling process was not, as popularly believed, an accidental discovery, but a scientific result which could not have been delayed much longer, and which, in all probability, could not have escaped Dewar. This fascinating advance, I believe, is largely due to the powerful work of this great Scotchman. Nevertheless, Linde’s is an immortal achievement. The manufacture of liquid air has been carried on for four years in Germany, on a scale much larger than in any other country, and this strange product has been applied for a variety of purposes. Much was expected of it in the beginning, but so far it has been an industrial ignis fatuus. By the use of such machinery as I am perfecting, its cost will probably be greatly lessened, but even then its commercial success will be questionable. When used as a refrigerant it is uneconomical, as its temperature is unnecessarily low. It is as expensive to maintain a body at a very low temperature as it is to keep it very hot; it takes coal to keep air cold. In oxygen manufacture it cannot yet compete with the electrolytic method. For use as an explosive it is unsuitable, because its low temperature again condemns it to a small efficiency, and for motive-power purposes its cost is still by far too high. It is of interest to note, however, that in driving an engine by liquid air a certain amount of energy may be gained from the engine, or, stated otherwise, from the ambient medium which keeps the engine warm, each two hundred pounds of iron-casting of the latter contributing energy at the rate of about one effective horse-power during one hour. But this gain of the consumer is offset by an equal loss of the producer.
Much of this task on which I have labored so long remains to be done. A number of mechanical details are still to be perfected and some difficulties of a different nature to be mastered, and I cannot hope to produce a self-acting machine deriving energy from the ambient medium for a long time yet, even if all my expectations should materialize. Many circumstances have occurred which have retarded my work of late, but for several reasons the delay was beneficial.
One of these reasons was that I had ample time to consider what the ultimate possibilities of this development might be. I worked for a long time fully convinced that the practical realization of this method of obtaining energy from the sun would be of incalculable industrial value, but the continued study of the subject revealed the fact that while it will be commercially profitable if my expectations are well founded, it will not be so to an extraordinary degree.
My main interest in all this was just the basic principles involved. As I've mostly highlighted.
Heat/energy converted to mechanical work could produce "a very low temperature by transforming heat into mechanical work."
Now, according to the older "caloric theory" heat was not transformed in passing into a heat engine. It only "flowed through" the engine like water being let down by a water wheel.
Personally, when investigating all this, I was just a retired mechanic. I could care less about the various scientific theories of heat. I just wanted to know how Stirling engines work so I could build one, because I was trying to just survive living off grid.
So, am I trying to build an engine that lets heat pass through, or am I trying to build an engine that transforms or actually, so to speak "consumes" heat as a "fuel" leaving behind cold?
Do I want to retain heat in the engine until it is fully utilized or do I want to facilitate the TRANSFER of heat through the engine as quickly as possible?
I mentioned earlier how my efforts at supplying and then REMOVING heat did not work. I was going by what I had been told. You have to add heat to get the gas to expand and drive the piston, then you have to take that heat away so the gas can cool off and contract so the piston could return.
As a mechanic, I found that was not effective or practical. I would have to dig deeper to figure out how these engines REALLY work.
So ai started devising experiments to try and find out what really goes on inside a Stirling engine.
The basic question was: does heat go THROUGH, or just go IN and "disappear".?
RE: Heat Engines (Stirling & Nitinol) - ovun987 - 07-22-2024
This is all very interesting, Tom. Really appreciate you taking the time to directly post those Tesla quotes. Your work has me intrigued! Keep it up!
RE: Heat Engines (Stirling & Nitinol) - Tom Booth - 07-22-2024
BTW...
I have been a participant/member on the "Stirling and Hot Air engines" forum going back to at least 2006.
https://stirlingengineforum.com/viewtopic.php?t=77
There may have been a few earlier posts but I think that was probably the first thread I started, back when I was first grappling with just trying to understand how a Stirling engine works so I could build one as a matter of survival and comfort living off-grid in the hills of upstate New York.
I Started many more threads between then and now. So that is probably 20 years in total that I've been studying Stirling engines, as I think I spent a few years just randomly browsing the internet and had joined several similar groups and forums prior to finding that one. There were a couple Yahoo Groups and some YouTube videos, but the above thread is essentially the beginning when I really buckled down and got serious about building a Stirling engine.
After trying, unsuccessfully to construct a working engine based on the "known principles" I had learned I began looking deeper into Thermodynamics:
At that time I started another thread on the Stirling engine forum that contains some significant material:
https://stirlingengineforum.com/viewtopic.php?t=478
That was four years later in 2010.
This was my opening post, as can be seen, I was begining to recognize those things about heat engines that Tesla wrote about back in his article in 1900. Heat, going into a heat engine, it seems, does not really go THROUGH the engine, but in a sense "disappears" inside the engine as it is converted into "WORK" or the mechanical motion of the engine:
Tom Booth
Stirling Engine Thermodynamics
Post Tue Feb 23, 2010 6:12 pm
I've been reading quite a bit about thermodynamics lately. Especially in regard to the fact that when a gas is "made to do work" it looses heat or gets cold.
This has been a hard concept for me to grasp, but apparently, when a gas does work of any kind, the heat energy in the gas is converted into "work" or the kinetic energy - such as moving a piston.
Now, formerly I had been under the impression that a Stirling engine functions by means of a temperature differential applied to it. One end of the displacer chamber is heated and the other end cooled - the air travels back and forth from one end of the chamber to the other and picks up or looses heat in that way...
But I'm becoming aware that there is also apparently something a little more subtle going on, that is, when the air in the chamber heats up and expands and then does work against the piston - the heat does not only travel to the "heat sink" at the cold end of the chamber but some of the heat is actually converted into work. In other words, what cools the hot expanding air back down is not so much, or not only coming into contact with the cold end of the chamber but heat is also lost on account of the gas being made to do work against the piston.
What I'm wondering is just how much heat is actually being absorbed in this way i.e converted into work as opposed to the heat being absorbed by the heat sink (the cold end of the chamber at ambient temperature).
If more heat is extracted as work than what actually reaches the heat sink, then theoretically, insulating the cold end of the displacer chamber against the external ambient temperatures would improve engine efficiency.
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.
If heat is being converted into work then the more work the engine is made to perform the cooler it should run. Maybe the problem with many model Stirling engines overheating is that they are being run without a load of any kind and therefore the heat, rather than being transfered to the load on the engine to do work is just building up and causing the engine to overheat.
Perhaps this is already a known fact but for me it is something of a new realization and I'm wondering if anyone with more knowledge and experience in this area might be able to confirm or refute this supposition.
Thanks.
Tom
I think it is worth reviewing at least the first few pages of that thread since I reference some of the source material I was looking at at the time.
It should be noted that this was quite some time BEFORE stumbling across Tesla's 1900 article covering the same subject matter.
It would still be many more years before I conducted any real hands on experiments to try and test these ideas.
BTW
That Stirling engine forum, with so much valuable material and years and years of discussion seems to potentially be in danger of disappearing.
I had been in very occasional contact with the forum owner by PM and email over the years but just within the past few months I have received no response, and the spam and trolling has gone unchecked.
This is what has finally forced me to seek out a new "home", which resulted in my finally landing here.
It would, I think, probably be a good idea to preserve some of those old threads, or the entire forum on some internet archives before it disappears forever, but that is a rather tedious undertaking. I try to do what I can from time to time, but any help in that regard would be appreciated.
Unfortunately, it seems to me that some hackers? may have gained partial admin access or something and have, if I'm not mistaken, altered or deleted some of the content already. At any rate, it appears that the site is no longer being actively maintained and is filling up with a lot of video game type and other spam threads.
RE: Heat Engines (Stirling & Nitinol) - Tom Booth - 07-22-2024
(07-22-2024, 10:55 AM)ovun987 Wrote: This is all very interesting, Tom. Really appreciate you taking the time to directly post those Tesla quotes. Your work has me intrigued! Keep it up!
Thanks, it's my pleasure. I'm grateful for the privilege.
RE: Heat Engines (Stirling & Nitinol) - Tom Booth - 07-23-2024
A few additional Nitinol engine
designs I found browsing around
the internet recently that look like
they could have some potential:
What I like about these is they utilize high temperature Nitinol that changes shape above ambient air temperature so it only requires warm water to operate rather than also requiring a bath of ice water.
RE: Heat Engines (Stirling & Nitinol) - Tom Booth - 07-23-2024
This may seem like a bit of an odd video to post, but maybe you will get the idea:
It should be possible to braid some thin shape memory Nitinol wire into a cable for multiplying strength and power output.
The reason I'm thinking along these lines is mostly because very thin Nitinol wire is quite reasonably priced. About $25.00 US for ten feet of wire (1mm), more or less depending on thickness.
Thicker nitinol rod and bar stock however gets astronomically expensive and probably wouldn't be much use for this application anyway as the thicker it is, the slower it responds, the longer it takes to absorb heat and change shape.
I'm thinking that a woven Nitinol cable could absorb heat nearly as fast as a single thin strand due to the tremendous increase in surface area.
RE: Heat Engines (Stirling & Nitinol) - GT899 - 07-24-2024
Hi Tom welcome to the forum and thanks for sharing all your amazing research it is definitely welcomed here!! Life is not a closed book but an infinitely open one of possibilities. I am very interesed in nitinol engines and want to experiment with this too at some point.