Magnetic Low Temperature Differential Stirling Engine 2
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- เผยแพร่เมื่อ 27 ธ.ค. 2016
- The Magnetic Low Temperature Differential Stirling Engine is one of the "must have" toys for the science minded, as well as for teachers, students, techies, engineers and the curious...not to mention those who simply those who want to wow their co-workers in the office or their gusts at the party. For more information on how to purchase your own, please contact Orlando@ScienceTubeToday.com
Nice explanation
Thank you for a very well done presentation. It is clearly stated, well illustrated, and easy to understand.
Thank you, Nimo.
Think the engine would run longer if the screws were nylon instead of metal.
Saw some other videos which describe the Stirling cycle via PV charts and they indicate that, during some parts of the cycle, the displacer is not moving. When you have a mechanical linkage for the displacer, I could not understand how they made this claim, so i figured it was a theoretical/ideal explanation. Interestingly, it appears this magnetic linkage much more closely approximates the theoretical Stirling cycle.
One problem/issue with this approach is that you’re dependent on gravity to move the displacer, so there are limits to how fast this can go. It would not work at all on orbit.
Thank you for posting
Thank you for watching. This is a great tool for teachers and students because it demonstrates the behavior of gases, heat conductivity of materials, magnetism, transformation of energy from one type to another, momentum and more. I love it :)
GRAN VIDEO ,BUENAZO
EXCELLENT explanation and presentation. There are many TH-camrs who could learn a LOT from you in this regard. Thank you for posting.
Thank you Carl. Very kind of you :)
Wow, great design, explanation and video production!
Thank you very kindly for your comment. Actually I have watched your videos in the past and loved them. Today I subscribed. Just as a note, I have made a few walk along gliders. Thank you for your enthusiasm and willingness to share. They are very fun. On my end, I like to build paper gliders that I launch, inside the house, at school, basketball courts, or outside when there is very light wind, or no wind at all (they are very delicate and must be trimmed with perfection, as you well know). I love to see the long, smooth glide. I used to fly hang gliders and I worked at a hang glider factory many years ago...So we all built these things during our lunch time. Maybe one of these days I will make and publish a video. Have a great day! STT
The magnet coupling allows for a gas tight chamber, but replaces the mechanical friction of the shaft passing through the seal with losses from the magnetic fields coupling and decoupling. I wonder what the total efficiency is.
I understand your concerns and I think they are valid. The magnet needs a steel sheaf to focus the magnetic field onto the displacer and minimise the stray magnetic field in the surrounding metal parts.
How large, to what weight and what power output is this scaleable?
muy bien explicado muchas gracias me suscribo y sigo pues yo tambien hago y me interesa el tema motores stirling de todo tipo estoy deseando fabricar un prototipo asi, un saludo desde España
Con mucho gusto. Gracias
Great video demonstration! One question: Wouldn't heating and cooling the air be a slower process than what is shown? the concept sound fine but the speed that the engine is turning is so fast for time it should take for air to cool and re-heat, No? also this model is using gravity, do the traditional ones use gravity as well? . Thanks in advance.
Hi Farid. First, thank you for your comment.
Regarding your first question: It takes quite a few minutes for us to boil water, and it takes a long time for that water to return to room temperature after being removed from the fire. It takes some time for our cars to warm up the engine, and when we turn it off, it takes time to cool off. Or when we heat up an iron to iron our clothes....We may naturally use these observations as a comparison with a stirling engine. These items have a very large "mass" that needs to be heated from a source of energy and cooled usually by dissipating heat into the environment. But, inside a Low Temperature Stirling Engine the heat exchange happens very fast because there is very little "mass" (air, hydrogen or helium) to be heated and cooled when coming into contact with large surfaces (top and bottom plate). Now, add to this the fact that once the wheel makes its first turn the kinetic energy of the wheel only needs a tiny amount of energy to keep it going - If you want to have an idea of how much energy is needed to keep the wheel going, just put your finger on it, and it will stop very easily (because the amount of energy you are dealing with is very small). Regarding your second question: Great observation! Yes, gravity pulls the displacer to the bottom of the chamber in this particular model. Other models use a "shaft" that links the piston to the displacer. The shaft pushes the displacer down, and pulls it up. Have a great day. STT
Flea power becomes molecule power. Wow, wow!!
This particular magnetic stirling engine is for demonstration purposes only. It is not intended to be used to do work. For that purpose, there are other types. :)
Hii
Thanks for great explanation video.
I have only one question ... ?? Is it self starting???
I made one LTD stirling engine and I know the traditional LTD stirling is not self starting. Would be great to be. I saw some design of self starting but I didn t find the good explanation for this
Hi Steli, No, this is not a self starting engine. Have you tried to Google for a self starting Stirling Engine? I don't know any in this category, sorry!
Thanks alot for your answer and again thanks for your explanation video
Is the momentum lost to pulling the magnets apart less than that of a permanently connected rod?
No more than a physical shaft in its place on a regular stirling engine.
How does atmospheric pressure drive the displacer back down when it's stuck to the piston magnet ? Wouldn't the two magnets act as an engine brake ?
In my opinion, a momentum of the fly wheel will force the displacer to overcome the power of the magnet.
@@ovrall Let's see. When the displacer is at the top (and in contact with the top plate) the flywheel has a momentum that keeps pulling the piston magnet away from the displacer magnet. At maximum distance the magnets can't "see" each other, and the displacer "falls" to the bottom of the chamber. As the flywheel continues, the two magnets approach again to a distance where they can again "see" each other, and the displacer magnet gets "picked up" by the piston magnet.
Is there a variation in performance if the temp differential is higher - much hotter plate, much colder plate - is there a recommended diff?
Thanks!
Yes, the temperature differential will make this engine go faster if the difference in temperature is greater.
Hi! Nice little engine clearly explained. Thank you. I'm a bit late to the party and hope you're still interested... The business of phase angle is troubling me. If the flywheel's angular speed is constant (pretty much true) the motion of the piston is sinusoidal. While the magnets are coupled the motion of the displacer tracks it in phase. When they decouple the displacer falls in a way determined by gravity and air resistance and then stays at rest. So I'm imagining a sinusoid with a flattened top, approximately. Most stirlingers say that a 90 degree phase angle is needed, or optimal, I'm not clear which or why. Anyway, I've seen a few engines that have a more abrupt flip-flop action, keeping the displacer longer at the extrêmes of travel than a sine would and not having a 90 degree phase angle, but rather zero or 180. Any rough idea of the effect on efficiency?
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@vicky rd
Back to school.
I think one magnet on the piston will b sufficient.a small metal strip on the displacer will work.
So if you sealed the displacer volume from the piston volume (by, say, taping off the hole) the machine wouldn’t work? It needs air to push the piston?
Yes, the air must pass from the bottom chamber to the piston to push or pull it.
I wanna see a 100% magnetic bearing LTD engine, it'd run from temp differences from a breeze I'd hope lol.
I wonder if this could be considered a form of Beta type Stirling Engine, given that the Piston cylinder is really just a extension of the heating "cylinder" and both the piston and displacer are driven on the same axis…
I believe it is still a beta type, yes. Only difference from standard beta types is the displacer piston is driven magnetically rather than mechanically.
@@konekoray9323 magnetically is still mechanically.
@@yakut9876 Alright, alright, but you know what I meant.
This is much simplier than a traditional ltd stieling engine
Yes, and much lighter too because the plates are made of aluminum, so as not to interfere with the magnets.
I have this one, but it cannot work no matter how I put heat into the bottom plate and kick start it.
Do you have suggestion what may be wrong? is it the timig, the seal, or something else
It is very hard to diagnose a problem without examining the parts and troubleshooting the engine. I would start by verifying that the movable parts are moving freely and not snagged or under a lot of friction. Check to see if any of the parts are broken or bent out of shape. The whole thing must be running very smooth. Check and write me back. I am curious to see what you find out.
i found some clue.
1.) the displacer foam is somewhat not fully level or horizontal. so when the displacer in top most position, it didnt completely displace the working air from cold top to hot bottom.
2.) the piston is not fully seal the cylinder. but i think this is not the main culprit. I have two machine, one with magnet, one with mechanical linkage. the one with mechanical linkage is working eventhough the piston is not perfectly sealing the cylinder
A recent reply by Orlando to another comment indicated that they have no more and may stop making them. So I don't know if you can make a claim under guarantee. This type of Stirling engine at such small scale can barely derive enough mechanical power to keep its own flywheel spinning. Classic mechanically coupled ones, precision engineered, can, and ramping up the temp differential makes them go faster. But this design is "accidentally" half way towards a resonant engine, due to the fixed time of the displacer falling under gravity, which does not get quicker with greater differential. Check if the leakage is via the piston (soapy water). If not maybe one of the o-rings is bad? Hope you get it working, best wishes. But it's very marginal.
The hot water is never placed below the plate when the engine is running? What is the magnet doing if the atmospheric pressure and temp gradient cause the displacement?
the displacement is caused by the large black insulating foam. When the magnetic link breaks it falls to the bottom...swooshing the hot air around the cold plate...causing a slight vacuum/lowering of pressure. This can easily be a connecting rod link, but for whatever reason they chose to use a breakaway magnet.
@@claywest5322 i think the are saying using the magnet remove friction losses that would be caused by the connecting rod. and once the magnet is not too strong then its resistance when the working piston is moving away from displacement piston is negligible. I seen one in which they used a large magnet for the entire working piston and they use ferro fluid instead of a piston ring to make an air tight seal. No lie, the ferro fluid was a very smart idea
Thx😊😊😊😊😊😏😎😉 your so😎😎😎😎 means for awesome
I want to build one that is scaled up so that the flywheel is a pulley that can turn a small generator. What do I do to get that done. Please post a reply!
You are going to need a lot of lathe work, or maybe cnc, a lot of maths also.
A good place to beging is this:
ntrs.nasa.gov/api/citations/19830022057/downloads/19830022057.pdf
Also, this can give you an idea on how complex it can go:
th-cam.com/video/GqIapDKtvzc/w-d-xo.html
@@luckytrece4985 Oh I got that! What I want is the SIMPLE not the complex. If you can create motion you can create energy! That is simple inertia. The question is, scaliing up that simple thing above and seeing how big it has to be to get enough intertia into that flywheel that can be bled off to spin a generator.
That is where my engineering absolutely fails. I have no idea what to do or what the dimensions should be, particularly the size of the displace compared to the size of the cylinder it's in.
I am really trying to stick to "KISS" Keep It Simple Stupid. Complex usually first introduces a lot more crap that can go wrong.
@@andrewwinter7843 Well...
The dimensions of the displacer, piston, the tube itself, etc, have to be calculated with thermodynamic and mechanic equations, so, you have two options, search for an example with a similar size to what you need and try to replicate it, or go by test and failure wich can conduce to a lot of learning and a lot of work and expenses.
A Very good answer. Sadly I will be reduced to trial and error. I really would like to see if I can one to turn a 1 Kw generator. I have an idea for a heat source no one else talks about, Im going keep that idea close to the vest, lest it prove to be a collosal fail. I suck at being embarrassed
what material the displacer is made ?
The displacer is a sponge. it is very lightweight.
I'm qurious... what kind of energy this think can produce? Is it able to make 10W or so?
i'm curious too
This Stirling engine is for demonstration purposes only. There are other types that can actually produce usable energy.
This Stirling engine is for demonstration purposes only. There are other types that can actually produce usable energy.
Sorry but if the magnet attracts with the same force with which it pushes, what's the point of putting it?
It replaces a mechanical linkage and solves the phase angle problem (between piston and displacer) automatically
@@cslloyd1 Are you saying that the efficiency of the magnet is high compared to using mechanicals part?
@@nator1654 to be honest, I don’t grok Stirling engines well enough to make that call, but i have seen videos where people mention adjusting the relative timing of the displacer and the power piston. This eliminates that issue, for better or worse.
I have also seen videos where they discuss the ideal “Stirling cycle“ and using a sinusoidal direct linkage does not approximate that very well. Conversely, I think this magnetic mechanism allows for a “dwell” on one half of the cycle (I think the hot side, where it sits on the bottom for a period). I’m pretty sure that’s an improvement. On the other hand, this magnetic scheme depends on gravity for the displacement from cold to hot. This can be very limiting if the engine tries to run at higher speeds since air resistance makes the displacer movement slower than if there was a mechanical linkage pushing it back down.
In short, it’s quite complex and very difficult to say without experimentation. Someone needs to do a video about Stirling design and which parameters affect performance and efficiency.
مما يصنع القرص او المكبس الداخلى للمحرك..وشكرا.
The function of the piston is to move the wheel.
How much energy per hour?
@spikedpsycho
Thank you.
One teacup’s worth‼️🤪(Less the loss due to friction…)
If you turn the engine upside down you may be able to get sunlight to power the engine.
ytams1 that would be simple if you have a way of inverting gravity..... ;) . The magnets decouple when the air is hot and now needs to be cooled. The displacer will fall onto whichever plate is lower, so that's the one that needs to supply heat and the other one needs to lose it. You don't want the sun heating the top plate whichever way up you place the machine. Suggestion: keep the machine the way up shown here and arrange for a small shaving/makeup mirror (magnifying) to focus sunlight onto the bottom plate. That should work very well unless you make it so hot that the foam displacer melts!
@@raykent3211 Mine works fine upside down,I don't think gravity plays a significant part in the operation of these stirling engines. Its more to do with expansion and contraction of the gas ( air )
@@pinballrobbie very interesting, thanks. I was a bit cagey about the explanation offered at around 2:50 , that the magnets decouple and the displacer falls under its own weight, due to gravity. The displacer, even with the tiny magnet is light and has substantial air resistance. Too slow? Other designs can operate in any orientation, but I still can't see how this could. Is yours actually the same as this one? If so, is it very slow (maybe 120rpm) and can it run upside down on unfocused sunlight, as for example the conventional mechanically linked Kontax can? Ignore me if if I'm pestering, but I'm intrigued and would be grateful for any info. Thanks again for the response.
you dont show how the magnets work.
Hi Frenchie, As you can see in the video, there are two small magnets. One embedded in the center of the displacer, and the other attached to the bottom of the moving piston. At first the two magnets are together, but as the piston moves up, the two magnets separate far enough and can't hold the displacer at the top of the chamber...so the displacer falls to the bottom...and waits for the piston to come back down again and be so close that it will attract the displacer up to the top of the chamber again. - The magnets are set up in a way that the "south pole" of the piston magnet face the "north pole" of the magnet embedded in the displacer...In magnets, different poles attract (like north attracts south, and south attracts north)...but same poles repel each other (north repels north, and south repels south)...Hope this helps. STT :)
ScienceTubeToday This is an amazing design. Congratulations for being a genius.
It's cool, but not scalable unfortunately. Will always be just a toy.
a toy? not scalable? wrong twice!
@@JohnnyDeur it requires a magnet. Try and get a large magnet. Better not get it near any steel, youll never get it off. Just a toy.