Thermo Mechanical Generator for more cheap energy than the Rhombic Stirling engine to go off grid?
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- เผยแพร่เมื่อ 25 เม.ย. 2024
- In this video I show you the beginning of the investigation into which Stirling engine concept could become the successor to the Rhombic Stirling.
On my journey to generate some useful energy with different stirling engines I would like to try a different approach.
Which Stirling concept I will realize next is a decision that will cause a lot of work for a long time.
The Thermo Mechanical Generator is an ingenious vibrator Stirling engine with a diaphragm instead of a piston and a spring-mounted displacer.
Its unique design eliminates the fundamental problems with wear and friction with which I had great problems with my Stirling engines.
The TMG was developed to run for several years without maintenance in remote locations.
It would therefore be perfect as a micro cogeneration unit for domestic use to go off grid.
The TMG was invented in 1967 by a team led by E. H. Cooke-Yarborough at the Harwell laboratories in the United Kingdom.
It was intended as a very long life, electrical power source in remote areas.
Many of the advantages of the TMG sound very tempting and the unique design seems to be able to solve exactly the problems I have been struggling with for years.
My Stirling engines with kinematic gears are too complex and therefore too expensive and maintenance-intensive due to wear and friction.
The TMG also involves difficulties in design and production that I can hardly estimate and that could prove to be unsolvable.
At first I saw a lot of potential in the uniquely elegant concept for my next big generator project.
But the more I have looked into it, the more my doubts have grown as there are many complexities.
What do you think of the TMG, please let me know and write your opinion in the comments.
Thank you very much for your attention.
Thank you so much for the fantastic TMG artwork from my wonderful daughter Anna
Many thanks to @barumman for the photos of his TMG, please visit his channel with many fantastic engines
Thanks for the background music:
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I would love to see a TMG, Great work! :)
Thanks
Kudos to you on your fabrication skills and persistence, you have my respect. I have been studying and contemplating my own design for years now and will say, my vote is for the TMG. It solves too many difficult problems of the other designs to be dismissed for the difficulties of design and fabrication. NASA has already demonstrated one running continuously now for over a decade. It looks to be the most reliable and does not necessitate high mechanical tolerance fit on the high temperature components, a critically important consideration I think. Since you would be using in a stationary setting, compactness and high pressure is not as important as would be for a car. To fabricate the diaphragm, I would suggest hydro-forming. Good luck! I wait eagerly to watch your progress.
Thanks for your kind comment.
The TMG is really nice, I have problems with its big diameter, low power and its difficult balancing of the forces.
Thank you for your honest and impressive attempts for power generation - I have no answers that might help :-( my mind however has been very stimulated and motivated by your experiments and constructions. I really do appreciate your dedication and practical approach - please keep up the good work.
Thanks for your nice comment!
Good presentation and explanation of your reasoning pro´s and con´s. Now do the next thing and then the next until you got about 5 concepts or so and create a combination matrix where you choose the design. Don´t forget a stilring engine is not the only viable way. You can use turbines or steam engines instead as well. They too have little moving parts are multi fuel capable, efficient and can be produced at home or you 3D print some metal parts, 150 bucks or so but this way it can be way more efficient with inner cooling geometries and you don´t even need to make the thing yourself. Oh and don´t forget the simpler designs as well which are lower tech like a 4 cylinder stirling without any need for displacers because it has double working pistons for instance. This way your powrt output can increase, you don´t need complex manufacturing and you didn´t need 4 main components. All in all the TMG is a good idea however it needs more than one person to work on the design and solve some issues first. The idea is tempting but it´s not really much more efficient than other designs and it is complex in it´s control and manufacturing. I would place it on that decision matrix and go on with other ideas. =)
Thanks for your good thoughts as always....
What you write is exactly what I want to do with some extra suggestions from you.
I want to take a lot of time now and examine the various concepts in order to decide on one and then concentrate fully on it.
I would like to use the youtube swarm intelligence to do this, as you get a lot more ideas, suggestions and solutions than if you just think about one thing yourself.
Thats the main reason for me to make these videos besides the fun.
Thanks a lot for your ideas !!
@@myengines2443 "...I want to take a lot of time now and examine the various concepts in order to decide on one and then concentrate fully on it...." This really is great. You did such a great job with the original design. I can´t wait to see what you will come up with.
"... would like to use the youtube swarm intelligence..." This is a great idea. There are a lot very smart people here.
Where I am, I use a wood furnace and have a water spring going at all time. These engines look very sexy to me... great work!
Thanks!
Great video
Thanks!
I am still enamored with thermoacoustic generation. Heat flow forces a loud sound, which pushes a speaker coil. All the difficulty is then focused on the resonance block (i think its properly called a matrix) that slows down the pressure waves long enough to gather thermal energy.
That difficulty is broken down into two parts:
1) How do you manufacture it?
2) Where in the resonance tube do place it for optimal effect?
There are plenty of approaches to dealing with this difficulty. None of them are perfect.
Regardless, this is my answer to the question.
Thanks for your nice suggestions.
The thermoacoustic engines (standing and traveling wave) are the subject of my next video I think...
I think it would be awesome and viable, flux switching is relatively easy compared to what you normally do. I’d be glad to offer advice, I build generators all the time!
That sounds nice!
Thanks for your support!
Interesting mechanism...
Yes it really is, but the problems with it...
A recent 'volute spring displacer' video from another channel (re)peaked my interest in stirling engines. They are suggesting that this displace has natural resonance, and it is stimulated with electro-magnet/voice-coil.
Interesting as with CPU control the timing vs piston would be variable/adjustable to hit peak performance. Spring could then be re-manufacture for the optimium resonance.
Sounds very interesting but also quite complicate.
Thanks for your suggestions!
Maybe a double piston/diaphragm controlled by voice coils and a microcontroller would work?
@@RingingResonance that's exactly what I have in mind. And to 'fold' the layout so that it's either side of a rocket stove ...
The longevity of this design is such that you could maybe simplify the design and manufacture of the diaphragm to something that has less longevity but still very worth doing.
Yes, that might be a option for experimenting, thanks.
It made me wonder if you might use a linear alternator idea on the stirling engine, with flexure springs, or bearings, controlling the vertical stroke/ restoring force on the "exhaust stroke', instead of converting to rotation...magnets and motor/generator design has improved a lot in the last decade, and it might just be possible to use a "linear motor" design as the generator with the stirling piston/cyclinder arangement?
Yes, this is made in the "conventional" free piston Stirling which I want to investigate in detail soon as possible candidate 3 or 4!
Very good information. Have you looked at free piston linear sterling engines?
Thanks for your praise!
The free piston Stirling engines will be in the focus of my interest in the next weeks!
and do remember, a stirling engine/generator should only be 1 part of a multi-part energy system, so if you create Nikola Tesla's steam turbine connected to a generator, then use the hot steam from the turbine exhaust to run a stirling generator, then after all the steam is condensed back into water, you could potentially use a hydro generator to extract the last bit of energy from the system.
Yes "waste" heat is a precious resource.
I want to use it to heat the home (cogeneration unit) in winter and in summer the solar energy is usually enough.
If not, your idea comes into play.
Thanks
NASA builds similar nuclear powered thermal generators for satellite power. Sterling coolers are a common use case with a flexible diaphragm and leaf spring.
For making spring designs more easily you might try CNC cut sheet metal. Because sheet metal is so easy to cut a smaller diy cutter would work good enough.
It sounds to me like it's time to learn a new skill set and build some new tooling! How exciting!
You mean a laser or water jet cutter?
I already have a good diy "Deckel FP0" milling machine which could also do this job as you can see in my older videos.
My diy pulse EDM would also be very good for this...
barumman has milled his springs.
Thanks for your suggestions!
Wait...space is a vacuum, but stirlings require air...or gas...
what gas?
@@Iowa599 Stirling machines are closed working gas engines - the gas inside is what you bring along in them into space. Although, you have to count on gas escaping the system over time, at some rate.
@@salec7592 yeah, I know, but what gas are they filled with?
r134a?
I have seen ca 1998 a tmg at Neuhausen/Switzerland in a development lab of the company SIG that was said to generate 1kw at resonating 50hz. If remember right it was not big in diameter but maybe 3 to 4 times longer.
It was intended as a home chp. I saw it running. As fare as I remember development was stopped as the local power station company didn't like the idea a asked crazy price for the meter (return power to the grid). It's a pity but I can't help you further on with any contacts..
Was it really a TMG or a free piston Stirling engine with conventional piston and displacer?
I think I heard about it but can't remember and can't find any information about it.
Thanks for your hint it would be nice if you could tell more about it...
@@myengines2443
Sorry, it was just a short visit with the aim to eventually supply them with a measure and control system.. I believe they had a normal spring under a piston, resonating with the grid frequency. I think it was a well balanced bug not complex machine. Was only a short visit and soon after the project was canceled as it was non economical to sell energy to the grid. Also I think it was technically working. Sorry but that's all I remember. Looking forward to see if you can get something working. Mike
@@michaeleitel7186 Thanks a lot for your information!
Aneroid (barometer) boxes expand and contract depending on difference between inner and atmospheric pressure. They are basically two diaphragms and a rim holding them together.
I have to look at them if some principle can be adapted to the TMG, thanks!
The spring mechanism, a flexure, appears to be amenable to some more rigorous design, and might be easily cut by laser, or water jet ... the larger diameter might even be cut with plasma...
Isn't the 1 kw Microgen Stirling Engine that's been in production for years now a TMG? They must have overcome a lot of the disadvantages you mentioned in order to be mass produced.
I think its a free piston Stirling wit "conventional" piston and displacer which has even more problems with wear, friction ad piston/displacer alignment.
It would be interesting to test the performance of a thermo-acoustic or liquid piston engine pushing and pulling a magnet through a coil.
Instead of just burning your wood you can use a wood gasifier with an of-the-shelf ICE generator + exhaust heat exchanger to produce heat and electricity.
I will investigate other Stirlings like the thermo acoustics in the next weeks, look out for new videos!
My main fuel will be self produce biogas (look at my diy digester-video) but only when I need too much energy (in winter) I want to use wood and maybe woodgas.
I want to try to avoid the use of an ICE but if I fail with my attempts I have to...
Thanks for your help
In diaphragm the g is silent, idk why
if it is 90% efficient, if the hot side was heated by the sun, with a big mirror/collector, and the ground to cool the cold side, how would the efficiency of mechanical compare to solar in efficiency genereting electricity?
I think photovoltaic cant be beaten, I want to use it as a backup of my solar plant when the sun is not shining.
(we have a long and dark winter here in Germany!)
Thanks for your thoughts!
Sorry for the misspelling, its a hard word for germans!
@@myengines2443 I think your analysis is correct, this is not a start from scratch do-it-yourself project. The design has already been done and the knowledge of the HoMach design must be somewhere. To work as micro CHP this must be produced as a white good, like a refrigerator.
The advantage of Stirling engines is that they can utilise a poor fuel, like wood, refined fuels like natural gas, propane or diesel for micro CHP are better converted by an internal combustion engine.
My Solar PV supplied me with excess electricity 237 days this last year and I only need to generate electricity on average 5kWh a day for the other 128 days. In these days of LiPo batteries that only requires a generator run time of a couple of hours a day.
My wish would be for a woodfired TMG running constantly outputting 300W with the cold side heat running underfloor at
Stirling engines are more efficient than solar cells. The efficiency of photovoltaic cells ranges between ( 18 % - 26 % ), but the efficiency of Stirling engines is much higher, reaching about ( 51 % ), with the possibility of being more than that. Also, any fuel can be used on Stirling engines. Including sunlight, it can be of multiple uses and is not limited to “ generating electricity ” as mechanical energy can be used directly without converting to electricity. Moreover, it is more reliable and more durable.
The TMG has low losses and should therefore have good efficiency, and complex mathematics are much easier today with the help of computers. Springs don't need to be build from spring steel and membranes need no copperbronce, you may use stainless steel. I think the main construction decision is the displacer, withstanding temperature changes, vibration, and mediating the temperatures. Multiple experiments may be neccessary.
I am not sure about the low losses of the TMG.
The number of multiple experiments is what makes me doubt.
Its very frustrating if you can't get an engine to run.
I thought the displacer is a simple standard part in comparison to the complex balancing of the springs/diaphragm/linear alternator forces.
What do you mean with the displacer problem?
Thanks for your helpful comment!
@@myengines2443 The displacer is the cruical part in a stirling. What the regenerator is in an alpha stirling configuration must be acconplished by the displacer here. So the displacer has to have a thermal mass and better is not circumvented by the air but the air should pass thru it to be cooled/heated while passing from one side to the other, kind of a sponge.
If the TMG will not start, it should be possible to excite it by applying AC to the coils. If the spring does not match the pendulum weight of the displacer, it should be possible to dampen it by applying a load to the coils.
The flat plate springs could be modernized rather that using the design that is here, you should be able to copy the sunpower Stirling plate spring design, multiple thin spring plates could be stacked and added and removed experimentally to determine the correct rate, then you wont have to make multiple hard to machine thick ones and they can just be water jet cut, inexpensively.
Silicone rubber is a lot more temperature resistant and probably wouldn't need water cooling at all, it might be possible to even mould one from something like flue sealant and a 3d printed pattern.
Thanks a lot for your suggestions.
Do you mean the Sunpower spring which is formed like a spiral?
Trying multiple layers is a great idea for experimenting!
I also thought of and used silicone rubber on my Stirling engines, its a very good and easy to use material.
Greetings
@@myengines2443 Yes, i imagine they are fairly well optimized by now, I also noticed that there are two sets to hold the shaft central, you could probably take a screen shot of one of the springs upload it into CAD.
Did you think about converting the rhombic drive one you have to free piston? you could use a car subwoofer coil and magnet or something similar as a generator.
@@ChrisDay-sx4lv yes, that are some good suggestions, thank you.
I think to match my needs I have to manufacture everything from bar stock as I always do.
It is much more work but then everything can be made as designed and you don't have to make any compromises.
Please aim for 1 kilowatt from unlimited 90C water. Organic rankine cycle might work better in all parameters thanks to phase change working fluid. I like the linear motor design. What about going strong, long and slow instead of fast short weak ?
An engine with 1 kilowatt from 90C water has to be very large like the sunpulse.
It is an interesting concept but not my type of engine.
A larger stroke needs a conventional piston/displacer with the problems I had with the rhombic but we will see whats next...
@@myengines2443 I think he meant an engine similair to a steam engine but then closed loop. That will run on pressure difference. You can use a vane pump or even better a scroll pump as an engine. De AC pump of Toyota Prius: DENSO HFC134A Klimakompressor has a scroll pump an can be used as engine, you can maybe even use the build in motor coil as a generator!
As working fluid you can use Butane/propane which you heat/cool with an external heat exchanger ;-)
It seems the fine balance of either solution, whether in tuned diaphragms/mass or sealing surfaces, is going to take a great deal of effort. Perhaps some form of low friction low tension PTFE piston rings mixed with tight tolerances, minimal thermal expansion, and labyrinth-style sealing? I do not think there is an elegantly simple (in both design and implementation) solution at this point. Multiple stirling fan like devices linked together (mechanically or electrically)?
Unfortunately I think that you are right....
The little Stirling fans have a power of only a few watts so I would need many.
I also think they are not very durable when they have to run 24/7.
Thanks for your suggestions
Nice idea! But how about double acting gamma? You can find it at the Jim Symanski’s engine
I know this engine and it is nice.
Now I would like to try something other than a kinematic engine because I want to reach a durability of several thousand hours of unmaintained operation for domestic use!
Thanks for your suggestion I will look at his engine again!
Have you explored the rotary designed stirling engines? They are much simpler to build, I haven’t seen anyone seriously attempt to scale one such design up.
Yes I saw some designs but never heard of a running one.
Its an interesting concept but that there isn't any functional one may have its reason...
Your idea comes on my list and many thanks for that!!
@@myengines2443 Mdevink here on TH-cam has a few small LTD toy models which work fine. But yeah. Would be interesting to research whether they can be scaled up. 🤗
Anyway. Love your work. :)
NASA did a lot of research into and made a free piston stirling engine, maybe see if you can find some information about that for inspiration.
Yes, I did a lot of investigation in old NASA documents...
In the next weeks I will look there even more as they did a lot of research in the field of the free piston Stirling which will be one of my next topics...
Thanks
A closed cycle turbine has a slightly lower efficiency than a Stirling engine but a conventional rotating generator can be used and it has only bearings connecting moving parts to static parts
Thanks for your suggestion, I will inform myself of the closed cycle turbine.
Does it run with steam or gas?
*closed cycle gas turbine
It has external combustion with an heat exchanger and a working fluid such as nitrogen, hydrogen or helium just as a stirling engine. They are used as efficiency boosters on power-plants so information is easy to find
Magnetic bearings or even air bearings have practically zero wear or losses.
Thats a good suggestion but i can't find any real closed gas turbine system working, do you know any examples? or its more of a teorical thing?
They are used in power plants as a second second stage. Search for two stage gas turbine power plants
Wasn't aware of Whispergen's actual configuration. Downloaded several NASA papers many years ago. They had some very good efficiencies', but needed close tolerances and somewhat exotic materials. 60-100 Watts output, if I recall correctly. Intended for satellite use.
I think the Whispergen is a "conventional" free piston engine which is very high tech and has a lot of the problems I am dealing with my Stirlings.
But thanks for you suggestion
Beryllium copper is not *that* exotic. I see it available on Amazon? And it may be optimal but not strictly necessary.
The low power output for the 1967 engine design is likely due to low working gas pressure. You may be able to run higher pressures to increase the output.
I see a lot of parts in the design that could be made by spin forming sheet metal. That won’t increase the diameter limit of your lathe, but you might be able to adapt a milling machine to spin form a large part.
I’ve researched Stirling engines for years and concluded that a diaphragm based system was the only practical way forward. For a small, DIY engine the sliding friction in the displacer was too difficult to overcome and a diaphragm fixes that. Please give it a go!
Beryllium copper is not so easy to form because of its spring property why its chosen for.
Higher pressure may be a solution when you put a tight cover over the diaphragm so that the pressure difference is not too high.
But I think there is a reason why Harwell and also HoMach both worked with very low pressures.
This is really an interesting topic which has to be explored!
If someone knows more about pressurization a TMG it would be very nice to get some information!
@@myengines2443 Is you chose to work with Beryllium please be very careful. It is highly carcinogenic. Grinding dust is very hazardous. A gear manufacturer I used to work for, turned downed work that contained Beryllium.
Ich würde mich über eine Webseite freuen auf der man die Texte nachlesen kann und ein paar Fotos von dem Projekt zu sehen sind. Sehr gut gemacht. Ich freue mich schon auf das nächste Video
Danke für deinen netten Kommentar.
Leider ist das Videodrehen schon so viel Arbeit, dass ich für eine Webseite wohl keine Zeit finde.
Have you seen the "Inresol" sterling engine they were making in.... Sweden I think, a few years ago? Could run on anything and was quite literally the most impressive sterling I ever saw. Company went out of business it looks like though. Website down and only a few videos on TH-cam you can still see.
When you think they were impressive plz look at the work of philips...
@@myengines2443 Will do thx
Have you ever looked into an organic Rankine cycle? I'm guessing the same concept could also be applied to a reciprocating engine.
I will look at it, many thanks
You can try to combine 2 engines one against horizontally other to move one magnetic part, so power would be doubled. Also, original magnetic part with the use of neodymium magnets would much more efficient, you wouldn’t need to move upward heavy magnets every time.
Ok, I have to think abut this.
Its always nice to have the heaters in a multi cylinder engine as close to each other as possible to make it easier but if the advantages outweigh the disadvantages perhaps.
Thanks for your suggestions
seems the use of the watts linkage can really reduce side friiction and wear on the pistons. I would love a CHP in 1kw range
Looks interesting.
The reason why I use the complex rhombic drive is exactly that I want to reduce side friction and wear on the pistons.
Thanks for your help!
@@myengines2443 let us know about further improvements
What about the Alfa stirling or the free piston generator?
Both concepts I will investigate in the next weeks.
Thanks
Hmm, thats rather interesting.
Thanks!
I really think you are on to something. Stirling engines should be able to reach much higher efficiency due to less wasted energy, plus the option of energy recovery. I think to maximize efficiency, you need to split the energy input and working fluid from the generator to gain efficiency from something like supercritical CO2. Internal combustion engines lose over 15% efficiency from exhaust heat alone. In a sterling engine, there are mainly 3 sources of recoverable energy. 1. Waste heat in "boiler" or combustion chamber walls + exhaust. 2. Working fluid post expansion cycle radiator 3. Working fluid, post compression. This recovery can be done using fuel to raise combustion efficiency/temperature, or pre-heating working fluid.
For your current problems:
You can produce your springs by electrochemical etching with little more than a printer and a battery. DIY pulse jet engine leaf spring valves have been made this way for many years. Another option is PCB resist foils or printing a stencil, cutting it out, and using spray paint to cover the parts you want to protect. Then you submerge in salt water and connect a battery.
An option for producing diaphragms is to use a set of toroidal rings to press a wave pattern into a thin sheet of metal, in a mix of stretching and shaping of the metal. The "corrugations" in addition to the stretching give the metal the 360 degree flex and are commonly made from stainless steel.
If you find that increased magnet travel is more efficient than force in the electrical transformer, you could try a lever to trade one for the other.
I think Ideally you would want an opposed piston design and either avoiding the diaphragm through harmonic balancing of 2 springs, or a free piston design replacing the spring.
Thanks for your many suggestions, I will investigate them!
Grind the edges if you chem etch leaf springs. Need to remove rough edges for high cycle fatigue
I would like to see a design that uses the sterling engine to make use of the waste heat from fridges, hvac system, washer and dryer, and ovens etc. A design of the house might need to be altered to make use of this efficiently like all those machines are close to each other in a stack connected via tubes to the sterling engine.
For the relatively small (except ovens) temperature difference you would need a LTD Stirling which has very little output and may only be reasonable if the amout of waste heat is very large
hmm. I would think a household waste incinerator with something like this atop could be way better source of heat.
Yes, burn plastic. reburn, reburn, reburn. extract extract. turn turn. sinewave come. vapour vapour. converted later.
Might be able to use nitinol foil for the membranes? Not cheap, but super-elastic and limitless cycle life.
Thanks for the hint, I will check this!!
@@myengines2443 in terms of the complex math involved with the spring resonance, etc. It's certainly the case that at the time it was a complex affair, but modern software has made it a lot more accessible; I wish I knew an applied mathematician as they'd be able to point me in the right way. As for the spring... They're commonly manufactured in a wide variety of materials and called flextures. I'm sure one of those companies would have a service available to make them to order
Check out Robert Murray. He has a cheap and easy sterling like the one developed at nasa
Thanks, I will look at his channel
Why not 3D print the diaphragm in TPU and laser cut the spring steel?
I think his technology and development is way past that.
Laser cutting the spring steel is an option when I have problems with milling or eroding it.
But 3D printed TPU diaphragms would not be durable enough, look at my older video of the durability of 3D printed parts.
Thanks for your thoughts!
How about 3d printing laminated materials? For example: first layer be printed from PC, then second layer from TPU, then third layer from. PC and so on. Prusa 4 can do that.
Also, for heat resistance, you could integrate cooling channels into the 3d print and use a cold gas or perhaps a liquid to cool the elastic assembly in order to maintain its strength during operation.
Also, for the diafragm you can try a wire mesh formed by pressing it into a 3d printed 2 part mold, then inject high heat resistant silicone in the mold to make a sealed membrane.
I was looking at NASA's free piston Stirling engine and came to the same conclusion: how the hell do I design the springs? I was thinking of replacing them, at least at the design stage, with linear actuators (i.e., controlling the alternator and adding an alternator to the displacer) and using a digital feedback loop to find the optimal regenerative forces. But I tend to fix everything with software, so what the hell do I know?
Yes its complicated...
Honestly, a great concept. But each design has its benefits and advantages. Stirling engines are efficient, long-lasting, reliable, and durable engines. It is not a good idea to limit their use to generating electricity. Using mechanical energy directly without conversion has its applications, and large displacement generates more energy.
1:35
It is not correct to say without " mechanical drive " Because everything is mechanical, but it is correct say, without " physical/visible material drive ".
Also, the gears system ( the mechanical system in general ) is a very simple, reliable, efficient system and not complicated ! You can also simply use appropriate materials or use cushioning to reduce the impact of various forces, thus greatly reducing “ friction and wear.”
Note: less electronics and electrical circuits, means a simpler, more reliable, more efficient, and durable system.
Yes you are right with many things as you can see with the electronics problems we often have with modern cars.
But the electrics in an liner alternator is not vulnerable and very durable I would say.
Thanks for your suggestions
Is your sterling engine not oil lubricated? If not, then why not?
It has to run dry because any oil would contaminate the heat exchangers, especially the regenerator which is made of very fine wire screens.
That causes a lot of problems and makes things much more complicate...
@@myengines2443 Is it possible to use dry lubrication such as powders? Or will this have the same problem perhaps.
Wouldn't a opposed piston give it more torque
Opposite piston kinematics has rarely been done because it is quite impractical as far as I know, but thanks for the tip
TMG is the future. Look at NASA's free piston stirling. Its small tube that generates 1-3kW with 2 moving parts. (Membrane is a dead end. No friction piston on 2D spring only).
I will make it experimentaly with arduino and fotooptor (for positioning) and some coils to push displacer magneticly. Extremly dificult to sync but possibly can be done.
NASA built also a TMG?
Or do you mean their Free piston Stirlings?
@@myengines2443 free piston. You should consider amount of work that You will use at another rombic stirling vs free piston. Ive already cutted 2D springs. Its not so hard.
You need non contact sensor arduino and some coils to push displacer in right moment. Consider it well becouse Your time is priceless. ❤️
This generator reminds me about Nikola Tesla's Reciprocating engine: US514,169 - Reciprocating Engine, February 6, 1894 Clearly the principle is not of a moving fluid, but the similarities are quite obvious.
Nikola Tesla is always interesting, I will look out for his engine.
Thanks
These engines work better when when the gas used to move the pistons is lighter, like helium. Encapsulating these parts in a chamber of helium greatly increases it's output. Not sure if or how this would help you, but i figured sharing this here wouldn't be a waste of time.
Yes I made a few experiments with helium and have a big bottle of helium here in my workshop.
Thanks for your suggestion!
Maybe try this type of engine V4-275R Stirling engine
Maybe a low tech multicylinder configuration will be possible, I will put this on my list...
Thanks
i think there are simpler linear sterling engine designs with the same advantages. you should pursue those instead. NASA had a paper on one a number of years back. I don't think it had any diaphragms.
I think you mean the Free Piston Stirling engines, this is the subject of my next video, thanks.
Jumping rotor thats spinning with dual springs pushing down, old clock makers have design to make self running motor
I am not sure what you mean but I will inform myself, thanks
I think your rhombic drive needs an oil system. Maybe even try different working gasses like refrigerants in combination of PAG oil. Build it more like a heat-pump system. They have many moving parts with lots of friction and still last a long time. Fully hermetically sealed and closed loop oil system. Build it larger so that you can get similar useful energy but with lower temperatures.
Unfortunately it has to run dry because of the heat exchangers what causes a lot of problems...
I tried helium but have to make more experiments...
Thanks for your comment!
I think that the problem of friction is exaggerated, especially if appropriate bearings are used at each joint. This is the most important goal of bearings, which is to make the thing move freely, and the choice of materials and design of the mechanisms also plays a role.
@@myengines2443 What kind of problems? A thin oil that's dissolved into the working gas might be fine.
@@myengines2443 Why should oil be a problem? Your supposed to oil the crank case and piston, not the heat exchanger! 😂
Put some thin oil in it, some oil scrapers on the piston, and pump that sucker up with a view atmospheres of helium!
Dia-fragum?
Yes, I know.... its a hard word for a german
Is that a sex thing?
Maybe you could just retrofit a small gasoline engine with a specialized carburetor that improves fuel efficiency drastically
Do you mean to use my biogas?
weisst du wie die WhisperGen Stirlinggeneratoren aufgebaut waren? hast du schon mal überlegt den Viebach Stirling nachzubauen? ev. würde ich auch mal einen blick in die patente von frauscher.motors lohnen?
Von den Frauscher Motoren habe ich noch nicht so viele Infos, muss ich nachholen danke.
Der Rhombenstirling ist dem Viebach Stirling recht ähnlich und ich habe die Zeichnungen damals gekauft, Grüße an Michael...
Über die free piston Stirlings ala Whispergen kümmere ich mich bald intensiv...
Danke für deine Hilfe
Are you aware of Whispergen ? Sounds like you are duplicating what they sell.
I think the Whispergen is a "conventional" free piston engine and its quite high tech.
I want to discover the other direction and want to go to more low tech.
@@myengines2443 Whispergen used four alpha-configuration Stirling engines and a wobble yoke or swash plate (I forget which); their solution was not the same as a free piston Stirling engine. If you do a search for images of their engine, you'll see the mechanical system they used. Free piston systems don't have mechanical linkages governing the motion of the moving parts.
Whispergen 's engine wasn't a free piston based system. An image search of their engine shows that they used a "wobble yoke" to control the movement of four pistons in a double-acting alpha configuration.
@@Berkana yes you are right, sorry I confused it with an other engine.
But it is also very high tech and expensive.
FYI the 'g' in 'diaphragm' is silent, at least in modern English. It is pronounced "diafram".
Thanks, its a hard word for a german...
@@myengines2443 No worries. Americans can't pronounce German words like "impfpflicht", "rechtsschwengkung" and "eichhörnchen".
dai·uh·fram ... not diafragm
Thanks, I am always happy to learn!
dai·uh·fram dai·uh·fram dai·uh·fram hope I don't forget, its a hard word for a german...
@@myengines2443 Du lernst es noch =)
hehe@@sierraecho884
skip the free piston calculations and use a mechanical linkage, combine the good points of both, you may need to stretch your manufacturing knowledge a bit to come up with a efficient new design, separating the power piston from the displacer volume is foolish in the Harwell design, I would start with an existing efficient linear generator and work my calculations from that so you get the output you want in the first place, your mechanically linked rhombic drive will never compete with a Harwell style of generator it just has too many friction points, I will think some more on this, putting heat in one end and getting electricity out the other end efficiently has some appeal to me
Yes, thats also my thinking...
If the appropriate bearings were used for each point, friction would be negligible !
Contact Ken Wheeler
Why not just skip ahead to a micro steam turbine? only a handful of moving parts.
Don't know either, with such little power output, it doesn't even seem that efficient in either space or power density
Maybe I could imagine a gas turbine to run on my biogas, but isn't producing that much steam dangerous and expensive?
Actually the invention of the Stirling engine was intended to prevent boiler explosions.
@@myengines2443 this youtube video th-cam.com/video/AYydc43FGBU/w-d-xo.html
shows a way to make a boiler that really can't "explode" and is "cheap" and easy to make. (Stainless steel brake line is kinda pricey, but seems ideal for the app) pair that "boiler" with a tiny turbine.. As far as "expensive" idk... this tiny coil boiler seems really efficient, and feeding a small turbine may not take as much fuel as you imagine.
@@myengines2443 Yep, by Rev Robert Stirling if I remember right. A man of god and science.
Thanks for your information, I will inform myself about it and think about it!
The bigger one generates only 150W? That's hardly worth the effort. This one th-cam.com/video/adLZIDxM8tQ/w-d-xo.html seems similar design but it's 1kW
Yes you are right, 150 watts is really to less.
But maybe with higher pressure a bit more is possible.
300 watts constantly produced would be enough for me.
The engine you linked is a free piston Stirling with which I think I would have bigger problems with wear and friction than with the Rhombic.
Piston/displacer alignment and control is really an issue here but I will inform myself about them intensively soon.
Thanks for your suggestions!
I guess it depends on how you qualify. For me I am interested in boosting solar shortfall in winter, for an off-grid home.
150W running 24/7 would be ~3kW.hr per day, which is around 50% of our daily usage...
Too complex for home (diy) production.
Yes I also think so...
Funny that you failed but the British navy used them in subs as a quiet engine for decades. So… I think it’s just you.
thats a terrible design for the generator...
it is tricky to design.
you have a given stroke. yay.
magnetic fields want to flow as loops in iron cores. gaps create reluctance, leakage, and limit the power. you want the smallest air gap possible. the stroke length limits the overlap and width of cores and coils, the flux one can carry in a given lump of iron, and the coil size one can wind on that iron. all this data is pretty standard material, gathered over years. available if you look into winding transformers or motors...
i spent a bit of time playing with teslas oscillator, always mean to return to the bits in a box and finish it, lol...
you use a magnetic piston. or electromagnetic, in teslas case. visualise the flux as forming a small toroid around it. so you have two pole pieces in the form of a C either side, coil wound in the middle of the C. now the flux flows through the Ccores.
with the piston central, all its magnetic flux flows through the C cores. cuts the coil mounted on the C-core. creates EMF... (when moving...!)
with the piston at either extremity, the pole piece of the Core has to be wide enough to short the magnetic field of the piston. the flux flowing simply through the end of the Core, not the coil. no EMF.
why? as the piston changes from mid stroke to the end and back, the area of iron overlapping, that is, the circuit through which the magnetic flux flows, ideally has to remain constant. you dont want an air gap that is changing as it affects the power flow, the coupling of the magnetic circuits. it also reduces cogging as the attraction of the magnet to iron is "constant" through the stroke. ideally the piston should sit in the coil anywhere. the only forces it experiences are once its moving and a current is induced in the coil.
you need the magnetic field of the piston to make as efficient a coupling as possible, with as much change of the magnetic field as possible, to make it work.
another issue is that the magnetic field always flows through the cores in the same direction, and they tend to magnetise... need very soft iron with very little remnance. and it halves the amount of change you can get... rather than full flux one way to full flux the other way. it technically doesnt even produce true AC... sinuously pulsed DC?
so yeah... theres a relationship between stroke length, the length of the piston, and the dimensions of the pole pieces and coils to make a generator that can make use of the power in the free piston...
Thanks for your extensive detailed help!
I have to think about it and investigate the information.
Many thanks!
Heat engines are pointless in a renewables world , why not start investigating long term storage . Maybe a closed cycle liquid gas system for example ?
I don't think so, as long as the long term storage problem is not solved you have to convert biogas and other sources into electricity.
And experimenting with this topic is not my thing.
You're confusing heat engines with combustion engines. All combustion engines are heat engines, but not all heat engines are combustion engines.
@@ElijahDecker sorry maybe i should been more explicit , but it seems that making electricity from any temperature differences is very inefficient , but pressure difference like from liquefied gas to gas at atmospheric pressure might be more productive , then use excess electricity to re liquefy that gas at times of abundance . A closed cycle so even noxious gasses could be used in the process .
@@myengines2443 meaning like the liquid air battery being experimented with at the moment .
@@JohnSmith-sz4gv do you know something about the approximate efficiency of this technique?
You should consider abandoning these very inefficient engine and concentrate on internal combustion engines.
There are so many IC engines out there to choose from.
But then I will get other problems when using my "dirty" fuels biogas and woodgas in micro IC generators!