Stirling engine development for cogeneration of cheap DIY energy to become off grid and independent

Here I show you my way to get more power out of the Rhombic Stirling engine and improve its reliability and durability.
With various measures such as optimizing the running surfaces with the piston rings and the roller bearings of the rhombic drive, I am trying to make the Stirling engine capable of continuous operation.
In this way, we can use it to support our electricity generation and cover our electricity needs in the most climate-neutral way possible and become independent self-suppliers.
This was followed by extensive test runs to optimize the balance between friction and sealing of the piston running surfaces.
During these test runs, I once again realized the immense importance of friction in the Stirling engine.
The relatively small friction differences in my test series resulted in power differences of almost 300 watts.
There is a huge potential in the correct design of the running surface pairing which I still have to exploit.
The Stirling engine delivers very little power per cycle as only a small proportion of the working gas is involved in the complete Stirling process, in contrast to the combustion engine where almost all of the working gas passes through the entire cycle.
A little too much contact pressure on the piston rings and the Stirling will only run with very little power.
As it would take too long to develop the system ready for use, I now want to investigate the potential of various alternative Stirling concepts such as the Thermo Mechanical Generator, Thermoacoustic engine, Thermal Lag engine or another Free Piston Stirling concept.
I would be very happy to hear your experiences and suggestions about alternative Stirling engines
Thanks for your interest
Thanks for the background music:
Song: Jim Yosef - Eclipse [NCS Release]
Music provided by NoCopyrightSounds
Free Download/Stream: ncs.io/eclispe Watch: • Jim Yosef - Eclipse | House | NCS

[@mikenorfleet2235]

The Stirling engine has been well studied by engineers engine enthusiasts, but take it from NASA that the most efficient Stirling configuration is in the free-piston variety, if you have the stomach for the complicated power electronics that come along with it. Converting linear motion of the springs into usable power is harder than spinning configurations that are easy to slap a generator on and get useable electric power. Also Stirling is used heavily in the cryogenics industry check out some of their designs.

[@myengines2443]

Yes, a linear alternator for generating electricity is not as easy as a conventional rotary generator. But I read of efficiencies also in the region of 90 % if done well. (Harwell) Unfortunately I found very little information about them. Thanks for your comment

[@AttilaBlade]

@@myengines2443 Hi there, I suggest to you to hack a tear dropped LG linear reciprocating fridge compressor for your free piston project in the future, because that is cheap, but the engineers patented that as a high efficiency linear technology inside that (on the base of the SUNPOWER linear motor). I opened few pieces and I saw that technically possible to change the piston and valve combined central-parts to your piston with low friction. There works super strong flat Neodymium magnets inside.

[@myengines2443]

@@AttilaBlade thanks a lot for this hint, I will inform myself about that and give it a try. By the way many thanks for your great videos on your channel I am watching a lot at the moment deciding which alternative Stirling concept I will choose for the next engine! Please go on making videos your content is great!

[@AttilaBlade]

@@myengines2443 Thank you! If you send me an email, I'll send back few disassembling pictures about that and few pdf files if you want. Just to reduce the searching time. BLADE sps.: I want to make new contents, but my job is so busy now, and new workshop isn't ready to it. I feel my head will blows up if I can't start the experiments ASAP. Lot's of idea grows inside. Thanks, anyway!

[@myengines2443]

@@AttilaBlade sorry for your difficulties in the past I heard about that and hopefully you can start experimenting again soon! The Stirling community needs you! I would be very nice and kind of you if you could send me information about the linear components. My email is [e-mail] Nice to hear of you!

[@Trebseig]

I absolutely love the quality of your work! Please never stop working on the stirling engine. I say the world needs it: a high quality, low/mid power stirling engine to drive an electric generator. Ok I have one wild suggestion, something I have wanted to do myself for ever (but I don see when I wil lbe able to): a turbine version! Not sure if we can call it a stirling, but it is the same principle. Normal turbines, or Tesla tubine maybe, whatever works best.

[@ntesla66]

I agree with everything you said!

[@myengines2443]

Thanks for your kind comment! It would be nice if you could explain your suggestion in detail! Greetings

[@Trebseig]

@@myengines2443 Shall I explain here or by email?

[@myengines2443]

@@Trebseigbetter here than can all other people take part on the discussion. The swarm intelligence can'be overestimated! It helped me a lot of times when people here looked at a problem from a different angle and then came up with solutions that I would never have thought of. That's one of the main reasons why I make videos here on KZbin! I hope to hear from you soon and with best wishes

[@Trebseig]

@@myengines2443 Agree, I'll go swarm intelligence! I will make a new comment, or a number of comments, all start with "Turbine Stirling Engine suggestion". Would love to see your and everybody's replies!

[@nerd1000ify]

Your engineering is super, and the machine work even better. Stirlings are a fascinating topic, I have long wanted to build one but haven't a good idea of how to engineer the design. However, if you actually want to charge your house battery (as opposed to optimising the Stirling for fun, which I completely understand wanting to do!), you might be better off using your biogas as fuel for a conventional 4-stroke Otto cycle engine. Your biogas being mostly methane should have excellent knock resistance, so an Otto cycle engine could operate at high compression ratio and achieve impressive thermal efficiency, much better than what is feasible for the Stirling. Also it has much higher power output, so mechanical efficiency is less of a problem. Of course, you could then use the Stirling as a bottoming cycle to recover energy from the exhaust gases of the Otto cycle engine, which would make the whole system even better!

[@myengines2443]

I have to admit that I thought on this blasphemous idea :-) as I say on the end of the last Video! But I think it causes other problems as the impurities in the biogas or woodgas. If everything else fails I will try it!

[@benhoffmann6870]

This is a wonderful project, very excited to see how you evolve it. Nicely done engineering.

[@myengines2443]

Thanks a lot for your nice comment!

[@sams5803]

I am shocked that you don't have way more followers. You got me hooked within 30 seconds! I am about to binge watch your videos.

[@myengines2443]

Thanks a lot for your nice words, thats what me keeps going!

[@barumman]

Unfortunately the KZbin algorithm favours content that is low quality click bate as opposed to the high quality content you will see here.

[@IronGoober]

The amount of work you've put into this engine is so impressive.

[@myengines2443]

Thanks a lot for your kind comment!

[@75blackviking]

Very, very impressive craftsmanship. I'm blown away.

[@myengines2443]

Many Thanks!

[@allanfahrenhorst-jones6118]

You definitely need to talk to more people who have used this engine. Is it better to have a couple of smaller engines or one bigger engine. You could also just use the small engine in conjunction with a steam or hot water system in the winter to help charge the batteries. Using solar is best in pairs so the wattage is higher then inverter to scale down.

[@olavkokovkin7009]

Thank you so much for the development. I plan on the same journey and your experience is so valuable. Thank you for sharing

[@myengines2443]

Thanks for your nice comment! Plz begin, it is much fun and very educational and show your work here on yt, it is always nice to see it. What do you plan to do? Best wishes and good luck!

[@nobodynever7884]

Amazing. Just subscribed. Can't wait to see the progress in the future.

[@myengines2443]

Thanks!

[@ATomRileyA]

Love your work, really enjoy seeing your progress.

[@myengines2443]

Thanks a lot for your kind comment!

[@Milkybar3320011]

Taurozzi pendulum engine had very low friction, only aware of this because of KZbin. Love the channel too

[@myengines2443]

Thanks

[@mustfindaway]

How come so many forget simple design. Hats off to you, and if i may here is a verbal blueprint. 1 single rod 2 pistons on the rod center AC. I leave the rest to you

[@ronroberts110]

The earliest Alpha Stirlings had a small air pump in order to maintain two atmospheres of pressure inside the engine, to increase the mass of the gasses. It had a relief valve to maintain the internal pressure at its highest peak. They simply accepted that there would be leakage past the seals. Of course, your work in identifying the best seals and the optimum rings' radial sealing pressure is very useful and beneficial. I am most curious about encapsulating the entire engine, except of course the heater and cooler for the displacer. A sealed housing would allow me to use Helium. I think there may be a possibility to add a small relief valve between the crankcase and the interior of the displacer cylinder. If the helium pressure is two atmospheres in both of them, then once it is cycling the displacer pressure will cycle up and down. When the pressure is low inside the displacer, the valve will allow a tiny amount to flow from the crankcase into the displacer. And when the displacer pressure is higher, a small amount will leak past the piston rings into the crankcase.

[@myengines2443]

Yes thats right, I also tried a valve and the "one way piston ring" (look for it and you willl find) and it worked nice. The crankcase is sealed with a face seal and is very tight. I use air at 10 bar and made a few tests with helium but have to do more testruns! greetings

[@stevecreasey3737]

Fab! Really interesting, hope you keep developing your ideas!! ❤

[@myengines2443]

Thanks!

[@pipsqueak2009]

Very interesting. Thank you for documenting your experiences on this video.

[@myengines2443]

You are welcome!

[@nathanb62]

wow. Great summary of an incredible amount of work.

[@myengines2443]

Thanks

[@constants_are_variable]

Ohhh this scratched my sterling engine itch really well, excellent job! Sub right away!

[@myengines2443]

Thanks!

[@ntesla66]

I could only reiterate everything @Trebseig said. I've been playing around with the "turbine" idea for sometime and haven't formed a good working solution. Wave Disk engines have been the focus in an attempt to get some form of thermo-acoustic type Stirling cycle to propagate. A more pragmatic approach is certainly the resonant free piston linear electric generators.

[@myengines2443]

That are really some good thoughts, I hope you can report more on this. Keep up and best greetings...

[@Geri_crs]

use low friction engine oil(like 5w15 or Tansfromer oil) it will enhance you compression and sealment, and make you were much less

[@myengines2443]

Oil will unfortunately clog the regenerator and contaminate the heat exchanges, so the engine has to run dry! This makes things a lot more complicate what many writers here find fault but its not so easy as it looks... Greetings

[@StirlingLighthouse]

Very impressive work! Thank you 🙏

[@myengines2443]

Thanks!

[@MrSteelAu]

Thank you for sharing, the amount of extra efficiency is very expensive making it redundant or even counterproductive so by making the engine efficient you are substituting higher maintenance and labour costs. Basically your aim for extra efficiency to save money is doubling the cost by improving 7%. The old saying of save money at all cost (save $10 by spending $30 )

[@myengines2443]

You are right, the calculation must be carefully considered. Thanks for your kind comment!

[@Howie672]

Thanks for a great video

[@myengines2443]

Thanks!

[@Username9182736451]

Thanks for working on this.

[@myengines2443]

You are welcome!

[@sierraecho884]

You have FINALLY listened to xD I am glad you move on with the design. I don´t think you will ever be able to reach the reliability, output and ease of manufacturing with a rhombic drive. I am eager to see what you come up with. Please share your findings along the way with us =)

[@myengines2443]

Hi sierraecho, your persistence has also led me to try out a completely different Stirling concept. :-) Thanks for your help, I will continue to report a lot here, the feedback is very motivating! Best wishes!

[@sierraecho884]

@@myengines2443 Stay motivated my friend, your work really is great =) I am sure you will find a way.

[@myengines2443]

@@sierraecho884Thanks alot!

[@caked3953]

The only stirling I ever saw in a household setting was a free piston one, mounted on a biomass burner and coupled with battery as buffer for 24h peak consumption. As long as you are not magnetically decoupling the engine I don't know how much you can optimize this build. On the other hand I would like to be surprised by an well optimized engine! I follow this experimental research for a while now and really hope you find a viable solution for your home someday!

[@myengines2443]

Thanks!

[@pirobot668beta]

Piston rings in a motor are necessary due to the high compression ratios needed for complete combustion. Stirling's don't have this requirement, as combustion is a separate process outside of the engine. Lose the piston rings; a close-fitting graphite piston and polished cylinder walls is all you need.

[@myengines2443]

The problem with this (I tried it exactly this way) is that the piston expands more than the cylinder and this is hard to get tight and work with low friction!

[@protean15]

To increase the specific energy of the engine, you need to increase the thermal capacity of the expansion medium. In this case compress the air inside the system to several atmospheres. Normal ICE engines suffer the same constraint. Without a compression stroke, a conventional ICE is anemic. When Phillips was experimenting with sterling drive engines, they pre-compressed the expansion gas quite a bit, though I don't remember the pressure off the top of my head. If you think of a heat engine as a device that steals a bit of the kinetic energy of the gas molecules every cycle, and temperature is simply an average of the speed of these molecules, then increasing the number of molecules at the same temperatures increases the amount of energy harvested. Your engine losses due to friction and thermal leakage will remain essentially the same, but getting more energy per cycle will allow your engine to have increased net output.

[@myengines2443]

Yes, you are right. The rhombic Stirling is pressurized to 10 bar with air and I made experiment with helium at 5 bar. Philips worked with a pressure of 200 bar hydrogen and more what is far to dangerous for me. Thanks

[@protean15]

@@myengines2443 Interesting. I am way out of my element here (please excuse the pun), but would CO2 or Ar have more heat capacity as their molecules are heavier? Seems like each molecule at same temperature and pressure would have 3 to 4 times the kinetic energy.

[@AndreC240]

I’m really looking forward to your deep dive on thermoacoustic generators.

[@myengines2443]

After the TMG in the next video next days I will take a deeper look at them. Greetings

[@barumman]

​@@myengines2443 I shall be very interested in seeing that, best wishes. :)

[@myengines2443]

Nice to hear of you Mr barumman. Do you allow me to use some screenshots of your TMG videos? Many thanks for your nice work that inspired me a lot!

[@barumman]

@@myengines2443 Certianly, you are very welcome. :)

[@OldWrench59]

I have been interested in Stirling cycle and hot air engines for a very long time and have built quite a few. Nothing to come even close to the efforts you have achieved though! However, there is an automotive A/C compressor that I have used quite successfully in a "Ross Yoke drive Gamma, a crank and slider Gamma, a twin beta scotch yoke, and a crank and slider twin cylinder Beta" engine. The compressor block is a "York" twin-cylinder old-fashioned piston compressor. It has a 1.875-inch bore on both cylinders, and the liner is cast iron I believe. These were used on just about every car in the world from the late fifties through the late 80s. They have an area to each side of the twin bores that makes a great water jacket and a place to tie in the cooler because of their location. I have always wondered how well one could work if properly built. Here in the US, they are still common, and can still be purchased new. The twin beta I built runs exceptionally smooth because of good balance. I wish you could see one, if for nothing else, food for thought!🙂

[@myengines2443]

Very interesting, I will look for this! Thanks for your nice comment!

[@Berkana]

Here's a piston and cylinder combination you should try. This is known to have extremely low friction: use a graphite piston on a borosilicate glass cylinder. You can get an exact fit, or even somewhat of a tight fit, and it will still have minimal friction. Look for videos of Airpel brand airpots. That's where graphite pistons in glass cylinders are typically employed.

[@myengines2443]

Yes I also tried glass/graphite combination but at 10 bar pressure and 300 watts power its not sturdy enough. And glass is hard to machine for me.

[@Berkana]

@@myengines2443 how about using silicone whose surface is impregnated with graphite for the seals? Would that work?

[@RobWhittlestone]

Sehr beeindruckend, der heimischer Maschinenpark! Super Arbeit auch wenn das gewünschte Ergebnis ausbleibt. Und Dein Englisch ist auch sehr gut. Ich besuchte ein technische Gymnasium und fing an, einen kleinen Stirlingmotor zu bauen - wurde leider nicht fertig bevor ich an der Uni ging. Alles Gute, Rob in Switzerland

[@myengines2443]

Danke!

[@Tim-Kaa]

Great videos

[@myengines2443]

Thanks!

[@charliemopps4926]

I think you need to consider using a lubricant instead of the rings... but choose a lubricant that has good heat transfer properties. Keep the entire cylinder bathed in it and let that form your seal.

[@myengines2443]

Unfortunately the engine has to run dry! But thanks for your suggestions!

[@user-pu2ho4ip3d]

Teflon coated..? Like..Slick 50. I used it on a car.6 cylinder was getting 20MPG went to 32MPG. A 1964 Dodge dart. Had to adjust Carburetor three times.. Started running faster and faster just on idle. Fuel air mixture brought way down. Ran beautiful. Quicker Throttle response. Acted more like hair trigger. :) That stuff was gold man. Grey/yellow color.. 25$ a quart. Back in the day. Only needed one. With Oil change. Replaces one quart of oil. one time process. Run it for 1500 miles. Oil change again.. done. Standard oil changes after that. ( Won't work with stainless steel.) Age 67.

[@myengines2443]

Sounds nice I will inform myself about it, thanks

[@Synaps4]

Wouldnt it be better to aim for an engine design with a simpler and larger piston that runs at a slower cycle? A slower but larger piston should take much less wear per hour, and given that your goal is home use, keeping the engine small doesn't seem like an important goal. A slower engine might also manage to use a diaphram style piston seal without wearing it out, allowing for much lower machining tolerances.

[@myengines2443]

Yes a diaphragm design like the TMG is very interesting and I do a lot of research at the moment on this type of engines. A larger diameter is both far more expensive and MUCH more machining work. Do you know how many work it was to make the heater head diameter 100mm of 1.4571 stainless steel on the lathe? Nevertheless I just bought a piece of 130mm 1.4571 to build a bigger version of the rhombic in the future! Thanks for your suggestions!

[@jonjoem-walton7381]

Look into the details of the sterling engines used by the AIP (air independent propulsion) systems on some submarines. Newer designs are obviously restricted however the older designs can be found.

[@myengines2443]

Yes these topics are very interesting but also very complicated and high tech what I want to avoid... Thanks for your suggestion!

[@StanislavZachazevski]

I do have whispergen Stirling in my workshop, non working unit, they did use three 1.5mm thick black ptfe piston rings (carbon or carbon molybdenium filled i guess) and thin wire round spring for pressure it. They have 30 Bar of mean pressure, but piston ring pressure using "finger meter" is very, very soft.

[@myengines2443]

The whispergen is a fantastic engine, very nice to have one. Yes the piston ring tension has to be much lower than I thought at begin, friction is so important! Thanks for your inside information. You are always a great help! Greetings!

[@AttilaBlade]

Hi Stanislav, this is not a problem, because the spring and the high pressure Helium both gives the right frequency, dumping effect etc... with the masses. When we increase the pressure the gas change the frequency a lot.

[@StanislavZachazevski]

​@@AttilaBlade i think you are speaking about a free piston stirling engine. Whispergen is 4 piston dual acting alfa stirling.

[@AttilaBlade]

@@StanislavZachazevskiYep, you're right! I was confused with what the "piston spring" means here. Thanks for your correction.

[@QuakeDragon]

I remember my great grandfather fixing a friction issue by using some lead [Pb] to fix a piston that kept binding. (I was very young) I remember him rubbing a chunk of lead on the piston (rotated in a lathe) and again in the engine block (attached to and rotated by a small electric motor). After reassembly, he hand cranked it for awhile and the issue cleared up. That tractor engine still runs to this day. Not sure this is a 'good' idea, as we now know lead ti be pretty dangerous.. but it still seemed noteworthy enough to share.

[@myengines2443]

Good old school!

[@christopherbusch1933]

Perhaps it was tin or babbitt. Babbitt is a very good bearing surface. Lead is a terrible one.

[@QuakeDragon]

@@christopherbusch1933 that is very possible. I had completely forgotten about babbit.

[@bolwem50]

I was involved in the development of the Microgen 1kW free piston engine. For a home build engine I think a Ross yoke, Alpha type engine is the way to go. There's fewer parts than in a half rhombic engine.

[@myengines2443]

Yes I also thought a lot of times about an alpha engine with Ross yoke and actually I designed several complete Ross kinematics but always stayed at the beta as the heat exchanger layout is so elegant!

[@Madkite]

I had some sterling concepts I wanted to try out. Just need to live to 156. 1. A double acting double piston conventional sterling but with pistons 180 degree opposite so they oppose. Then you increase the pressure of the working fluid. So it could be many times atmospheric pressure. The problem here would be leakage on the joint between the sliding conectig rods and atmosphere. Alternatively the enter mechanical engine and generator is put in a pressure vessel. So it can't leak. 2. Stirling turbine. Just like a normal turbine you have a compressor and a power turbine. The compressed gas can be heated, and the exhaust couod be cooled. This could also be contained in a vessel so it could be running at many times atmospheric pressure and have even the generator contained inside. So there is 0 chance of leakage. Maybe the generator couod be between the compressor and power turbines on the shaft. I proposed increasing pressure as one of the very limiting factors is the power to weight and so size. You need a huge one to do any real work. If it's using a working gas at somthing like 5 bar. Then it will need 5 times the energy per a given volume to heat. And so you get 5 times the energy out. Meaning a small engine could make a lot more power. Or exploit waste heat like form a chimney without needing to be ginormous.

[@myengines2443]

Sounds really nice, you don't have to live to 156, just do in NOW!

[@Random-dq8ew]

Impressive.

[@myengines2443]

Thanks!

[@mileshodkinson9983]

There was in the 70s a type of engine created with curved pistons and curved block, which laimed to be lower in piston friction. He was from somewhere in south america.

[@mikehughesdesigns]

MYT engine - Raphial Morgado (Mighty Yet Tiny)...

[@mileshodkinson9983]

@mikehughesdesigns I think you are right, that sounds like him, Google has other patent holders and Wikipedia has someone else mentioned too so there might be useful.info if it's an approach worthy of any consideration. I recently sketched out a linear generator with opposed pistons, not Sterling but ice.....I don't have the skills to build, only imagineer :)

[@CriticalThinkingSociety]

You could experiment with a scotch yoke with two linear bearings above and below the Scotch yoke. And maybe even a linear bearing in your cold side piston.

[@myengines2443]

Yes I also thought some time ago about a bearing in the cold piston rod. Thanks!

[@typha]

I wonder if there would be any way to incorporate flexure hinges rather than using bearings and so forth.

[@myengines2443]

Yes you are right that is exactly what I want to realise in the next engine. A free piston or diaphragm engine like TMG which has no bearings or sliding surfaces. I show my investigations in the next video soon!

[@andrewjackson244]

Have you thought about wood gasification? I know that's not as sophisticated as the stirling, but I think woodgas will be very important in the energy-deprived future we are heading into.

[@myengines2443]

I already produce biogas in a small diy digester, look at an older of my videos. If I need more energy in winter I plan to build a wood gasifier also! Thanks for your comment!

[@BrokenLifeCycle]

Have you considered slapping on thermoelectrics to scavenge the waste heat?

[@gregkelmis2435]

I forget which European country it’s one of those Scandinavian countries I believe opted not to use nuclear submarines and build submarines with Sterling engines for electrical generation. They found 50 KW what is the maximum size it was still efficient don’t know which variant they used, but worth looking into.

[@ferrumignis]

What was the heat source for the Stirling engines?

[@lordsqueak]

@@ferrumignis as I recall, they burn diesel.

[@georgehamilton6624]

Thanks for the video, could you please tell me what those books you were reading are called at 5:41 ? i would love to have a look as i am looking to power my workshop with a thermal engine like this :)

[@myengines2443]

Hi, look at a few comments under this one there I named them! I also want to heat my workshop shed with the engines! Greetings

[@Trebseig]

Turbine Stirling Engine - Suggestion (01) What is it? A Turbine Stirling Engine is ... like a steam turbine, but without steam/water ... like a stirling engine, but without piston(s) without displacer and without everything going back and forwards all the time. It can be a closed or an open system, although I prefer closed; keeps it clean, gives control over gas type and pressure. It works on a heat difference which can be high can be low. Heating and cooling is done by heat exchange. There also is heat regeneration, but with a constant flow direction, non alternating.

[@zthihasan5169]

I love to see the alpha Stirling engine, as far as I found it the most powerful one among the Stirling engine variant. and a lot more simple mechanical part compared to this rhombic drive. ( I really love mechanical engineering since I was child but due to restriction, I am application developer now)

[@myengines2443]

The alpha configuration is mechanical really more simple but then has other problems like piston side loads etc. It will maybe only lower the problems I have with the complex rhombic drive. What I want to try is to eliminate the problems of friction and wear nearly completely, some Free Piston designs are made for 100000 hours and more!

[@MykoGeek]

have you tried giving all your friction surfaces a WPC treatment. it’s not a coating so it doesn’t screw up your tolerances basically it’s a surface treatment that is like shot peening or sand blasting but it use extremely small ceramic media that is very spherical. it’s a win win for you since it gives your sliding surfaces far less friction and it also extends the lifetime of the part. look up what is wpc treatment by motoriq he breaks it down pretty good. or just watch a few shorts on wpc treatment i think it could be what gives you the lifetime and power that you need since you can have far closer tolerances without affecting friction very much just look at the part of motriq video where he puts the rod into the cylinder and puts his thumb over the open end of the cylinder he compresses the rod and it’s able to hold pressure but once he removes his thumb the rod slides through like the cylinder wasn’t even there

[@myengines2443]

This sounds very interesting! I will look for this WPC technology if it is suitable for the Stirlings. Many thanks for your hint this is what I need!

[@atntaltd]

amazing

[@myengines2443]

Thanks!

[@pa2922]

Too much moving parts, Think a step back and try to use a 2 stroke crankshaft with hybrid bearings. But a very very good clip and damn good maschine work respect

[@myengines2443]

The dry running pistons cause a lot of problems thats the reason for the complex rhombic drive! Thanks for your nice comment!

[@CriticalThinkingSociety]

You could experiment with the cold side piston having fins that dip into a coolant in the down movement.

[@myengines2443]

This will contaminate the crankcase and thus the working space or how do you mean it? Thanks for your thoughts!

[@CriticalThinkingSociety]

@@myengines2443 It could be cooling and lubrication oil or you could just make a container that is on the edge of the wall with a shouldered hole for the moving parts to move through. Think water fountain minus the middle part.

[@FBPrepping]

You're a master. I have seen this concept but it seems the development is not fully completed. Jeez you have even electroerosion machining equipment?? Awesome. How about covering the parts with a coating like Electroless Ni-P? it seems to work very good as a sealant and against friction.

[@myengines2443]

Thanks for your nice comment, I will inform myself for Ni-P coating. Greetings

[@Karma8Kami]

It might be a lot more dangerous but wouldn't it be a lot simpler to build a pressure boiler and just use steam under pressure to generate power? Then slap this thing on top for passive thermal gain or something?

[@myengines2443]

I am not sure if steam engines are the right solution for me and an additional Stirling just for the waste heat of the steam engine will make it even more complex... But thanks for the suggestion!

[@salec7592]

1. reciprocating engines would have losses due to acceleration and deceleration of pistons. 2. Thermal engines would be more efficient on higher pressures (more molecules per volume) of working gas. But for that, with closed cycle, whole containment should be pressurized and sealed. Perhaps look into using machine which has partial phase change of working fluid. Reinventing steam power, sort of.

[@waldschratdersandersmacht]

pistonring-springs in meinem hatte ich anstelle metallischer federn. einfach radial komprimierten weichen schlauch unter die ringe gelegt. - ähnlich wie o-ringe. macht schön gleichmässigen andruck, und dichtet die ring-rückseite zusätzlich. nachteil: lebensdauer?

[@myengines2443]

Sehr gute Methode die ich auch schon mal angedacht habe, irgendwo müssten noch silikon schläuche rumligen die ich dafür angeschafft habe. Ist die auch a Arbeitskolben anliegende recht hohe Temperatur kein Problem für die Kunststoffschläuche? Viele Grüße

[@waldschratdersandersmacht]

@@myengines2443 hatte ich in der stückliste von meinem bauplan zum VM2. ich hatte winzigen silikon-isolierschlauch aus dem elektronik bereich verwendet. die sind leider mit dem schmieröl aufgequollen. - nach paar wochen, und entsprechender längeneinkürzung ging das dann erstaunlich gut. meine kolbenringanzahl, kohlegefülltes teflon, und noch öl... zu viel des guten... vor allem das öl, und kondenswasser haben probleme gemacht.

[@keithfarrell3370]

Genius

[@myengines2443]

Thanks!

[@nuttyDesignAndFab]

most piston rings run with lubrication. in the engine world engineers have been going to lower tension rings for better fuel economy since the early 2000s. Have you considered just grabbing some off the shelf rings? also the cylinder bores need to be iron, or nikasil plated as other uncoated metals tend to spall. Some engines use Metal Matrix Composite (MMC) and that surface seems very slippery, but I don't know how its made.

[@myengines2443]

Piston rings and coatings from ICE engines I know of need lubrication which I cant use in the Stirling. I look for MMC but don't think its different! Thanks for your help

[@ET_AYY_LMAO]

Wow what a sweet engine setup, the display was very interresting, what sensors did you use?

[@myengines2443]

Oh, a lot of. The most ports of the Arduino Due are used. 2 photo switches 1 for rpm and 1 for crank angle to recognize the piston positions for the real time pV diagram. A load cell for torque, a vibration sensor, several ds18x temperature sensors, 2 pressure sensors a voltage divider an current sensor (works quite bad, cant find any precise...), a few I forgot now and a lot of actuators. The sketch is pretty long and the Due has to work really hard! I love modern microcontrollers, I am an electronics newbie and its so easy and so much fun to work with them! And the speed is amazing, the flywheel has 60 or 90 (I think so, maybe a few more or less, have to count..) slots which switch the photo sensor and with 2000 rpm I can precisely recognize each one and run even a LOT of code before the next slots reaches the switching point... Greetings

[@ET_AYY_LMAO]

@@myengines2443 I am amazed at the level this project has reached, first time seeing it. I really enjoyed this video. I dream of building a nice stirling engine in the future that can reach over 150w of power and be relatively maintenance free, so your videos are certainyl inspirational. Keep up the good work. I subscribed, looking forward to your next update. I follow a lot of amateur engine builders and its the first time I see someone plot out the engine cycle on a screen using a microcontroller, I think its great - Genius even for experimentation.

[@wazza33racer]

A company in the USA makes stirling engines commercially for remote power applications. It is a single free piston coupled to a linear generator.

[@myengines2443]

Free Piston Stirling engines are the next candidate in this series, thanks!

[@allbionics]

I am still wondering about a direct temperature to electromagnetic generation link; getting to a design where the mechanical oscillatory movement is directly converted into electric induction. Such a design would minimiz mechanical gearing and kinematic energy conversion. I live on an acreage in the Canadian Rockies and I am very interested in such a possibility.

[@therealchayd]

I've seen somewhere in the past the some companies have made free piston stirling engines that use the sun's heat when placed at the focus of a reflective parabolic dish. The rapidly reciprocating piston moves a magnet past a coil to make power.

[@myengines2443]

Thats what I am currently looking at, look out for a new video in a few days where I will describe my new ideas.. Thakns and many greetings

[@shaner.5]

You should research total seal Piston rings. Because I think what you need to do Is use a gas expansion rings or gapless ring, if not he can make, you a ring that's super thin and has no blow by. worth the research.

[@myengines2443]

Yes, I have to improve the piston rings and cylinder/piston fit a lot, but at the moment I need to motivate me to explore an other concept that I am researching at the moment. In the next days I show the first candidate in my list , the TMG.

[@sethg6157]

What about electron discharge mechineing to make a truly pefect cylinder piston fit

[@myengines2443]

I dont think that this will work as the surface quality is not good enough, after finishing the fit will not be perfect...

[@carlbrenninkmeijer8925]

impressive! I think that the efficiency is given by the Carnot cycle. Microgen produced a Stirling. It is a shame that they are not available

[@myengines2443]

Theoretical the Stirling cycle has the efficiency of the carnot cycle which is the maximum. Practically it has not! The classic Stirling engine is simply too complicated!

[@arkatub]

Hi, can you increase the power per cycle by operating at higher pressures? The whole device in a very high pressure environment, encapsulate the mechanical parts.

[@myengines2443]

The engine is still pressurized to 10 bar and more is too dangerous for me...

[@gabrielbennett5162]

That can be dangerous. High pressure risks an accidental "diesel effect."

[@patricf209]

Sieht sehr Interessant und nach viel Arbeit aus.: Aber warum unbedingt ein Stirling? Wenn ich es richtig verstanden habe , erzeugst du dein Gas selber im Garten? Wären Peltier TEGs eine Alternative? Oder kann das Gas nicht auch einen Verbrenner (Langsamläufer) befeuern?

[@myengines2443]

Peltier Elemente haben einen sehr schlechten Wirkungsgrad und sind empfindlich und brauchen deshalb eine aufwändige Überlastungsregelung. An einen Verbrenner habe ich auch schon gedacht, wär aber erstens langweilig und lauter und zweitens ist das auch nicht so unproblematisch u. a. weil die Verbrennungsräume empfindlich auf unreines Brenngas reagieren. Holzgas herzustellen ist dann auch nicht so schön. Danke für deine Gedanken und viele Grüße

[@flubalubaful]

Would it not be better to perfect the 300w engine. What is your output goal 1000w?, and what about price?

[@myengines2443]

I don't want to stop improving the Rhombic but at the moment I need something new. The problems are the complexity of the engine and thus its maintenance intervals and its price. At the low power levels it has to run permanently and the wear will make the service interval quite short. 1000 watts would be a good number than it has to run only a few hours per day... The price would be because of its complexity far to high to sell.

[@user-zm4yg9xv8q]

Try tungsten disulfide powder for friction problems. I add it to grease pivot points and bearings and it makes them last forever. The runout or slop never increases because of the imbedded slippery yet strong particles. The more load and jolts the more the particles get worked into the metal. There will then be no metal to metal contact. For dry applications like the one you are working on, it will also work into the surfaces, resulting in a lower friction outer surface. Graphite breaks down and moly doesnt really work great and is too low concentration from most suppliers. Tungsten is a super material and reacted it becomes small and soft apparently. The um powders from suppliers i have purchased this from seem all legitimate. I think it would work well in a sterling engine.

[@myengines2443]

Thanks for this nice hint! I tried molybdänum sulfide and it worked a bit. I will look out for tungsten disulfide

[@andrewh12838]

The Thermo Mechanical Generator basesd on the Harwell design seemed to be a goof micro chp device, developed originally to use heat from decaying radioisotopes it morphed into a generator with long service intervals for light buoys. HoMach in England made some?? for the Irish maritime service in the 1980s. I can find no trace of one now. 150W electrical output for 1500W propane thermal input. Ideal for an underfloor heaing system . Only drawback seems to have been a loud 400Hz hum

[@myengines2443]

In a few days I show a new video about the TMG, maybe it will be my next engine.. Thanks for your suggestions

[@russbernard8666]

Try making ring less pistons from 4032 hyperutetic aluminum alloy. In hi performance racing engines using a 4” diameter piston we run .0002-.0005” skirt clearance. This is high Silicon low expansion material

[@myengines2443]

With ring less pistons I had problems because the piston expands more than the cylinder and its quite difficult to find the right clearance. So low expansion material sounds nice. I will inform myself about 4032, many thanks for your help

[@MrBeugh]

I've often wondered if a Sterling engine could work for power generation on the Moon using the temperature differential between sunlit and shadow areas.

[@stevensmutko1408]

Yes and no. it requires a working gas, the moon has no atmosphere if it were inside a dome structure it would likely cause to much heating due to inefficiencies. But you should look into RTGs they are the ultimate solution for space travel that's why all modern rovers use them. Super long lasting around 50+ years and steady consistent power. Only draw back is radiation would need to be a sufficient distance away from human settlements.

[@mantis3dfx]

Would the use of ceramic components contribute to the reduction of frictional losses enough perhaps? 🤔

[@myengines2443]

Ceramics are a very interesting topic and there are some machinable on the market but they are expensive. Hopefully I will try theme once!

[@stevensmutko1408]

Have you considered using graphite piston rings they are a natural lubricant but are very fragile. Just a thought. Good luck.

[@myengines2443]

Thanks for your help and yes I tried graphite

[@Trebseig]

Turbine Stirling Engine - Suggestion (04) Efficiency? The efficiency of a Turbine Stirling Engine, depends upon many factors, but mainly on how high is the temperature difference is. With a LTD the resistance in the machine is relatively high. If the engineering has been done well, but the efficiency is still low, that is not really a problem IF the temperature difference source is: plenty, clean and free.

[@FadeToEvil]

You need also take a look at Ericsson cycle.

[@myengines2443]

Its an open Stirling like cycle I think, what are the advantages? Thanks and many greetings!

[@triplestangman]

line2line coating make an abridable coating that wears itself in for use in out of round applications

[@myengines2443]

Thanks, I will look out for it!

[@hunnybunnysheavymetalmusic6542]

If you can encase your system in a pressure vessel, you can vastly increase your efficiency and peak power output.

[@myengines2443]

It is already loaded with a mean pressure of 10 bar and I don't want to use a higher pressure, its too dangerous for me!

[@fritzeder1847]

To reduce the heater volume üressure should be above 50bar as heat radiation absorption in the gas starts to amtter

[@myengines2443]

50 bar is far too much for me. This will make things also much more complex! But thanks for your suggestion!

[@Trebseig]

Turbine Stirling Engine - Suggestion (03) The bad. Bad relative to a normal stirling engine.. The precision of the turbine parts needs to be very high. The turbine needs to spin much faster. It is hard to get enough compression. There is a lot of internal wind resistance.

[@trawqad7723]

Hi. Would you tell me what book you use at 5:39?

[@myengines2443]

The books are: Free Piston Engines Walker/Senft Stirling and Thermal Lag Engines Allan Organ Stirling Engines - without the Hot Air Allan Organ (I dont know if you can buy it, its self published I think, he kindly send it to me after some discussion..) And a paper about the Thermal Lag engine I think you can read the title maybe with a amagnifying glass . Greetings

[@whateverrandomnumber]

Wouldn't a Seebeck generator (also wrongly known as "Reverse Peltier") with an electric motor be more efficient and lower maintenance?

[@myengines2443]

Seebeck modules have a very low efficiency as far as I know but I will investigate this too. I ordered a few elements a few weeks ago and will make tests with them and report here!

[@whateverrandomnumber]

@@myengines2443 on the positive side, unless you melt the solder, there's zero maintenance or parts to exchange. Bonus points if you need electricity in the end, and not mechanical power. Some cooling would benefit both the Seeback effect, and the PV efficiency. Do I'd investigate the benefits of an active cooling solution.

[@gr0nis]

Do you have a Patreon for supporting your stirling engine endeavours? I would really like a Stirling engine for off-grid power, but I don't have the skillset, time or the willpower to develop one myself. However, I do see that you do, so I would like to contribute and encourage your development efforts. Maybe this could increase the probability slightly for developing a working design (regarding power, endurance, cost, etc) for an off-grid Stirling engine.

[@myengines2443]

I haven't any supporting possibility so far as I thought that my content is too special and my chanel too small. But since you asked, I have now added a PayPal link to my KZbin homepage. It would of course be great if someone donated there, that would of course motivate me a lot and possibly give me more time to develop Stirling engines and make videos! But these kinds of great comments are also a great motivation and for me the reason for my KZbin videos. Thanks alot and best wishes!

[@Trebseig]

Turbine Stirling Engine - Suggestion (02) The good. 2 negatieves for the stirling engine: large size and weight for its power. Typical for a turbine is: small size and weight for its power. 2 other negatieves for the stirling engine: quite a lot of large moving parts, and most moving parts move back and forth. In a Turbine Stirling Engine there is just 1 large moving part, which includes a compressor a turbine and an electric generator(also start motor).

[@gustavgnoettgen]

What kind of cycle does it use?

[@mitchhaelann9215]

Can you run a stirling engine off the waste heat lost by a hot water heater? I have this stupid idea for a farm-tower that uses a series of hydraulic ram pumps to move water up a tower in stages, each stage incorporating a small waterfall that will spin a tesla turbine to generate power, and when the water gets to the top, it is boiled using a mix of the electricity generated below and thermal energy from a series of solar ovens ringing the exterior, the purified steam collected and condensed (and heat extracted via Stirling generator to produce more power), then held for long-term storage to be used as drinking/bathing water.

[@myengines2443]

If you only have the hot temperature as low as 100 degrees celsius the engine has to be very big to get reasonable amounts of power. But it had been done and can be effective but its not my type of engine. Thanks for your thoughts!

[@mitchhaelann9215]

@@myengines2443 I was thinking more like 230 celsius, but thanks!

[@waldschratdersandersmacht]

hey ralf, hast du dich schon mal mit verbrennungsluftvorwärmung beschäftigt. steigert den systemwirkungsgrad, entschärft den wärmeübergang heizgas->erhitzer, z.b. mittels abgas-gegenstrom-wärmetauscher. aber hat auch nachteile: systemkomplexität steigt. 2 weitere neue wärmetauschgrenzflächen. erhöhte anforderungen an die brennkammerwerkstoffe, und potentiell mehr stickoxide wenn nicht flox betrieb... am rande: hab da mal unabsichtlich in einer pelletfeuerung den schürhaken mit dem rost verschweißt ;-))) bei der sunmachine brauchten wir eine schweißer-schutzbrille für den blick durch's schauglas...

[@myengines2443]

Das sind ja interessante Erfahrungen! Verbrennungsluftvorwärmung ist natürlich ein sehr interessantes Thema und unerlässlich um den Wirkungsgrad zu steigern. Ich habe aber natürlich zuerst die Aufgabe einen vernünftig laufenden Stirlingmotor zu haben bevor ich mich um solche weiterführenden Dinge kümmern kann. Aber danke für deine Erfahrungen! Viele Grüße

[@waldschratdersandersmacht]

@@myengines2443 stimmt! du bist genau auf dem richtigen weg.

[@togowack]

I am almost done my 60 cc Stirling Engine. As I said in previous videos of yours, I think your swept volume is too low. I see 50 fins for air movement of the cooling ring where the Ross engines would have 250. Yes machining fins is hard but that is the key IMO.

[@togowack]

Actually what is the depth of those fins? The ross fin depth was .100 inch, maybe you do have a similar swept volume if they are deeper but fewer in number.

[@myengines2443]

The depth of the fins is 8 mm or nearly 0.3 inch. I designed them with the similarity formulas of Allan Organ after the GPU-3. I know this is not perfect but probably not too wrong. I also controlled the heat exchanger surface areas and volumes with new formulas based on lower pressure engines and they also seem to fit. But you are right, more surface area is always better as far as the dead volume does not get to big. I have to look it up but I think there are more slots in the rhombic engine. Please show your engine on your channel, it sounds very interesting. Thanks for your nice thoughts!

[@togowack]

@@myengines2443 I've been showing off your engine to my friends as an example of German technical ability. Mine is nowhere near as smooth and space age. Rough castings. I would post a video soon with cast fins but don't want to give too much hard won details away to the public. It would be a month to assemble with existing parts but I am 3D printing an SLA hot end out of aluminum brass with 125 fins at .100 depth in castable resin. Am looking forward to experimenting with fins and would go in same direction you did with fewer fins and higher depth. I still think your basic engine design should be capable of 500 watts. My driveline is mostly made of aluminum (connecting arms and pivot joints). The pistons are thin cast iron and the cylinders cast bronze. (this might be backwards but you can see it at Chris Workshop). With such a heavy flywheel required on these engines I'm not sure if it matters how heavy the axle components are.

[@vf19blue]

Not a Sterling i know, but why not a small steam engine? I remember seeing an off grid example years ago. IIRC it was about 3kw equivalent.

[@myengines2443]

You would need a lot of steam for this, is this possible with not too much efford?

[@bradhoffman77]

you want it for winter but aren't using cold and hot to get best results

[@Dr._Spamy]

StirlingEfficiency StirlingPower

[@myengines2443]

You can't say that in general terms! Philips for example made very powerful and efficient engines which were simply too expensive.

[@ronaldmasterbud1551]

I Think That You Should Look @ it As An Aircraft Engine, ( Very High Run Time ) or Chainsaw ( High Hp, but very Low Tq. ). Industrial Hard Chrome Cylinder, W/ 1mm plain Iron Gapless ring. Or Nitrated Cylinder Running 1mm Gappless Chrome Faced Ring. Using The Best Quality Full Synthetic """ Mist """ Lubrication of the Cylinder in Say a 0W-5 grade or even Just Straight 2 stroke oil. I Use it in Many High Load Applications. Hopefully this Can Help.

[@myengines2443]

Unfortunately the pistons have to run dry, that causes a lot of problems and the reason why many things have to be so complicated... Thanks for your thoughts

[@deangdmppajj4692]

I'm not sure that i fully understand the science of all the intricacies of your engine, so just a thought. Have you tried ceramic piston rings ?

[@myengines2443]

I have not tied them as I dont know where to buy. I would need them for a bore of 60mm are they availiable for reasonable prizes? Thanks for your hint!

[@mrstevecox7]

Have you thought of Graphite piston surfaces?

[@myengines2443]

Yes I tried it but maybe I have to try it again... thanks

[@mrpurcountry]

I would try Teflon rings

[@myengines2443]

I tried it but Teflon is too soft and it has not so low friction as you would think. I also tried carbon and glass reinforced PTFE types. The tribological plastic I use now, IGUS W300, is much better.

[@308dad8]

You are wanting to use an engine to run a generator for permanent off grid power? What are you going to use to run it that’s cheap compared to buying power from the grid?

[@myengines2443]

I use my self made biogas from my diy micro biogas digester you can see it in an older video!

[@ferrumignis]

The rings seem very wide, and the cylinder surface not hard enough. You could use Nikasil perhaps, "two stroke stuffing" had some success doing this in his own garage. Thick rings require more power sapping pressure to seal well, there is a reason pretty much every ICE uses very thin rings.

[@myengines2443]

The problem is that they have to run dry so some self lubricating compound has to be used. Nikasil needs lubrication I think? Thanks for your help!

[@CriticalThinkingSociety]

Please increase the distance or insulation between your hot and cold sides.

[@myengines2443]

The regenerator is between the hot and cold spaces but you are right over the cylinder alot of heat is travelling to the cold side. Thats a disadvantage of the beta design which has other benefits.

[@jebise1126]

bronze has small friction. can you get bronze piston rings?

[@myengines2443]

Unlubricated I think the friction and wear will be worse. But I thought about it and have to inform myself.. Thanks