DIY thermoacoustic Stirling engine for reliable self made cheap energy to go off grid
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- เผยแพร่เมื่อ 29 ก.ย. 2024
- Here I show you the finishing touches to my thermoacoustic Stirling engine.
It is an initial test machine to gain experience and then gradually build larger and more powerful engines.
The thermoacoustic cycle requires no moving parts and its great reliability and durability make it ideal for supporting our solar plant.
So I would like to generate cheap energy with the self-built DIY micro CHP in order to become off-grid as quickly as possible.
My attempts to support our energy supply with wood or self-produced biogas during periods of low sunshine made my Stirling generators with different drive mechanisms like the rhombic drive more and more complex.
The relatively new concept of the thermoacoustic Stirling engine is a radical simplification of the Stirling cycle.
Movable mechanical components are only required to utilise the thermoacoustic energy generated.
In the last two videos, I presented the thermoacoustic Stirling engine and showed the production of the first required parts.
Now all that was missing was the regenerator and a few little things and I could finally start the first test run.
Of course, I also had to deal with setbacks and problems.
At first, I carried out initial tests with provisional set-ups.
After I made a proper power extraction unit and made several changes to the feedback loop, the regenerator and the general settings, I finally had my first successful test run.
The first big step has been taken, a working prototype on which I can gain practical experience.
Of course, the power output is not high with such a small and simple machine, but I can experiment with what brings more performance to plan the next more powerful engine.
I have a lot of improvements planned and am already thinking about a larger version.
The next variant will probably be another low-pressure borosilicate glass machine with a larger volume to study the differences and effects of the changes.
I also have to delve deeper into the complex thermoacoustic theory to be able to plan improvements successfully.
Before I carry out further test runs, I would like to measure the thermoacoustic and mechanical performance using pressure sensors, frequency measurements and a linear generator in order to be able to carry out meaningful optimization tests.
I don't yet know which type of linear generator is best suited for this.
If you have any suggestions as to which linear generator offers advantages or how I can improve the thermoacoustic Stirling engine, please write them in the comments!
Many thanks for watching!
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Thanks for this! Looks very promising. For the generator, I propose iron less design, that will avoid lateral forces to the power piston. Put 1 to 3 neodym magnets on the piston (each 2mm thick, 25mm diameter), then put 2 coils with a distance of 1 cm each and a coil thickness in z-direction (magnet moving axis) of 1 cm. Operate the power piston vertically and to avoid the piston falling down, place opposite magnetized magnet below piston.
Thanks for your nice suggestions, I ordered yesterday a few 10mm diameter neodym magnets and will make some experiments with different coils.
The hint with the vertical power piston is very good, if I get problems with the heavy magnets I will try it!
I'm very happy that your engine worked out! A small step for man, a huge step in the right direction for power generation!! Congratulations! I will keep tuned to see how this series of engines progress, since you have a huge talent for manufacturing. Hope to see that EDM machine in use too, it was awesome.
Thanks for your kind comment, the EDM is always in use and make so many things possible.
Thanks very much for sharing. I am really looking forward to how you progress with this and admire your approach.
Many thanks for your kind encouraging comment!
You could try a Wells Turbine en.wikipedia.org/wiki/Wells_turbine - which will convert a bi-directional flow into rotary movement in a single direction
Many thanks for your hint, I will check it!
It looks like that turbine needs longer strokes of flow motion.
Or at least it looks like any time the flow reverses, you loose some energy to the reaction time of the airfoils. That is, unless you made the airfoils spring-loaded and tuned them to be perfectly in phase with the flow at the expected frequency.
I think an engine that you can stick in to a small fire and use to charge a cellphone with would be interesting, maybe a commercial product. For campers, preppers
That's spectacular, a few watts from something that size is fantastic. I wasn't able to find the video back, but there is someone making these for underdeveloped regions using loudspeakers and big-ass (maybe 6" across) thermally-stable plastic pipes. They were big and loud, and using a double-loop instead of a dead-end extraction section. However, with a lot of insulation and a cheap enough material for the main loop you could probably get away with an enormous and powerful engine.
I also hope so and will experiment a lot the next weeks.
As soon as I get some meaningful results I will report with a new video!
Thanks for your kind comment!
Hi, I am new to your channel, but I find it very interesting. Will it make sense to connect Sirling to Ground-coupled heat exchanger? There is air pressure and temp difference. And also infrared heater panel could also be an option, because when you use it is only heating air but also items in house which are becomeing capacitors of heat. Also think about how turbin in diesel works or raptor engine where they reuse pressure to accelerate engine.
It sounds like this is the future for 'small' alternative off-grid energy sources :ø)
Solar, Wind, Sound - HOT
I also find the principle realy very promising.
Thanks for your kind comment!
That "no moving parts - _except for the power generation"_ feature is so agonizingly disappointing to my brain for some reason.
Too bad we always want electricity. If anyone wanted their power in the form of pulsed gas flows, it could truly work without moving parts.
And too bad we always generate it by "spinning a thing" (even in combustion engines), so that there is barely ever any need for a good linear generator design.
If you need much cooling you can use it really without any moving parts, as many examples of thermoacoustic coolers show.
At the moment I am constructing a linear generator and hope it will work, and I also hope to come along without a flywheel.
Fascinating work.
Thanks!
It's great to see your prototype working!
On the topic of increasing total output of the engine, I have an interesting design which has simple structure and has many potential benefits.
The design uses stack effect to both boosting the output and converging power from multiple thermoacoustic engines.
I've sent a E-mail to your TH-cam mail address.
The mail contains both picture and descriptions of my concept and design.
If you are interested, please check your mail.😉
Excellent video - have you thought about 3d printing in plastic and casting components in aluminum? Just thinking of trying to make this more accessible.
From what I remember, you lose a great deal of efficiency in linear generators over rotary ones. You may want to try a slider-crank mechanism to go straight to a classical alternator/generator.
If I can't get a good linear generator built, I will use a rotary one but that makes things more complex what I want to avoid!
Thanks for your suggestion!
using piezoelectric generator instead of electomagnetic coil? or maybe triboelectric nano generator
Nice build. I hope you'll find a way to optimize it to get more power out of it.
Thanks!
I think your rhombic engine is a much better design. The only thing that I would change on your rhombic is put the power and displacer pistons on opposite sides instead of the one inside the other.
Very promising, keep up the good work!
Und schönes Wochenende 🙂
Vielen Dank, dir auch!
You could just try a good full range neodymium speaker with high sensitivity from parts express. That should translate into higher efficiency power output.
I have heard that loudspeakers have a very low efficiency but I will check your suggestion, thanks for your help!
That's great progress!
Thanks!
Maybe a switched reluctance generator could be worth investigating… for example check out episode 1048 of Robert Murray-Smith.
Thanks for the help, I will look out for this!
My guess is that the most suited for this application would be a piezo-electric membrane as a generator.
I don't think those are manufactured though. I know there's a "fan" that's ridiculously expensive for it just being a flat piece of metal that swings back and forth but in the form of a generator it probably doesn't even exist.
Pretty sure piezo speakers don't work very well like that.
Piezo electrical transducers are used in low power engines but they are not very efficient afaik.
Seeing this, i can't help but wonder if it(or other stirling engine) could run with just the heat off a solar thermal battery system, could make for an incredibly cheap & rugged emergency power source, but would the efficiency be completely impractical?
If the temperature of the thermal battery is very high it can work with an acceptable efficiency.
The higher the temperature the higher the efficiency of the Stirling.
I would say that my thermoacoustic Stirling starts to work at about 200°C, I will make efficiency tests when my test stand is ready!
If the weight of the linear generator is a concern for the resonant frequency of the whole system I would have the coils in the piston and the magnets in the stationary part. If suitable magnets aren't available you could have both stator and piston as electromagnet coils. Actually come to think of it that may be better anyway. You would be able to make changes to the field strength on the fly for testing. And in a final product the output could be managed by a microcontroller.
That sounds really smart, I will think about it and inform myself !
Thanks for your help and if you have more information I would be very grateful!
Congratulations! I am not a generators expert, but this looks pretty good: th-cam.com/video/virZhMw9FK4/w-d-xo.html , but I couldn't make a good generator out of a speaker.
Thanks for posting me the link to your fantastic website!
And I will check TK's generator!
I've only recently found your channel, and I'm loving the content. Thanks for doing this and keep up the good work.
Thanks!
Idk why but mine doesn't work, I used a single test tube and put some type of thick steel wool and a wet cloth to cool the other side, but idk the diaphragm keep getting bloated and it just doesn't work even tho I made a super tiny hole to let excess air out, eventually the test tube broke and I didn't make any progress and also I don't wanna make it look like any other Stirling engine with a flywheel I want it to be as linear as possible
Mmh, look at the correct distance of each component, the steel wool has to be packed very light, maybe look at videos of Attila Blade!
I wish you good luck!
Ever thought of making 3 phase version and tune it to 50hz?
If my calculations are correct one need about ~2,83m regenerator length between cylinders using hydrogen as working gas
Idea is to make it directly produce 3 phase current, fine tuning done with temperature control, also working fluid pressure
I'd put magnets in Halbach array in round magnets with hole to hold them with a rod
As for dummy load before building proper linear generator, you could put magnets in copper pipe that is submerged, temperature change over time would give estimate of generated power
To make it run as an AC generator is a goal very far in the future but a good idea!
I think 50 Hz is pretty close to the typical frequency of a thermoacoustic Stirling.
I am currently building my test stand for the TA Stirling including a simple linear generator.
It has a dia. 10 mm magnet oscillating through several coils inducing a low current that hopefully can be measured for performance comparisons.
How did you build the resonator piston? Is it plastic? Did you use balloon? And also is it air tight?
The piston is plastics (W300) running in a cast iron cylinder.
The engine is airtight but the piston is not absolute tight and has therefore very low friction.
Ok, I know you're trying to supplement your solar, but I wonder the following:
If you generate extra solar energy during the summer months, what do you do with it? I wonder if you could electrolyze water, then extract and store hydrogen for combustion later? Seems like a clean fuel with excellent combustion properties, although long term storage would be bulky and would have to be very secure.
Thoughts?
That sounds nice but it will be a hobby for its own!
When the battery is full in summer I try to use much energy or otherwise no electricity is converted!
@@myengines2443 I see, I wasn't aware that you have a battery rig. I suppose it would be terribly expensive to have a rig that kept enough spare power for winter...
Perhaps commercial development of vanadium batteries may change that calculation in the future.
Either way, thanks for your videos!!
Very cool, are all your machines converted from manual to CNC?
Yes, the Lathe and the Deckel "FP 0" Mill are converted from manual to CNC.
Look at my older videos where you can see the details!
Sirling engines are very interesting, but the economics of solar/battery and wind/battery are getting more and more favorable every day due to increasing volume and tech advancements. In terms of solutions for getting electric power from burning fuel the progress that is being made in thermoelectric generators is bringing them closer to a practical $/W ratio. I think it is unlikely that Stirling engines will have a major role to play in energy production unless they can be used with thermal waste situations like Data centers which has lots of low grade heat.
You are right, waste heat is a big area of application for Stirling engines.
They also can't compete with solar cells WHEN the sun is shining but thats exactly when I want to use the Stirling engine: when the sun is not shining to load my solar battery.
I experimented with thermoelectric generators and informed myself about them some time ago and my conclusion was that they are not very efficient.
Have they improved?
@@myengines2443 I'm guessing that you've probably heard of the 40% efficient TEGs produced by MIT that run at high temps and use some kind of nanomaterials. I guess that the efficiency is great, but maybe expensive to manufacture and high temps could lead to rapid degradation. Personally, I love the fact that you are working with the most simple/unexplored approach possible to systematically see how much efficiency/performance you can get out of it. I am really looking forward to seeing how well the technology can scale and how much output you can achieve relative to size.
Good job, keep up the good work.
Use big speaker without membrane as power generator
In low power thermoacoustic engines loudspeakers are used but I heard they have only low efficiency.
But I will check that, thanks!
i will only give you props if you can build it using nothing but stuff you find out of the garbage and not using a mill or cnc stuff
The mill, lathe and cnc stuff is just used because I have the possibilities and its the fastest way for me to build it.
All components (except the power extraction unit, but then you could use a diaphragm or someting else...) can be made without these machines.
It all can be glued or taped and a 3d printer also makes things much more easy!
My goal is to make a much more powerful engine in the range of 100 watts which needs more complex parts which have to be machined on a mill and lathe.
If there is much interest I can present a construction plan of a working model without any machines!
@@myengines2443 most people watching are more interested in the proof of concept,
they do not care what tools you use.
if you can make a Stirling engine design that can make 100 watts (in what time scale?) then most of us will be impressed.
hope you get it working as you want, but why dont you blow the hot air to a turbine instead of the linear back and forth, by turbine I mean pelton turbine or ducted fan, after the heat acoustic pipe. yes acoustic turbine generator. acoustic = heat expansion pulse jet.
This is a very good suggestion but I didn't find much information about a bidirectional turbine and don't know much about turbines at all.
I will try to find more information about this as I think a turbine would be a very elegant way to use the acoustic power!
Many thanks for your help!
@@myengines2443 well you can always try one-directional first, ie when blowing out, not when going the other direction, like a put-put boat.
@@myengines2443 try pelton turbine, its one-way anyways, just pulse blow on the blades.
@@myengines2443 if you think two directional turbines then the rotation inertia is too much to be pulsed, you would need to have two turbine tubes that flow the opposite ways. ie valves on the tubes that let the air pulse flow only one direction.
by "put-put" boat I mean "pop pop" boat. but pulsating air, instead of pulsating water, heat engine
Ohhh damnnn it worrkss! Amazing man I'll look forward with efficiency improvements♥️
Thanks!
i'm developing one too
Very nice, plz show it in a video.
Many greetings..
I was hoping that you would dive deeper into this topic as I also see this as a very promising option for the small scale generation in the 500W range. Looking forward to your next videos!
Thanks!
How many watts?
I will measure that now and report it in one of the nexts videos.
I hope this is it, you worked pretty hard and this engine looks so beautiful.
Thanks!
Have you tried making a hybrid Stirling engine that can be connected to cars with Internal Combustion Engines since they produce a lot of waste heat?
Yes, it is an old idea. Why no one made it possble yet?
Yes this is the topic of several research institutions.
But I just want to build a micro chp for heating the house and producing electricity form our wood and self build biogas digester!
And we don't have a car ;-).
Thanks for your kind comment!
congatulation on sucsesful movment!
Thanks!
Bravo.......screw the glass......but ........Stirling has the most patents ........great read.......ok......helium filled.......two free pistons .....linear ......space stuff.....buy old space ship......or buy the space station ......get a shake flash light it has all the parts.....cheers