Free piston Stirling Engine with linear alternator lights up incandescent bulb

[cellman64]

it is so succesful



[kalaa216]

great job done.can you plz tell me the details how you made this engine.because i myself would really want to build this engine...

[blg53]

@kalaa216 Thanks. Unfortunately I don't have any drawings or anything like that because I built it by trial and error from bits of scrap, cans, glass cyringes, some tubing etc.. If you read my description on this and the previous videos as well as my answers to the previous comments that would be as much info as I can supply. remeber, you don't have to build an identical engine, do something similar, it is fun to just experiment. Good luck.

[yaochiuhqui]

@blg55 how did you calculate the springs constant, and where did u buy them?¿

Tnx very and congrats on the engine

[blg53]

@yaochiuhqui Thanks. I did not do any calculations. In fact, there are no springs there at all. In my commentary I referred to "virtual springs". They are formed by two sets of Neodymium magnets set to repel each other. I set the magnets by trial and error until both power piston and the displacer rod are "suspended" roughly half-way through their respective strokes before start of the engine.

[specallez]

I bet this would work great with a ferrofluid piston?

[blg53]

@specallez No, don't believe so. Ferrofluid is a liquid after all. It works great when there is no pressure to withstand as multiple example on youtube demonstrate. Unfortunately if it is asked to do a real job i.e. to overcome resistance it will not keep compression as the gas under pressure will simply bubble through a ferrofluid 'piston'..

[royalbrainwave]

Thank God for fast forward! This is one boring video making a big deal about nothing.

[eloid777]

can we get in touch some how to desciss this more?

[blg53]

@eloid777 Sure, my Skype id is bob_berg

[eloid777]

@blg53 check your youtube account sent ua message

[eloid777]

sepritine is a coil shaped as sin wave weaved with 2 other sin waves to produce

3 phase power then combined after recified to dc later

[eloid777]

few question about your moving piston in the glass syringe on the generator side... it has magnet on the outer diameter how many coloums of magnets around the piston... does the piston also have repling magnets placed adjacent on the shaft to centre in the syringe, i see the magnet on the top ....

Is the striling engine fill with a gass? hydrogen helium gas? how is the piston cooled water jacket?

[blg53]

@eloid777 The power piston has a large Neodymium magnet attache to its shaft. It serves dual purpose: 1. to provide a moving magnetic field for the alternator to generate electricity; and 2. to be a part of the virtual magnetic spring to keep the power piston gravity-neutral. The other part of the magnetic spring is a set of 8 smaller magnets sitting on a disk attached to the power cylinder (the non-moving part). They are set to repel the big magnet upwards thereby cancelling effects of gravity.

[eloid777]

@blg53

i see the neodymium on top for the coil, but are the magnet in the shaft pararrel to 8 magnet to the shaft

to center the piston in the cylinder

[blg53]

@eloid777 This engine is filled with just air. Helium is too expensive and hard to get hold of. I shudder to think how short a life will be of the displacer cylinder made of tin iron and heated to about 600 degrees if I fill the cylinder with Hydrogen, I would suspect a couple of hours, after which it'll crack due to hydridisation of iron. In any case my cylinder-piston tolerances are nowhere close enough to keep either of these small-molecule gases securely contained inside.

[eloid777]

@blg53

the trick here with hydrogen, you need to have electroyoce cell (hho) that makes pure hydrogen not hho or oxygen mix the amount hydrogen used would be less than 100-350 ml . hydrogen cant explode under a vaccum. if it leak with atmosphere it would be flame for 3 -5 sec and be gone... hydrogen can not explode at 600 degress unless it exposed to air or oxygen. if it leak out and was ignited it would be flame only as it depresserizes to atomosphere.. if you use only pure hydrogen gas.

[blg53]

@eloid777 The engine is mostly air-cooled. If I indend to demonstrate it running for a long time I also wrap a wet rag around the upper part of the displacer cylinder.

[eloid777]

your alternator need to be sepritine 3 phase alternator with laminated iron core

[blg53]

@eloid777 You are probably right, unfortunately I don't know that sepritine is. I did try coils with iron core, but found that I need one hell of a strong armature to keep the from slamming into the large Neodymium magnet attached to the power piston. Was not practical for a small device like this.

[josephdupont]

SO WHAT ABOUT BIGGER COILS? ARE YOU LOADING THIS UP AS MUCH AS YOU CAN??

[blg53]

@josephdupont This coil was the best resistance match that I could produce for the 0.25W bulb. Bigger or smaller coils do not load the engine quite as much. I believethat this is as close to the maximum power output as I can achieve from an unpressurised hot air engine of this size made with no lathe. I do have a plan for my next project to increase power by pressurising the air around the engine, but this is some time in the future.

[TheBattleWagon]

I would use it to power a spark coil from an automobile. much more power will issue forth.

[blg53]

@TheBattleWagon

No, it won't. Spark coil will not match well with any decent load like a lamp. When unloaded it will produce a huge voltage. But it has very high internal resistance due to the large number of winds. So when loaded the voltage drops next to nothing. In any case, the power produced depends on the engine, not the coil. The bad coil adds losses. No kind of coil will give you gain in power, that's physically impossible.

[blg53]

I did achieve much higher output power when I heated the engine with a propane torch instead of the spirit burner. But I thought it was a bit of an overkill for the engine of this size.

[TheBattleWagon]

I would imagine this power if sent to an inductive coil, like an old condenser? or a spark coil from an automobile would be capable of powering a crystal radio, or small light?

[blg53]

@TheBattleWagon

Indeed. The power produced is plenty for a small radio or a set of LEDs. Don't need any different coil from the one I have, but the output voltage needs to be rectified and smoothed.

[TheBattleWagon]

Bracket, again exuse my poor spelling.

[blg53]

@TheBattleWagon

No problem :o)

[TheBattleWagon]

Now use a braket to mount a second magnet of opposing polarity above the displacers magnet, and by rasing and lowering this magnet you will change how fast the engine will bounce the powered piston that moves the magnetic plunger.

[blg53]

@TheBattleWagon

Yes I tried that already. It does work like you described to a certaing degree when the engine is unloaded. With the load the effect is much smaller, it stalls the engine quite quickly after briefly accelerating it.

[Kywdo]

!!!

[somwarpeth]

Very Nice project !

Can you send your Email ?

[blg53]

Thanks !

I don't quite understand your question. I can send an email, but what email. And send you whom ? Or are you asking my email address ?

[IronGoober]

This is great! I've been really wanting to make a free piston engine, but haven't had enough time lately. I really like this one, the use of the magnets for a spring seems to make thing much easier than using an actual spring. I also think that using magnets would make the motion of the displacer less sinusoidal and therefore closer to the ideal stirling cycle. Great job, I really like your work.

[blg53]

Thanks. Magnetic springs are definitely better than mechanical ones, those are just too fiddly and difficult to tune. Whereas magnetic one are very easy to adjust by moving the sleeve magnets up and down. They also create no mechanical friction, obviously a big advantage. Your point about the displacer timing is also true, at slow oscillations you can actually spot the slight delay in the displacer rod movements, it tends to hang about in the extreme positions before reversing.