Thermal Expansion Motor

Many of these devices fall into the category of "Bessler Wheels." They have no magnetic parts and no electrinic parts. They simply utilize sliding or swinging mechanisms along with gravity to make them run.

Thermal Expansion Motor

Postby Kevlar » Wed May 04, 2005 1:11 am

Has anyone worked with freon or one of it's many chemical offshoots.

I've put together a small Minto engine, but am having a heck of a time moving the liquid from one end to another without overpressurizing my containers. I have not had a containment failure yet and wish to avoid one. I am using a solar still to heat water, and using the water as my thermal conducter for the transfer container which works fine and I am able to pretty closely monitor and adjust the heat. My big problem is with the transfer of the liquid during the boiling stage.

When I increase my transfer pipe size (in an effort to move more liquid, I end up pushing both gas and liquid, which ruins the effiecency.

This is my first time working with the material R134a, so anyone with some advice would be helpful.
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Postby dkmacmillan » Sat Aug 20, 2005 5:19 am

I've never built a Minto Wheel, but it seems to me, just by looking at one, that you should be able to speed things up a bit by bending the pipes a little in the direction you want it to turn. Does that make sense to anyone else? I mean, if the hot tank is straight down, the condensing side shouldn't be at TDC right? A couple of degrees to one side should not only pull the wheel in that direction but possibly give a spot in the tank where puddles could form making it gain weight & rotation faster.
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Postby pertyfly » Sat Aug 20, 2005 8:07 pm

I've not built one either, but think about this. If the top one is tilted, then the bottom one (and all others) are tilted too. If the top is tilted in one direction, then the bottom is tilted in the opposite direction. This means, that you're in the same predicament. You still have the same situation where the are right exactly above eachother, except now they have a bend in the line :-) However...if you can get them to tilt dynamically somehow....then you have something Heh
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Postby pertyfly » Sat Aug 20, 2005 9:50 pm

This idea got me thinking. I was wondering about having a hinge setup, where each one was on a hinge that would only swing one way.

The first thing I thought of was hinged so it would only bend into the direction of rotation of the wheel, then I saw that it wouldn't flop until it was quite a bit past TDC, and probably wouldn't help, and maybe hinder it (due to the slightly closer distance to centre, and therefore less effective energy). Also, because the opposing side would be at full distance, and half all of that mass to pull up (farther distance from centre). I am not sure, however if the volume difference would counteract, and maybe it would work fine. *shrugz*

So, then (thinking about the possible drawback of the first hinge thought) I was wondering what would happen if you put hinges in the opposite direction. In a way so that all of them going up were hinged down slightly and therefore closer to centre (and less effective mass to raise). This way, the side on it's way down would be straight out all the way, and have full energy on it's way down, but on the way up it would have less of a negative effect on it. Again, I don't know if this would be of benefit, but at first glance it would appear that it may.

Any help at all, even a slight increase in efficiency would make it even better

BTW, when I speak of hinging, I don't mean all out 90 degrees or anything. I am just talking partial. Maybe 45 degrees or something. Maybe a better angle upon testing would be found.

Any thoughts? I would like to hear, both positive and negative
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Postby dkmacmillan » Sun Aug 21, 2005 11:19 am

Maybe the tanks could be screwed into a single manifold with valves that only opened on one side, off TDC. Something like a check valve that works on gravity
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Postby BillyHydrogen » Mon Dec 12, 2005 12:27 am

I have not studied this motor to great extent. Maybe try to use r-22 as your freon. It is alot less expensive and is not a blend . The pressures are higher and it works well with mineral oil. If you use 134-a it needs a vegetable based oils and will get somewhat sticky in mineral oil. I do hvac for a living, if you need any info on refrigerants I can get it for you.
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Postby jjbeamish » Wed Jan 04, 2006 10:10 am

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Postby Orange_Crusader » Fri Jul 20, 2007 1:14 am

Sounds like a pretty cool project, at least a lower-power consuming way to use solar energy. Anyone else built one on a smaller scale than 10 feet?
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Postby Helioechidna » Tue Oct 02, 2007 10:01 pm

I've built these kind of wheels before and the low boiling fluids are terrible at performing any useful work. i.e. Freons, ether, dichloromethane...
Use pentane or something that boils at close to this range.
Low boiling fluids have too much pressure in the top chambers that waste energy when it is compressed by the fluid filling into them.
Compressing a gas requires work to be done.
It's like driving around with the brake on.
At just under 120F, the cooling cycle temperatures, most of the Pentane is starting to condense and so there is less vapour to compress and less energy wasted.
If the cycle is maintained at just above and just below 120F (~50C)
Reasonable power can be obtained.
Make sure the lower tank is fully submered (evenly heated) during the transfer period (not much more than 20degrees past BDC bottom dead centre) The fluid is very suceptable to small temperature variations and if part of the tank is leaving the bath before the fluid is transfered you end up having the fluid transfer it's energy out through the exposed part.

http://www.youtube.com/watch?v=bs_OtCsDJoY

This is my small engine working.
I have a 20liter tank system that turns over (slowly)with the lower half in the sun.
With warm water it generates just over 200W continuously.
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Thermal Engines

Postby mrdovie » Fri Nov 02, 2007 7:31 pm

I think Mr Wizard used a metal wire around a heated wheel that ran to a smaller wheel. The wire expanded from the heat of the big wheel, and a ratchet kept the wire from backing up. So, new wire from the little wheel was heated and warm wire from the big wheel was spent off and allowed to cool. the wheel kept turning as long as the big metal wheel was heated.
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Re: Thermal Expansion Motor

Postby Simeon » Fri Nov 11, 2011 2:10 am

I have a shaft in that has a few dia's that are -.01/-.03mm tolls on a short section that’s 30mm OD, the 30mm section is in the middle of the shaft and is
17mm long. There is also a 12mm -0.01/-0.03mm section each end of the
shaft for about 15mm each end.

Material is 316 stainless, and will be fully roughed out before letting to settle
before finish machining and "polishing" into tolerance.

How would I go about calculating the growth on diameter per degree C?
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