# Solar/heat engines



## watcher (Sep 4, 2006)

Anyone here have any experience or plans for building heat engines? Specifically Stirling engines and Mintos wheels. What I'd really like are plans that allow for building a small scale model that would allow me to understand the basics as well as being able to up scale to build a full sized machine.

I have found plans for small Stirling engines but they are not much more than toys that have no practical use even if you could up scale them.

The plans I have found for Mintos wheels have been theoretical plans for large machines that would be very difficult to down size.

I'd like to start off with a small model with a plan of moving up to a middle size machine to pump water and maybe later on a large machine to generate electricity and/or run some type of cooling/AC unit.


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## SolarGary (Sep 8, 2005)

Hi,
Not sure this helps much, but here is one:
http://www.windstuffnow.com/main/newpage3.htm

Gary


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## Windy in Kansas (Jun 16, 2002)

Stirling model: http://jnaudin.free.fr/html/stirling.htm

Directions to make your own from scratch: 
http://www.steamengine.com.au/stirling/models/buildme/index.html

Good information site:
http://www.stirlingengine.com/

Professionals? http://www.mech.canterbury.ac.nz/research/stirlingcycle.shtml

Interesting reading: http://keelynet.com/

You may wish to read this about the Wally Minto Water Wheel before proceeding too far. http://www.keelynet.com/interact/Arc_1_98-7_98/00001793.htm

Link to site that tells Popular Science article of water wheel: http://www.eskimo.com/~billb/freenrg/minto.html

I have also wanted to play around with the Wally Minto Water Wheel designs. I really thought that when new laws went into affect that propane bottles had to have the OPD valves (overfill protective device) that the old bottles would be plentiful and could be had for such a project. Never really found that to happen. Too many of old bottles seem to be recycled for meth manufacturing for ammonia. The ammonia corrodes the valve.

I envisioned using black pipe for the spokes and POL to pipe fittings to hold the bottle to the pipe. Thread Tight on the POL to keep the bottle in place.
OR bottle holders with flex tubing to the bottles.

The more spokes and bottles the more power one should have. Length of pipe would also determine some of the power as the larger arc would give more gravity time for the bottle fall from top to bottom of the cycle. 

I guess I'll proceed to experiment when I build my mad scientist lab to help educate my grandsons. Perhaps that would spark their inventive genius to good use.

You might enjoy this site: http://www.scienceforums.net/


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## watcher (Sep 4, 2006)

Windy in Kansas said:


> I have also wanted to play around with the Wally Minto Water Wheel designs. I really thought that when new laws went into affect that propane bottles had to have the OPD valves (overfill protective device) that the old bottles would be plentiful and could be had for such a project. Never really found that to happen. Too many of old bottles seem to be recycled for meth manufacturing for ammonia. The ammonia corrodes the valve.
> 
> I envisioned using black pipe for the spokes and POL to pipe fittings to hold the bottle to the pipe. Thread Tight on the POL to keep the bottle in place.
> OR bottle holders with flex tubing to the bottles.
> ...


I'll check out the links.

For testing that might work but for large scale I don't think 20# LP bottles would work very well. Don't you think the tank weight to fluid ratio would be too small. I'd like to find some 6-8 inch AL irrigation pipe to use. After some reading it seems that having an odd number of 'sides' would be better because then your filling tank would already be past the 12 o'clock position. The problem with it is you have to have two pipes with check valves to make it work.

The larger the diameter of the wheel the more power you get but there is a break even point (I saw the math on a site somewhere) where the gas pressure isn't enough to push the liquid from the bottom to the top.

Have you thought about how to smooth out the movement? I know the inertia of a really large wheel should keep it moving fairly smoothly but with a smaller wheel I'm thinking you might need a flywheel.


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## mightybooboo (Feb 10, 2004)

IIRC Mother Earth News tried to build a Minto Wheel and it was a bust.
Sounds good tho,had my interest piqued for sure.


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## watcher (Sep 4, 2006)

mightybooboo said:


> IIRC Mother Earth News tried to build a Minto Wheel and it was a bust.
> Sounds good tho,had my interest piqued for sure.


I read the story a while back and it seems to me the problem was they used pipes that were too small. That made the transfer rate too slow to work well.

Mythbusters built one using 20# LP tanks. It worked but it was small (IIRC, 4 tanks and probably about 5 foot diameter) and they also used what looked to me to be very small pipes.

I read an idea from a website that got me to thinking. This guy was thinking of something like a well water pressure tank. That way the expanding gas would push against a bladder and push the fluid up the pipe. I don't know how hard it would be for a DIY'er to build something like that but I do like the idea of being able to keep the gas and liquid apart. Then you might be able to use a heavier fluid that otherwise the gas might dissolve in. There is the fact that with a system like that if you sprung a leak you wouldn't lose everything.


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## mightybooboo (Feb 10, 2004)

Minto wheels

[ame]http://www.youtube.com/watch?v=bs_OtCsDJoY&feature=related[/ame]

[ame]http://www.youtube.com/watch?v=bs_OtCsDJoY&feature=related[/ame]


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