MadModder
Gallery, Projects and General => Gallery => Topic started by: sbwhart on November 08, 2013, 08:42:24 AM
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A few weeks ago a friend from the club said he was trying to help a young engineer with a school project, a Stirling engine, and he was struggling to help could I give him any advice.
Now I must admit that I've been trying to avoid Stirling engines as I know they are tricky beasts, but I thought our resident expert and curator of the Stirling Orphanage Dave stilldrilin was just the man to ask so I acted as a bit of a go between, and then it happened I got :proj: for building a Stirling engine. I loosely followed the Tom John drawing and advice and encouragement from Dave.
As I feared it was a far from straight forward project but after many false starts and reworking I got it going.
I'm pleased to say that our young student engineer got his going as well
So a big thank you to Dave for all his help.
Stew
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Nice work Stew. Looks like it is up to your usual high standards! I have always wanted to do a LTD stirling. Maybe one day...
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Very nicely done Stew! :clap: :clap:
Pleased I could help. :thumbup:
David D
(Just sorted your YouTube link, Stew).
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Oh yeah... We can blame David for everything! :lol:
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nice :clap: :clap: :clap:
are the plans available for that ?
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Oh yeah... We can blame David for everything! :lol:
Now we mustn't be too hard on Dave after all he has a lot of orphans to look after
nice :clap: :clap: :clap:
are the plans available for that ?
Angus:- The plans are on John Tom http://www.john-tom.com/StirlingPlans/LiveSteamStirling.pdf but be warned if you follow them to closely it wont work. Main things I changed are:-
1:- CD disc for the fly wheel.
2:- Polystyrene displacer cylinder needs to be a closer fit on diameter with less clearance at top and bottom stroke.
3:- I used a paper gasket with gasket sealer.
4:- The piston is ally made as light as possible
the displacer cylinder is a bit of 110mm diameter * 3mm wall Perspex but my friend used a bit of 4" ish diameter drain pipe.
The swept volumes needs to have a ratio greater than 50 to 1
Thanks for your interest and
Good luck
Stew
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Oh yeah... We can blame David for everything! :lol:
Oh, heck! :scratch:
Sigh......... (http://freesmileyface.net/smiley/angels-and-demons/saint-0095.gif) (http://freesmileyface.net)
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thanks for the link...... another project for the winter list
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Nice work Stew!
I have one that I've experimented with, and changed the displacer from expanded polystyrene foam, to a piece of Scotchbrite pad. I was curious to see if an open mesh displacer would work as well as a solid insulator if it gained from regeneration that way what it lost to permeability. It ran well with either displacer. Can't remember which was better.
Yours looks very nice.
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will do one of them one day :nrocks:
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Nice work Stew!
I have one that I've experimented with, and changed the displacer from expanded polystyrene foam, to a piece of Scotchbrite pad. I was curious to see if an open mesh displacer would work as well as a solid insulator if it gained from regeneration that way what it lost to permeability. It ran well with either displacer. Can't remember which was better.
Yours looks very nice.
Now that is a good idea using the scotch bright pad, I'd really like to get it working off hand heat so that is well worth trying.
Stew
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Scotchbrite!! :bugeye:
Thanks Steve! I wonder how much heat it can stand, compared to balsa wood....... :scratch:
David D
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I would try to keep the displacer itself under 50C. Of course it runs somewhere around an average of the hot and cold sides. But if it stops at the bottom end it could reach close to the end plate temp.
Melting temp might be higher, but if the material sags at its upper temperature range, it will contact the displacer cylinder at the bottom and rob energy that way.
Here's the engine I mentioned with the replacement displacer:
(http://i786.photobucket.com/albums/yy150/vtsr/vtsr/TecumsehBuild/SirlingScotchBrite.jpg) (http://s786.photobucket.com/user/vtsr/media/vtsr/TecumsehBuild/SirlingScotchBrite.jpg.html)
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And a start I made on a much larger more complex (internally) version.
It's a little outside of the (hat) box, in terms of LTD configuration in most ways. Not sure why I stopped work on it -- I was almost done. Maybe I should take it up again.
(http://i786.photobucket.com/albums/yy150/vtsr/vtsr/TecumsehBuild/SirlingScotchBriteLarge.jpg) (http://s786.photobucket.com/user/vtsr/media/vtsr/TecumsehBuild/SirlingScotchBriteLarge.jpg.html)
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WOW, Steve!!! :bugeye:
Is that a diaphragm. As opposed to a power piston? :scratch:
"Maybe I should take it up again". Well.... I, for one. Think you should! Soon!! :D
David D
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WOW, Steve!!! :bugeye:
Is that a diaphragm. As opposed to a power piston? :scratch:
"Maybe I should take it up again". Well.... I, for one. Think you should! Soon!! :D
David D
Yes I think you should too.
I've been running mine on and off for the past few days, adjusting/fiddling with it:- made a better displacement piston, and I've taken a few funny kicks out of the motion slowly slowly its getting better will run for 21 minutes on one cup of boiling water. I'm thinking of changing all the moving parts from brass to ally to get the weight down.
I've also got some glass tube to try with a graphite piston but I wont to get the best out of what I've got at the moment before I try that one.
Bugger this Stirling :proj:
I've got a real bad dose
Dam you Dave :lol:
Stew
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Don't want to hijack here so Stew, send me elsewhere if it is! David, no. not a diaphragm, it's a just a big square displacer cylinder.
My daughter and I tried getting the smaller one running -- it has sat unused for about 3 years I reckon. After fiddling around with it, we took it apart finally, and substituted the old foam displacer, and got it running again.
It has mostly aluminum sliding parts, and they were definitely not running together well. I didn't build this one, and it looks like it could really use a "David style" rebuild. The gland leaks for sure, and the aluminum power piston in aluminum cylinder just isn't good -- I did find a good sized divot in the inside of the cylinder near the top -- must have always been that way -- anyway filed it down. We did get it running -- but it could be a lot better.
Maybe I will work on that big one -- you guys are getting me caught up in this, too! Getting the first one running brought back some of the fascination with seeing something sit on top of a cup of hot water running for a half hour. It's weird to walk away from something like that, forget about it for awhile, and come back in the room and see it is still running. :scratch:
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Stew, Steve.........
These engines are infectious....... Aren't they! He, he, he....... :lol: :lol:
Enjoy! :thumbup:
David D
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Nice work Stew - works a damn sight better than mine! I have to have boiling water on the bottom and ice at the top to have it turn a steady 30 rpm!!