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Forum Index : Other Stuff : Big Stirling engine

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govertical
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Joined: 11/12/2008
Location: United States
Posts: 383
Posted: 06:08am 13 Jul 2015
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https://youtu.be/HqdoCzNAzHM

https://youtu.be/rGFiaL_gYhU


Greeting, I found a stirling engine project that looks like it will drive a F&P. I am attempting to duplicate.

Suggestions welcome.
just because your a GURU or forum administer does not mean your always correct :)
 
govertical
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Joined: 11/12/2008
Location: United States
Posts: 383
Posted: 07:10am 13 Jul 2015
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I have to finish the linkage and I should be testing in a few days. I am fabricating a Gamma configuration.

just because your a GURU or forum administer does not mean your always correct :)
 
Gizmo

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Joined: 05/06/2004
Location: Australia
Posts: 5078
Posted: 10:01pm 15 Jul 2015
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I'm not a fan of rubber bellow pistons. They introduce a lot of friction, which is the natural enemy of a stirling engine.

For an engine that size you could probably find a piston from a air compressor or small 2 stroke engine, and make a bore to suit, ideally from a piece of seamless steel pipe. The bore should start off slightly smaller than the piston, honed to get a nice finish. Then carefully machine down the piston so it just barely fits, a tight fit. Then some fine grinding paste and work the piston until its a smooth fit. The trick is to work the piston to suit the bore, not the other way.

A piston will never be a perfect seal, but has very low friction.

Glenn
The best time to plant a tree was twenty years ago, the second best time is right now.
JAQ
 
govertical
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Joined: 11/12/2008
Location: United States
Posts: 383
Posted: 01:57am 16 Jul 2015
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https://youtu.be/v_e0981CLDI

https://youtu.be/jl9tw6Ysb4s

https://youtu.be/9jQgAnPrwbM

https://youtu.be/H2IGvceQQ0s

Hi, thanks for the info. My first attempt was with a metal piston and I failed. Thanks again.


My real problem is finding away to make the displacer rod air tight and still have low friction..Edited by govertical 2015-07-17
just because your a GURU or forum administer does not mean your always correct :)
 
MacGyver

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Joined: 12/05/2009
Location: United States
Posts: 1329
Posted: 06:23am 30 Sep 2015
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govertical

I've built a few Sterling-cycle toys and as for the displacer piston, it doesn't need to be tight at all. In fact, it should be a VERY loose fit. All it does is shuttle a slug of air from a cold spot to a hot spot. The hot air entering "wants" to cool down and vise versa. Mine actually made some small noise as it ran.

The looser the better for the shuttle piston.

As for the "power" piston, I had the best luck using a very thin diaphragm as a seal. The solid part of the piston basically just pumped back and forth, my having ran the connecting rod through a "cross-head" to offset the swing from the crank.


. . . . . Mac
Nothing difficult is ever easy!
Perhaps better stated in the words of Morgan Freeman,
"Where there is no struggle, there is no progress!"
Copeville, Texas
 
govertical
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Location: United States
Posts: 383
Posted: 08:00am 30 Sep 2015
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Hi, thanks for the info. I am stuck getting ready for winter. Hopefully I will something operational by spring. Thanks again.
just because your a GURU or forum administer does not mean your always correct :)
 
govertical
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Posted: 01:34pm 31 Mar 2016
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Project Video

Project update:

I have to fix a air leak and add a tire valve so I can increase the internal pressure a small amount.
Showing signs of life.... 4 rotation before the internal pressure dropped.

Hot side about 600 F, cold side about 80 F.
just because your a GURU or forum administer does not mean your always correct :)
 
Gizmo

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Posted: 02:00pm 31 Mar 2016
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I know I've mentioned this before, lots, but get rid of that diaphragm piston and make a proper piston and sleeve.

You can see how much pressure is wasted when the orange diaphragm in your engine expands and collapses. If you have a proper piston, this pressure isn't wasted. Yes you get a little leakage, but nothing like the energy wasted on a diaphragm piston.

Glenn
The best time to plant a tree was twenty years ago, the second best time is right now.
JAQ
 
govertical
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Joined: 11/12/2008
Location: United States
Posts: 383
Posted: 02:33pm 31 Mar 2016
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Hi. Thanks for the info. I have to improve my machining skills, so I am using what I can fabricate or purchase off the shelve. This is my first attempt.

This project is using a diaphragm and getting great results.

https://youtu.be/rGFiaL_gYhU

I traced the air leaks using soapy water and found many.

Thanks again.



just because your a GURU or forum administer does not mean your always correct :)
 
govertical
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Joined: 11/12/2008
Location: United States
Posts: 383
Posted: 10:33am 01 Apr 2016
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Example of gas motor conversion
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govertical
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Location: United States
Posts: 383
Posted: 10:59am 01 Apr 2016
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One other problem found, crank arm set screw was loose and allowed the phase to shift. Proceeding with repairs.
just because your a GURU or forum administer does not mean your always correct :)
 
bitdog
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Joined: 13/11/2016
Location: United States
Posts: 15
Posted: 08:07am 17 Nov 2016
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If your cylinder is vertical wouldn't this reduce friction? Hot side up, cold side down. Heat rises, cold settles.
If your F&P is too much for a sterling, maybe a LG DBB116Y01 4681ED1004A 310 Vdc 110watt 1.5 amp. from a dish washer and a L7815 for a regulator?
https://www.encompassparts.com/item/6691557/LG/4681ED1004A/Motor_Assembly,dc,washer
I was considering a sterling for my DIY Waste Vegetable Oil Burner house heater, Runs 24-7, 600F, heats 3 story house to 80F at 18F outside, heats my hot water 120 gal 160F, & you can cook on top. Uses no electricity or tech. Moving parts = one door hinge. And now it needs a sterling, & a cold water tank for the cold side of the sterling. Then hot out of that tank top goes into the hot water tank so the cold tank gets colder every time I use hot water. Which would force me to clean up when I needed electricity.
Bitdog
 
govertical
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Joined: 11/12/2008
Location: United States
Posts: 383
Posted: 10:44am 17 Nov 2016
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Hi, thanks for the info. Reducing friction is my biggest problem. I put the stirling project on the back shelf, I am still working on a taboo project. Thanks again.
just because your a GURU or forum administer does not mean your always correct :)
 
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