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Longest cylinder Stirling Engine?
Posted: Wed May 29, 2024 7:58 am
by Spacefog_
What is the longest cylinder you ever seen on a Stirling Engine?
So far I have found the Huxtable hot air engine
https://www.olds.com.au/stirling/ but there has to be something longer.
Re: Longest cylinder Stirling Engine?
Posted: Wed May 29, 2024 11:38 am
by Spacefog_
Re: Longest cylinder Stirling Engine?
Posted: Fri Jun 07, 2024 6:23 pm
by Fool
The book, "THE EVOLUTION OF THE HEAT ENGINE", by Ivo Kolin, has a description of the "Lehmann Engine". Page 69.
It is a Beta and has:
Cylinder: 197 cm, about 6' 6"
Bore: 35 cm, about 13.78"
Stroke: 17.4 cm, about 6.9"
Displacer: length 147 cm, about 4' 9.9", diameter 34.3 cm
Timing: 65°
It is extra long to separate the hot and cold sections.
It allegedly is the engine Schmidt used to model his Schmidt Theory.
The following link is for someone attempting, I think not sure, to make a model or remake a full sized Lehmann:
https://yogisworkshop.wordpress.com/201 ... gine-ep-1/
Re: Longest cylinder Stirling Engine?
Posted: Sat Jun 08, 2024 8:55 pm
by Fool
The Lehmann is one horsepower, about 750 Watts at 100 RPM. 4% efficiency.
Re: Longest cylinder Stirling Engine?
Posted: Sun Jun 09, 2024 3:38 pm
by matt brown
According to the hotairengines.org site,
http://hotairengines.org/closed-cycle-e ... hmann-1867
the 1 HP version has these specs with ~1.75 volume ratio
- 1 HP Lehmann specs.png (64.29 KiB) Viewed 1158 times
Hmmm, typical 2-3 bar charge pressure with low volume ratios (typical DIY values) has indicated output around 1w per liter per rpm. And as a sidebar, scalar effect for rpm relates to piston speed (think fps) vs gas speed differential where the bottom line is that a larger engine (think longer stroke) will run slower than a smaller engine within the same T and P ratios. A whimpy LTD might run 1000rpm but that ain't nothin' in fps. Most DIY attempts scheme rpm as if picking candy, clueless as to how it scales.
There's a more precise rule of thumb for indicated output that I can't recall, but similar PLAN for HP. Going backwards, if this beast had only .04 efficiency, I don't see how it managed even 1 HP.
Re: Longest cylinder Stirling Engine?
Posted: Mon Jun 10, 2024 6:34 am
by Fool
Phillips, in the 1940's, proved that rpms and pressure are as important as surface area, conductance, stroke and bore. All we need for a practical engine is to copy what they did with available modern materials and manufacturing technology.
The question now becomes cost per useful energy. And can it be an easy enough DIY homemade project.
