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Is there a perfect ratio between cylinder size.
Posted: Thu Oct 20, 2016 1:24 pm
by WildBillCody
I'm going to build a Gamma, What size should my power cylinder be compared to my displacer cylinder? I would think you would want a bigger displacer. Also is there a perfect size tube diameter between the two. I am shooting for a 10" flywheel, I am also planning on it powering it's own water pump to move cooling water around the displacer. TIA
Re: Is there a perfect ratio between cylinder size.
Posted: Thu Oct 20, 2016 6:29 pm
by thanh-cuibap
I think that there is one best rates! but I do not know and no one talks about it all, you do this link step by step ... and then gradually learn from experience
http://www.stirlingengineforum.com/view ... f=1&t=2124
Re: Is there a perfect ratio between cylinder size.
Posted: Fri Oct 21, 2016 3:03 am
by Ian S C
The ratio for GAMMA and BETA motors (high temp) is 1.5 : 1, the displacer being the larger of the two. A conventional displacer in the form of a hollow cylinder has a length three times it's diameter. The gap between the displacer and the hot cap ranges from .020/.5 mm up depending on the size of the motor, a larger motor might have 1/8"/3.5 mm.
Ian S C
Clarification
Posted: Fri Oct 21, 2016 5:01 am
by Alfista
Here is a rough outline : The classic design calls for the swept volume of the displacer to be 1.5 times the (working) volume of the power cylinder. As this ratio increases, the requirement of the temperature differential goes down. Specific output tends to go down as does the rpm range. Engines between with a ratio of 5 : 1 to 30 : 1 may be thought of as medium temperature differential engines, and those from about 50 : 1 to 100 : 1 as low temperature differential engine. As the ratio goes up, the engine must be ever larger to reach the same power level as the smaller, high temperature differential engine.
Here is a link to one of Robert Sier's pages : http://www.stirlingengines.org.uk/modeng/note.html
Re: Is there a perfect ratio between cylinder size.
Posted: Fri Oct 21, 2016 8:26 am
by WildBillCody
Thanks everyone, very helpful.!
Re: Is there a perfect ratio between cylinder size.
Posted: Tue Oct 25, 2016 2:36 pm
by WildBillCody
I just read over that page, very informative, one thing that comes to mind, the tube that runs from the top of the diffuser cylinder to the power cylinder, what diameter should that be? I'm thinking the bigger the better for easier transfer of air?
Re: Is there a perfect ratio between cylinder size.
Posted: Tue Oct 25, 2016 9:46 pm
by thanh-cuibap
I usually make the diameter of the pipe between 2 cylinders about 3 -> 5mm,