Gamma Stirling Engine Power Piston Bore to Stroke Ratio

[keepleft99]

Hello,
I am designing a Gamma Stirling Engine for a university project. I couldnt find any information on the optimal bore to stroke ratio for the power piston. Is there an optimum ratio for it? At the moment I have gone for a 1:1 ratio. with 30mm diameter.

Thanks for the help.

Andy

[Bumpkin]

Hi Andy. Most of the same considerations apply as to other engines; friction vs. displacement vs. sealing. Flow, dead-space, vibration, packaging, and your own manufacturing skill and available materials figure too. The square bore/stroke ratio is probably common for good reason, but there's nothing written in stone, and for a gamma connected to the cool end of the displacer chamber you have many material choices even including a rubber diaphragm.

A whole other topic, on the other hand, is an ideal ratio of Displacer swept volume to power piston volume. Add in dead space to determine the overall ratio of volume change. This should be less than the absolute temperature difference of the internal working fluid. (How much less seems to be open to debate.)

In my opinion the Gamma type engine is best suited to moderate to low temperature use, where the extra dead space has less effect (as a %) on the lower expansion/contraction ratio.

Disclaimer; All of the above are only random thoughts from a total amateur.

Bumpkin

[Nikhil Bhale]

A whole other topic, on the other hand, is an ideal ratio of Displacer swept volume to power piston volume. Add in dead space to determine the overall ratio of volume change. This should be less than the absolute temperature difference of the internal working fluid. (How much less seems to be open to debate

Bumpkin

This is a new concept/idea for me. Can you tell me the units in which volume has to be measured for the above comparison. Cu mm or cu cm or cu inches.

Regards
Nikhil

[MikeB]

Nikhill - the calculation Bumpkin is suggesting uses a ratio at its core, so the units do not matter.

[santoshdd]

Hi Andi, I am also working on university project of Gamma Stirling engine. Can we work together.