Scaling Stirling Engine?

Discussion in 'General Engine Discussion' started by john_k, May 16, 2019 at 11:59 PM.

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  1. May 16, 2019 at 11:59 PM #1

    john_k

    john_k

    john_k

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    Good day all,

    I have been considering for some time building a Stirling engine but the difficulty has arisen what to use as the displacer piston. The plan suggests an aluminium cigar tube (not an option) so have been looking for a substitute. I have now found a suitable part, however it is rather larger - Ø27mm. than the plan calls for - Ø20mm. I have read that some designs of model engine do not re-scale well (or not at all). Would this apply to the Stirling engine or is it feasible to increase the size to accommodate the larger component? Thanks for your comments and advice.

    cheers John K.
     
  2. May 17, 2019 at 1:28 AM #2

    Longboy

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    Go ahead and build your engine. Stirlings have been modeled with various size cylinders and the operating principle doesn't care.
     
  3. May 17, 2019 at 1:56 AM #3

    Cogsy

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    Not sure about eBay in your part of the world but where I am eBay is full of cheap cigar tubes if you're having trouble sourcing them. From ~$5 for a stainless one LINK , $10ish for 5 aluminium LINK or $15ish for 10 aluminium LINK. The last 2 are even advertised as stirling displacers. I've never heard of them being used for displacers but it does seem like a good/simple way to go.
     
  4. May 17, 2019 at 5:12 AM #4

    Hopper

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    Stirlings seem to scale OK. Especially a relatively small change like you mention. It's best to try to keep the ratio between the swept volume of the power cylinder to the swept volume of they dispacer cylinder about the same. So if you increase the bore of the displacer cylinder by a few per cent, just add about the same percentage to the bore of the power cylinder. But it's not critical.
     
  5. May 17, 2019 at 6:36 AM #5

    minh-thanh

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    Why don't you make the displacer piston with a diameter 20 mm ?
     

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