Heavy or lightweight displaser for more horsepower?

Discussion on Stirling or "hot air" engines (all types)
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Wellington
Posts: 143
Joined: Mon Apr 18, 2016 4:02 am

Heavy or lightweight displaser for more horsepower?

Post by Wellington » Thu Jan 18, 2018 6:14 am

Hello all. i want to build a stirling that produces good horsepower. Should i use a light weight displacer or a heavy displacer?
Thanks All. Regards
Wellington.

Trevor
Posts: 189
Joined: Sun Nov 06, 2016 4:07 am

Re: Heavy or lightweight displaser for more horsepower?

Post by Trevor » Thu Jan 18, 2018 2:58 pm

Hi Wellington
A displacer that is extra light weight is very beneficial. Make it light as possible yet sturdy and do not use aluminium as the displacer as in high heat they will melt or distort badly. Ian can show you some photos of what can happen using alloy as a displacer.
Trev

Ian S C
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Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: Heavy or lightweight displaser for more horsepower?

Post by Ian S C » Fri Jan 19, 2018 2:29 am

Wellington, yes use light weight steel, or stainless steel. Weight just causes extra friction, also the thicker metal conducts heat along it faster than thin metal. The thin metal acts as a regenerator picking up and dropping heat as the air goes past.
As Trev says, don't use aluminium if you want any power out of the motor, it will work as long as you don't use too much heat.
Ian S C
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Wellington
Posts: 143
Joined: Mon Apr 18, 2016 4:02 am

Re: Heavy or lightweight displaser for more horsepower?

Post by Wellington » Fri Jan 19, 2018 12:46 pm

Trevor wrote:Hi Wellington
A displacer that is extra light weight............
Trev
Thank Trevor. will steer clear of aluminium displacer.
regards
Wellington

Wellington
Posts: 143
Joined: Mon Apr 18, 2016 4:02 am

Re: Heavy or lightweight displaser for more horsepower?

Post by Wellington » Fri Jan 19, 2018 12:48 pm

Ian S C wrote:Wellington, yes use light weight steel, or stainless steel. Weight just causes extra friction....................
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Yep. I imagine the friction would go up. On another note: I remember once seeing a german website which sold lots of different stirling engines but can no longer find it. Any ideas which website that might be?
Wellington

Ian S C
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Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: Heavy or lightweight displaser for more horsepower?

Post by Ian S C » Sat Jan 20, 2018 3:39 am

I think the German outfit you are thinking of may be Bohm. I bought one from Jaycar a couple of years ago, looks ok, but a bit feable.
Ian S C
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