How to create a stirling cold cycle?

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

How to create a stirling cold cycle?

Postby Wellington » Sat Jan 20, 2018 7:51 am

Can anyone explain the basics or provide a link on how to make a stirling refrigerator.
Thanks

Alfista
Posts: 79
Joined: Thu Feb 18, 2016 9:14 pm

Re: How to create a stirling cold cycle?

Postby Alfista » Sat Jan 20, 2018 9:33 am


If you drive the engine in the forward direction, the displacer will drop in temperature. According to Sier, it was first described by William Thomson (1847).


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

Re: How to create a stirling cold cycle?

Postby Ian S C » Sun Jan 21, 2018 1:25 am

After I built my Ross Yoke ALPHA motor, I joined it via a belt drive the one of my other motors, and over about 20 minutes I let them run. The ambient temperature at the time was +20*C, and at the end of the test, the end of the hot cap on the ALPHA motor was -20*C, a drop of 40*C, no doubt that if it was driven harder, the temperature would have been greater. A small industrial sized cryocooler(reversed Stirling Engine) uses a 10hp electric motor.
Ian S C

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

Re: How to create a stirling cold cycle?

Postby Wellington » Sun Jan 21, 2018 10:05 am

Ian S C wrote:After I built my Ross Yoke ALPHA motor, I joined it via a belt drive the one of my other motors, and over about 20 minutes I let them run. The ambient temperature at the time was +20*C, and at the end of the test, the end of the hot cap on the ALPHA motor was -20*C, a drop of 40*C, no doubt that if it was driven harder, the temperature would have been greater. A small industrial sized cryocooler(reversed Stirling Engine) uses a 10hp electric motor.
Ian S C


Thanks again Ian. If i understand you correctly, no alterations are required. you just drive a stirling backwards.
All the best

Alfista
Posts: 79
Joined: Thu Feb 18, 2016 9:14 pm

Re: How to create a stirling cold cycle?

Postby Alfista » Sun Jan 21, 2018 11:21 am

Wellington,

If you drive a gamma engine in the direction of normal rotation, with the displacer leading by 90 degrees of crank rotation, then the normally hot end of the displacer will become colder. In an alpha engine, if you drive the engine in the direction of the one piston leading the other by 90 degrees (instead of the other direction where a piston would lead by 270 degrees), then the leading piston will cool.

Wayne

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

Re: How to create a stirling cold cycle?

Postby Ian S C » Mon Jan 22, 2018 3:46 am

As Wellington says, turn it in the normal direction. The cold end will get hot, so good cooling is required, liquid cooling is best, but good air cooling will do quite well. If you build a motor just for cooling, make the crankshaft and con rods heavier, and make the whole motor generally heavier, and you can tighten up the clearances a little, and use light piston rings if need be.
Ian S C

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

Re: How to create a stirling cold cycle?

Postby Wellington » Mon Jan 22, 2018 11:55 am

Alfista wrote:Wellington,

If you drive a gamma engine in the direction of normal rotation, with the displacer leading by 90 degrees...........


Thanks Wayne

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

Re: How to create a stirling cold cycle?

Postby Wellington » Mon Jan 22, 2018 11:56 am

Ian S C wrote:As Wellington says, turn it in the normal direction......
Ian S C


thankyou Ian

Ian S C
Posts: 2045
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: How to create a stirling cold cycle?

Postby Ian S C » Tue Jan 23, 2018 3:54 am

If you did happen to drive it in the "wrong" direction, the hot cap would heat up, and the cold end would cool. I got my LTD motor to run in reverse by cooling the bottom, and heating the top.
Ian S C


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