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How to create a stirling cold cycle?

Posted: Sat Jan 20, 2018 7:51 am
by Wellington
Can anyone explain the basics or provide a link on how to make a stirling refrigerator.
Thanks

Re: How to create a stirling cold cycle?

Posted: Sat Jan 20, 2018 9:33 am
by Alfista

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).


Re: How to create a stirling cold cycle?

Posted: Sun Jan 21, 2018 1:25 am
by Ian S C
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

Re: How to create a stirling cold cycle?

Posted: Sun Jan 21, 2018 10:05 am
by Wellington
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

Re: How to create a stirling cold cycle?

Posted: Sun Jan 21, 2018 11:21 am
by Alfista
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

Re: How to create a stirling cold cycle?

Posted: Mon Jan 22, 2018 3:46 am
by Ian S C
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

Re: How to create a stirling cold cycle?

Posted: Mon Jan 22, 2018 11:55 am
by Wellington
Alfista wrote:Wellington,

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

Re: How to create a stirling cold cycle?

Posted: Mon Jan 22, 2018 11:56 am
by Wellington
Ian S C wrote:As Wellington says, turn it in the normal direction......
Ian S C
thankyou Ian

Re: How to create a stirling cold cycle?

Posted: Tue Jan 23, 2018 3:54 am
by Ian S C
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