Alpha type stirling engine Problem

Discussion on Stirling or "hot air" engines (all types)
imranakhtar
Posts: 3
Joined: Sun Jan 01, 2017 3:41 am

Alpha type stirling engine Problem

Postby imranakhtar » Sun Jan 01, 2017 8:05 am

Hey i have built an alpha type stirling engine using two honda 70cc cylinders and their pistons. Using the same crankshaft (modified it to have two connecting rods). The problem is that it does not run not matter how much heat i provide it does not spin more than 2-3 rpm by rotating the flywheel by hand while heating and friction b/w pistons is not that much, less than the normal engine because i have done some finishing and leakage is the same as in any motorcycle engine cylinder due to same rings and arrangement. I got the design from a video on youtube (https://www.youtube.com/watch?v=u_b8tB54Zj8) and tried to build it according to the design and availability of resources. I am using iron chips from lathe machine in regenerator. Here are some of its pictures
http://imgur.com/3JFnaps
http://imgur.com/KKNW9IW
Please suggest some improvements and what could go wrong with the engine. :cry:

Aviator168
Posts: 308
Joined: Tue Feb 08, 2011 2:29 pm
Location: Brokeville, NY. USA

Re: Alpha type stirling engine Problem

Postby Aviator168 » Sun Jan 01, 2017 12:01 pm

Please provide data for the following questions to start.
What is the total volume (including dead volume) of the engine?
What is the hot/cold gas temperature? I am not talking about heater and water temperature. I am talking about the temperature of the gas in hot and cold cylinder respectively.

cbstirling2
Posts: 113
Joined: Sat Dec 17, 2016 9:35 pm

Re: Alpha type stirling engine Problem

Postby cbstirling2 » Mon Jan 02, 2017 7:57 am

I think he's looking for a ballpark advice.
I don't know much about alphas, with head off, your engine must spin very freely.
On one of my models was running poorly, so I lubrication with graphite and now it runs really good. I suspect those motorcycle Rings might be a problem.
CBStirling2

Aviator168
Posts: 308
Joined: Tue Feb 08, 2011 2:29 pm
Location: Brokeville, NY. USA

Re: Alpha type stirling engine Problem

Postby Aviator168 » Mon Jan 02, 2017 4:22 pm

The bigger problem is. If your engine does not run because of seal ring friction, the engine is not produceing much power anyway.

derwood
Posts: 113
Joined: Sat Dec 11, 2010 10:15 pm

Re: Alpha type stirling engine Problem

Postby derwood » Mon Jan 02, 2017 6:52 pm

You need to replace those pistons with graphite pistons.

Ian S C
Posts: 1970
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: Alpha type stirling engine Problem

Postby Ian S C » Tue Jan 03, 2017 3:52 am

Close fitting cast iron pistons without rings might be more durable in a power producing motor. Ordinary piston rings have no place in a Stirling Engine. I put an answer to some of your questions in another site, covering the regenerator.
Ian S C

cbstirling2
Posts: 113
Joined: Sat Dec 17, 2016 9:35 pm

Re: Alpha type stirling engine Problem

Postby cbstirling2 » Tue Jan 03, 2017 9:43 am

Ian, what do you think is a lifetime of a graphite piston? What about Teflon?
CBStirling2

Ian S C
Posts: 1970
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: Alpha type stirling engine Problem

Postby Ian S C » Wed Jan 04, 2017 1:29 am

Don't know about Teflon or graphite, but I do know that cast iron in a steel bore(a bit of bored out galvanised water pipe has done over 2000 hrs with no measurable wear, that was my second motor built in 1994. It has just lately developed a leak in the hot cap that will need some major repair. Ian S C
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derwood
Posts: 113
Joined: Sat Dec 11, 2010 10:15 pm

Re: Alpha type stirling engine Problem

Postby derwood » Wed Jan 04, 2017 10:22 am

cbstirling2 wrote:Ian, what do you think is a lifetime of a graphite piston? What about Teflon?


If your cylinder walls are smooth the piston will last a very long time. Ive been using the same piston for years. It is also very easy to machine.


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