Stirling engine as college project

Discussion on Stirling or "hot air" engines (all types)
severin
Posts: 6
Joined: Tue Mar 19, 2013 4:55 am

Re: Stirling engine as college project

Postby severin » Thu Apr 18, 2013 12:28 am

We don't know what you mean by motifying the hot piston? Why would we need to modify it with our engine type?

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

Re: Stirling engine as college project

Postby Ian S C » Thu Apr 18, 2013 2:32 am

The motor in the animation is an ALPHA type,which is fitted with two pistons. The cold piston is conventional, but the hot one needs a fitting similar in form to a displacer, this is to keep the heat away from the crown of the piston, to keep the temperature at that end as low as possible. The two complete pistons should weigh as near as they can to equal. Ian S C

vamoose
Posts: 272
Joined: Tue Jul 03, 2012 12:16 am
Location: Australia

Re: Stirling engine as college project

Postby vamoose » Fri Apr 19, 2013 2:03 am

Guys
Here are some videos of An Andy Ross based design, ALPHA Engine (90 deg V) with a 'Heylandt Crown' as mentioned by Ian.

http://www.youtube.com/watch?v=3y5X11MXsRc

http://www.youtube.com/watch?v=5pdqDQwehlk


Here is a link to Andy Ross's free E-book (its worth reading some sections multiple times, as they are full of very valuable information)

http://stirling.atw.hu/MSE.pdf

The Heylandt Crown and longer cylinder wall also has the benefit of increasing the surface area on the hot side, for increased heat exchange, without increasing dead space 'too much'.
vamoose

PS. the guy in the video is enthusiastic with his explanations, but doesn't really seem to understand too much about Stirling engine operations (not that i claim to be an expert myself).
Last edited by vamoose on Sat Apr 20, 2013 9:09 pm, edited 1 time in total.

Chriske
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Joined: Sat Oct 02, 2010 1:24 am

Re: Stirling engine as college project

Postby Chriske » Sat Apr 20, 2013 6:34 am

Hi,

indeed as Ian already wrote : You didn't pick the simplest motor to start with..!

Some of Andys' engines, he will answer all questions but will not support them anymore. Meaning there are no more casted crankcases available anymore for these 'old' engines. That's what he told me by mail.
I would go for Andy's B-20 instead, that's what he proposed to do a while ago when I myself was informing on that B-15.
This B-20 is by far easier to build and more powerful compared to his B-15. Some say this B-15 engine will produce a 100+ watts output... don't believe it, just ask Andy..! It will produce maybe and if well made some 10 to 15 watts, pressurized it will produce about 30 watts.

Anyway I have plans of Andy's B-20 converted to metric (with Andy's permission) I already sent him a copy. Already started building this B-20 myself, but on hold because of all these Open door preparations in our school next month (May 5). I had to redraw the crankcase, made it out of barstock. When finished and build I will send my final (metric) drawings to Andy. If you're interested I'll send you a copy of these drawings. Caution...! this metric B-20 version has not been built yet...! So no guarantees...!

His Double V engine is two B-20 engines operating on a common crankshaft.
http://www.youtube.com/watch?v=0ix_rHxU54w


Chris
Mijn thuis is waar mijn draaibank staat...

Chriske
Posts: 86
Joined: Sat Oct 02, 2010 1:24 am

Re: Stirling engine as college project

Postby Chriske » Sat Apr 20, 2013 6:59 am

Severin,

I teach in a small technical school Duffel (Belgium).
The kids I work with are age 14 to 18 years old. They all very much like to work on these projects. They all work in groups, not as individuals, and because of that they like working in 'my' workshop. In fact they look forward to it every single day...!
I wish more colleagues would also build these engines instead of a hammer or a plumb line.

Chris
Mijn thuis is waar mijn draaibank staat...

severin
Posts: 6
Joined: Tue Mar 19, 2013 4:55 am

Re: Stirling engine as college project

Postby severin » Mon Apr 22, 2013 10:59 am

Okay, we get what you guys say... Well we're almost done building our stirling engine and we changed bits and parts during it. We've tweaked it from advice from you guys, and we hope it is going to work properly, if we'll upload videos and pictures :).

Thanks!

And that's sounds awesome Chriske, we're also a techical school, more like a technical college :).

Ian S C
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Location: New Zealand

Re: Stirling engine as college project

Postby Ian S C » Tue Apr 23, 2013 3:28 am

Got my fingers crossed for you, if you are as free from friction as you can be, have the minimum of leaks, you have a very good chance of it running ok. Ian S C

vamoose
Posts: 272
Joined: Tue Jul 03, 2012 12:16 am
Location: Australia

Re: Stirling engine as college project

Postby vamoose » Tue Apr 23, 2013 6:39 am

Image+1
Keep us posted

magnustraun
Posts: 5
Joined: Thu Mar 14, 2013 12:56 am
Location: Denmark

Re: Stirling engine as college project

Postby magnustraun » Tue Apr 23, 2013 9:42 am

https://www.dropbox.com/s/d70jfqvwxsdb4pd/Photo%2023-04-13%2013.42.33.jpg

Hey guys this is what it looks like so far. hope you can open the picture.
btw.the connection rods points beside the cylinders because we haven't got the pistons yet.
have a nice day

theropod2
Posts: 147
Joined: Tue Aug 16, 2011 5:05 am

Re: Stirling engine as college project

Postby theropod2 » Tue Apr 23, 2013 4:17 pm

magnustraun wrote:https://www.dropbox.com/s/d70jfqvwxsdb4pd/Photo%2023-04-13%2013.42.33.jpg

Hey guys this is what it looks like so far. hope you can open the picture.
btw.the connection rods points beside the cylinders because we haven't got the pistons yet.
have a nice day



Hey,

Is it this motor?

[img=center]https://photos-2.dropbox.com/t/0/AAB1Fnxj6L9JmbcKz78p4Ho8fQ9qKoPiz8NaJIiYVYu_8A/12/12119272/jpeg/1024x768/3/1366765200/0/2/Photo%2023-04-13%2013.42.33.jpg/jdLuils3vHLop3HGI4pMWJczRdfz-lgWk4RS8xJ5WOM[/img]

Click on quote to see how I did that. I just linked to your image (the stuff inside the [] brackets)

What are the two long "arms" along side the cylinders?

R

ETA: Would a cross support between the "rails" supporting the cylinders be advisable? The stresses between that 90* arrangement might be an issue.

Ian S C
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Location: New Zealand

Re: Stirling engine as college project

Postby Ian S C » Wed Apr 24, 2013 3:24 am

What are you going to have as a flywheel, by the look of the photo I'd be looking at 150 mm diameter more or less, and about a Kilogram weight. Ian S C

severin
Posts: 6
Joined: Tue Mar 19, 2013 4:55 am

Re: Stirling engine as college project

Postby severin » Wed Apr 24, 2013 4:11 am

As explained the two arms are outside of the cylinders as we are still waiting for our pistons, they will be mounted when we get the pistons.

Our flywheel has a diameter of 150mm. The weight is adjustable as more weight can be added to the flywheel, the minimum weight of the flywheel 1,2 kg. Note though that we have two flywheels.

magnustraun
Posts: 5
Joined: Thu Mar 14, 2013 12:56 am
Location: Denmark

Re: Stirling engine as college project

Postby magnustraun » Wed Apr 24, 2013 6:39 am

https://www.dropbox.com/s/cxwiz3duvzm9u4c/Photo%2024-04-13%2015.12.45.jpg

Hej guys finally we got the pistons (it's the one in the picture) it is about 1 kilogram and should fit in to the system aften a small modification (it's 110 mm in diameter and the cylinder is only 108mmbut we got the tools! Any last suggestion on the wight of the flyweel? Have a nice day!

magnustraun
Posts: 5
Joined: Thu Mar 14, 2013 12:56 am
Location: Denmark

Re: Stirling engine as college project

Postby magnustraun » Wed Apr 24, 2013 7:42 am


Ian S C
Posts: 1464
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: Stirling engine as college project

Postby Ian S C » Thu Apr 25, 2013 3:27 am

Don't take this too badly, but that looks like a piston for a diesel engine of considerable horse power, it's very heavy, and has piston rings that you do not want. The cavity in the crown is just dead space, you'v got to remember that your motor is going to have less power than a low powered lawn mower.
If your pistons going to be that weight, your two 1.2Kg flywheels might not be big enough, you could keep that weightbut increase the diameter.
Is the piston cast iron, or aluminium ? Ian S C


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