Homemade Engine with Generator

Discussion on Stirling or "hot air" engines (all types)
Alfista
Posts: 91
Joined: Thu Feb 18, 2016 9:14 pm

Homemade Engine with Generator

Post by Alfista » Wed Jul 13, 2016 5:53 pm



Here is a video of my homemade Stirling engine with generator. The engine is based loosely on the Kouhoupt vertical design. It uses classic dimensions for the most part. Kouhoupt was a wonderful designer. The plans, as published, build an engine with a 1.125" bore. They are published by Village Press.
[youtube][/youtube]
This engine has a 3" power piston and a 3.3125 inch stroke in a gamma configuration. I made the displacer by building a wooden buck then covering it with aluminum sheet from beer and pop cans, then turning the ends for it from 4" aluminum discs turned to shape on the lathe. The displacer is all sealed up with high temperature silicone gasket making sealant.

The displacer cylinder is also my design. Unlike the original, I made mine in two parts separated by a teflon insulating ring. This engine is water cooled by thermosyphoning.

The generator is a .5 hp Dayton permanent magnet motor. Rated at 180vdc @1725 rpm.

The flywheel is too small but it was the biggest that I could manage on my 9" lathe. In the original, the uprights are made of aluminum. I made mine of oak with pressed in, oilite bearings.

I am not sure that I have optimised the sprocket ratios. Right now, the ratio is 23:18. 23 on the engine side, 18 on the generator. The output is just over 16v which should work nicely for 12 volt batteries. I plan to try some other ratios soon.

Last edited by Alfista on Thu Jul 14, 2016 5:02 pm, edited 1 time in total.

Alfista
Posts: 91
Joined: Thu Feb 18, 2016 9:14 pm

Engine and generator under load

Post by Alfista » Thu Jul 14, 2016 1:59 pm


Here is a video of the engine running, charging a battery and with an 80 watt load. I changed the 8" flywheel to a 16" flywheel and changed the generator sprocket to 20T. [youtube][/youtube]

Now the ratio is 23:20.

Thanks for watching !

Wayne

Alfista
Posts: 91
Joined: Thu Feb 18, 2016 9:14 pm

Running without a load

Post by Alfista » Thu Jul 14, 2016 3:25 pm


Finally, a short clip of the engine running without a load.
[youtube][/youtube]


Ian S C
Posts: 2142
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: Homemade Engine with Generator

Post by Ian S C » Fri Jul 15, 2016 4:22 am

I have not checked out your vidios yet(I,m on dial up), but you could get a bit more heat in/power out if you used a stainless steel displacer. I'll have a look at the beginning of the week.
Ian S C

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

Re: Homemade Engine with Generator

Post by derwood » Fri Jul 15, 2016 6:29 pm

Nice engine. I don't think it produces 80 watts though.

Alfista
Posts: 91
Joined: Thu Feb 18, 2016 9:14 pm

Re: Homemade Engine with Generator

Post by Alfista » Fri Jul 15, 2016 7:01 pm

No, of course not. If it did, there would be no significant voltage drop.

Ledlights
Posts: 8
Joined: Wed Jul 13, 2016 11:37 pm

Re: Homemade Engine with Generator

Post by Ledlights » Sun Jul 17, 2016 12:28 pm

Hi Wayne,

Very nice work indeed, it looks like a great project.

Have you measured the hot and cold side temperatures? You might be able to push the engine with a bit more delta T? Also, I wonder how high geared you could go with the generator? I didn't notice any drop in revs when you placed it under load so I wonder if you could push it a little harder?

Steve

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

Re: Homemade Engine with Generator

Post by Ian S C » Mon Jul 18, 2016 3:59 am

A couple of suggestions: if you want to try more fly wheel, there is room inside the frame to mount the other FW, that you used in the first video. You could loose a bit of weight possibly on the crank webs, and anything that moves, an ounce/gram here and there all help. I don't know (I'LL guess) I think a light heat fused plastic belt (3 mm/4 mm diameter) might transmit the power you are getting more efficiently, and is good to at least 2000rpm. These motors are never finished if you are prepared to keep modifying it, but a warning, only change one thing at a time. Good work, keep it up.
Ian S C

Alfista
Posts: 91
Joined: Thu Feb 18, 2016 9:14 pm

reply to Ledlights

Post by Alfista » Mon Jul 18, 2016 5:58 am


Ledlights
Thanks for your kind words about the engine. You make a good point about trying to push the engine. In the original of the load test video, the sound quality made it much easier to hear the effect of the generator load on the engine at the moment when the battery is connected to the generator. In the youtube degraded version, that is not so clear. In a previous test, I reach higher voltage before connecting generator to battery but having less torque, overall it did not perform quite as well in the task of battery charging. So I changed the sprocket on the generator from 18 to 20, lowering the generator speed a little but giving more torque. The first video, "Stirling engine with generator" used the smaller flywheel. The 16" flywheel (although a bit too large) gave a nice improvement to the overall running, smoothing out the stroke without reducing RPM.

I have not measured the temperature difference, but had good results from the "seat of the pants" test. After I put up these videos, I carefully cut the lengths of new water lines, (the old ones also had some obstructions) making sure that I had no interruptions in the inclination of the lines. The water stayed a very good temperature in spite of such a small reservoir. I mostly attribute this to the teflon insulator between the hot cap and cold section.


Alfista
Posts: 91
Joined: Thu Feb 18, 2016 9:14 pm

reply to Ian

Post by Alfista » Mon Jul 18, 2016 6:37 am

A couple of suggestions: if you want to try more fly wheel,
You could loose a bit of weight possibly on the crank webs, 

Ian,
thank you for your post. You may not have noticed the last couple videos with the larger flywheel, although a bit too large at 16" it did make a nice improvement. One of the most noticeable improvements that I was able to make in building the engine was adding weight to the power piston crankshaft web in the form of counterweights. It increased the speed of the engine and improved the balance. I may experiment a bit more with it and I have not yet tried adding counterweights to better balance the displacer.

I would reject the notion of replacing the chain drive with a belt drive. Roller chain is more efficient and has less friction. If I had easy access to a lighter gauge chain, then I would try it.

Although I am able to cut my own gears in my shop and although gear drive is a bit more efficient than the roller chain, the chain drive has some nice advantages. It is quieter, less expensive, and makes it super easy to experiment with different ratios. The cost and easy availability of these parts is very attractive. All I had to make were the spocket hubs !


Ian S C
Posts: 2142
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: Homemade Engine with Generator

Post by Ian S C » Wed Jul 20, 2016 2:38 am

I don't think the 16" FW is too big, a slightly larger one like that, running at fairly low revs is better than a smaller, but heavier one. This is what happens to aluminium displacers. Ian S C
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DSC01133 (800x600).jpg
DSC01133 (800x600).jpg (170.21 KiB) Viewed 4870 times

Alfista
Posts: 91
Joined: Thu Feb 18, 2016 9:14 pm

A photo of my homemade engine with generator

Post by Alfista » Thu Sep 08, 2016 10:01 am


Here is a still shot.



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stirlingpower1_resized.jpg
stirlingpower1_resized.jpg (281.34 KiB) Viewed 4598 times

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

Re: Homemade Engine with Generator

Post by Ian S C » Fri Sep 09, 2016 4:10 am

Alfista, have you tried reversing the pulleys, putting the small one on the crankshaft, and big one on the generator, it will reduce the revs at the generator, but allow the motor to run more freely, with more torque at the generator end.
I still think you have about the right size for the flywheel.
Ian S C

Alfista
Posts: 91
Joined: Thu Feb 18, 2016 9:14 pm

Re: Homemade Engine with Generator

Post by Alfista » Mon Sep 12, 2016 6:43 am

Alfista, have you tried reversing the pulleys, putting the small one on the crankshaft, and big one on the generator, it will reduce the revs at the generator, but allow the motor to run more freely, with more torque at the generator end.
Thank you for your reply Ian. Yes, I have tried that combination and several others. I believe that I mention in one of my posts that I slowed down the generator speed in order to allow the engine to run faster. It is an excellent suggestion but already done. Thank you. :wink:




Ian S C
Posts: 2142
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: Homemade Engine with Generator

Post by Ian S C » Tue Sep 13, 2016 1:51 am

I have a winch that I fit to one of my motors, a 1 3/4" bore BETA motor, I can't just remember the gear reduction, I think it maybe something like 60:1, so about 10 rpm with the motor running at about it's best speed for power of 600 rpm, I demonstrate it hoisting a 20L plastic container of water.
Ian S C

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