My last made Stirling engine : an alpha Ross 38 cm3

[Chris_74_fr]

Hi,

Let me presents to you my last engine. An alpha Ross 38 cm3 :

[youtube]https://youtu.be/LLzFi9aZcBM[/youtube]

With this engine, I was curious to see how cold it can makes. I made a try and was very surprised by the temperature it reaches and how quickly it was reached. It is less than indicated in the picture. You can see how at the end of the video.

[youtube]https://youtu.be/_BPUKsU4UTM[/youtube]

I think it can makes much better because the engine was leaking during the test. The cast iron piston and his cylinder was not enough accurately machined. Since, I have made a new cylinder and I have accurately adjusted the piston with it. But I have not yet made a new test. I have to replace the cold aluminium piston and his brass cylinder by a new made of cas iron without seals.

[burnit0017]

Hi, great work, thanks for posting.

[mastrovetraio]

Merci. Surtout pour la video du "faire du froid", assez claire. Chapeau !

[Ian S C]

Well done. when I built a Ross Yoke ALPHA motor, the first thing I did with it was connect it by belt and pulleys to one of my larger BETA motors and after 20 minutes the temperature of the hot cap was - 20*C, no doubt with a more powerful drive motor, a somewhat lower temperature could be obtained. This is the motor, with it's generator, but minus it's radiator, I normally run it this way. There is a cover for the crankcase to allow pressurisation, but I need to fit a seal on the crankshaft.
Ian S C
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[Chris_74_fr]

Thank's :)

Ian S C -> What you say is very interesting for me and confirms to me that my engine has potential. With the cordless drill, the engine was drove at 1000 rpm.-20°C was obtained at 3mn10s and when the battery fails at 4mn08s the temperature was -21,4°C. The most surprising for me is that this engine is not refresh by water and there is no radiator. In despite of that, it manages to evacuate efficiently the heat. And like I says it was leaking... To optimize it I would to buy a thermal camera, to see how the heat is dissipated into the body of the engine in the goal of add radiators at the good place. And work on the sealing of the pistons. The dead volume too can be strongly reduced. Because this engine is made with a few parts of a engine I made three or four years ago (which was very disappointing) and obviously, this parts are not optimized for this engine. And like you, I will make a sealing carter to pressurize it.

What is the displacement of your engine? I precise that the 38 cm3 of my engine is the difference between the max volume and the minus volume. The bore is 39 mm and the stroke 26 mm so the swept volume by a piston is 31 cm3.

[PlaniTechic]

Hi Chris,

This is a really nice engine you made. Thanks for sharing. Do you have any idea how much power it's putting out?
And there's one more question: In your video you mention the use of quadring-rings for sealing the compression piston. What is this exactly and how do you install it in order to get a good sealing without too much friction?
Keep up the good work

Plani

[Chris_74_fr]

Hi Plani,

The quadring ring seals : http://www.google.fr/search?q=quadring& ... 67&bih=693

I don't have yet mesured the power. I will make measurement later. For the quadring, this is not a good solution anyway. I leave that and I am going back to piston without seals. I will make a piston and a cylinder made of cast iron this week to replace the aluminium piston with seal. The problem with seal is exactly what you say. It is very difficult to have a very low friction with a good sealing. In fact it not possible to have the both at the same time. And an another problem is that the more the engine heats, the more the seal rubs.

[Ian S C]

I think my cryocooler experiment was run at about 600 rpm. The cylinders of the Ross Yoke motor are 35 mm bore x 20 mm stroke. The BETA motor that drove it 1 3/4" bore, and a power stroke of 3/4", both motors are about the same power out put. The BETA motor is basically to a design Dyna by James G. Rizzo in volume 1 of "The Stirling Engine Manual".
Ian S C

[PlaniTechic]

Chris,
Thank you for the explanation. I think too it's best to have cast iron pistons and cylinders for this size of engines. It takes just some careful machining to get a very close fit without any unnecessary friction.
Let us know how the new piston and cylinder turned out. It will be very interesting to see the difference.

Plani

[osman]

Thank you for sharing your nice work. I am student and I am doing some research about Stirling engine, I wonder if you can share your design with me. cheers

[Ian S C]

To get the best cooling, the motor being driven needs a very good cooling system it's self, the faster the heat can be conducted away the better. If you use water, and the supply is limited, it wont take too long to boil it, or to put it another way, as well as cooling at one end, you have a heat source at the other.
Ian S C