Stirlingengineforum.com

Hello fellow Stirling Fanatics!

I am in the process of designing a small but torque-y v-twin Alpha Stirling engine and I need some guidance as I move forward. I've perused the forum for a few months now, and have yet to find the exact information I'm looking for. Hopefully you can help!

Ideally, I would like to use a 1.5" diameter power piston; should I use this diameter for both pistons? (From what I've read thus far, I'm still confused as to the difference in calculations between alpha engines with 2 pistons vs beta/gamma engines with a piston and a displacer).

I have yet to define the stroke, as I am unsure of my calculations. Right now, I'm guessing the stroke will be about 2". Torque is more important than high rpm for my needs. Can you help me determine a torque-y stroke? How about the volume of my cylinders? Also the ideal swept volume?

FYI, the hot piston will be heated between 200F and 400F (but usually at 350F), while the cooling piston will slowly raise in temperature from 100F to 200F. Is this enough heat differential to get my engine to run? Please advise.

I'd like my engine to run somewhere between 500 and 1000 rpm; the slower the better. Do you have any advice how I can design the engine to run low RPMs?

Any advice would be greatly appreciated. Thank you in advance.

TJ4Stirling

TJ4Stirling, first, if you want any power out of you motor 200*F to 400*E is not enough, you should be looking at 1000*F to 1300*F, a dull red heat.
I'd recommend 1" to 1.5" for the stroke, and as the stroke lengthens so should the length of the connecting rods, to keep the angle of thrust down, and there by the side thrust on the pistons, this helps reduce the friction.
Both pistons are the same diameter. The hot piston has a cap on it, called a Heylandt Crown, this keeps the direct heat away from the piston its self. Both pistons should weigh as near as possible, the same.
An ALPHA motor has two fitted pistons, GAMMA, and BETA motors have one fitted piston, and a displacer.
Why do you want low speed? If you want any power, aim for 1000 to 2000 rpm, free running, and your best power should be some where around 1/3 to 1/2 of that.
200*F would be what is known as a low temperature differential motor, it is slightly different in its ratios, and usually run at 60 to 100 rpm with only enough power to turn the motor over. Ian S C