Soda can Stirling engine - 860 rpm

[It's more interesting if you advance past the 2:00 minute mark] This is my second attempt at a simple soda can engine. It will run slowly on one or two tea candles, but on an alcohol flame, as I show in this video, it really flies and I've clocked it at 860 rpm!

The displacer is actually a moving regenerator, a single piece of steel wool trimmed and shaped to fit the soda can and held in place with perforated bottoms from other soda cans. The diaphragm is made of bicycle inner tube rubber, the bottom of a soda can, a bottle cap, and a 1.5" PVC cap trimmed down a bit. It's attached to the cylinder can with a 1/2" PVC elbow.

The crank is of 1/8" stainless steel rod, the flywheel is the lid from a paint can, counterweights are magnets from old hard drives. The smokestack is made from a rolled-up soda can. I used some aluminum foil tape to hold things together.

I found it a bit difficult to get the thing balanced and it's still not quite right, but at least it doesn't jump around too terribly even at high rpm's. A lot of fun to build and even more to run!

Category:

Science & Technology

Tags:

• Coke
• soda
• pop
• can
• Stirling
• engine
• hot
• air
• motor
• alternative
• energy
• external
• combustion
• heat
• regenerator
• AT
• appropriate
• technology
• www.appro-tec.com

[arsacd]

hi sir, could u teach us how to build this engine?

please!

[approtechie]

@arsacd Man, I wish I had time to play around more with these soda can engines and come up with plans and all! Maybe some day I'll do it just for fun, but for now I'm concentrating on my newest larger engine in hopes of producing some significant power. People who are living in difficult circumstances far from the grid need some form of appropriate motive power and I'm hoping to provide a solution for them. The soda cans have been too fragile to consider for this purpose.

[Toerme]

Is there any differences in efficiency if you use diaphragm or a piston?

[approtechie]

@Toerme I much prefer the diaphragm since it reduces the sealing and friction problems a lot. You just have to make sure the diaphragm doesn't have to stretch, or else you lose power doing the stretching. The diaphragm has to be pre-formed to the shape it will take at maximum stroke. And I use rubber, not balloons.

[Toerme]

@approtechie Thanks for answering :D ..another thing I thought about, how would it work if I switched places between cooling and heating? Cooling the displacer cylinder from the bottom and provided heat from above? I thought because heat travels upwards? Never seen a stirling constructed that way..

[approtechie]

@Toerme Yes, you can interchange them but the engine will run in the reverse direction then. Alternatively, as many builders do, just turn the engine upside down - heat the same end but now the heat escapes upward. This is a common technique, but more difficult to get even heating. Turning the engine sideways is easier and even more common.

[gearheadmcneil1]

Its a com for sunkised...lol

[Mr3wheeledbike]

Runs good, must be a ford, taste better must be by coke!

[approtechie]

@BocajBinLadin Actually I cut the top off the cylinder and jammed another can down into it.

[UncleRice00]

That's pretty awesome for a couple soda cans and an erector set.