Stirling Engine

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My project is a Stirling engine, made with recycled stuff. I have never found a better use for discarded exercise machines than conversions, beautiful flywheels, bearings and other assorted hardware. Just reconfigure the position of the existing parts, add a few extra parts... The unit is 80% done and estimated completion is March 1 2015. The Stirling engine will produce 100 watts of electricity, 100 gallons of hot water at 160 degrees and heat the cabin it is located in. Thank you for following the project.

The Unit is a beta type stirling configuration and it uses a rhombic drive to move the displacer and piston with a 90 degree phase relation. The first picture is a modified exercise bike with the flywheel moved to the pedal crank shaft. The gears are starter ring gears for small gasoline engines. The second picture is the water cooled cylinder and piston. I used an old tractor cylinder and cut off the top portion. A thin stainless steel sheet wraps around the fins. Cold water enters the fins at the bottom and exits at the top through a 1/4 inch copper tube. The third picture is the heat tube . Fire will impinge directly on this tube. . The displacer is constructed using stainles steel screen and will be filled with stainless steel scrubbies purchased at my local box store.

The displacer rides on a shaft that is attached to the threaded end of the main tube. This allows the displacers clearence to be very close to the main tube.

The piston:

Two teflon rings are cut into the steel piston. The piston is held in perfect alignment by the welded piston bracket. The alignment of this part is very important for long lfe of the engine. You can see the gland which is a 3/4" npt flare and nut used in propane applications. I machined a teflon seal that fits into the nut .

By tightening the nut the seal is 100% and the friction against the shaft is very low.

Insulator Rings;

This material is a fiber board used under ceramic tiles. It machines easily but I cut it and sand it wearing a dust mask. I have used it in many projects.

In the final assembly I will seal the unit with high heat silicone rubber. In addition to the fiber insulator a second insulator made of a hardwood pictured above is used. An aluminium ring clamps the insulator assembly together.

Here the cylinder has been assembled and insulated from the heat tube.

I wanted to show what is taking place inside the engine for one revolution of the flywheel. The first picture the piston is fully extended and the displacer is fully extended. The third picture the piston and displacer are fully retracted.

These two pictures above show the piston a displaced position at 90 degrees. The Brass nut on the displacer shaft allows ajustment of the displacer.

These two pictures above show the piston and displacer at 180 degrees. The displacer fits right into the piston.

The displacer is packed with 18 stainless steel scrubies in the larger section. When the displacer is complete I will weigh it and record the data .

  • 1
    Step 1

    1. One of the most important design criteria in constructing any stirling engine is the transfer of heat through the material that connects the cold portion to the hot portion. The cold and hot sections must be insulated from each other. Ideal conditions heat should only transfer through the working gas that is the air,nitrogen or helium. The amount of heat that will transfer through the gas is a factor in the thermal efficency of the engine.

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Joseph Lavoie wrote 02/25/2015 at 18:12 point

Ryan, I live On beautiful Francoise Lake, near Burns Lake. Burns Lake is our closest town.

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Ryan Barber wrote 02/25/2015 at 17:37 point

Hey Joseph,

If you don't mind me asking, where in BC are you? I'm also living in a small cabin in BC and my brother in law and I have talked about building sterling engines coupled to our wood stoves for a couple years now.

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Joseph Lavoie wrote 02/25/2015 at 17:16 point

The british thermal units or BTU required to heat the cabin are based on a 60 degree  F. day . This means that when the temperature out side drops below 60 degrees F. , we need to add heat. The cabin I am using for a test will be less that 600 sq feet, and well insulated. The wood burning unit that I am using will produce 6000 to 10000 BTU per hour. Your question is a very good one, I may have to open a window or two when the unit is running full out. 

The color is the finishing touches and I have not committed a scheme for it yet. Thanks for your interest in my project. Joseph.

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pmcdonald7734 wrote 02/25/2015 at 03:44 point

How  big is the  cabin it's going in ,what colour  will you  paint it?

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