Stirlingengineforum.com

Hello,

I am a mechanical engineering and for my final project I am designing a Stirling engine. I choose to base my model off of the General motors GPU-3 Stirling. This Stirling engine is a rhombic beta type.

My question is I am trying to design the regenerator for the engine and was looking to see if someone point me into the right direction? I am curious on what materials and how I should design it. We will be using the machine shop to design all the parts after modeling and doing analysis on them in SolidWorks.

Thanks for all the help these forums have helped us tremendously so far.

I'm not an engineer, but the few things about regens I do know are:

- Packing should have a high surface area (packed metal discs with holes or steel wool/coarse swarf are common choices). Metal is the most common choice as it's easy to shape and conducts heat well, though in theory something non-conducting could work.
- Don't make it restrict gas flow too much. You should be able to blow through it and maintain a flow of air, though there will always be a slight resistance. If it restricts air too much it is probably over-packed. On the other hand, loose packing could move and cover the exit hole like a flap valve so try to retain the packing in place as much as possible.
- Don't make it too large. Big air spaces contribute to "dead space" and sap power from the engine. The definition of "too large" depends heavily on your engine, so just try to keep it compact in your design.

Wikipedia has a nice short description of how a regenerator works. You can find the article here:
http://en.wikipedia.org/wiki/Stirling_engine

Jim Larsen
http://stirlingbuilder.com

Most people use stainless steel wool. Can be found at the dollar store.

I have been wondering about a rotary regenerator, made from a disc drive platter (has its own bearings and motor). Basically, you have the advantage of a larger surface area even if you only use a quadrant of it. The surface tension and fluid friction against the rotating plates could be an issue if it opposes the rotation of the discs, but perhaps this can be remedied by twin one way valving.
It might even be used as a generator, like a tesla steam turbine. Fluid friction would spin it, and with the one way valving, it just might work.
Just a thought.

A good material is stainless steel shim stock, about .002" is a good thickness. Ian S C