Want to build a Stirling Cycle engine as a test mule for alternative power production. To get started, I'm looking for design specifics such as optimum temperature differential, best volume ratios for hot side compared to cold side. these seem like they should be simple but I can't find anything saying so.

 

Hot side to cold side volume: should it be a simple 1 to 1 ratio or in practice does a slightly different ratio work better?

 

Is a larger temperature differential always better of is there a efficiency sweet spot?

 

Lots more question but answers to these would provide a great starting spot.

The higher the temperature difference, the higher the efficiency, I'd say. The only limit to this trend is that you start losing a lot of efficiency if its so hot that the heat leaks out, but in a simple home made Stirling engine, you should not have to worry about that kind of limit. You just don't want to have so much heat that part of you're engine melts. I've made one before, and 2 cylinders of the same size works fine, the real deciding factor is the cycle you design for you're pistons. I use a sinusoidal cycle in which the hot side is one fourth of a period ahead of the cold side, just because of the simplicity of design using parts made from paperclips, but if you need to increase efficiency further, you can have both of you're piston rods connected to circular tracks in a disc which is spun by their pushes and pulls. You can design the track to have the optimal cycle for a 2 cylinder Stirling engine, which you can find online (I've seen videos on Youtube depicting it, calculated it using a computer program). This would be VERY difficult, however, and you don't get that much worse efficiency just using a regular sinusoidal cycle.

Want to build a Stirling Cycle engine as a test mule for alternative power production.

 

There's nothing "alternative" about a Stirling engine

 

To get started, I'm looking for design specifics such as optimum temperature differential, best volume ratios for hot side compared to cold side.

 

The higher the temperature differential, the more efficient the engine, in theory at least. In practice, a melted puddle of metal is not particularly efficient.

Justonuim, thanks for the help. Do you know if there is an ideal volume for the regenerator compared to the cylinders?

 

Mr. Sceptic, thank you for the info. I realize that Stirling cycle is not new, the alternative part of my plan is the heat source. Since we are not talking internal combustion the Stirling cycle is ideal for my use, since any heat source ought to do. For instance, I'm aware that a company is already trying to develop a solar powered Stirling Cycle generator, but about other sources. Richard Branson is trying to help spur cellulose ethanol, but what about just burning yard waste, trash or methane (sewer gas). Energy is all around us not just light but heat. what if we could harvest heat from the atmosphere, or the oceans? At any rate Stirling Cycle allows me to look at the practicality of different fuels and heat sources using one relatively simple engine.

there are already modular powerstation scale stirling engines in use. again, not really alterative, but mainstream.

The regenerator should be as small as possible to maximize efficiency, but you will have to compromise size with functionality. Personally, I never bothered to make one, I never needed efficiency in my Stirling engine; I was only making it rotate a CD and look nice on my shelf, not perform a task.