Pistons

[leading edge]

Greetings from South Africa.My name is Corrie and i would like to build a 5KW generator powered by a stirling engine.Would it be better to build a multi cylinder unit or would a twin cylinder work??.What size would the pistons be??? What would be the drawback of making the pistons square instead of round,sounds crazy but if rings are not used square is easier to fabricate.We have a massive invader tree problem and so have plenty fuel.Could someone also guide me as to wether it would be better to go for a gas from wood system to drive a internal combustion engine..Waiting in anticpation.Corrie.

[Aviator168]

Just buy a gasifier and feed the gas to an IC. Or if you want a stirling, there are 5kw commercial stirling engines you can purchase.

[Ian S C]

Square is possible, but can you machine a piston to fit a ?cylinder? with no more than say .0005" out in any direction, a cylindrical shape is easier, bore the cylinder to a nominal size, hone it so it is dead round and parallel, then lap it to a mirror finish. Now make the piston to fit. On a simple Sterling Engine it's best not to use rings. You know it fits when you put it in the cylinder and it slides down under it's own weight(not too fast), and when you put your hand over the end of the cylinder the piston stops, or slows to barely moving. I recommend that you use cast iron for the piston, and for the cylinder, although steel, or stainless steel would be alright.
Ian S C

[Andy]

Hi Corrie, quick guess, is load shedding killing you?
The questions that you ask make me think that you are not familiar with engines of any kind. You are also looking for a cheap solution to your Eskom problem...
Before you waste your time and money I want to give you a heads-up.There are no proper info around to answer your questions, and those that have won't share it. Those that share it, do so because it is what they think, not know. And what they know won't give you 5KW.
Stirling technology that is available to the open market (us mere mortals) is in its infancy. Like any other engine before it, the efficiency if a stirling is a direct result of the tolerances used in manufacturing its components.
I have done tool making in my previous life, there is no way to get the fit perfect between a square piston and its cylinder. Round is going to be the way forward.
The best example of a (potentially) power producing stirling is the GENIOUS Stirling. You will find them on You Tube. They won't share intimate details, but they share enough to give hope to the idea of middle class people having Stirling generators at home.

[leading edge]

Thank you for the input,As i can see Stirling is to varied so i think for the short term i will go with Aviator,s idea of using a gasifier and a ic motor .Will keep you up to date with the progress.

[Ian S C]

leadingedge, I would think that you would be able to pick up an old "hit and miss" engine in SA, this with the gasifier system will run for years at 500-600rpm with little maintainance. Get that up and running, then you can think of building a hot air engine to replace it.
Ian S C