> Interesting site with animated sterling engine
>
> http://www.keveney.com/Vstirling.html
>
> This has to be one of the better descriptions on how a Stirling 
> engine
> works.

It's good. But may be misleading as that is only one Stirling 
configuration - most have one power piston and one "displacer" which 
is NOT acted on by the gas but instead is used solely  move gas 
between hot and cold spaces at appropriate times.

Arguably *THE* most important feature of a  Stirling engine is the 
regenerator. This is a through flow heat exchanger. When cold gas 
flows into it from the cold side it picks up heat left from prior hot 
gas which has flowed through it in the reverse direction and leaves 
behind coolth. When hot gas subsequently returns in  the opposite 
direction it leaves behind heat energy and picks up coolth. The 
performance and efficiency of a Stirling engine live and die with the 
regenerator quality. It ideally has infinite thermal capacity,. zero 
dead volume and no pneumatic resistance. It has zero thermal 
resistance at right angles to the gas flow and infinite thermal 
resistance in the direction of the gas flow. Clearly in practice 
compromises must be made.

Brief operation summary:

- Cold gas flows from cold to hot space picking up heat left in 
regenerator and then being further heated by hot side heater. Gas in 
hot side expands and pressure of the whole system rises equally.

- Piston is driven by expanded gas.

- Hot gas flows from hot side to cold side via regenerator, leaving 
heat in regenerator and being cooled by cold side cooling. Gas in cool 
side contracts and pressure in whole system drops.

- Piston is driven by the contracted gas.

Cycle repeats.
All Stirling  engines work like this.


        RM



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