General discussion of Stirling Engine part 3

3. Stirling Cycle

The working principal of the Stirling engine and P-V diagram of Stirling cycle are shown in follows figure. The Stirling cycle is consisted by 4 thermodynamic processes; Isovolumetric heating process(on P-V diagram, descrived by 1-2) , Isothermal expansion process(2-3), Isovolmetric cooling process(3-4), and Isothermal compression process(4-1).

Animation（The browther JAVA^(TM)1.1.X avairable is required.）

1-2; Isovolumetric heating process

The piston keep to stay on top. The pressure of working gas in cylinder is increase by heating.

2-3; Isothermal expansion process

The working gas expand with keeping its temperature. The engine occuer the work.

3-4; Isovolmetric cooling process

Now the piston keep to stay on bottom. The pressure of working gas in cylinder is decrease by cooling.

4-1; Isothermal compression process

The working gas is compresed with keeping its temperature.

The heat wasted in the Isovolmetric cooling process(3-4) is equals supplyed heat in the Isovolumetric heating process. Therefore using the heat wasted in the Isovolmetric cooling process to the heat for the Isovolumetric heating process, by adopting regenerator, cycle's thermal efficiency became follows equation

Where Th is higher temperature and Tc is lower temperature. This efficiency equals to efficiency of Carnot cycle, therefore Stirling cycle has the highest efficiency.

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