How it works

One of the unique characteristics of the Stirling engine is that it has the same amount of gas in the system at any point. So in order to make it work we add heat, hot or cold, to cause a cycle. By adding heat it will cause the gas to expand pushing it to the cold side of the engine where it cools and compresses the gas and repeats. 

The cycle can be put into a general form. 

• Heat expansion
  • Heat is inputted up from an outside source,ex: solar,candle,warm body of some sort..., causing an expansion of the gas pushing the piston
• cooling
  • As the piston moves up pushing the gas it moves the gas to the cooler side 
• compressing
  • The gas is now compressing and heat is being pulled out of the system letting the piston fall back down
• heating
  • the cycle then repeats

Stirling Cycle

The Stirling cycle is what gives the engine its name. This is the pressure vs volume graph of the cycle: 

• ​1-2:​ Is an isothermal expansion. This is where the heat is constant and the cylinder volume increases
• 2-3: Is an isochoric compression. This is where heat is removed but the volume of the cylinder stays the same.
• 3-4:Is an isothermal compression. This is where heat is constant and volume is of the cylinder is decreasing
• 4-1: IS an isochoric expansion. This is where heat is added back into the system but containing a constant volume in the cylinder.

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