How a Stirling Engine Works

Infinia is one of the world’s leading organizations at harnessing the full potential of Stirling cycle machines.

Animation of Infinia Stirling Engine

Originally developed by Robert Stirling in 1816, the Stirling cycle uses a working fluid (typically Helium, Nitrogen or Hydrogen gas) in a closed cylinder containing a piston. Heated on one end and cooled on the other, the expansion and cooling of the gas drives the piston back and forth in the cylinder. The work performed by this piston-motion is used to drive a generator (in Infinia’s case, a patented linear alternator) or to create pressure waves to drive a compression process.

The cycle can be operated in reverse by using the generator as a motor to drive the piston. In this case, the continuous expansion and cooling of the working fluid caused by the piston motion creates a cooling effect. These types of systems are called Stirling coolers (also referred to as cryocoolers) and can maintain temperatures as low as 10 Kelvin (-263°C, and –442 °F)

Our partners at the NASA Glenn Research Center, have put together some excellent educational materials about the science of the Stirling Cycle.