| Heat engines |
| Rankine cycle engines |
| Stirling Cycle Engines |
| Brayton Cycle Engines |
| Kalina Cycle Engine |
| More about engines |
The Stirling cycle engine (also called an "external" combustion engine) differs from the Rankine in that it uses a gas, such as air, helium, or hydrogen, instead of a liquid, as its working fluid. Concentrated sunlight, biomass, or fossil fuels are sources potential fuels to provide external heat to one cylinder. This causes the gas to alternately expand and contract, moving a displacer piston back and forth between a heated and an unheated cylinder.