The Stirling Engine
Back to Basics: The Stirling engine is simple, efficient, quiet, and can use virtually any heat source
Originally conceived in 1816 as an industrial prime mover to rival the steam engine, the Stirling engine's practical use was largely confined to low-power domestic applications. The Stirling engine is noted for its high efficiency, quiet operation, and the ease with which it can use almost any heat source.
Combining modern technology with this simple design offers considerable promise in helping solve many of today's energy problems. [with video]
Compatibility with alternative and renewable energy sources has become increasingly significant as the price of conventional fuels rises and continued climate change concerns. The engine is currently generating interest as the core component of micro combined heat and power (CHP) units over less efficient and more dangerous steam systems.
A beta Stirling (shown above) has a single power piston arranged within the same cylinder on the same shaft as a displacer piston. The displacer piston is a loose fit and does not extract any power from the expanding gas but only serves to shuttle the working gas from the hot heat exchanger to the cold heat exchanger. When the working gas is pushed to the hot end of the cylinder it expands and pushes the piston.