Stirling Engine

A Stirling engine, which is a heat engine of external combustion piston engine type whose heat exchange process allows for the near ideal efficiency in the conversion of the heat into the mechanical movement by the following Carnot cycle as closely as is practically possible with the given materials.

Stirling engine’s invention is credited to Scottish clergyman Rev. Robert Stirling in 1816 who made significant improvements to the earlier designs and took out the first patent on it. Robert Stirling was later assisted in its development by his engineer brother named James Stirling.

The inventors sought to create a safer alternative to steam engines of the time, whose boilers will often exploded due to the high pressure of steam and the inadequate materials. It will convert any temperature difference directly into the movement.

The Stirling engine will works by repeated heating and cooling of usually sealed amount of working gas, usually air or other gases such as hydrogen or helium. This is accomplished by moving the gas between hot & cold heat exchangers, the hot heat exchanger being a chamber in thermal contact with an external heat source, for e.g. a fuel burner, and the cold heat exchanger being a chamber in the thermal contact with an external heat sink, for e.g. air fins.

The gas will follow the behavior described by gas laws which describe how a gas pressure, temperature and the volume are related. When the gas will be heated, because it is in sealed chamber, the pressure rises and this

acts on the power piston to produce a power stroke. When the gas will be cooled, the pressure drops and this means that less work needs to done by the piston to recompress the gas on the return stroke, which will be giving a net gain in the power available on shaft. The working gas flows cyclically between the hot and the cold heat exchangers.