The Stirling Heat Engine is a heat engine that functions when enough heat is supply as a source to the engine. Robert Stirling invented the engine in 1816. The source can be anything from solar energy, chemical energy, to nuclear energy. The Stirling Engine operates by cyclic compression and expansion of any gas particles (including Noble gas). It relies on the principle of thermal expansion, that gas particles expands (isothermal expansion) when heated and compresses (isothermal compression) when cooled.
Engine operates by cyclic compression and expansion of any gas particles (including Noble gas). It relies on the principle of thermal expansion, that gas particles expands (isothermal expansion) when heated and compresses (isothermal compression) when cooled.
The engine itself composes of a cylinder, a displacer piston (green), a power piston (orange), and a flywheel (rotating disc on the right). The displacer piston consists of about one third the volume of the cylinder. Working gas resides on both side of the displacer piston, and during the operation of the engine both sides always consist gases of different temperature. There is a slight gap between the displacer piston and the cylinder, so gases can exchange freely by pulling or pushing the power piston. When heat is supplied to the bottom part of the cylinder, the bottom portion of the cylinder heats up, causing the gas in that portion to expand, thus pushes the cylinder upwards. Cold air thus slips through the gap and enters the bottom portion of the cylinder; in exchange the hot air goes upwards and enters the rear portion of the cylinder. At this point the displacer piston moves down because cold air now resides at the bottom of the cylinder, this marks as a completion of one cycle. The next cycle begins when the bottom potion air heats up again and pushes the displacer piston upwards.
The Stirling Heat Engine in practice achieves the highest thermal efficiency among all heat engines. The engine does not require much maintenance; it is more reliable and quite when compared to internal combustion engines. Due to the nature of the engine the engine has a low power output, to increase the power output the engine needs to hold up more working fluid (gas), causing the increase to the size of the engine, as well as its production cost.
In modern world application, as the gas prices rises up quickly and people focus more and more about clean and green energy, more people are starting to pay attention to Sirling Engine. Although due to its high production cost and low power output it is not widely adopted by power plants, the engine has a wide use in submarines or space shuttles because of its reliability and quiet operation.
References:
http://www.bekkoame.ne.jp/~khirata/academic/kiriki/begin/general.html