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How a Stirling Engine Works

How a Stirling Engine Works

A Stirling Engine works by shifting air from one side of an engine where it cools & contracts, and then transferring it to the opposite side of the engine where it heats and expands.During both of these stages the contracting

or expanding air is made to act upon a piston. The piston is pushed during the contraction stage and “sucked” during the contraction stage.The stirling engine is an external combustion engine. Most engines that people see and use everyday are internal combustion engines. Internal combustion engines require a specific fuel ie. a four stroke engine need petrol/gasoline, a diesel engine requires diesel fuel, a jet engine requires kerosene etc.

How a stirling engine works

How a stirling engine works

A stirling engine however can run on almost any fuel source, some of them can actually run in reverse on a cold source of energy as opposed to a hot source of energy.

Types of Stirling Engines

There are several types of stirling engine. The one i find most interesting is the Gamma type. They can be made to run on the heat of your hand, or in reverse on the cold of an ice cube, engines like these are called low temperature differential stirling engines (LTD Stirlings) and are a great toy and a masterpiece of mechanical engineering. I have one at home that runs off the excess heat from my television and quietly ticks over like a kinetic sculpture.


2K56 with con-rod

2K56 with con-rod

The Invention of the stirling engine & how it works

The original stirling was invented in 1816 by Robert Stirling. At that time steam engines were

just in their infancy and the metals of the time were not as strong or reliable as they are nowadays, as a result many people lost their lives due to steam engine boiler explosions. Robert Stirling took it upon himself to design a low pressure engine and came up with the stirling cycle engine.

Unfortunately, while the engine was very quiet and used less fuel than steam engines of the time, it lacked the power to be widely used during the industrial revolution or for any transport purposes. Even to this day no major use has been found for the stirling engine in all their forms. Modern diesel engines are now more efficient than the most efficient Stirling engine ever built, although stirling engines do not have anywhere near s much money or resources pumped into their development as diesel engines would.

In the 1970s, Ford, GM and the American Motor Company spent millions of dollars developing a family sized car powered by a stirling engine. The reason it did not sell is because unlike most other engines, a stirling engine needs to be heated up for a short while before it will run, obviously people do not want to have to start a fire underneath their cars every morning before they go to work.

Various types of Low temperature differential stirling engines, kits and plans are available from another website here.

Below is the video showing how an LTD Stirling engine works in more detail.

Video showing how a stirling engine works



Stirling Engines will undoubtedly undergo some more transformation in the near future. They are currently being developed my MSI, a company that designs and builds PC motherboards. They are incorporating stirling engine technology into their motherboards, whereby the heat of the motherboard powers the stirling engine which then cools the motherboard by means of a fan attached to the flywheel.