A stirling is a highly efficient engine that dosen't work by combustion and is almost noiseless.It uses the energy that is produced by a gas that expands or contracts as its temperature changes.Stirling engine has a cold side and hot side. the cold side is kept cold and the hot side is kept warm.If you happen to switch the cold sides and hot sides the engine would just spin in a diffrent direction. What make stirling engins so great is the fact that they produce no noise, no emisions and can't explode.Stirling engines has the potential to achieve the highest efficiency of any real heat engine.Certain types of stirling engines can use a regenerator. A regenarator is a device that boosts the effiecency of a stirling engine. A regenarator is a simple device and is usauly made with wire mesh and inserted in the pipe that connects the hot side and cold side of a stirling engine. It works by absorbing heat when the air flows from the hot side to the cold side and then gives the absorbed energy back to the air when the air is moving back to the hotside again.
There are three distinct types of stirling engines.Namely Alpha Beta and Gamma
The first type is an Alpha stirling.
Alpha stirlings have two seperate power pistons in seperate cylinders, one hot piston and one cold piston. This type of stirling engine has a great volume to power ratio but has technical issues with the seals in the hot piston failing due to the high temperatures.The pistons in a Alpha stirling is offset by 90 degrees.I found this great animation at
http://www.keveney.com/Vstirling.html. The green grid in the pipe connecting the two pistons is a regenerator
The second one is the Beta stirling.
In a Beta stirling have two pistons in one cylinder. The first piston is a air tight power piston and the second is a losely fitted displacment piston.The displacement piston only displaces the air fron the hot side to the cold side and vice versa.Notice the 90 degre difference on on the flywheel between the two pistons below.90 degrees is a golden rule in stirling engine and they all feature it in some way or the other.
I got this image from
wikipedia.
The third is the Gamma stirling.
An Gamma stirling is almost indentical to Beta stirling and the only difference is that there pistons have their own seperate cylinders and they both still share the same flywheel.
Other types
There are other types of stirling engines too.I'm not going to go much into this types because most of them are mainly concept and patenets , but the most notable in this group is the Fluidyne engine and the free piston Stirling.
Stirling engines are use in cryocoolers(this happens when you attach a motor to the shaft causing the pistons to move and heat the hot side and cools the cold side)to reach very low temperatures.
Stirling engines are used on a large scale to use solar energy and convert it to electricity with the help of generators.Here's a
LINK to large scale project that uses stirling engine to use solar enery.
Stirling engines are also used as a heatpump(very much like crocooling just at room temperature).MSI (Taiwan) recently developed a small stirling engine that cools personal computer chips.As soon as the sirling starts heating up it drives a fan that cool the chip. I realy love this use because it's basically a computer fan that needs no external power.
stirling engines is ideal for usage in submarine wich is always surounded by water.stirling engines help make submarines much quieter that nuclear or diesel genarators.
