A Stirling engine is a heat engine that operates by cyclic compression and expansion of air or other gas (the working fluid) at different temperatures, such that there is a net conversion of heat energy to mechanical Work. More specifically, the Stirling engine is a closed-cycle regenerative heat engine with a permanently gaseous working fluid. closed cycle, in this context, means a thermodynamic system in which the workiokng fluid is permanently contained within the system, and regenerative describes the use of a specific type of internal heat extanger and thermal store, known as the regenerator. The inclusion of a regenerator differentiates the Stirling engine from other closed cycle hot air engines.

Step 1: How Does It Work?

Stirling cycle involves a series of events that change the pressure of the gas inside the engine, causing it to do work.

There are several properties of gasses that are critical to the operation of Stirling engines:

If you have a fixed amount of gas in a fixed volume of space and you raise the temperature of that gas, the pressure will increase.If you have a fixed amount of gas and you compress it (decrease the volume of its space), the temperature of that gas will increase.

Step 2: How Does It Work? (continued...)

here are four parts to the Stirling cycle.

1.Heat is added to the gas inside the heated cylinder, causing pressure to build. This forces the piston to move down. This is the part of the Stirling cycle that does the work.

2.The left piston moves up while the right piston moves down. This pushes the hot gas into the cooled cylinder, which quickly cools the gas to the temperature of the cooling source, lowering its pressure. This makes it easier to compress the gas in the next part of the cycle.

3.The piston in the cooled cylinder starts to compress the gas. Heat generated by this compression is removed by the cooling source.

4.The right piston moves up while the left piston moves down. This forces the gas into the heated cylinder, where it quickly heats up, building pressure, at which point the cycle repeats.

Step 3: The History of the Stirling Engine

The stirling engine is perhaps the simplest form of engine. The engine, then called the economiser, was first developed and patented by Rev. Robert Stirling in Edinburgh, Scotland in 1816. Robert Stirling not only developed and built heat engines, but was also a reverend in the Church of Scotland. His engine was later explained and further developed by Professor McQuorne Rankine in the mid 1800's. However, the engine was never developed for common use.
The Stirling engine always took a back seat to more popular engine designs such as the steam engine and the internal combustion engine. But today as people have forcasted an eventual end to the fossil fuel source, the stirling engine concept has regained the interest of many developers. The engine can run on a variety of fuel sources and has a work output far closer to the theoretical ideal efficiency than most engines. Progress has come a long way, and there are several companies now who develope stirling engines. There has even been built a stirling engine that delivers 5000 hp.