- published: 20 Oct 2014
- views: 41172994
A Stirling engine is a heat engine operating by cyclic compression and expansion of air or other gas, the working fluid, at different temperature levels such that there is a net conversion of heat energy to mechanical work.
Originally conceived in 1816 as an industrial prime mover to rival the steam engine, its practical use was largely confined to low-power domestic applications for over a century.
Typical of heat engines, the general cycle consists of compressing cool gas, heating the gas, expanding the hot gas, and finally cooling the gas before repeating the cycle. The efficiency of the process has an upper limit set by the efficiency of the equivalent Carnot cycle operating between the same hot and cold temperatures.
Like the steam engine, the Stirling engine is traditionally classified as an external combustion engine, as all heat transfers to and from the working fluid take place through a solid boundary (heat exchanger). This contrasts with an internal combustion engine where heat input is by combustion of a fuel within the body of the working fluid. Unlike a steam engine's (or more generally a Rankine cycle engine's) usage of a working fluid in both its liquid and gaseous phases, the Stirling engine encloses a fixed mass of permanently gaseous fluid such as air.
Coordinates: 56°07′02″N 3°56′23″W / 56.117222°N 3.939722°W / 56.117222; -3.939722
Stirling (Gaelic: Sruighlea pronounced [ˈs̪t̪ruʝlə]) is a city and former ancient burgh in Scotland, and is at the heart of the wider Stirling council area. The city is clustered around a large fortress and medieval old-town beside the River Forth. Historically it was strategically important as the "Gateway to the Highlands", with its position near the boundary between the Scottish Lowlands and Highlands, and its crossing of the Forth, the nearest to the river mouth.
Once the capital of Scotland, Stirling contains the Great Hall (restored 1999) and the Renaissance Palace (restoration completed 2011) within the Castle that rivalled any building in Europe at the time. Stirling also has its medieval parish church, The Church of the Holy Rude, where King James VI was crowned King of Scots on 29 July 1567. The Holy Rude still functions as living church with a service every Sunday.
Stirling is a centre for local government, higher education, retail, and light industry. Its population in 2008 was 33,710, for Stirling itself, the wider urban area including Bridge of Allan and Bannockburn has a population of 45,750. This makes it the smallest city in Scotland: indeed it is smaller than many of Scotland's larger towns.