Editing Stirling engine (section)

== Name and classification ==
[[File:Stirlingmotor in Betrieb.JPG|thumb|Stirling engine running]]

Robert Stirling patented the first practical example of a closed-cycle [[hot air engine]] in 1816, and it was suggested by [[Fleeming Jenkin]] as early as 1884 that all such engines should therefore generically be called Stirling engines. This naming proposal found little favour, and the various types on the market continued to be known by the name of their individual designers or manufacturers, e.g., Rider's, Robinson's, or Heinrici's (hot) air engine. In the 1940s, the [[Philips]] company was seeking a suitable name for its own version of the 'air engine', which by that time had been tested with working fluids other than air, and decided upon 'Stirling engine' in April 1945.<ref name="Hargreaves-1991-2.5" /> However, nearly thirty years later, Graham Walker still had cause to bemoan the fact such terms as ''hot air engine'' remained interchangeable with ''Stirling engine'', which itself was applied widely and indiscriminately,<ref name="Walker-1971" /> a situation that continues.<ref name="sterlingbuilder" />

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) thus isolating the combustion process and any contaminants it may produce from the working parts of the engine. This contrasts with an [[internal combustion engine]], where heat input is by combustion of a fuel within the body of the working fluid. Most of the many possible implementations of the Stirling engine fall into the category of [[reciprocating engine|reciprocating piston engine]].{{citation needed|date=July 2020}}