外燃机如蒸汽机是利用燃料燃烧加热循环工质（如蒸汽机将锅炉里的水加热产生的高温高压水蒸气输送到机器内部），使热能转化为机械能的一种热机。

• 外燃机
  • 蒸汽机
  • 蒸汽轮机
  • 斯特林发动机

An external combustion engine (EC engine) is a heat engine where a working fluid, contained internally, is heated by combustion in an external source, through the engine wall or a heat exchanger. The fluid then, by expanding and acting on the mechanism of the engine, produces motion and usable work. The fluid is then cooled, compressed and reused (closed cycle), or (less commonly) dumped, and cool fluid pulled in (open cycle air engine).