Editing Carnot heat engine (section)

== Modern diagram ==
[[File:Carnot heat engine 2.svg|300px|thumb|right|Carnot engine diagram (modern) - where an amount of heat ''Q''<sub>H</sub> flows from a high temperature ''T''<sub>H</sub> furnace through the fluid of the "working body" (working substance) and the remaining heat ''Q''<sub>C</sub> flows into the cold sink ''T''<sub>C</sub>, thus forcing the working substance to do [[mechanical work]] ''W'' on the surroundings, via cycles of contractions and expansions.]]

The previous image shows the original piston-and-cylinder diagram used by Carnot in discussing his ideal engine. The figure at right shows a block diagram of a generic heat engine, such as the Carnot engine. In the diagram, the "working body" (system), a term introduced by Clausius in 1850, can be any fluid or vapor body through which [[heat]] ''Q'' can be introduced or transmitted to produce work. Carnot had postulated that the fluid body could be any substance capable of expansion, such as vapor of water, vapor of alcohol, vapor of mercury, a permanent gas, air, etc. Although in those early years, engines came in a number of configurations, typically ''Q''<sub>H</sub> was supplied by a boiler, wherein water was boiled over a furnace; ''Q''<sub>C</sub> was typically removed by a stream of cold flowing water in the form of a [[Condenser (heat transfer)|condenser]] located on a separate part of the engine. The output work, ''W'', is transmitted by the movement of the piston as it is used to turn a crank-arm, which in turn was typically used to power a pulley so as to lift water out of flooded salt mines. Carnot defined work as "weight lifted through a height".
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