Carnot Cycle

A Carnot Cycle (named after N.L. Sadi Carnot, who introduced it in 1824) is an ideal engine that employs two adiabatic and two isothermal processes. Such a cycle is shown in the figure on the right. The process from a to b is an isotherm (at temperature TH), b to c an adiabat, c to d another isotherm (at TL), and d to a the second adiabat. The work done during one cycle of the Carnot Cycle is the yellow area. The efficiency of the Carnot engine depends only on the two temperatures:

$\epsilon$Carnot = (TH - TL) / TH

A Carnot engine is reversible. Run backwards (a -> d -> c -> b -> a), it turns into the Carnot refrigerator with performance:

K = TL/(TH - TL)

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