The Carnot Cycle: The Ideal Heat Engine

The Carnot cycle is a theoretical model of the most efficient heat engine possible.
It was introduced by French engineer Sadi Carnot in 1824, earning him the title “father of thermodynamics.”
The cycle uses two isothermal (constant temperature) and two adiabatic (no heat exchange) steps.
Its efficiency depends only on the temperatures of the hot and cold reservoirs.
The bigger the temperature difference, the higher the maximum efficiency.
No real engine can beat Carnot efficiency—it’s the ultimate ceiling.
Steam, gas, and jet engines all fall short because of friction, leaks, and other losses.
The Carnot cycle shows why cooling systems and refrigerators also have efficiency limits.
It provides a benchmark for comparing real engines against the ideal.
Though purely theoretical, the Carnot cycle guides modern engineering and energy research.