Carnot heat engine

Follow an ideal gas through four reversible processes and see how reservoir temperatures set the maximum possible efficiency.

1 · Isothermal expansionHeat enters from the hot reservoir while the gas expands.

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Gas temperature600 K

Pressure—

Volume—

Efficiency50.0%

Net work—

Pressure–volume diagram

Energy flow

The four processes

Two isothermal stages exchange heat at constant temperature. Two adiabatic stages change temperature without transferring heat.

Carnot efficiency

η = 1 − T_c / T_h

A greater temperature difference raises the theoretical maximum efficiency. Temperatures must be in kelvin.

An ideal limit

The model assumes an ideal gas, no friction or heat leakage, reversible processes and quasi-static heat transfer. Real engines always perform below this limit.

Model note: Educational ideal-gas model. Values are internally consistent approximations intended to show the shape and energy balance of a reversible Carnot cycle.