Heat Engine
A physical device that converts thermal energy absorbed from a high-temperature heat source into mechanical work, discharging waste heat to a cold sink.
Governing formula
W = Q_hot - Q_cold, η = W / Q_hot
SI unit
W (J/s)
In depth
Operates in cyclic fashion. According to the Second Law, no heat engine can convert 100% of absorbed heat into useful mechanical work.
Examples in the real world
Steam turbines in power stations, gasoline automobile engines, and jet aircraft engines.