Carnot Theorem

No heat engine operating in a cycle between two given thermal reservoir, with fixed temperature can be more efficient than a reversible engine operating between the same thermal reservoir.

• Thermal efficiency η_th = Work out/Heat supplied

• Thermal efficiency of a reversible engine (η_rev)

η_rev = (T₁ – T₂)/T₁

• No engine can be more efficient than a reversible Carnot engine i.e η_rev > η_th