Work out carnot efficiency instantly with clear inputs, formula shown and shareable results.
No heat engine between two reservoirs can beat 1 - Tc/Th, and only a reversible one reaches it. Between 800 K and 300 K the ceiling is 62.5%, so 625 J of every kilojoule could become work and at least 375 J must be rejected. Real engines fall well short - a modern gas turbine reaches about 40%.
Carnot efficiency
efficiency = 1 - Tc / Th, temperatures in kelvin
Rejected heat
Q(cold) = Q(hot) x Tc / Th
Because it requires infinitely slow, frictionless, fully reversible operation. Any finite power output means irreversibility and lost work.
Raise the hot temperature or lower the cold one. Materials limit the first, ambient conditions the second, which is why combined cycles chase every extra degree.