Real vs Ideal Engine

Ideal (Carnot) engine: reversible, infinitely slow, max efficiency.

Real engines: irreversible, finite speed, lower efficiency.

Sources of inefficiency: friction, turbulence, heat leakage, fast non-quasi-static processes, incomplete combustion.

Real engine efficiency = η_real < η_Carnot = 1 − T_c/T_h.

Carnot's theorem: NO engine can exceed Carnot efficiency; only reversible engines reach it.

Practical efficiencies: gasoline ~25-35%, diesel ~35-45%, gas turbine ~30-40%, combined cycle ~50-60%.

Higher T_hot (more efficient) requires advanced materials — engineering trade-off.

Engine output power = efficiency × heat input rate.