Study of the Extreme Value of the Efficiency of Heat Engines in the Process of Arbitrary Cycles

Carnot's Theorem discusses the extreme value of the efficiency of heat engines' cycles. Starting from the graphs of P-V and T-S and the second law of thermodynamics, the extreme value of the efficiency of heat engines in the process of arbitrary cycles is studied. The result shows that the efficiency of the heat engine in Carnot cycle is the greatest of all arbitrary cycles.