Can we evaluate the efficiency of Rankyne Cycles by a Diagram T-s?

Question

We can change a standart Rankyne Cycle with reheaters, feedwaters, etc etc. If we look at each diagram T-s, are we able to directly conclude which type of Cycle has a higher efficiency?

Answer 1

For a continuous cyclic process like this, operating at steady state, the open system version of the first law of thermodynamics tells us that the net heat added Q is equal to the net shaft work Ws. If the process is operated reversibly, the heat inputs and outputs through the various segments of the cycle are determined by the integrals of TdS, and, of course, the net heat Q is the integral of TdS around the cycle. So the shaft work is also equal to the integral of TdS around the cycle. Under these circumstances, the T-s diagram can be used to evaluate the cycle efficiency.