The effect of a number of open feedwater heaters on the thermal efficiency of an ideal cycle is to be studied. Steam leaves the steam generator at 20 MPa, 600C, and the cycle has a condenser pressure of 10 kPa. Determine the thermal efficiency for each of the following cases.
A: No feedwater heater.
B: One feedwater heater operating at 1 MPa.
C: Two feedwater heaters, one operating at 3 MPa and the other at 0.2 MPa.