1. A steam turbine receives 5 kg/s steam at 400?C, 10 MPa. One flow of 0.8 kg/s is extracted at 3 MPa as saturated vapor, and the remainder runs out at 1500 kPa with a quality of 0.975. Find the second-law efficiency of the turbine.
2. Calculate the irreversibility for the process described in Problem 4.154, assuming that heat transfer is with the surroundings at 17?C.
Problem 4.154
A mass-loaded piston/cylinder shown in Fig.P4.154, containing air, is at 300 kPa, 17?C with a volume of 0.25 m3, while at the stops V = 1 m3. An air line, 500 kPa, 600 K, is connected by a valve that is then opened until a final inside pressure of 400 kPa is reached, at which point T = 350 K.