18 Due 4/9

1. In a steam power plant, the steam generator (boiler) sends water at 20 MPa and 700$\POW9,{\circ}$C into the turbine. It comes out of the turbine at 20 kPa. It then enters the condenser, which it exits at 40$\POW9,{\circ}$C. It then enters the pump which pressurizes it and sends it back into the boiler. You will need to make appropriate assumptions about the four devices to complete the data. Then construct the phases at all four stations between devices in four separate $Ts$ diagrams. In the diagrams, list no more than is needed to construct the phase, but do list the values of the curves/points used. Finally, find the specific work coming out of the turbine. Also find the power produced by the turbine, if possible.

2. R-134a at 1MPa and 30$\POW9,{\circ}$C passes through an adiabatic expansion valve in which the pressure decreases to standard atmospheric pressure. Construct the initial phase in the $Ts$ diagram. In the diagram, list no more than is needed to construct the phase, but do list the values of the curves/points used. Then find the final quality and the entropy generated.

3. Steam at 15 kPa and a quality of 90% enters a constant pressure condenser at a rate of 3 kg/s and exits it as saturated liquid. The heat is transferred to cooling water with an average temperature of 17$\POW9,{\circ}$C. What is the entropy generated?

4. Air at 1000 kPa and 500 K enters an isobaric heat exchanger at a rate of 0.2 kg/s and exits at 300 K, having been cooled down by the ambient air at 300 K. Find the total rate of entropy generation. Use constant specific heats from table A.5, not table A.7.1.