18 C9cd. Due 11/16

1. You want to cool your cryogenics experiment by pumping pressurized liquid nitrogen through it. What is the power needed for a reversible pump that pressurizes 20 g/s of liquid nitrogen at 77.3 K from 200 kPa to 1MPa? Make appropriate approximations.

2. A typical specific heat ratio for the hot combustion gases entering the turbine of a jet engine is 1.25. For the gas constant, just use the one for air. Assume that the gases enter the turbine at 640 kPa and 927$\POW9,{\circ}$C, and exit at the ambient pressure of 100 kPa at a rate of 2 kg/s. Also assume that the specific heat ratio is constant going through the turbine, and that the turbine is adiabatic and reversible. Find the exit temperature, power, and heat flow. Do not compute any volumes, specific or not, when solving this question.

3. UNGRADED: A compressor takes in saturated steam (free of water droplets) at 1000 kPa and compresses it to 17.5 MPa and 650$\POW9,{\circ}$C.
   1. Show the process in both the $Pv$ and $Ts$ diagrams. Also show the process of the comparable ideal compressor in the diagrams. Also show and mark the 1000 kPa and 17.5 MPa isobars and the 650$\POW9,{\circ}$C isotherm in the diagrams.
   2. Find the enthalpy and entropy at 17.5 MPa by averaging between 15MPa and 20 MPa in B.1.3 for the following temperatures: 550$\POW9,{\circ}$C, 600$\POW9,{\circ}$C, and 650$\POW9,{\circ}$C.
   3. Find the isentropic efficiency.
   4. Find the total entropy production.

4. Air is blown into a well insulated turbine at 1227$\POW9,{\circ}$C and 1 MPa and exits at 100kPa. The isentropic efficiency is 85%. Find the work produced by the turbine and the total entropy generated.