12 Due 2/27

1. A stream of 0.5 kg/s R 134a at 20$\POW9,{\circ}$C and $x=0.9$ enters a mixing chamber through a throttle and is then mixed with a 2 kg/s stream at 100$\POW9,{\circ}$C and 500 kPa. The R 134a exits the mixing chamber at 50$\POW9,{\circ}$C and 500 kPa. Construct all phases that are not given in a $Pv$ diagram. Label the lines with their values. Find the heat going into the mixing chamber.

2. If high pressure steam is needed for some purpose in a power generation plant, it is often bled off from the high pressure side of the turbine. This is called cogeneration. Assume a well insulated turbine takes in 50 kg/s of steam at 10 MPa and 600$\POW9,{\circ}$C, and that 10 kg/s at 400 kPa and 200$\POW9,{\circ}$C is bled off, while the remaining steam exits at 100 kPa and a quality of 0.8. Construct the phase of the bled-off steam in the $Tv$ diagram and so verify that it is indeed still steam. Find the power the turbine generates, and compare it to the power it would generate if no steam was bled off.

3. A stream of 2 kg/s of neon at 200$\POW9,{\circ}$C and 100 kPa mixes with a stream of 3 kg/s of neon at 100$\POW9,{\circ}$C and 100 kPa. The neon exits at 100 kPa and 50 kW of heat leaks out to the surroundings. Find the exit temperature.

4. Water enters a turbine with a velocity of 150 m/s at 200 kPa and 300$\POW9,{\circ}$C at a rate of 5 kg/s. It exits the turbine at a pressure of 100 kPa and low velocity. The turbine produces 4 MW of power and loses 400 kW of heat to its surroundings. Construct and name the phase at the entrance in a $Pv$ diagram, narrow down the exit conditions, construct and name the phase at the exit using a $Pv$ diagram and find the exit temperature and quality if defined. Ignore the height difference between the entrance and exit.