Problem 1:
Air is contained in a well-insulated piston-cylinder assembly with a paddle wheel connected to an external electric motor. Initially, the volume of the air in the cylinder is 0.02 m3, the pressure is 1.5 bar, and the temperature is 400K. The electric motor is turned on, the paddlewheel turns and work transfer occurs, and then the electric motor is turned off. The temperature of the air at the final state is 950 K. Use the ideal gas air tables to solve this problem.
(a) Draw the initial and final states of the air on a p-v diagram.
(b) Determine the final pressure (bar) and volume (m3) of the air in the cylinder.
(c) Calculate the paddle wheel work transfer (kJ) for the process.
Problem 2:
Ammonia enters a control volume at a temperature of 150oC and a pressure of 16.0 bar. The incoming volumetric flow rate is 10 m3/s through a pipe that is 0.5 m in diameter. The ammonia is cooled in the device and exits either as a saturated liquid at 6.0 bar or saturated vapor at 6.0 bar. The saturated vapor exits through a pipe with a diameter of 0.5m. The mass flow rate of saturated liquid ammonia exiting the control volume is measured to be 20 kg/s. The saturated liquid leaves through a pipe 10 cm in diameter.
Assume steady state and uniform flow at each inlet or exit.
(a) Determine the velocity (m/s) and mass flow rate (kg/s) for the ammonia stream entering the control volume.
(b) Determine the velocity (m/s) and mass flow rate (kg/s) of the ammonia saturated vapor stream leaving the control volume.
(c) Determine the velocity (m/s) of the ammonia saturated liquid stream leaving the control volume.